Patent Publication Number: US-2021169532-A1

Title: Interspinous Process Spacing Device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 16/005,084, filed Jun. 11, 2018, which is a continuation of U.S. application Ser. No. 15/338,770, now U.S. Pat. No. 10,010,354, issued on Jul. 3, 2018, which is a divisional of U.S. application Ser. No. 14/713,006, now U.S. Pat. No. 9,668,786, issued on Jun. 6, 2017, which is a continuation of PCT Application No. PCT/US2013/070590 filed Nov. 18, 2013 which claims priority to U.S. Provisional Application No. 61/727,411 filed Nov. 16, 2012, the entire contents of which are hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to devices for use during spinal surgery, and methods pertaining thereto, and more particularly to devices and methods for providing spacing between adjacent spinous processes. 
     BACKGROUND OF THE INVENTION 
     Spinal discs and/or other vertebral changes can cause spinal disease that often leads to patient discomfort or even paralysis. For example, intervertebral spinal discs, which lie between adjacent vertebrae, can break down or degenerate, resulting in disc fluid loss and consequently resulting in a loss of disc flexibility. In addition, discs can become thinner, allowing the vertebrae to move closer together, may tear or crack in the outer layer and/or the annulus of the disc, and/or bulge outwardly. Facet joint degeneration may also lead to spinal disease. Physical trauma (e.g., accidents, injuries, strains, etc.) may cause spinal column changes, and spinal stenosis can cause the spinal canal to narrow due to excessive bone growth and/or thickening of tissue. In all of these conditions, the spinal canal through which the spinal cord and the spinal nerve roots pass may become narrowed, creating pressure on nerve tissue. Such pressure can cause pain, numbness, weakness, or even paralysis in various parts of the body. 
     Some methods for treating spinal diseases, such as those described above, limit the movement of adjacent vertebrae relative to one another to limit the additional pressure on the local nerve tissue by maintaining a minimum disc space and/or space surrounding the adjacent vertebrae. Various methods have been performed to maintain this minimum space, including disc implants and spinal fusions. One method includes implanting a spacer between two adjacent posteriorly extending spinous processes, which in effect maintains a maximum space between the corresponding vertebrae. Some existing spacer implant devices are implanted by affixing the device to adjacent spinous processes. Existing spacer implants, however, do not provide complete access to insert bone growth promoting substances into the spacer after implant. In addition, existing spacer implants do not provide structural integrity between two adjacently implanted spacers. Moreover, the procedures required to implant existing spacer implant devices are overly complicated, requiring the use of multiple tools to position, tighten, and secure the implants to the spinous processes. 
     Therefore, there remains a need for improved interspinous process spacer implants. 
     SUMMARY OF THE INVENTION 
     Various embodiments described herein provide devices and associated methods for treating spinal disease. According to one embodiment, an interspinous process spacing device is provided. The device includes a first attachment side and a second attachment side, whereby each attachment side includes one or more slots formed in the outer surface and oriented proximate one end for receiving fasteners extending inwardly from a second interspinous process spacing device. The device further includes a spacer tray positioned between the first attachment side and the second attachment side, the spacer tray extending in a substantially perpendicular orientation from the first attachment side and slideably insertable through a tray slot formed in the second attachment side, wherein the spacer tray is adapted to retain adjacent spinous processes in a spaced apart orientation. The device further includes securing means for securing the second attachment side relative to the first attachment side, wherein, upon securing the second attachment side relative to the first attachment side by the securing means, the interspinous process spacing device is engaged with the adjacent spinous processes. 
     According to one embodiment, an interspinous process spacing device is provided with a first attachment side and a second attachment side, whereby each attachment side includes one or more slots formed in the outer surface and oriented proximate one end for receiving fasteners extending inwardly from a second interspinous process spacing device. In one embodiment, the slots are elongated to receive a fastener from a second interspinous process spacing device along a range of distances therein. In one embodiment, the slots may be narrowed by a clamping mechanism and thereby tightened to secure a fastener received therein. 
     According to one embodiment, an interspinous process spacing device is provided with a first attachment side and a second attachment side, whereby each attachment side includes one or more fasteners extending inwardly from each of the first attachment side and second attachment side. In one embodiment, the fasteners are each adjustably carried within an elongated fastener frame to engage a slot in another interspinous process spacing device along a range of distances therefrom. In one embodiment, the fasteners may be secured at a selected position within the fastener frame and thereby at a set distance away from an adjacent interspinous process spacing device. 
     In one aspect, the spacer tray comprises an arcuate cross-sectional shape and is substantially open and accessible from the posterior direction. The spacer tray is adapted to retain bone growth promoting substance and to maximize the open space above the spacer tray and between the spinous processes, wherein the bone growth promoting substance is packable after engaging the first attachment side and the second attachment side to adjacent spinous processes. In another embodiment, the spacer tray comprises two separate members forming a space therebetween. 
     According to one aspect, the securing means can include at least one of: (a) at least one worm drive assembly; (b) at least one rack and pinion assembly; (c) at least one screw extending between and operably connecting the first attachment side and the second attachment side; (d) a geared rack and ratchet assembly; or (e) at least one set screw assembly. 
     In one aspect, there are at least two spaced apart securing mechanisms extending between and operably connecting the first attachment side and the second attachment side, wherein each of the at least two spaced apart securing mechanisms can be independently and incrementally actuated causing each end of the attachment sides to engage the respective spinous process independently. 
     According to one aspect, the interspinous process spacing device is a first interspinous process spacing device, and a second interspinous process spacing device is included. The second interspinous process spacing device includes a first bent attachment side and a second bent attachment side, wherein each bent attachment side comprises a substantially flat end and an offset end adapted to overlap an adjacent portion of the respective attachment sides of the first interspinous process spacing device. 
     According to one aspect including a second interspinous process spacing device, each of the first attachment side and the second attachment side of the second interspinous process spacing device has one or more integration means for integrating and attaching the offset end of the second interspinous process spacing device with a portion of the respective attachment side of the first interspinous process spacing device. 
     According to various aspects, the first interspinous process spacing device may be implantable inferior or superior to the second interspinous process spacing device. 
     In a different embodiment, an interspinous process spacing system is provided. The interspinous process spacing system includes a first interspinous process spacing device and a second interspinous process spacing device. The interspinous process spacing device comprises two substantially flat attachment sides and a first spacer tray positioned therebetween, wherein one of the two substantially flat attachment sides is slideably positionable over the spacer tray. The second interspinous process spacing device comprises two bent attachment sides and a second spacer tray positioned therebetween, wherein each of the bent attachment sides comprises a substantially flat end and an offset end. After implantation of the first interspinous process spacing device on a first and a second adjacent spinous process, the offset ends of the two bent attachment sides of the second interspinous process spacing device at least partially overlap respective adjacent ends of the substantially flat attachment sides of the first interspinous process spacing device when implanting the second interspinous process spacing device on the second and a third spinous process adjacent to the second spinous process. 
     According to yet another embodiment, an interspinous process spacing device kit is provided. The interspinous process spacing device kit may include: a first interspinous process spacing device comprising a first attachment side and a second attachment side, the first and the second attachment sides of the first interspinous process spacing device having a substantially flat configuration; at least one additional interspinous process spacing device comprising a first attachment side and a second attachment side, the first and the second attachment sides of the at least one additional interspinous process spacing device having a bent configuration adapted to overlap a portion of a respective attachment side of the first interspinous process spacing device; and at least one insertion instrument adapted for retaining at least one of the first interspinous processing spacing devices or the at least one additional interspinous process spacing device and implanting the same. 
     The kit may include a first insertion instrument and a second insertion instrument, wherein the first insertion instrument is adapted for implanting at least one of the first interspinous process spacing devices or at least one additional interspinous process spacing device in a first orientation, and the second insertion instrument is adapted for implanting at least one of the first interspinous processing spacing devices or the at least one additional interspinous process spacing device in a second orientation. Each insertion instrument may include a first arm and a second arm, wherein the second arm is removably and pivotally attachable to the first arm. 
     According to one embodiment, an interspinous process spacing device is provided. The device includes a first attachment side and a second attachment side, whereby each attachment side includes one or more slots formed in the outer surface and oriented proximate one end for receiving fasteners extending inwardly from a second interspinous process spacing device. The device further includes a spacer tray positioned between the first attachment side and the second attachment side, the spacer tray extending in a substantially perpendicular orientation from the first attachment side and slideably insertable through a tray slot formed in the second attachment side, wherein the spacer tray includes a trough formed in a top surface of the spacer tray, and wherein the spacer tray is adapted to retain adjacent spinous processes in a spaced apart orientation. The device further includes securing means configured to engage the trough of the spacer tray to secure the second attachment side relative to the first attachment side, wherein, upon securing the second attachment side relative to the first attachment side by the securing means, the interspinous process spacing device is engaged with the adjacent spinous processes. 
     According to another embodiment, an interspinous process spacing device is provided. The device includes a first attachment side, a second attachment side, a spacer tray, and a securing means. The spacer tray extends from the first attachment side and is slideably insertable through a spacer tray slot formed in the second attachment side. The spacer tray is adapted to be positioned between a spinous process of a first vertebra and a spinous process of an adjacent second vertebra, and the spacer tray includes a trough formed in a top surface of the spacer tray. The securing means is configured to engage the trough of the spacer tray to secure the second attachment side relative to the first attachment side. 
     According to yet another embodiment, an interspinous process spacing device is provided. The device includes a first attachment side, a second attachment side, and a spacer tray. The spacer tray extends from the first attachment side and is slideably insertable through a spacer tray slot formed in the second attachment side. The spacer tray is adapted to be positioned between a spinous process of a first vertebra and a spinous process of an adjacent second vertebra. The first attachment side and the second attachment side each comprise a central portion, a first wing portion, and a second wing portion, wherein inner surfaces of the first wing portion and the second wing portion are angled relative to an inner surface of the central portion. 
     According to another embodiment, a rasp tool for preparing an implantation site for an interspinous process spacing device between a first spinous process and an adjacent second spinous processes is provided. The rasp tool includes a first arm having a proximal end and a distal end, and a second arm having a proximal end and a distal end, wherein the first arm and the second arm are pivotally connected to one another. The rasp tool also includes a first measurement wing extending from the distal end of the first arm, and a second measurement wing extending from the distal end of the second arm. The first measurement wing includes a sharp tip configured to ease insertion between the first spinous process and the second spinous process. The first measurement wing and the second measurement wing are configured to move between a closed position and an open position by pivoting the first arm and the second arm. 
     According to yet another embodiment, a method for implanting an interspinous process spacing device is provided. 
     According to yet another embodiment, a method for treating a spinal disorder including implanting one or more interspinous process spacing devices is provided. 
     According to yet another embodiment, a method for manufacturing an interspinous process spacing device is provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects and advantages of the present invention will be better understood and more readily apparent when considered in conjunction with the following detailed description and accompanying drawings which illustrate, by way of example, embodiments of interspinous process spacing devices, and in which: 
         FIG. 1  is a profile view of three interspinous process spacing devices, according to an example embodiment. 
         FIG. 2A  is an isometric view of a second attachment side of an interspinous process spacing device, according to an example base plate embodiment.  FIG. 2B  is a top view of a second attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 2C  is a back view of a second attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 2D  is a side view of a second attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 2E  is a top view a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 2F  is an isometric view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 2G  is a side view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 2H  is a back view of a first attachment side of an interspinous process spacing device, according to an example embodiment. 
         FIG. 3A  is an isometric view of a second attachment side of an interspinous process spacing device, according to an example linker plate embodiment.  FIG. 3B  is a top view of a second attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 3C  is a back view of a second attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 3D  is a side view of a second attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 3E  is a top view a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 3F  is an isometric view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 3G  is a side view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 3H  is a back view of a first attachment side of an interspinous process spacing device, according to an example embodiment. 
         FIGS. 4A-4E  are views of securing means integrated with interspinous process spacing devices, according to example base plate and overlapping link plate embodiments.  FIG. 4A  is a top view of two interlinked interspinous process spacing devices.  FIG. 4B  is a top view of one secured interspinous process spacing base device and one unsecured interspinous process spacing link device.  FIG. 4C  is an isometeric view of one secured interspinous process spacing base device and one unsecured interspinous process spacing link device.  FIG. 4D  is a back (outside) view of a first attachment side of an interspinous process spacing device having a base plate fastened to a link plate device.  FIG. 4E  is a back view of a second attachment side of an interspinous process spacing device having a base plate fastened to a link plate device. 
         FIG. 5A  is a back view of a first attachment side of an interspinous process spacing device having a base plate fastened to a link plate device showing maximum rotational range when connected to a first aperture, according to an example embodiment.  FIG. 5B  is a back view of a first attachment side of an interspinous process spacing device having a base plate fastened to a link plate device showing maximum rotational range when connected to a second aperture, according to an example embodiment.  FIG. 5C  is a back view of a first attachment side of an interspinous process spacing device having a base plate with multiple overlapping apertures in an inch-worm formation, for receiving a fastener of another link plate device, according to an example embodiment. 
         FIG. 6A  is an isometric view of a set of a base plate interspinous process spacing devices having a gradient of spacer tray widths, according to an example embodiment.  FIG. 6B  is an isometric view of a set of link plate interspinous process spacing devices having a gradient of spacer tray widths, according to an example embodiment. 
         FIG. 7A  is a side view of a L5-S1 sacrum interspinous process spacing base device, according to an example embodiment.  FIG. 7B  is an isometric view of a L5-S1 sacrum interspinous process spacing base device, according to an example embodiment.  FIG. 7C  is an isometric view of a first attachment side of an L5-S1 sacrum interspinous process spacing base device, according to an example embodiment.  FIG. 7D  is an isometric view of an alternative L5-S1 sacrum interspinous process spacing link device, according to an example embodiment.  FIG. 7E  is an isometric view of a second attachment side of a L5-S1 sacrum interspinous process spacing link device, according to an example embodiment. 
         FIG. 8A  is an isometric view of an interspinous process spacing device, according to an example embodiment.  FIG. 8B  is an exploded isometric view of an interspinous process spacing device, according to an example embodiment.  FIG. 8C  is an exploded isometric view of an interspinous process spacing device, according to an example embodiment.  FIG. 8D  is a side view of an interspinous process spacing device, according to an example embodiment. 
         FIG. 9A  is an isometric view of a first attachment side of an interspinous process spacing device link plate with an alternative spacer tray, according to an example embodiment.  FIG. 9B  is an exploded isometric view of a first attachment side of an interspinous process spacing device link plate with an alternative spacer tray, according to an example embodiment.  FIG. 9C  is an exploded isometric view of a first attachment side of an interspinous process spacing device link plate with an alternative spacer tray, according to an example embodiment.  FIG. 9D  is an isometric view of a first attachment side of an interspinous process spacing device link plate with an alternative spacer tray, according to an example embodiment. 
         FIG. 10  is an isometric view of an alternative interspinous process spacing device, according to an example embodiment. 
         FIG. 11A  is an isometric view of an alternative interspinous process spacing device, according to an example embodiment.  FIG. 11B  is an isometric view of the first attachment side of the alternative interspinous process spacing device integrating an alternative worm-gear advancement mechanism for the first and second attachment sides, according to an example embodiment.  FIG. 11C  is an isometric view of the alternative interspinous process spacing device, according to an example embodiment.  FIG. 11D  is an isometric view of the alternative interspinous process spacing device implanted onto a spine, according to an example embodiment. 
         FIG. 12A  is an isometric outside view of the first attachment side of the alternative interspinous process spacing device, according to an example embodiment.  FIG. 12B  is an isometric inside view of the first attachment side of the alternative interspinous process spacing device, according to an example embodiment.  FIG. 12C  is an isometric view of a floating receiving member of the alternative interspinous process spacing device, according to an example embodiment.  FIG. 12D  is an isometric view of a floating receiving member of the alternative interspinous process spacing device, according to an example embodiment.  FIG. 12E  is an isometric view of a floating receiving member of the alternative interspinous process spacing device, according to an example embodiment.  FIG. 12F  is a side view of a floating receiving member of the alternative interspinous process spacing device, according to an example embodiment.  FIG. 12G  is an isometric view of the interface of a floating receiving member integrating with the first attachment side of the alternative interspinous process spacing device, according to an example embodiment.  FIG. 12H  is an inner isometric view of the interface of a floating receiving member integrating with the first attachment side of the alternative interspinous process spacing device, according to an example embodiment.  FIG. 12I  is an outside rear view of the interface of a floating receiving member integrating with the first attachment side of the alternative interspinous process spacing device, according to an example embodiment.  FIG. 12J  is an isometric view of an alternative interspinous process spacing device, according to an example embodiment.  FIG. 12K  is an isometric view of an alternative interspinous process spacing device integrating an alternative advancement mechanism for the first and second attachment sides, according to an example embodiment.  FIG. 12L  is an isometric view of an alternative interspinous process spacing device integrating an alternative advancement mechanism for the first and second attachment sides, according to an example embodiment. 
         FIG. 13A  is an isometric view of a top down or universal surgical instrument for implanting and compressing/advancing two attachment sides of an interspinous process spacing device, according to an example embodiment.  FIG. 13B  is a side view of a universal surgical instrument for implanting and compressing/advancing two attachment sides of an interspinous process spacing device, according to an example embodiment.  FIG. 13C  is a side view of a universal surgical instrument for implanting and compressing/advancing two attachment sides of an interspinous process spacing device, according to an example embodiment.  FIG. 13D  is a detailed side view of a universal surgical instrument for implanting and compressing/advancing two attachment sides of an interspinous process spacing device, according to an example embodiment. 
         FIG. 14A  is a side view of a first arm of a top down or universal surgical instrument for implanting and compressing/advancing two attachment sides of an interspinous process spacing device, according to an example embodiment.  FIG. 14B  is an alternative side view of a first arm of the example embodiment.  FIG. 14C  is an alternative side view of a first arm of the example embodiment.  FIG. 14D  is a side view of a second arm of the example embodiment.  FIG. 14E  is an alternative side view of a second arm of the example embodiment.  FIG. 14F  is an alternative side view of a second arm of the example embodiment. 
         FIG. 15A  is a side view of a separate first and second arm of a top down or universal surgical instrument for implanting and compressing/advancing two attachment sides of an interspinous process spacing device, according to an example embodiment.  FIG. 15B  is a side view of a further advanced (almost engaged) first and second arm of a top down surgical instrument for implanting and compressing/advancing two attachment sides of an interspinous process spacing device, according to an example embodiment. 
         FIG. 16A  is a side view of a top down or universal surgical instrument for implanting and compressing/advancing two attachment sides of an interspinous process spacing device showing an unengaged mechanical actuation means, according to an example embodiment.  FIG. 16B  is a side view of a top down surgical instrument for implanting and compressing/advancing two attachment sides of an interspinous process spacing device showing an engaged mechanical actuation means, according to an example embodiment.  FIG. 16C  is an isometeric view of a top down surgical instrument for implanting and compressing/advancing two attachment sides of an interspinous process spacing device showing the mechanical actuation means, according to an example embodiment. 
         FIG. 17A  is a side view of a second inserter arm of a surgical instrument for implanting an interspinous process spacing device, according to an example embodiment.  FIG. 17B  is an alternative side view of the second inserter arm of the example embodiment.  FIG. 17C  is an alternative side view of the second inserter arm of the example embodiment.  FIG. 17D  is a side view of the first arm of the example embodiment.  FIG. 17E  is an alternative side view of a first arm of the example embodiment.  FIG. 17F  is an alternative side view of a first arm of the example embodiment. 
         FIG. 18A  is an isometric view of a first and second inserter arm of a surgical instrument for implanting an interspinous process spacing device, according to an example embodiment.  FIG. 18B  is a view of the retained first and second inserter arms of the example embodiment.  FIG. 18C  is a side view of the retained first and second inserter arms of the example embodiment. 
         FIG. 19A  and  FIG. 19B  show a view of a compressor tool positioning first and second inserter arms of a surgical instrument for implanting an interspinous process spacing device, according to an example embodiment. 
         FIG. 20A  is a side view of a compressor tool for implanting an interspinous process spacing device, according to an example embodiment.  FIG. 20B  is an isometric view of a compressor tool for implanting an interspinous process spacing device, according to an example embodiment.  FIG. 20C  is an alternative side view of a compressor tool for implanting an interspinous process spacing device, according to an example embodiment. 
         FIG. 21A  is a side view of an interspinous process space measurement instrument, according to an example embodiment.  FIG. 21B  is an isometric view of an interspinous process space measurement instrument, according to an example embodiment.  FIG. 21C  is an isometric view of an interspinous process space measurement instrument, according to an example embodiment.  FIG. 21D  is a top view of an interspinous process space measurement instrument, according to an example embodiment. 
         FIG. 22A  is a side view of an embodiment of a link wing with an extension fastener adjustably slideable within a fastener frame, according to an example embodiment.  FIG. 22B  is a side view of a base wing with a single hole, according to an example embodiment. 
         FIG. 23A  is a side view of an alternative link wing with an elongated slot to receive a fastener, according to an example embodiment.  FIG. 23B  is a side view of an alternative base wing with two elongated slots, according to an example embodiment. 
         FIG. 24A  is an exploded side view of a first and second inserter arm of a surgical instrument for implanting an interspinous process spacing device, according to an example embodiment.  FIG. 24B  is a close-up view of the pivoting member of the second inserter arm of the example embodiment.  FIG. 24C  is a close-up view of the pivot channel of the first inserter arms of the example embodiment. 
         FIG. 25A  is an isometric back view of a rasping tool for implanting an interspinous process spacing device, according to an example embodiment.  FIG. 25B  is an isometric front view of a rasping tool for implanting an interspinous process spacing device, according to an example embodiment.  FIG. 25C  is a side view of a rasping tool for implanting an interspinous process spacing device, according to an example embodiment. 
         FIG. 26A  is an isometric view of a first attachment side of an interspinous process spacing device, according to an example base plate embodiment.  FIG. 26B  is a top view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 26C  is a front view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 26D  is a back view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 26E  is a side view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 26F  is a section view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 26G  is a detailed section view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 26H  is a section view of a first attachment side of an interspinous process spacing device, according to an example embodiment. 
         FIG. 27A  is an isometric view of a first attachment side of an interspinous process spacing device, according to an example base plate embodiment.  FIG. 27B  is a side view of a first attachment side of an interspinous process spacing device, according to an example embodiment. 
         FIG. 28A  is an isometric view of a first attachment side and a second attachment side of an interspinous process spacing device, according to an example embodiment, shown in a spaced apart state.  FIG. 28B  is an isometric view of a first attachment side and a second attachment side of an interspinous process spacing device, according to an example embodiment, shown in a spaced apart state.  FIG. 28C  is an bottom view of a first attachment side and a second attachment side of an interspinous process spacing device, according to an example embodiment, shown in a spaced apart state.  FIG. 28D  is a front view of a first attachment side and a second attachment side of an interspinous process spacing device, according to an example embodiment, shown in a spaced apart state.  FIG. 28E  is a side view of a first attachment side and a second attachment side of an interspinous process spacing device, according to an example embodiment, shown in an attached state.  FIG. 28F  is a top view of a first attachment side and a second attachment side of an interspinous process spacing device, according to an example embodiment, shown in an attached state. 
         FIG. 29A  is an isometric view of a first attachment side and a second attachment side of an interspinous process spacing device, according to an example embodiment, shown in an attached state.  FIG. 29B  is an isometric view of a first attachment side and a second attachment side of an interspinous process spacing device, according to an example embodiment, showing rotation of angled wings.  FIG. 29C  is an isometric view of a first attachment side and a second attachment side of an interspinous process spacing device, according to an example embodiment, showing rotation of angled wings. 
         FIG. 30A  is a front view of a second attachment side of a first interspinous process spacing device and a second attachment side of a second interspinous process spacing device, according to an example embodiment, shown in an attached state.  FIG. 30B  is a front view of a second attachment side of a first interspinous process spacing device and a second attachment side of a second interspinous process spacing device, according to an example embodiment, shown in an attached state.  FIG. 30C  is a front view of a second attachment side of a first interspinous process spacing device and a second attachment side of a second interspinous process spacing device, according to an example embodiment, showing rotation of the second attachment side of the first interspinous process spacing device. 
         FIG. 31A  is an isometric view of a rasp tool, according to an example embodiment, showing first and second interspinous process spacing device measurement wings in a closed state.  FIG. 31B  is an exploded isometric view of a rasp tool, according to an example embodiment.  FIG. 31C  is a detailed isometric view of a rasp tool, according to an example embodiment, showing first and second interspinous process spacing device measurement wings in a closed state.  FIG. 31D  is a detailed isometric view of a rasp tool, according to an example embodiment, showing first and second interspinous process spacing device measurement wings in a closed state.  FIG. 31E  is a detailed isometric view of a rasp tool, according to an example embodiment, showing first and second interspinous process spacing device measurement wings in an open state. 
         FIG. 32A  is an isometric view of a first attachment side of an interspinous process spacing device, according to an example base plate embodiment.  FIG. 32B  is a top view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 32C  is a front view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 32D  is a side view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 32E  is a section view of a first attachment side of an interspinous process spacing device, according to an example embodiment. 
         FIG. 33A  is an isometric view of a first attachment side of an interspinous process spacing device, according to an example base plate embodiment.  FIG. 33B  is a top view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 33C  is a front view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 33D  is a side view of a first attachment side of an interspinous process spacing device, according to an example embodiment.  FIG. 33E  is a section view of a first attachment side of an interspinous process spacing device, according to an example embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As required, detailed embodiments of the invention are disclosed herein. However, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the invention in virtually any appropriately detailed structure. 
     Embodiments of the invention provide interspinous process spacing devices and methods for their use and manufacture. As described above, an interspinous process spacing device provides a spacer inserted between posteriorly extending spinous processes of adjacent vertebrae to maintain minimum spacing between the spinous processes. Accordingly, a single interspinous process spacing device is designed to limit movement of only two adjacent vertebrae. According to certain embodiments described herein, an interspinous process spacing system is provided with at least two individual interspinous process spacing devices implantable in an integrated, overlapping configuration. This integrated and overlapping configuration improves the stability of the adjacent vertebrae since the two attachment sides are engaged with each other, thus increasing the surface area of each individual attachment side that can engage the surface of the respective spinous process, since the two attachment sides do not have to attach adjacent to each other, but overlapping such that one is attached to the top of the other. The invention provides that a single interspinous process spacing device of two attachment sides, also referred to as a pair of base plates, can be implanted alone having an integration mechanism, such as apertures therein, for future implantation of an overlapping second interspinous process spacing device of two attachment sides, also referred to as a pair of link plates. 
     According to one embodiment, a first interspinous process spacing device is implantable on two adjacent vertebrae by affixing to the spinous process of each vertebrae. A second interspinous process spacing device is implantable on the next adjacent vertebrae (e.g., in the superior or inferior direction) by affixing to the spinous process of the adjacent vertebrae and affixing to the adjacent end of the first interspinous process spacing device already implanted. According to one embodiment, to achieve this integrated configuration, the second (and succeeding) interspinous process spacing device has attachment sides in a bent configuration to overlap the attachment sides of the first interspinous process spacing device. The interspinous process spacing devices can include an integration mechanism, such as, but not limited to, a ball and socket arrangement or a pin and hole (aperture or slot) arrangement, or a pin and overlapping holes arrangement, or a hinge arrangement, or a bone engaging spike and hole arrangement for securely overlapping attachment sides of a first and second interspinous process spacing device and, in the case of a spiked integration mechanism, further engaging the spinous process. In various embodiments, the integration mechanism may allow for overlapping attachment sides of first and second interspinous process spacing devices without requiring a bent configuration of the attachment sides, as further described below. 
     Each of the interspinous process spacing devices includes a first attachment side and a second attachment side in an approximately parallel orientation relative to each other. Each of the attachment sides aligns and selectively engages a respective side of two adjacent spinous processes to retain the implant in position. Thus, the attachment sides are adjustable in a substantially perpendicular direction relative to their orientation (e.g., along the axis of the spacer tray extending between them) to permit closing and tightening them on the spinous process sandwiched therebetween. In one embodiment, the inner surfaces of each of the attachment sides include multiple fasteners (e.g., teeth, barbs, hooks, spikes, or any other gripping surface or other suitable attachment means) protruding therefrom, which interface with the surfaces of the spinous processes to facilitate attaching the attachment sides thereto. In one example, the fasteners can be positioned at or near the edges and/or corners of each attachment side to align with the spinous processes during implantation. 
     In one embodiment in which multiple interspinous process spacing devices are intended to be used to fasten to more than two adjacent vertebrae, the attachment sides of the first interspinous process spacing device have a substantially flat configuration, whereas the attachment sides of the second (and any subsequent) interspinous process spacing device are formed in a bent configuration, such that a portion of each attachment side is offset from the remaining portion of the attachment side to permit overlapping the first interspinous process spacing device during implantation. As such, the offset portion is set out a distance approximately equal to, or slightly larger or smaller than, the thickness of the attachment side. To improve securing the second interspinous process spacing device to the first, the outer surfaces of the attachment sides of the first interspinous process spacing device may include apertures (e.g., holes, slots, etc.) oriented to receive fasteners extending from the inner surfaces of the offset portion of the attachment sides of the second interspinous process spacing device where the two overlap. Inserting some of the fasteners of the second interspinous process spacing device into the first device increases the purchase and stability of the two devices together, improving the effectiveness of the implant. In other embodiments, however, other means for allowing an overlapping arrangement of multiple interspinous process spacing devices can be used. 
     In addition, according to various embodiments described herein, the interspinous process spacing devices include an improved spacer tray configured to permit increased access and provide an increased area for bone growth above the spacer tray and between the spinous processes after implant. Access to the tray space and maximized open space between the spinous processes after implant is beneficial when providing a bone growth promoting substance to fuse the spinous processes above the spacer tray. The amount and orientation of the bone material can have direct consequences on its ability to promote bone and other tissue in-growth, further strengthening the implant and its fixation to the vertebrae. By orienting the spacer tray such that it will be positioned proximate the vertebrae when implanted, bone and other tissue in-growth is improved by increasing the surface area, and the amount and proximity of the bone growth promoting substance to the vertebrae and other tissue. The spacer tray can vary in length, width and in rotatable position about an axis defined by its length. 
     As described, at least one attachment side of each interspinous process spacing device is configured to slide along the spacer tray to allow closing the attachment sides on the adjacent spinous processes. Each interspinous process spacing device further includes securing means to secure the attachment sides in position upon engaging the spinous processes. The securing means may vary according to different embodiments, which include, but are not limited to, worm drive mechanisms, gear and pinion mechanisms, ratchet and gear mechanisms (like a lock tie or cable tie), cam mechanisms, one or two spaced apart screws connecting the two attachment sides, any variation of the aforementioned mechanisms with only a single or multiple screw/gear/ratchet mechanisms, etc., one or more set screws, a separate clamping means combined with a set screw, or any combination thereof. 
     Embodiments that have at least two spaced apart securing mechanisms allow tightening each side of the interspinous process spacing device independently. As such, the attachment sides can be tightened using a “walking” approach by alternating between incremental actuations of each mechanism. Tightening each side of the interspinous process spacing device independently allows the attachment sides to close on the adjacent spinous processes in a more tight and secure configuration irrespective of varied thicknesses or shapes of the spinous processes. Otherwise, without providing independent variability when tightening each end of the attachment sides, the interspinous process spacing device may not as securely engage adjacent spinous processes having varied thicknesses. Moreover, the two spaced apart securing mechanisms may optionally avoid having to use a separate clamping and/or insertion instrument to secure the interspinous process spacing device to the spinous processes, which is required by prior devices to achieve tight fixation. However, in some embodiments described below, one may opt to use an additional insertion instrument, which may be used to provide the initial orientation and attachment or clamping of an interspinous process spacing device to the spinous processes, while the interspinous process spacing device and its integrated securing means may be used to achieve final fixation and secure engagement to the spinous processes. However, other securing mechanisms described herein that do not include two spaced apart mechanisms provide the additional advantages of a single device for securing and the unique application of mechanical securing components that tighten the two attachment sides, which simplifies the implantation procedure. 
     The present invention provides an interspinous process spacing device, comprising a first attachment side and a second attachment side, each attachment side comprising one or more slots formed therein and oriented proximate one end for receiving fasteners extending inwardly from a second interspinous process spacing device. The interspinous process spacing device further comprises a spacer tray positioned between the first attachment side and the second attachment side, the spacer tray extending from the first attachment side and slideably insertable through a spacer tray slot formed in the second attachment side, wherein the spacer tray is adapted to retain adjacent spinous processes in a spaced apart orientation. The interspinous process spacing device further comprises securing means for securing the second attachment side relative to the first attachment side, wherein, upon securing the second attachment side relative to the first attachment side by the securing means, the interspinous process spacing device is engaged with the adjacent spinous processes. In certain embodiments of the interspinous process spacing device, the one or more slots for receiving fasteners from a second interspinous process spacing device are oriented proximate each end of the first attachment side and the second attachment side. In certain embodiments of the interspinous process spacing device, the one or more bone fasteners extend inwardly on one end of the first attachment side and the second attachment side. In certain embodiments of the interspinous process spacing device, the one or more bone fasteners extend inwardly on each end of the first attachment side and the second attachment side. 
     In certain embodiments of the interspinous process spacing device, each attachment side has a central portion and two wing portions extending in opposite directions from the central portion, and the one or more bone fasteners and the one or more slots for receiving extension fasteners from a second interspinous process spacing device are located on at least one wing portion. In certain embodiments of the interspinous process spacing device, each wing portion has more than one slot for receiving extension fasteners from a second interspinous process spacing device. In certain embodiments of the interspinous process spacing device, one wing portion of the first and second attachment sides has one extension fastener extending inwardly for attaching to another interspinous process spacing device. 
     In certain embodiments of the interspinous process spacing device, the means for securing the second attachment side relative to the first attachment side is a bearing screw extending posteriorly through a central portion of second attachment side to the tray slot. In certain embodiments of the interspinous process spacing device, the tray slot engages the spacer tray with freedom of movement to permit at least 20 degrees of lateral rotation of the second attachment side relative to the first attachment side prior to engaging the securing means. 
     In certain embodiments of the interspinous process spacing device, the spacer tray comprises a T-shaped cross-section, and the tray slot in the second attachment side has a reciprocating T-shape. In certain embodiments of the interspinous process spacing device, the bottom of the T-shape is medially disposed from the first attachment side, and the cross-sectional shape tapers to a point on the spacer tray to facilitate insertion of the tray through the ligament and angled insertion of the tray through the tray slot in the second attachment side. 
     In certain embodiments of the interspinous process spacing device, the spacer tray has an arcuate longitudinal shape, such that the spacer tray extends in a posterior curvature to facilitate angled insertion through ligaments and into the tray slot. In certain embodiments, at least the end portion of the spacer tray extends in an arcuate shape corresponding to the arc created when the sides are attached to a pivoting insertion tool and are drawn together, as described in more detail below. In certain embodiments of the interspinous process spacing device, the spacer tray extends perpendicularly before the posterior curvature to facilitate angled insertion through the tray slot. 
     In certain embodiments of the interspinous process spacing device, the spacer tray comprises an arcuate cross-sectional shape such that upon implanting, the spacer tray is posteriorly open and accessible. In certain embodiments of the interspinous process spacing device, the spacer tray is adapted to retain bone growth promoting substance, wherein the bone growth promoting substance is packable after engaging the first attachment side and the second attachment side to adjacent spinous processes. 
     In certain embodiments of the interspinous process spacing device, the securing means for securing the second attachment side relative to the first attachment side is at least one set screw extending through the central portion from the posterior orientation to the tray slot to secure the second attachment side to the spacer tray in a substantially fixed position. In various embodiments, the securing means comprises at least one of: (a) at least one worm drive assembly; (b) at least one rack and pinion assembly; (c) at least one screw extending between and operably connecting the first attachment side and the second attachment side; (d) a geared rack and ratchet assembly; or (e) at least one set screw assembly. 
     In certain embodiments of the interspinous process spacing device, the securing means comprises at least two spaced apart securing mechanisms extending between and operably connecting the first attachment side and the second attachment side, wherein each of the at least two spaced apart securing mechanisms can be independently and incrementally actuated causing each end of the attachment sides to engage the respective spinous process independently. 
     In certain embodiments of the interspinous process spacing device, the first and second attachment side each have an insertion instrument receptacle posteriorily located on each attachment side. In certain embodiments of the interspinous process spacing device, the size, shape or indicia of the insertion instrument receptacle on the first attachment side is different from the size, shape or indicia of the implantation instrument receptacle on the second attachment side in order to facilitate connection to the correctly corresponding ends of the insertion instrument. 
     In certain embodiments, the interspinous process spacing device is a first interspinous process spacing device (or pair of base plates), and further comprising a second interspinous process spacing device (or pair of link plates) comprising a first offset attachment side and a second offset attachment side, wherein each offset attachment side comprises a substantially flat end and an offset end adapted to overlap over an adjacent portion of respective attachment sides of the first interspinous process spacing device and having fasteners extending inwardly therefrom receivable into the slots in each attachment side of the first interspinous process spacing device. 
     In certain embodiments of the interspinous process spacing device, the substantially flat end further comprises one or more bone fasteners extending inwardly and one or more slots formed therein for receiving fasteners extending inwardly from a third interspinous process spacing device. In certain embodiments of the interspinous process spacing device, the first attachment side and the second attachment side of the second interspinous process spacing device each have an integration means for integrating and attaching the offset end of the second interspinous process spacing device with a portion of the respective attachment side of the first interspinous process spacing device. 
     In certain embodiments of the interspinous process spacing device, the integration means comprise fasteners extending inwardly from the second interspinous process spacing device which pivotally engage the one or more slots formed in each attachment side of the first interspinous process spacing device, such that the second interspinous process spacing device can pivot through a 155 degree angle with respect to the first interspinous process spacing device. In certain embodiments of the interspinous process spacing device, the second interspinous process spacing device can pivot through a 120 degree angle with respect to the first interspinous process spacing device. In certain embodiments of the interspinous process spacing device, the second interspinous process spacing device can pivot posteriorly and anteriorly through substantially equal degrees with respect to the first interspinous process spacing device. 
     In certain embodiments of the interspinous process spacing device, the integration means comprises at least one of: (a) one or more fasteners extending from the inner surfaces of the offset end and receivable by the one or more apertures formed in the respective attachment side of the first interspinous process spacing device; (b) at least one pin extending from the inner surfaces of the offset end and receivable by the one or more apertures formed in the respective attachment side of the first interspinous process spacing device; (c) a domed surface extending from the inner surface of the offset end and receivable by a dome-shaped recess formed in the respective attachment side of the first interspinous process spacing device; (d) a textured surface formed on the inner surface of the offset end and mateable to a textured surface formed on the outer surface of the respective attachment side of the first interspinous process spacing device; or (e) a textured domed surface extending from the inner surface of the offset end and receivable by a complementarily-shaped textured recess formed in the respective attachment side of the first interspinous process spacing device. 
     In certain embodiments of the interspinous process spacing device, the offset ends of the second interspinous process spacing device are offset by a distance approximately equal to the thickness of the respective attachment side of the first interspinous process spacing device. In certain embodiments of the interspinous process spacing device, the first interspinous process spacing device is implantable at an inferior position relative to the second interspinous process spacing device. In certain embodiments of the interspinous process spacing device, the first interspinous process spacing device is implantable at a superior position relative to the second interspinous process spacing device. 
     In certain embodiments, the interspinous process spacing device is configured for implantation at the L5-S1 vertebrae and comprising a first angled attachment side and a second angled attachment side, wherein each angled attachment side comprises an angled end adapted to accommodate a sacrum. In certain embodiments, the first and second angled attachment sides are each selectively adjustable for optimizing the angle to fit the particular patient&#39;s sacrum anatomy and then securing the selected angle. The ends opposite the angled sacrum attachment ends can have bone fasteners extending from the inner surfaces thereof and one or more apertures therethrough, allowing the device to serve as a base plate for receiving fasteners on a second superiorly located spacing device. Alternatively, the ends opposite the angled sacrum attachment ends can be offset and each have a fastener (such as a bone fastening spike) extending from the inner surfaces thereof, allowing the device to serve as a link plate to be received within one or more apertures in a second superiorly located spacing device. Both embodiments permit rotational optimization of the relative angle between the first and second spacing devices to fit the patient&#39;s anatomy. In certain embodiments of the interspinous process spacing device, the angled end of each angled attachment side of the interspinous process spacing device further comprises one or more angled fasteners extending from the inner surface at an angle other than ninety degrees and adapted for engaging the sacrum. 
     In certain embodiments of the interspinous process spacing device, each attachment side has a central portion and two wing portions extending in opposite directions from the central portion superiorly and inferiorly, and the inferior wings each have the angled end adapted to accommodate a sacrum and have one or more bone fasteners extending inwardly therefrom, and the superior wings each have one or more slots formed therein for receiving extension fasteners from a second interspinous process spacing device. 
     In certain embodiments of the interspinous process spacing device, the superior wings each have one or more bone fasteners extending inwardly therefrom. In certain embodiments of the interspinous process spacing device, the superior wings each have an extension fastener extending inwardly for attaching to another interspinous process spacing device. In certain embodiments of the interspinous process spacing device, the bone fasteners on the inferior wings each comprise a bone screw or movable spike or an axially expandable spike to engage the bone disposed through the wing. In certain embodiments of the interspinous process spacing device, the bone fasteners on the inferior wings further comprise one or more stationary spikes extending inwardly therefrom at angle different than an angle at which the bone screw or movable spike is disposed through the wing. 
     In certain embodiments of the interspinous process spacing device, the superior wings each have more than one slot formed therein for receiving fasteners extending inwardly from a second interspinous process spacing device. In certain embodiments of the interspinous process spacing device, the superior wings permit a fastened second interspinous process spacing device to pivot up to a 155 degree or a 60 degree angle with respect to the interspinous process device for implantation on the sacrum at the L5-S1 vertebrae. 
     The present invention further provides an interspinous process spacing system, comprising a first interspinous process spacing device and a second interspinous process spacing device, wherein the first interspinous process spacing device comprises two substantially flat attachment sides and a first spacer tray positioned therebetween, wherein one of the two substantially flat attachment sides is slideably positionable over the spacer tray. In certain embodiments of the interspinous process spacing device, wherein the second interspinous process spacing device comprises two offset attachment sides and a second spacer tray positioned therebetween, each of the offset attachment sides comprises a substantially flat end and an offset end. 
     The invention provides in certain embodiments that after implantation of the first interspinous process spacing device on a first and a second adjacent spinous process, the offset ends of the two offset attachment sides of the second interspinous process spacing device at least partially overlap respective adjacent ends of the substantially flat attachment sides of the first interspinous process spacing device when implanting the second interspinous process spacing device on the second and a third spinous process adjacent to the second spinous process. 
     In certain embodiments of the interspinous process spacing device, each of the offset ends of the two offset attachment sides comprises an integration means for integrating and attaching the offset end of the second interspinous process spacing device with a portion of the respective attachment side of the first interspinous process spacing device when overlapping. 
     In certain embodiments of the interspinous process spacing device, the integration means comprise fasteners extending inwardly from the second interspinous process spacing device which pivotally engage the one or more slots formed in each attachment side of the first interspinous process spacing device, such that the second interspinous process spacing device can pivot through a 155 degree angle with respect to the first interspinous process spacing device. 
     In certain embodiments of the interspinous process spacing device, each of the substantially flat attachment sides and the offset attachment sides comprises one or more bone fasteners extending from the inner surface for engaging respective spinous processes when implanted. In certain embodiments of the interspinous process spacing device, the substantially flat end on each of the offset attachment sides of the second interspinous process spacing device comprises one or more slots formed in an outer surface for receiving one or more fasteners extending from an inner surface of a respective offset attachment side of a third interspinous process spacing device adapted to overlap the substantially flat ends of the second interspinous process spacing device. 
     In certain embodiments the invention provides an interspinous process spacing device kit comprising: a first interspinous process spacing device comprising a first attachment side and a second attachment side, the first and the second attachment sides of the first interspinous process spacing device having a substantially flat configuration; a second interspinous process spacing device comprising a first attachment side and a second attachment side, the first and the second attachment sides of the second interspinous process spacing device having an offset configuration adapted to overlap a portion of a respective attachment side of the first interspinous process spacing device; and at least one insertion instrument adapted for retaining at least one of the first interspinous processing spacing devices or the at least one additional interspinous process spacing device and implanting the same. 
     In certain embodiments of the interspinous process spacing device, each interspinous process spacing device further comprises a spacer tray positioned between the first attachment side and the second attachment side, the spacer tray having a width and length extending from the first attachment side and slideably insertable through a tray slot formed in the second attachment side, wherein the spacer tray is adapted to retain adjacent spinous processes in a spaced apart orientation, and wherein the kit further comprises a plurality of alternatively sized first and second interspinous process spacing devices having different spacer tray widths. 
     The present invention further provides a surgical instrument system for implanting an interspinous process spacing device, comprising a means for positioning a first arm and a second arm in alignment for securing the interspinous process spacing device onto spinal processes. In certain embodiments of the surgical instrument system for implanting an interspinous process spacing device, the proximal and distal ends are offset to provide an unobstructed view of the distal ends when holding the proximal ends. In certain embodiments, each arm permits an engaged attachment side of the interspinous process spacing device at least 5 degrees, or at least 10 degrees, and up to 30 degrees, of rotation about an axis defined by the engagement element on the distal end of the arm. In certain embodiments of the surgical instrument system for implanting an interspinous process spacing device, the engagement element comprises an engagement projection which releasably engages an instrument receptacle on the attachment side of the interspinous process spacing device, a mount for movably holding the engagement projection, and an implant guide extending distally past the engagement projection which engages an outer surface of an engaged attachment side of the interspinous process spacing device. 
     In certain embodiments of the surgical instrument system for implanting an interspinous process spacing device, the engagement projection on the second arm provides access to a securing means on the second attachment side of the interspinous process spacing device to secure the second side to the first side. In certain embodiments, the engagement projection is a threaded screw which engages a reciprocal threaded instrument receptacle instrument on the attachment side of the interspinous process spacing device. In certain embodiments, the threaded screw on the second arm is cannulated to provide access therethrough to a securing means on the second attachment side of the interspinous process spacing device to secure the second side to the first side while the second side is engaged to the second arm. 
     In certain embodiments of the surgical instrument system for implanting an interspinous process spacing device, the size, shape or indicia of the insertion instrument receptacle on the first attachment side is different from the size, shape or indicia of the insertion instrument receptacle on the second attachment side to facilitate connection to the correctly corresponding ends of the insertion instrument. 
     In certain embodiments of the surgical instrument system for implanting an interspinous process spacing device, the proximal ends of the first and second arms are releasably connectable at more than one selected distance. In certain embodiments of the surgical instrument system for implanting an interspinous process spacing device, the central portions of the first and second arms are releasably and rotatably connectable. 
     In certain embodiments, the present invention provides a top-down surgical instrument system for implanting an interspinous process spacing device, comprising a first arm having a proximal end, an elongated central portion and distal end, wherein the distal end has an interspinous process spacing device engagement element for posteriorly engaging a first attachment side of the interspinous process spacing device having a spacer tray extending inwardly therefrom. Certain embodiments comprise a second arm having a proximal end, an elongated central portion and distal end, wherein the distal end has an interspinous process spacing device engagement element for posteriorly engaging a second attachment side of the interspinous process spacing device having a spacer tray slot therein for receiving the spacer tray. In such embodiments, the second arm is removably and pivotally attachable to the first arm about an axis for positioning the first arm and the second arm in alignment for securing the interspinous process spacing device onto spinal processes. 
     In certain embodiments of the surgical instrument system for implanting an interspinous process spacing device, the second arm further comprises a pivot member or pin located on the central portion and the first arm further comprises a pivot channel or slot with a proximally oriented opening and a distally oriented curved retaining edge, such when the pin is slideably engaged in the slot against the retaining edge the first and second arms are removeably and pivotally attached to form a hinge, wherein the hinge permits positioning the first arm and the second arm in alignment for securing the interspinous process spacing device onto spinal processes. 
     In certain embodiments of the surgical instrument system for implanting an interspinous process spacing device, when the first and second arms each have a respective first and second attachment side of the interspinous process spacing device engaged thereto, and the first and second arms are attached at the hinge, drawing the proximal ends of the arms together will align and insert the spacer tray into the spacer tray slot of the first and second attachment sides of the interspinous process spacing device for securing the interspinous process spacing device onto spinal processes. 
     In certain embodiments of the surgical instrument system for implanting an interspinous process spacing device, the first arm further comprises a releasable locking mechanism for selectively securing the pin of the second arm into the slot of the first arm. In certain embodiments, the releasable locking mechanism is a leaf spring on the central portion of the first arm in blocking communication with the slot, such that the pin on the second arm can deflect the leaf spring during insertion into the slot and remain therein when the leaf spring returns to blocking communication to maintain the pin against the retaining edge on the first arm, and wherein the leaf spring can be manually disengaged from blocking communication with the slot to release the pin and separate the first and second arms. 
     In certain embodiments of the surgical instrument system for implanting an interspinous process spacing device, the surgical instrument comprises means for mechanically actuating the insertion instrument to close and open the first arm and the second arm for tightening the second attachment side relative to the first attachment side. In certain embodiments, the means for mechanically actuating is a ratchet bar pivotally mounted to the proximal end of the second arm and selectively engageable to the proximal end of the first arm, wherein the ratchet bar has a plurality of teeth on the proximal surface thereof which engage a corresponding flange on the proximal end of the first arm. 
     In certain embodiments of the surgical instrument system for implanting an interspinous process spacing device, the ratchet bar has one or more indicators of predetermined length corresponding to space between the mounted sides of the interspinous process spacing device. In certain embodiments, the ratchet bar further comprises a threaded track and a nut riding thereon outside the proximal end of the first arm for mechanically forcing the proximal ends of the arms together. 
     The present invention further provides a surgical instrument system for implanting an interspinous process spacing device, comprising a first arm having a proximal end, an elongated central portion and distal end, wherein the distal end has an interspinous process spacing device engagement element for posteriorly engaging a first attachment side of the interspinous process spacing device having a spacer tray extending inwardly therefrom. Such an embodiment also comprises a second arm having a proximal end, an elongated central portion and distal end, wherein the distal end has an interspinous process spacing device engagement element for posteriorly engaging a second attachment side of the interspinous process spacing device having a spacer tray slot therein for receiving the spacer tray. This embodiment can further be used with a compressor tool for positioning the first arm and the second arm in alignment for securing the interspinous process spacing device onto spinal processes. 
     In certain embodiments of the surgical instrument system for implanting an interspinous process spacing device, the compressor tool has a proximal handle end a central portion and a distal pair of opposing tangs moveable throughout a range between an open position and a compression position. In certain embodiments, the distal end of each arm comprises compressor tool guide channels and compression point indentations therein for receiving the compressor tool tangs. The compression points permit delivery of substantially equal amounts of pressure across each attachment side of the plate, allowing less invasive surgical implantation with a single compressor tool than would be required with multiple compression points and multiple compression tools. In certain embodiments, the tangs have distal compressor tips extending inwardly for engagement within the corresponding guide channels and compression point indentations on the arms, wherein the compression tool can rotate about an axis defined by the compressor tips so as to provide a user with a range of approach angles and approach from either side of the implantation tool and compress the arms to secure the aligned interspinous process spacing device onto spinal processes. 
     In certain embodiments of the surgical instrument system for implanting an interspinous process spacing device, the proximal end of one arm further comprises a retaining latch disposable on the distal end of the other arm to retain the arms in position relative to each other and in alignment for securing the interspinous process spacing device onto spinal processes. 
     In certain embodiments of the surgical instrument system for implanting an interspinous process spacing device, the surgical instrument comprises means for mechanically actuating the insertion instrument to close and open the first arm and the second arm for tightening the second attachment side relative to the first attachment side. In certain embodiments, the means for mechanically actuating is a ratchet bar pivotally mounted to the proximal end of the second arm and selectively engageable to the proximal end of the first arm, wherein the ratchet bar has a plurality of teeth on the proximal surface thereof which engage a corresponding flange on the proximal end of the first arm. In certain embodiments, the ratchet bar has one or more indicators of predetermined length corresponding to space between the mounted sides of the interspinous process spacing device. In certain embodiments, the ratchet bar further comprises a threaded track and a nut riding thereon outside the proximal end of the first arm for mechanically forcing the proximal ends of the arms together. 
     The present invention also provides a surgical instrument for selecting an interspinous process spacing device. In certain embodiments, the selection instrument comprises a first arm having a proximal end, an elongated central portion and distal end, wherein the distal end has a first interspinous process spacing measurement wing extending therefrom comprising a first spinous process stop element and a perpendicular wing template, and a second arm having a proximal end, an elongated central portion and distal end, wherein the distal end has a second interspinous process spacing measurement wing extending therefrom comprising a second spinous process stop element and a perpendicular wing template. In certain embodiments of the surgical instrument, the first and second arms are pivotally attached about an axis for positioning the first and second interspinous process spacing measurement wings to measure space between adjacent spinal processes. The instrument also allows for selection of an adjacent base plate or link plate superior or inferior to the existing implanted plate. 
     In certain embodiments of the surgical instrument, the measurement device can further comprise first and second wing templates adapted to overlap respective first and second adjacent spinal processes to determine space available on each spinous process for engaging an interspinous process implant. In certain embodiments, the instrument determines the space available for implantation of either a base plate device or an overlapping link plate device. In certain embodiments, the instrument can be adapted such that the proximal end of the first or second arm has a measuring element attached thereto with indicia to register length to the proximal end of the other arm, wherein said length corresponds to space between adjacent spinal processes as measured by the first and second spinous process stop elements. In certain embodiments of the surgical instrument, drawing the proximal ends of the arms together separates the wings to measure space between adjacent spinal processes. In one embodiment, the first or second wing template, or both, comprises a fastener template extending therefrom adapted to engage with a slot on an attachment side of an interspinous process spacing device previously implanted to determine space and orientation available for overlapping engagement of a link plate onto a base plate. 
     Example embodiments of interspinous process spacing devices are further described with reference to the  FIGS. 1-12 . Extending posteriorly from each vertebra are spinous processes. Laminae connect the spinous processes to respective transverse processes. Facet joints between the processes of adjacent vertebrae guide articulation of the vertebrae. Interspinous process spacing devices as described herein may be implanted between adjacent spinous processes of any of the cervical, thoracic, and/or lumbar vertebrae. 
     As shown in  FIG. 1  are three engaged interspinous process spacing devices—a first base plate type interspinous process spacing device  130 , a second link plate type interspinous process spacing device  132  overlapping the superior end of the first interspinous process spacing device  130 , and a third link plate type interspinous process spacing device  134  overlapping the inferior end of the first interspinous process spacing device  130 . The first interspinous process spacing device  130  includes a first attachment side  140  and a second attachment side  142 , engaging either side of the adjacent spinous processes. Similarly, the second and third interspinous process spacing devices  132 ,  134  include a first attachment side  144  and a second attachment side  146 . According to this embodiment, the attachment sides  144 ,  146  of the second interspinous process spacing device have an offset configuration to permit overlap with the first interspinous process spacing device  130 . Thus, each of the first and second attachment sides  144 ,  146  of the second and third interspinous process spacing devices  132 ,  134  has a substantially flat end  148  and an offset end  149 , with the offset being approximately the anticipated thickness of the first or second attachment side  140 ,  142  of the first interspinous process spacing device  130  (or a slight variation thereof), which is described and illustrated in more detail with reference to  FIGS. 2-4 . 
     According to various embodiments, the size and dimension of the first and the second attachment sides  140 ,  142 ,  144 ,  146  may vary according to the intended use of the interspinous process spacing devices  130 ,  132  which may vary based at least in part on the intended implant location on the spine, the patient size, the treatment, and the like. For example, attachment sides may vary in length and/or height to accommodate the varying sizes of spinous processes. Moreover, as described below with reference to  FIGS. 5A-5C and 7A-7E , attachment side geometry may be adapted for implanting at specific locations of a spine that require different configurations, such as at the L5-S1 vertebrae. 
     Similarly, spacer tray dimensions, as described below, may also vary in size, such as to accommodate varying patient and/or implant location anatomy. In one example, the spacer tray may have a substantially smaller width than is illustrated in  FIG. 1 , which may facilitate insertion through the ligaments existing between the spinous processes. Kits including interspinous process spacing devices with a range of spacer tray widths to select from are provided, such as shown in  FIG. 6A-6B . In certain embodiments, the spacer tray widths can be provided in increments ranging from less than or 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, to 18 mm, or more, such as shown in  FIGS. 6A-6B . Example spacer tray lengths can be 10 mm to 30 mm, or 23.4 mm. In another example, an interspinous process spacing device may not include a spacer tray. A spacer tray selection instrument is also provided and is described in more detail below with reference to  FIGS. 21A and 21B . 
     In certain example embodiments, the width of the wings on a base and link plate, such as shown in  FIGS. 2-3  can be 3 mm, the width of the central portion of the first attachment side can be 6 mm, and the width of the central portion of the second attachment side can be 8.5 mm. An exemplary height for the base plate and link plate attachment sides is 18 mm. 
     In certain example embodiments, the length of the wings on either side of the spacer tray can be 10.5 mm for a first interspinous process device base plate and 12.5 mm for a second interspinous process device link plate. Therefore, for an example device with a 8 mm spacer tray width, the total plate length for a base plate would be 29 mm, and for a link plate would be 31 mm. 
     Each of the interspinous process spacing devices  130 ,  132  may include a spacer tray  150  extending between attachment sides  140 ,  142  and  144 ,  146 , respectively. The spacer tray  150  is configured with surfaces to abut the spinous processes to maintain the spaced apart relationship of the spinous processes. According to various embodiments, as illustrated in  FIGS. 1-12 , the spacer tray  150  may have a substantially open configuration that is accessible from the posterior direction, which serves to maximize the surface area for bone growth promoting substances. Access from the posterior direction allows the surgeon to insert the bone growth promoting substance (or any other material to facilitate bone in-growth, structural support, and/or healing) after implanting the interspinous process spacing devices. Otherwise, without posterior access, the bone growth promoting substance must be inserted prior to implantation, which likely will not result in the most effective placement and/or quantity of bone growth promoting substance. In contrast to conventional interspinous spacers, which typically have a circular cross-section and occupy a substantial area between adjacent spinous processes, the spacer tray  150  described herein has a reduced cross-sectional profile and a tapered width on the leading front edge, which eases insertion between the ligaments occupying the space between adjacent spinous processes. The conventional devices often require significant retraction and/or cutting of the ligaments to implant a device because the larger, circular cross-section of the components existing between the sides cannot easily be inserted between the ligaments, increasing the difficulty, risk, and healing time of the implant procedure. 
     Accordingly, the spacer tray  150  described herein can be inserted between the ligaments without cutting due to its reduced, tapered, or flattened profile compared to the larger, circular cross-sections of other devices. However, in other embodiments, the spacer tray  150  may be configured in a variety of shapes and sizes to accommodate anatomical variation among patients and intended treatment and space correction, and to accommodate the positioning of a securing mechanism, as further described below. The spacer tray  150  may further optionally include apertures through the spacer tray  150 , which act to facilitate bone and tissue in-growth by maximizing the available surface area from the adjacent spinous processes and cause further fusion thereof. These and other features and variations thereof are discussed in more detail with reference to the following  FIGS. 2-12 . 
     Moreover, according to another embodiment, the spacer tray  150  may have a minimized width to increase the ease of insertion and to occupy less space between adjacent spinous processes. In fact, in one embodiment a spacer tray may not be included at all, and alignment, connection, and stability between the two attachment sides  140 ,  142  may be accomplished by way of the securing means, such as those described with reference to  FIGS. 8 and 10 . In this embodiment, the securing means may further serve to absorb impact from, and to limit movement of, one or more of the adjacent spinous processes, which otherwise would be achieved by a spacer tray. 
       FIGS. 2-7  show details of interspinous process spacing devices according to one embodiment, such as the first interspinous process spacing device  130  (as illustrated in  FIG. 1 ).  FIGS. 6-9  show example spacer tray  150  configurations, according to various example embodiments. The first attachment side  140  includes a spacer tray  150  extending in a substantially perpendicular direction from the first attachment side  140 . The spacer tray  150  shown is configured to have a substantially arcuate cross-sectional shape, permitting access to the tray after implanting the interspinous process spacing device  130 . However, the spacer tray may have any cross-sectional shape, such as, but not limited to, flat, angled, a partial square, a partial hexagon, a partial octagon, a T-shape, a cross shape, and the like, such as, but not limited to, those illustrated by example in  FIGS. 1-12 . The dimensions of the spacer tray  150  can depend upon the desired level of movement and/or size of the desired space to be retained between the two adjacent spinous processes. The spacer tray  150  may further optionally include chambers formed through the tray, which may be oriented to provide additional clearance of the spacer tray  150  from posteriorly facing bone surfaces (e.g., spinous processes, facet joints, etc.). Accordingly, a spacer tray  150  acts to maintain a minimum distance between adjacent spinous processes to move the vertebrae apart and relieve pressure on nerve tissue and/or facet joints. 
     The cross-sectional shape of the spacer tray  150  can facilitate insertion into the tray slot  210 . For example, as shown in  FIGS. 2-7 , the T-shaped cross-section, with the bottom of the T extending medially or downward into the spine provides a supporting lift for the tip of the spacer tray off of the vertebrae and into the tray slot. Similarly, the tapering cross-section of the tip of the spacer tray into a rounded point facilitates insertion into the slot, as well as facilitating insertion through the ligaments existing between the spinous processes. Finally, the arcuate longitudinal cross-section facilitates insertion when both sides are engaged with an insertion tool and being drawn together in an arc, as described below. 
     Moreover, the spacer tray  150  is shaped to permit access from the posterior direction, which increases the ease with which bone growth promoting substance is placed above the spacer tray  150  and proximate the vertebrae, while also increasing the available spinous process surface area. In some embodiments, bone growth promoting substance can be inserted in or near other areas of the interspinous process spacing device. Also as illustrated in  FIGS. 9B-9D , the spacer tray  150  can optionally include tray apertures  320  or other openings extending through the spacer tray  150  to further facilitate tissue and/or bone in-growth. Any number of tray apertures  320  may be included in any size, shape, or configuration. As used herein, bone growth promoting substance may include, but is not limited to, bone paste, bone chips, bone strips, structural bone grafts, platelet-derived growth factors, bone marrow aspirate, stem cells, bone growth proteins, bone growth peptides, bone attachment proteins, bone attachment peptides, hydroxylapatite, calcium phosphate, and/or other suitable bone growth promoting substances. 
     The second attachment side  142  includes a tray slot  210  having a similar shape as the spacer tray  150  to permit the spacer tray  150  to slide therethrough. Accordingly, the second attachment side  142  is slideably adjustable along the axis of the spacer tray  150  so the second attachment side  142  can move toward the first attachment side  140  when tightening to allow the attachment sides  140 ,  142  to be positioned along either side of, and secured to, the spinous processes. It is appreciated that in other embodiments, the spacer tray may extend from the second attachment side and slideably pass through the first attachment side, and that the orientation relative to the patient&#39;s spine may vary from that described and illustrated herein. 
     According to one embodiment, as is shown in more detail with reference to  FIG. 4  and  FIG. 6  (a simplified perspective view of an interspinous process spacing device), the tray slot  210  is sized slightly larger than the cross-section area of the spacer tray  150  to provide loose fitting of the second attachment side  142  over the spacer tray  150 , permitting at least slight angular movement of the second attachment side  142  relative to the first attachment side  140 , but providing enough constraint so as to retain the approximate orientation of the second attachment side  142  relative to the spacer tray  150 . As a result of this slight angular variation allowed, opposite ends of the attachment sides can be tightened independently and can adapt to adjacent spinous processes having varied thicknesses (e.g., permitting the attachment sides to close tighter or narrower on one end relative to the other, such as if one spinous process is smaller or narrower than the other). The size of the tray slot  210  relative to the spacer tray  150  may vary according to the desired level of angular variation of the second attachment side  142  relative to the first attachment side  140 . In other embodiments, however, the tray slot  210  may form a tight fit around the spacer tray  150  to prevent significant angular variation or other movement of the second attachment side  142  relative to the spacer tray  150 . The fit between the tray slot  210  and the spacer tray  150  further serves to absorb torque or any other force applied by the spacer tray  150  against the second attachment side  142 , providing increased stability of the attachment sides  140 ,  142  relative to each other and against the patient&#39;s spinous processes when implanted. 
     In certain embodiments of the interspinous process spacing device, the tray slot engages the spacer tray with freedom of movement to permit at least 20 degrees of lateral rotation of the second attachment side relative to the first attachment side prior to engaging the securing means. However, in other embodiments, the tray slot  210  may form a more secure fit with the spacer tray  150 , preventing significant angular movement therein. For example, in embodiments in which the securing mechanism utilizes a gearing mechanism, a tighter fit may serve to prevent cross-threading or poor meshing of the gearing mechanisms. 
     Also illustrated in  FIGS. 2-7  are fasteners  220  extending from the inner surfaces of each of the attachment sides  140 ,  142 . The fasteners  220  improve the ability of the attachment sides  140 ,  142  to engage the spinous processes and/or serve as an integration means to engage the exterior surface of the adjacent interspinous process spacing device, such as is illustrated in and described with reference to  FIGS. 5A-5C . In certain embodiments of the interspinous process spacing device, the integration means comprise fasteners extending inwardly from the second interspinous process spacing device which pivotally engage the one or more slots formed in each attachment side of the first interspinous process spacing device, such that the second interspinous process spacing device can pivot through a 155 degree angle with respect to the first interspinous process spacing device. In certain embodiments of the interspinous process spacing device, the second interspinous process spacing device can pivot through a 60 degree angle with respect to the first interspinous process spacing device. In certain embodiments of the interspinous process spacing device, such as illustrated in  FIGS. 5A-5B , where multiple apertures are provided for the fastener, and where multiple apertures partially overlap as illustrated in  FIG. 5C , the second interspinous process spacing device can pivot through a range of angles with respect to the first interspinous process spacing device. It is understood that the device can be configured for pivotal rotation of the first interspinous process spacing device relative to the second interspinous process spacing device through any range of degrees desired including for example 180, 170, 160, 155, 150, 140, 130, 120, 110, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 5 and 0 degrees. In certain embodiments of the interspinous process spacing device, the second interspinous process spacing device can pivot posteriorly and anteriorly through substantially equal or unequal degrees in each direction with respect to the first interspinous process spacing device. 
     The fasteners  220  illustrated in  FIGS. 2-7  are shown as teeth or barbs, but any other fastening or other securing mechanism may be used, including, but not limited to, pins, hooks, wires, spikes, straps, clamps, sutures, adhesives, or any other suitable fastening mechanism. Moreover, according to various embodiments, the fasteners  220  may be interchangeable with other types of fastening mechanisms and/or may be adjustable to accommodate varying anatomy among patients. In addition to, or in lieu of, the fasteners  220  shown in  FIGS. 2-7 , other integration means may be provided that facilitate the integration of and securement between two adjacent interspinous process spacing devices when implanted in an overlapping configuration. 
     In the embodiments shown in  FIGS. 1-7 , the fasteners  220  are projecting inward from second link plates  144 , 146  of the second interspinous process spacing device toward slots  315  in base plates  140 , 142  of the first interspinous process spacing device to pivotally engage the two devices together prior to further securing with securing means  230  which is in this embodiment a set or bearing screw. Bone fastening members  225  are shown on the inner surfaces of the plates. In certain embodiments, the bone fastening members alternately extend from each opposing plate to different points on the spinous process to minimize the potential for fracture by bearing directly on opposing sides of the bone. Examples of these and other integration members are illustrated in and described with reference to  FIGS. 1-12 . 
     Example securing means  230  are particularly illustrated by  FIG. 4  with set screw extending through the central portion of the second attachment side  142  onto the spacer tray  150  in the tray slot  210 . Various additional example embodiments illustrated and described in more detail with reference to  FIG. 8 . The securing means  230  illustrated in  FIG. 8  includes two spaced apart screws  310  extending between the attachment sides  140 ,  142  and oriented substantially along the same axis as the spacer tray  150 . In the embodiment illustrated in  FIG. 8 , the screws  310  extend through the second attachment side  142  through apertures  312  and are received by the complementary threaded collars  314  extending from the inner surface of the first attachment side  140 . However, it is appreciated that the screws  310  may instead pass through the first attachment side  140  and be received by collars on the second attachment side  142  in other embodiments. According to one embodiment, the threaded collars  314  extend a given distance from the inner surface of the first attachment side  140  so as to permit receiving the respective screws  310  while the attachment sides  140 ,  142  are still sufficiently separated, and to reduce the length of the screws  310 . The distance the threaded collars  314  extend may vary, but can be determined to extend the maximum distance without interfering with the vertebrae, other components of the interspinous process spacing device, and/or access to spacer tray  150  to provide bone growth promoting substance therein. Similarly, the orientation of the securing means  230  is chosen to avoid interfering with the vertebrae (e.g., the spinous process) during implantation, while also providing maximum securing and purchase strength of the attachment sides  140 ,  142  to the spinous process. In another example, one or more screws  310  can be positioned between the space of a spacer tray  150  formed from multiple members and creating a space therein. 
     Spaced apart screws (or other securing means, as described in more detail below) permit independently adjusting opposite ends of the attachment sides  140 ,  142  and thus independently securing opposite ends of the attachment sides  140 ,  142  to the respective spinous process. For example, during tightening, the superior screw can be incrementally tightened, then the inferior screw can be incrementally tightened, and so forth until each end of the attachment sides  140 ,  142  is secured to the respective spinous process. This method allows tightening the interspinous process spacing device by “walking” opposite ends, and thus accounting for varied thicknesses of adjacent spinous processes. Additional embodiments including spaced apart screws or similar spaced apart securing means are described with reference to  FIGS. 8A-8D . 
     Moreover, some example securing means described herein may generally avoid having to use a separate clamping and/or insertion instrument. By tightening the screws  310 , the attachment sides  140 ,  142  close on the spinous processes without any additional clamping or tightening force. However, other securing means described herein can be implanted using an insertion instrument to facilitate retaining desired positioning of the interspinous process spacing device and/or to tighten the attachment sides  140 ,  142  against the spinous processes. In certain embodiments, the insertion instrument can also aid in aligning and engaging the two attachment sides of the device without requiring removal of the spinous process ligament. For example, the device embodiments described may be used to initially insert and position an interspinous process spacing device, while the securing means of the interspinous process spacing device may be used to achieve final fixation to the spinous processes. Though, in other embodiments, a clamping and/or insertion instrument may have an integrated tightening means (e.g., geared, ratchet, lever, etc.) that facilitates securing an interspinous process spacing device to the spine by tightening the clamping instrument, while the securing means of the interspinous process spacing device serve to secure and retain the device in tightened configuration. 
     Additional securing means embodiments are illustrated in  FIG. 8  and  FIG. 10 .  FIG. 8B  illustrates the securing means as described, incorporating two spaced apart screws  310  passing through apertures  312  in the second attachment side  142  and threadably received by collars  314  in the first attachment side  140 . In this embodiment, the screws  310  are positioned posterior from the spacer tray  150  and substantially within the diameter of the spacer tray  150 , to avoid interference with the vertebrae upon implant. However, any other locations may be used as desired. In addition, according to other embodiments, more than two screws can be used, or only one screw can be used. 
       FIG. 8C  illustrates another embodiment of a securing means used to tighten the opposing attachment sides  140 ,  142  on adjacent spinous processes. In this embodiment, two spaced apart worm drive mechanisms include two screws  410  (i.e., the worms) passing through two apertures  412  in the second attachment side  142  and operably engaging worm gearing  414 . The worm drive mechanisms are adapted to provide movement along the axis of the spacer tray  150  as a result of the rotational forces applied to screws  410  that are transferred to the adapted worm gearing  414 . In this embodiment, instead of a traditional worm gear, a portion of the inner surfaces are toothed complementary to the screws  410 . Thus, when the screws  410  operably engage the teeth of the worm gearing  414  on the surface of the spacer tray  150 , the screws&#39;  410  threading passes along the worm gearing and causes the second attachment side  142  to move along the spacer tray  150 . It is appreciated that, in other embodiments, the worm gearing  414  may be on any other surface of the spacer tray  150 , or worm gearing separate from the spacer tray  150  may be provided. For example, in one embodiment, one or more screws (e.g., the worms) may rotatably extend through the inner surface of the first attachment side  140  and extend through apertures in the second attachment side  142 . In this configuration, which is essentially reversed from the above-described worm drive mechanism, the worm screw extending along the axis of the spacer tray  150  is turned against a worm gear rotatably affixed to one of the attachment sides  140 ,  142 , causing the second attachment side  142  to move along the screws. Again, in any of these embodiments, two spaced apart worm drive mechanisms permit the independent tightening, and thus the “walking” effect when closing the attachment sides  140 ,  142  on the spinous processes. 
       FIG. 8D  illustrates a side view of another embodiment of a securing means used to tighten opposing attachment sides  140 ,  142  onto adjacent spinous processes. According to this embodiment, two spur gear mechanisms include gearing teeth  420  formed on the inner or outer surfaces of the spacer tray  150 , much like that described with reference to  FIG. 8C , and a shaft and gear  422  rotatably affixed to the outer surface of the second attachment side  142  that meshes with the gearing teeth  420  of the spacer tray. This embodiment behaves similar to a rack and pinion, whereby the gearing teeth  420  serve as a rack and the shaft and gear  422  serve as the pinion. Accordingly, turning each of the shaft and gears  422  causes the gears to operably mesh with the gearing teeth  420  and close the second attachment side  142  toward the first attachment side  140 . It is appreciated that, in one embodiment of a spur gear mechanism (or any other securing means embodiments described herein), the shaft and gears can include a one-way or reverse lock-out mechanism to only permit rotation or movement in one direction—that which results in tightening the attachment sides together, but restricts movement in the opposite direction. In some embodiments, the one-way or reverse lock-out mechanisms may be selectively actuated, such that an operator may release them (e.g., to reposition the device, to remove the device, etc.). 
     According to another embodiment, a mechanism configured in a manner similar to a rack and pinion is used. Instead of the gearing being integrated with a spacer tray, this embodiment includes a separate geared rack extending from the first attachment side  140  and slideably positioned within an aperture formed in the second attachment side  142 . The aperture can be sized to permit the geared rack to slide within the aperture. Also integrated or adapted with the second attachment side  142  is a shaft and gear that meshes with the geared rack. This embodiment behaves similar to a rack and pinion, whereby the shaft and gear serve as the pinion for the geared rack, advancing the second attachment side  142  along the geared rack when the shaft and gear is turned, rotated, or otherwise actuated. Any one-way or reverse lock-out mechanism to permit rotation or movement in only one direction optionally can be incorporated in the securing means embodiment. In one embodiment, the gearing on both the geared rack  440  and the shaft and gear are complementarily angled with respect to each other, which serves to hold the position of the shaft end gear against the geared rack when tightened and resists backing out or otherwise loosening by the attachment sides  140 ,  142  when secured in place. 
     In one embodiment the fit of the geared rack within the aperture is a relatively tight fit to reduce angular movement of the second attachment side  142  relative to the geared rack, which may serve to reduce the potential of cross-threading or otherwise preventing meshing of the shaft end gear with the geared rack. In other embodiments, however, the fit may be looser, allowing at least partial angular movement of the second attachment side  142  relative to the geared rack. A looser fit may be used to allow the attachment sides  140 ,  142  to be positioned at an angle (i.e., not exactly parallel to each other) to account for differences in the width of adjacent spinous processes. 
       FIG. 10  illustrates another embodiment of a securing means used to tighten the opposing attachment sides  140 ,  142  on adjacent spinous processes. In this embodiment, a worm drive mechanism is used, similar to that described with reference to  FIG. 8C . The worm drive mechanism according to this embodiment includes a threaded shaft  446  extending from the first attachment side  140  and passing through an aperture  448  in a second attachment side  142 . According to one embodiment, the threaded shaft  446  can be configured like a threaded bolt integrated with, and extending from, the interior surface of the first attachment side  140 . The threaded shaft  446  can be fixed to the first attachment side  140  (either integrated or bolted thereto). A worm gear nut  450  is threadably received by the threaded shaft  446  from the outside of the attachment side  142 , holding the second attachment side  142  on the threaded shaft  446 . The worm gear nut  450  includes teeth or gearing on its exterior surface which operably meshes with a screw  452  (or other threaded shaft operable for turning by an operator). The screw  452  acts as a worm, causing the worm gear nut  450  to rotate around the threaded shaft  446 , which in turn causes the worm gear nut  450  to tighten or loosen on the threaded shaft  446 . Accordingly, by rotating the screw  452 , such as by using a screwdriver or other instrument received by a head of the screw  452 , the worm gear nut  450  can be tightened over the threaded shaft  446 , causing the second attachment side  142  to tighten toward the first attachment side  140  over the threaded shaft  446  and a spacer tray (not shown to simplify this illustration). 
     In one embodiment, the fit of the threaded shaft  446  within the aperture  448  is a relatively tight fit to reduce angular movement of the second attachment side  142  relative to the threaded shaft  446 , which may serve to reduce the potential of cross-threading or otherwise interfering with the meshing of the screw  452  with the worm gear nut  450 . In other embodiments, however, the fit may be looser, allowing at least partial angular movement of the second attachment side  142  relative to the geared member, such as may be used to allow the attachment sides  140 ,  142  to be positioned at an angle (i.e., not exactly parallel to each other) to account for differences in the width of adjacent spinous processes. Although  FIG. 10  shows a particular orientation and placement of the threaded shaft  446  and the screw  452 , any other orientation and/or configuration may be used. 
     In yet another embodiment of a securing means used to tighten the opposing attachment sides  140 ,  142  on adjacent spinous processes. In this embodiment, a worm drive mechanism is also used, similar to that described with reference to  FIG. 10 . However, according to this embodiment, the threaded member extending between the first attachment side  140  and the second attachment side  142  is configured differently. In this embodiment, the threaded member includes a fixed worm gear head positioned on the end of the threaded member extending through the aperture in the second attachment side  142 . The fixed worm gear head is in a fixed relationship relative to the threaded member, and which does not thread or otherwise turn independent of the threaded member. The threaded member of this embodiment is further configured to be received by and threaded into a threaded receiver, as is shown in the top view cross-sectional illustration. A screw operably meshes with the fixed worm gear head, and is configured in the same or similar manner as is described with reference to  FIG. 10 . Accordingly, when turning the screw, the fixed worm gear head causes the threaded member to thread into or out of the threaded receiver of the first attachment side  140 , which in turn causes the first attachment side  140  to tighten toward the second attachment side  142 . 
     According to one embodiment, the threaded member has an at least partially tapered end (e.g., configured as a screw), which threads into and out of the threaded receiver. In one embodiment, a threaded member with a tapered end can self tap the threaded receiver; though, in other embodiments, the threaded receiver has complementary threads already formed therein. In other embodiments, the threaded member has a substantially straight shaft with a substantially constant diameter at or near its tip (e.g., configured as a bolt). As described above, the fit of the threaded member within the aperture may be a tight or loose fit. 
       FIGS. 11A-11D  illustrate yet another embodiment of a securing means used to tighten the opposing attachment sides  140 ,  142  on adjacent spinous processes. This embodiment includes a worm gear configuration, similar to those described with reference to  FIG. 10 . According to this embodiment, however, the threaded member  451  extending between the first attachment side  140  and the second attachment side  142  is configured differently. In this embodiment, the threaded member  451  also includes a fixed worm gear head  457  (which may also be referred to as a “gear” or “worm gear” fixed on the end of the threaded member  451  extending through an aperture in the second attachment side  142  and operably meshing with the screw  452 . 
     However, the threaded member  451  of this embodiment is further configured to be received by and threaded into a floating receiving member  459  retained on the exterior surface of the first attachment side  140 , as is shown in more detail in  FIG. 11C . The floating receiving member  459  includes a threaded orifice having threads complementary to the threads on the surface of the threaded member  451 . The floating receiving member  459  is retained on the exterior surface of the first attachment side  140  by one or more pivotable retention means  461 , such as, but not limited to, retaining tabs, flanges, hooks, or other members adapted to retain the floating receiving member  459  while still allowing pivoting, rocking, translational, and/or angular movement relative to the attachment side  140 . As illustrated in  FIG. 11C , the pivotable retention means  461  according to this embodiment includes flanges or tabs  461   a  extending from the floating receiving member  459  and cooperating flanges or tabs  461   b  extending from the first attachment side  140 , overlapping the floating receiving member  459 , and loosely fitting between the flanges or tabs  461   a , thus retaining the floating receiving member  459  in place. According to this embodiment, the flanges or tabs  461   a ,  461   b  prevent rotation of the floating receiving member  459  while threading it over the threaded member  451 , but still allow at least limited pivoting, rocking, and the like due to the loose fitment of, and play existing between, corresponding flanges or tabs  461   a ,  461   b . The floating receiving member  459  thus allows the first attachment side  140  to be angled relative to the threaded member  451  (or an axis existing between the two attachment sides  140 ,  142 ) so the attachment sides are not required to be implanted in parallel orientation relative to each other. Moreover, according to one embodiment, the floating receiving member  459  can include one or more slits formed at least partially along the length of the threaded portion, as shown in  FIG. 11C , for example, which allows spreading the threaded portion for quick insertion of the threaded member  451  therein and subsequently pressing the threaded portion thereby engaging the threads. In one embodiment having one or more slits, a quick release mechanism may be included that spreads the spacing between the slits and disengages the floating receiving member  459  from the threaded member  451 . In yet another embodiment, a floating receiving member  459  can include a threaded portion that is split and further includes a locking screw or other similar feature that will allow fast insertion and quick release of the device. 
     The securing means includes a screw  452  that operably meshes with the fixed worm gear head  457 , such that, when turning the screw  452 , the fixed worm gear head  457  causes the threaded member  451  to thread into or out of the floating receiving member  459 , which in turn causes the first attachment side  140  to tighten toward the second attachment side  142 . 
     As shown in  FIG. 11A , the securing means according to this embodiment optionally includes a casing  453  that at least partially (or entirely, as illustrated) encases the end of the threaded member  451  and the fixed worm gear head  457  extending from the surface of the second attachment side  142  and providing access to the screw  452 . The casing  453  can protect the surrounding tissue from irritation or injury that may be caused by the components protruding from the interspinous process spacing device. It is further appreciated that a casing similar to that illustrated in  FIG. 11A  may be included with any of the other embodiments described herein, such as in a similar manner to at least partially cover components protruding therefrom (e.g., extending from the first and/or the second attachment sides).  FIG. 11A  also shows at least one set screw  455  threadably extending through the casing  453  for engaging the threaded member  451  upon implantation (not shown for simplicity in  FIG. 11B ). In other embodiments, a set screw may not be included, but other securing mechanisms may be used to prevent rotation or movement of the threaded member  451  and the second attachment side  142  relative to each other after implant. 
       FIG. 11D  illustrates two interspinous process spacing devices  130 ,  132  implanted with adjacent spinous processes  120 ,  122 ,  124 . Although there is no overlap shown between the attachment sides of the two interspinous process spacing devices, it is appreciated that, in various embodiments, the attachment sides may overlap as further described herein. 
       FIGS. 12A-12B  illustrate a different configuration of a nut, which may be used to threadably receive a threaded member, like the threaded member  451  described with reference to  FIGS. 11A-11D , according to one embodiment. The hemispherical nut  463  may be formed to have a hemispherical shape (or other shape having an at least partially spherical or domed shape at its apex) for rotatably and pivotally fitting within a concave portion  465  of a first attachment side  140  of an interspinous process spacing device. Although not illustrated in  FIGS. 12A-12B , in one embodiment, the first attachment side  140  may further include means for retaining the hemispherical nut with the first attachment side, particularly during implantation, which may include, but is not limited to, one or more clips, flanges, tabs, cages, straps, bands, springs, screws, and the like. For example, according to one embodiment, the first attachment side  140  may further include one or more flanges or tabs similar to the flanges or tabs  461   b  described with reference to  FIG. 11C , which extend from the first attachment side to at least partially overlap the hemispherical nut  463 , without unduly constraining its motion. Similarly, the hemispherical nut  463  may also contain one or more tabs or one or more detents adapted to cooperate with the retaining means extending from the first attachment side  140 , which will prevent the hemispherical nut  463  from rotating when threading a threaded member therethrough, but still allow pivoting and rotation of the hemispherical nut  463 . 
     As shown in  FIG. 12A , in one embodiment, the hemispherical nut  463  may have one or more slits  467  formed at least partially through its body. The one or more slits  467  permit the hemispherical nut  463  to expand for rapid insertion of a threaded member and subsequent collapsing on the threaded member to engage and secure with complementary threads  469  formed through the hemispherical nut  463 . In one embodiment, the one or more slits  467  may be formed so as to extend only partially through the body of the hemispherical nut  463 , and may stop before reaching the exterior facing surface of the hemispherical nut  463 . Additional inward biasing or tightening members, such as, but not limited to, one or more bands, springs, screws, and the like, may optionally be included to bias or force the slits  467  together and around the threaded member. In another embodiment, as shown in  FIG. 12A , the hemispherical nut  463  may be formed from at least two portions  463   a ,  463   b  (e.g., two equal halves), which are connected at or near the exterior facing end of the hemispherical nut  463 . Any means may be used to connect the two (or more) portions  463   a ,  463   b  of the hemispherical nut  463 , such as, but not limited to, one or more screws, bolts, welding, tacking, clamps, bands, pins, flanges, tabs, springs, and the like. In one embodiment, one or more spring members may be contained between the two portions  463   a ,  463   b  such that the spring member biases the portions in a more separated or open position and will be compressed to a more closed position to engage the threads  469  with a threaded member when the hemispherical nut  463  is pushed into the concave portion  465  of the attachment side.  FIG. 4B  illustrates the first attachment side  140  from the interior side, showing the fitment of the hemispherical nut  463  within the concave portion  465 . In one embodiment, such as is shown by example in  FIGS. 4M and 4R , the receiving side of the hemispherical nut  463  at or near the apex is at least partially concave to guide and direct the threaded member into the receiving threads of the hemispherical nut. In another embodiment, a quick release mechanism may further optionally be included, which will act to separate the hemispherical nut  463  to allow for unimpeded or minimally impeded removal of the threaded member from the hemispherical nut  463 . 
       FIGS. 12C-12I  illustrate yet another embodiment of a floating receiving member configured as a hemispherical nut formed from two separate halves. In this embodiment, as shown in  FIG. 12C , a hemispherical nut  490  includes a first half  490   a  and a second half  490   b . According to this embodiment, the hemispherical nut  490  includes a concave portion  492  formed at its apex, which serves to guide and direct the threaded member into the receiving threads  469  of the hemispherical nut  490 .  FIG. 12D  illustrates the exterior facing side of the hemispherical nut  490  and means for retaining the two halves  490   a ,  490   b  together. According to this embodiment, two opposing sides are recessed, creating recessed portions  493  and first and second ridges  494   a ,  494   b  through which a combination of screws and springs are inserted to hold the two halves  490   a ,  490   b  together. Moreover, the recessed portions  493  provide a surface against which retaining tabs or other retaining means are placed to retain the hemispherical nut with the first attachment side, as further described with reference to  FIG. 12I . 
       FIG. 12E  illustrates a side view of the hemispherical nut  490  according to this embodiment. As shown by this side view, the second ridge  494   b  includes a pair (or any number) of aligned apertures  496  extending through the ridges  494   a ,  494   b . In one embodiment, each ridge  494   a ,  494   b  further includes an additional recessed lip  497  formed with one of the apertures  496  for receiving and retaining a spring that creates an inward biasing force for retaining the two halves  490   a ,  490   b  together. In this embodiment, only a single recessed lip  497  is formed on each ridge  494   a ,  494   b  such that one aperture  496  has a recessed lip  497  formed on the first ridge  494   a , and the other aperture  496  has a recessed lip  497  formed on the second ridge  494   b  and with the opposite. This allows for springs to be inserted on opposite sides of the ridges  494   a ,  494   b  and through different apertures, as shown in  FIG. 12I .  FIG. 12F  illustrates a side profile view of the hemispherical nut  490 , showing the slit formed between the two halves and the profile of the hemispherical shape and the ridges  494 . 
       FIGS. 12G-12I  illustrate a first attachment side  140  and the interoperability of the hemispherical nut  490  therewith, according to one embodiment.  FIG. 12G  shows the exterior-facing surface of the first attachment side  140 , which includes a concave portion  465 . The concave portion  465  allows the hemispherical nut  490  to be pivotally and rotatably housed therein, allowing for independent movement of the two attachment sides when implanted to account for different spinous process size and anatomy.  FIG. 12H  shows the interior facing side of the first attachment side  140  with the hemispherical nut  490  contained within the concave portion of the first attachment side  140 . As described above and as is shown in  FIG. 12H , the hemispherical nut  490  itself can further include a concave portion  492  that facilitates guiding a threaded member centrally into the threads  469  of the hemispherical nut  490 . 
       FIG. 12I  illustrates the exterior-facing surface of the first attachment side  140  having the hemispherical nut  490  retained therein. According to this embodiment, the first attachment side includes one or more retaining members  495  for retaining the hemispherical nut  490  within the concave portion  465  of the first attachment side  140 , such as, but not limited to, tabs, arms, flanges, bands, screws, and the like. In this embodiment, the retaining members  495  include two arms attached to the attachment side  140  and extending over the recessed portions  493  of each half of the hemispherical nut  490 . The retaining members  495  may be removably attached to the first attachment side  140 , such as via one or more screws and the like, or may be permanently affixed or integrated with the first attachment side  140 , such as if the hemispherical nut  490  and the first attachment side  140  were manufactured together, or if the hemispherical nut  490  is pressure fitted within the retaining members  495 . Moreover, in one embodiment, the retaining members  495  are not secured against the recessed portions  493 , but instead provide a loose fit of the hemispherical nut  490  within the attachment side  140  to allow rotating and pivoting. 
       FIG. 12I  also illustrates screws  498  and springs  499  inserted through the apertures  496  of the ridges  494   a ,  494   b . As is shown as one example configuration, the first ridge  494   a  includes one spring  499  fit within the recessed lip  497  and retained by a screw  498  extending through the set of apertures and both ridges  494   a ,  494   b . The second ridge  494   b  similarly includes one spring fit within the recessed lip  497  and retained by a screw  498  extending through the other set of apertures and through both ridges  494   a ,  494   b . According to this configuration, each screw  498  is inserted in opposite directions through the ridges  494   a ,  494   b , retaining a spring  499  on opposite sides of the hemispherical nut  490 . However, other screw  498  and spring  499  configurations may be provided, or in some embodiments, a spring may not be included. 
     It is appreciated that, according to other embodiments, any of the features described with reference to  FIGS. 12B-12I  may be included in any other embodiment described herein, and any other feature described herein may be included with the embodiments of  FIGS. 12B-12I . For example, a quick release mechanism may be included, other floating receiving member configurations may be used, and the like. 
       FIG. 12J  illustrates yet another embodiment of a securing means used to tighten the opposing attachment sides  140 ,  142  on adjacent spinous processes. This embodiment is configured similar to the embodiment illustrated in and described with reference to  FIG. 10 ; although, instead of an integrated shaft and gear to drive the nut, a removable instrument  460  is used to engage and rotate a geared nut  462  threaded over an end of the threaded shaft  446 . Because the instrument  460  is removable and not integrated with the interspinous process spacing device, an additional positioning track  464  is integrated with the second attachment side. The positioning track  464  guides the instrument  460  to align its geared tip  466  with the teeth extending from the surface of the geared nut  462 . Although the positioning track  464  is illustrated as being configured in an L shape, any other track configuration may be used. For example, in another embodiment, the positioning track  464  may be configured as a hole aligned to cause the geared tip  466  to mesh with the geared nut. Moreover, in one embodiment, the positioning track  464  may be formed with thick side walls to facilitate maintaining alignment of the instrument  460  within the positioning track and in a vertical (or other desirable) orientation by providing increased surface area to guide the instrument  460 . Accordingly, operably meshing the geared tip  466  of the instrument  460  with the geared nut  462  and turning the instrument causes the geared nut  462  to thread on and off of the threaded shaft  446 , moving the second attachment side  142  toward the first attachment side. 
     As described above, the fit of the threaded shaft  446  within the aperture of the second attachment side  142  may be a tight or loose fit. In addition, although  FIG. 12J  shows a particular orientation of the threaded shaft  446  and the positioning track  464 , any other orientation and/or configuration may be used. 
       FIG. 12K  illustrates yet another embodiment of a securing means used to tighten the opposing attachment sides  140 ,  142  on adjacent spinous processes. According to this embodiment, a geared rack  470  and a ratchet member  472  operate in a manner similar to known cable tie mechanisms. In this embodiment, the geared rack  470  extends from the first attachment side  140  through an aperture  474  formed through the second attachment side  142 . The second attachment side  142  includes a ratchet member  472  formed on at least one of its surfaces (shown on the outward-facing surface, but may be on the inward surface in other embodiments). The ratchet member  472  operably engages with the teeth on the geared rack  470  and permits movement in one direction—the direction toward the opposing attachment side  140 . The operation of the ratchet member  472 , however, restricts movement in the opposite direction (e.g., loosening of the attachment sides  140 ,  142 ). In one embodiment, a release mechanism may be included to selectively allow movement in the opposite direction. Accordingly, by tightening the second attachment side  142  toward the first attachment side  140 , the ratchet member  472  secures the position of the two sides relative to each other. In one embodiment, a separate insertion instrument (e.g., pliers-type device) is used to achieve enough mechanical advantage to tighten the attachment sides  140 ,  142  on the spinous processes. An example of such a clamping device is illustrated in and described with reference to  FIGS. 13-20  below. 
     According to one embodiment, the geared rack  470  may be slideably positioned through both an aperture  478  formed in the first attachment side  140  and the aperture  474  of the second attachment side  142 , having a head  476  on one end which will abut the outer surface of the first attachment side  140 . In one embodiment, the head  476  is domed on the side that will abut the attachment side (i.e., adjacent to the shaft), which permits the geared rack  470  to rotate at least partially within the aperture  478  and allow the two attachment sides  140 ,  142  to vary in their angular orientation relative to each other and relative to the geared rack  470 . In one embodiment, the aperture  478  of the first attachment side  140  is also beveled or bored to accommodate the domed shape of the geared rack  470 . Moreover, in one embodiment, the aperture  474  formed in the second attachment side  142  can form a relatively tight fit with the geared rack  470  to provide secure engagement of the ratchet member  472  against the geared rack  470 . An aperture  474  creating a tight fit causes the second attachment side  142  to have a substantially constant angular relationship with the geared rack  470  (e.g., perpendicular); however, a looser fit between the head  476  and the aperture  478  in the first attachment side  140  still allows relative angular variation between the two attachment sides (e.g., to accommodate different thicknesses of adjacent spinous processes). 
     In addition, although  FIG. 12K  shows a particular orientation of the geared rack  470  and the ratchet member  472 , any other orientation and/or configuration may be used. 
       FIG. 12L  illustrates yet another embodiment of a securing means used to tighten the opposing attachment sides  140 ,  142  on adjacent spinous processes. According to this embodiment, a geared cam  480  is actuated by a shaft and gear  482  operably meshed with the geared cam  480  to cause the lobe of the cam to exert a force against a second attachment side  142 , in turn causing it to move toward the first attachment side  140 . According to this embodiment, a track  484  (which may be a spacer tray or a separate track) extends from the first attachment side  140  and through an aperture  486  in the second attachment side  142 . The geared cam  480  is pivotally fixed to the track  484  via an axle running through the cam  480 . Thus, when the shaft and gear  482  is turned, the cam  480  rotates about the axle and the lobe of the cam  480  moves toward or away from the outer surface of the second attachment side  142 , causing the second attachment side  142  to move along the track  484  toward or away from the first attachment side  140 . 
     As described above, the fit of the track  484  (and/or spacer tray) within the aperture of the second attachment side  142  may be a tight or loose fit. In addition, although  FIG. 12L  shows a particular orientation of the geared cam  480 , the threaded member track  484 , and the shaft and gear  482 , any other orientation and/or configuration may be used. 
     Although not illustrated in every figure, any of those securing means illustrated may further include one or more set screws, securing the second attachment side  142  (or whichever attachment side slides over the spacer tray  150 ) to the spacer tray  150  or the geared rack, threaded member, threaded bolt, track, etc. when tightened to fix the relative location of the two attachment sides  140 ,  142 . A set screw assembly can extend from the outer surface of the second attachment side  142  and through which a set screw is threaded to exert pressure on, and thus to secure the attachment side  142  to, the spacer tray  150 . In other embodiments, more than one set screw assembly can be employed. Moreover, the orientation of the set screw assembly can vary. 
     In addition, although the embodiments illustrated show the securing means oriented as generally extending from the first attachment side  140  and through the second attachment side  142 , it is appreciated that in other embodiments the opposite configuration can be provided, in which the securing means extends from the second attachment side  142  and through an aperture formed through the first attachment side  140 . 
       FIGS. 13-20  illustrate embodiments of a separate insertion instrument (implant inserter)  1110  that is optionally used to exert a clamping pressure on each of the attachment sides  140 ,  142  when securing the interspinous process spacing device in place against the spinous processes. In one embodiment, the attachment sides  140 ,  142  may include apertures or indentations shaped and positioned to receive the working ends of the insertion instrument  1110 , such that the insertion instrument  1110  may grasp the attachment sides  140 ,  142 , and operable to facilitate aligning and maintaining the insertion instrument  1110  in position. Accordingly, once the two attachment sides  140 ,  142  are clamped in a closed configuration, the securing means  1120  (e.g., any of those illustrated in and described with reference to  FIGS. 1-12  and, optionally or alternatively, a set screw) is operated to secure the second attachment side  142  in place relative to the spacer tray  150  and the first attachment side  140 . It is appreciated that any insertion instrument  1110  suitable for applying a clamping force on opposite attachment sides may be used. 
     For example,  FIGS. 13-16  illustrate another embodiment of an insertion instrument  1130  having a different configuration. According to this embodiment, a second arm  1134  is removably attached to a first arm  1132  of the insertion instrument  1130 . Thus, during implantation, the first arm, which retains one of the first or the second attachment sides  140 ,  142 , is used to place the one side of the device against the spinous processes via an approximate lateral insertion angle, after which the second arm  1134 , which retains the other attachment side, is attached to the first arm and pivots to place the other attachment side against the opposite side of the respective spinous processes, also laterally from the opposite side. Thus, an insertion instrument  1130  according to this embodiment reduces the size of the incision by allowing positioning one attachment side first using a separated first arm  1132 . Otherwise, if the two arms  1132 ,  1134  are attached prior to implant, the insertion instrument  1130  has to open almost twice as wide to permit inserting both attachment sides laterally while the spinous ligament is still intact. 
       FIGS. 13-16  show an example surgical instrument system for implanting an interspinous process spacing device, having a first arm  1132  having a proximal end, an elongated central portion and distal end. The distal end has an interspinous process spacing device engagement element  1162  for posteriorly engaging a spacer plate or first attachment side  140  of the interspinous process spacing device having a spacer tray  150  extending inwardly therefrom. The surgical instrument system has a second arm  1132  having a proximal end, an elongated central portion and distal end, wherein the distal end has an interspinous process spacing device engagement element  1164  for posteriorly engaging a locking plate or second attachment side  1142  of the interspinous process spacing device having a spacer tray slot  135  therein for receiving the spacer tray  150 . 
     The surgical instrument system has a means for positioning the first arm  1132  and the second arm  1134  in alignment for securing the interspinous process spacing device onto spinal processes. As discussed in more detail below, the means for positioning the first arm  1132  and the second arm  1134  in alignment can be along any portion of the arms  1132 ,  1134 , including at a hinge in the central portion or by a connecting member at the proximal portion, such as a latch or ratchet. As can be seen in this embodiment, the proximal and distal ends of the arms  1132 ,  1134  are offset to provide an unobstructed view of the distal ends when a surgeon is holding the proximal ends. 
     In the illustrated embodiment of the surgical instrument system for implanting an interspinous process spacing device, each arm  1132 ,  1134  has an interspinous process spacing device engagement element  1162 ,  1164  which has an engagement projection  1170 ,  1180  which releasably engages an instrument receptacle on the attachment side  140 ,  142  respectively, of the interspinous process spacing device, a mount  1172 ,  1182  for movably holding the engagement projection, and an implant guide  1174 ,  1184  extending distally which engages the outer surface of the attachment sides of the interspinous process spacing device. 
     As shown in  FIGS. 13-16 , the engagement projections  1170 ,  1180  are threaded screws which rotatably ride in the mount  1172 ,  1182  for engagement with the separate attachment sides  140 ,  142  of the interspinous process spacing device. The threaded projections are controlled by thumbscrews  192 ,  194 , which can also be remotely operated by a ratchet or other rotatable tool. 
     In the illustrated embodiment, each arm  1132 ,  1134  permits at least one of an engaged attachment side  140 ,  142  of the interspinous process spacing device at least 5 degrees, or at least 10 degrees, and up to 30 degrees, of rotation about an axis defined by the engagement element  1174 ,  1184  on the distal end of the arm  1132 ,  1134 . This permitted wobble of each or both of the attachment sides allows for implanting the device onto spinous processes with varying shapes and contours prior to securing the desired relative orientation by engaging the securing means  320  (e.g., a set screw) onto the spacer tray  150 . 
     In the illustrated embodiment, the engagement projection  1180  on the second arm  1134  provides access to the securing means on the second attachment side  142  of the interspinous process spacing device to secure the second side  142  to the first side  142 . In the embodiment shown, the engagement projection  1180  includes a threaded screw which engages a reciprocal threaded instrument receptacle on the attachment side  142  of the interspinous process spacing device. However, the threaded screw on the second arm  1134  is cannulated to provide access therethrough to the securing means on the second attachment side  142  of the interspinous process spacing device to secure the second side  142  to the first side  140  while the second side  142  is engaged to the second arm  1134 . The cannulation permits a surgeon to use a separate securing instrument extending through the engagement element  1164  to secure the implantable device onto a spinous process. 
     In certain embodiments of the surgical instrument system for implanting an interspinous process spacing device, the size, shape or indicia on each of the insertion instrument receptacle on the first attachment side is different from the size, shape or indicia of the insertion instrument receptacle on the second attachment side. In a coordinated manner, the size, shape or indicia on the device engagement element  1162  corresponds to that of the first attachment side  140 , and is different from the size, shape or indicia on the device engagement element  1164  which corresponds to that of the second attachment side  142 . As shown the engagement element  1162  has a single laser etch mark to match the second attachment side  142 , and the engagement element  1164  has a double laser etch mark to match the first attachment side  140 . 
     In the illustrated embodiment, the proximal ends of the first and second arms  1132 ,  1134  are releasably connectable at more than one selected distance. In particular, the central portions of the first and second arms  1132 ,  1134  are releasably and rotatably connectable. In such embodiments, the second arm  1134  is removably and pivotally attachable to the first arm  1132  about an axis for positioning the first arm  1132  and the second arm  1134  in alignment for securing the interspinous process spacing device onto spinal processes. 
     As shown, the second arm  1134  further comprises a pivot member or pin  1137  located on the central portion, and the first arm  1134  further comprises a pivot channel or slot  1135  with a proximally oriented opening and a distally oriented curved retaining edge  1136 , such when the pin  1137  is slideably engaged in the slot  1135  against the retaining edge  1136  the first and second arms  1132 ,  1134  are removeably and pivotally attached to form a hinge, wherein the hinge permits positioning the first arm  1132  and the second arm  1134  in alignment for securing the interspinous process spacing device onto spinal processes. 
     In use, when the first and second arms  1132 ,  1134  each have a respective first and second attachment side  140 ,  142  of the interspinous process spacing device engaged thereto, and the first and second arms  1132 ,  1134  are attached at the hinge, drawing the proximal ends of the arms together will align and insert the spacer tray  150  into the spacer tray slot  210  of the first and second attachment sides  140 ,  142  of the interspinous process spacing device, for securing the interspinous process spacing device onto spinal processes. 
     As shown in  FIGS. 13-16 , the first arm  1132  further comprises a releasable locking mechanism for selectively securing the pin  1137  of the second arm  1164  into the slot  1135  of the first arm  1132 . In certain embodiments, the releasable locking mechanism is a leaf spring  1139  on the central portion of the first arm  1132  in blocking communication with the slot  1135 , such that the pin  1137  on the second arm  1164  can deflect the leaf spring  1139  during insertion into the slot  1135  and remain therein when the leaf spring  1139  returns to blocking communication to maintain the pin  1137  against the retaining edge  1136  on the first arm  1132 , and wherein the leaf spring  1139  can be manually disengaged from blocking communication with the slot  1135  to release the pin  1137  and separate the first and second arms  1132 ,  1134 . 
     As illustrated, the surgical instrument system for implanting an interspinous process spacing device has a means for mechanically actuating the insertion instrument to close and open the first arm  1132  and the second arm  1134  for tightening the second attachment side  142  relative to the first attachment side  140 . In certain embodiments, the means for mechanically actuating is a ratchet bar  1190  pivotally mounted to the proximal end of the second arm  1134  and selectively engageable to the proximal end of the first arm  1132 , wherein the ratchet bar  1190  has a plurality of teeth  1195  on the proximal surface thereof which engage a corresponding flange  1296  on the proximal end of the first arm  1132 . The ratchet bar  1190  has a threaded track and a nut  1192  riding thereon outside the proximal end of the first arm for mechanically forcing the proximal ends of the arms  1132 ,  1134  together. 
     According to the embodiment of  FIGS. 13-16 , the first arm  1132  may include a pivot channel  1135  which is at least partially open to receive and retain a pivoting member  1137  extending from the second arm  1134 . Although an angled pivot channel  1135  is illustrated, the pivot channel  1135  may be embodied in any number of other various shapes, configurations, and/or dimensions that allow removably attaching and securing the second arm  1134  to the first arm  1132  and that allow the two to pivot relative to each other. To attach the second arm  1134  to the first arm  1132  after one attachment side has been inserted into the patient, the pivoting member  1137  of the second arm  1134  is inserted into and guided through the pivot channel  1135  and rests at the distal end of the pivot channel  1135  where it is secured but allowed to pivot (e.g., similar to separable shears). Therefore, only the second arm  1134  is pivoted toward the first arm  1132  to insert the other attachment side, while the first arm  1132  remains stationary. 
     As can be seen in  FIGS. 24A-24C , the first arm  1132  may include a pivot channel  1135  which is angled at the opening to receive and retain a pivoting member  1137  extending from the second arm  1134  at a greater variety of angles, analogous to a funnel. The pivoting member  1137  of the second arm  1134  is also angled or chamfered in a manner to facilitate insertion into the pivot channel  1135  at a greater range of angles, in order to ultimately rest at the distal end of the pivot channel  1135  where it is secured but allowed to pivot. Thus, the second arm  1134  can be engaged with the first arm  1132  with a greater degree of variability by the user, due to the respective chamfer and funnel configurations, and then can be secured to pivot toward the first arm  1132  to insert the other attachment side, while the first arm  1132  remains stationary. 
     With reference to  FIGS. 17-20 , the present invention further provides an embodiment of a surgical instrument system for implanting an interspinous process spacing device, comprising a first arm  1232  having a proximal end, an elongated central portion and distal end, wherein the distal end has an interspinous process spacing device engagement element  1262  for posteriorly engaging a spacer plate or first attachment side  140  of the interspinous process spacing device having a spacer tray  150  extending inwardly therefrom. Such an embodiment also has a second arm  1234  having a proximal end, an elongated central portion and distal end, wherein the distal end has an interspinous process spacing device engagement element  1264  for posteriorly engaging a locking plate or second attachment side  142  of the interspinous process spacing device having a spacer tray slot  210  therein for receiving the spacer tray  150 . This embodiment further includes a compressor tool  1200  for positioning the first arm  1232  and the second arm  1234  in alignment for securing the interspinous process spacing device onto spinal processes. 
     As illustrated, the compressor tool  1200  has a proximal handle end a central portion and a distal pair of opposing tangs  1222 ,  1224  moveable throughout a range between an open position and a compression position. In certain embodiments, the distal end of each arm  1232 ,  1234  comprises compressor tool guide channels  1242 ,  1244  and compression point indentations  1246 ,  1248  therein for receiving the compressor tool tangs  1222 ,  1224 . In certain embodiments, the tangs  1222 ,  1224  have distal compressor tips  1252 ,  1254  extending inwardly for engagement within the corresponding guide channels  1242 ,  1244  and compression point indentations  1246 ,  1248  on the arms  1232 ,  1234 , wherein the compression tool  1200  can rotate about an axis defined by the compressor tips  1252 ,  1254  so as to provide a user with a range of approach angles for compressing the arms  1232 ,  1234  to secure the aligned interspinous process spacing device onto spinal processes. 
     In the illustrated embodiment of the surgical instrument system for implanting an interspinous process spacing device, the proximal end of the second arm  1234  further comprises a retaining latch  1280  disposable on the distal end of the first arm  1232  to retain the arms in position relative to each other and in alignment for securing the interspinous process spacing device onto spinal processes. The latch  1280  can have a series of corresponding indentations for engagement on the first arm  1232 . The retaining latch  1280  the proximal end of the second arm  1234  can also have a series of transverse interlinking members, in a ladder configuration, for the proximal end of the first arm  1232  to engage and lock at different spacing intervals. This ladder configuration permits more stability of the first and second arms  1232 ,  1234  of the instrument when engaged for single-handed use, while the other hand of the user is available for manipulating the compression tool  1200 . 
     In certain embodiments, the surgical instrument system for implanting an interspinous process spacing device has a means for mechanically actuating the insertion instrument to close and open the first arm  1232  and the second arm  1234  for tightening the second attachment side  142  relative to the first attachment side  140 . As shown, the means for mechanically actuating is a ratchet bar  1290  pivotally mounted to the proximal end of the second arm  1234  and selectively engageable to the proximal end of the first arm  1232 , wherein the ratchet bar  1290  has a plurality of teeth  1295  on the proximal surface thereof which engage a corresponding flange  1296  on the proximal end of the first arm  1232 . The ratchet bar  1290  has a threaded track and a nut  1292  riding thereon outside the proximal end of the first arm  1232  for mechanically forcing the proximal ends of the arms  1232 ,  1234  together. 
     The insertion instrument can further include a flattened surface at or near the pivot point of the instrument. The flattened surface is adapted for striking with a mallet or tamp during insertion of the device to seat each attachment side. It is appreciated that, while the flattened surface can be integrated with the first arm of the insertion instrument, in other embodiments, a flattened surface may be integrated with another portion of the insertion instrument; however, it may be desirable to orient the flattened surface substantially above the device when implanted. 
     Moreover, according to alternative embodiments, the insertion instrument can further include one or more channels or partial channels (e.g., C- or U-shaped channels, etc.) formed in at least one of the arms through or alongside of which a tightening instrument (e.g., a screwdriver) can be inserted to operate the securing means. For example, according to one embodiment, the first arm includes a channel running at least partially along the length of the first arm. The orientation of the channel directs the tightening instrument through the channel to align with the securing means. For example, if the securing means includes a screw or other rotating mechanism, the insertion instrument can be configured such that when aligned with and attached to the interspinous process spacing device, the first channel aligns with the head of the screw or other rotating mechanism. In other embodiments, one or more additional channels may be formed in an arm of the insertion instrument, such that the additional channel or channels align with a set screw used to fix the position of the second attachment side relative to the first attachment side. In yet another embodiment, a rotating channel, which may be formed as a sleeve that rotates around the axis of the first arm, and indexed to stop at the desired orientations, is used to align with both the securing means and the set screw. In other embodiments, a single channel may be used to align a tightening instrument by re-positioning the arm of the insertion instrument to achieve the desired alignment. 
     As shown in  FIGS. 13-16 , the distal portion of each of the arms  1132 ,  1134  of the insertion instrument  1130  further includes a retaining means  1162 ,  1164 , respectively, for grasping or otherwise retaining the respective attachment side during implantation. In one embodiment, the retaining means on the first arm  1132  includes a first peg having a non-circular cross-sectional shape, such that it is insertable into a correspondingly shaped orifice formed in the respective attachment side (e.g., the second attachment side  142 ) and provides a friction fit for retaining the attachment side to the first arm  1132 . The non-circular shape prevents the attachment side from rotating on the first arm  1132  during implantation. In this embodiment, the retaining means on the second arm  1134  may include a second peg or pin having a circular cross-sectional shape, which is also insertable into a correspondingly shaped orifice formed in the respective attachment side (e.g., the first attachment side  140 ). Thus, during implantation, while the second attachment side  142  is in a fixed orientation when retained by the insertion instrument  1130 , the first attachment side  140  can rotate, which allows for easier alignment of the spacer tray extending from the first attachment side  140  into the slot of the second attachment side  142  and alignment of the securing means (e.g., threaded member) extending from the second attachment side into the receiving means (e.g., floating nut or hemispherical nut) of the first attachment side. In some embodiments, the floating, rotating, and/or pivoting behavior of the receiving means (e.g., floating nut or hemispherical nut) and the advantageously shaped interior surfaces (e.g., a concave shape, etc.) improve the ability to align the spacer tray and/or securing means while bringing the two sides together. It is appreciated that any other means for retaining attachment sides by the insertion instrument  1130  may be included, such as, but not limited to, one or more clips, brackets, clamps, releasable straps, and the like. For example, in another embodiment, the distal ends of each arm  1132 ,  1134  may be formed in a C-shaped or bracket-shaped clamp, within which a respective attachment side is retained. 
     It is appreciated that the insertion instrument configurations described herein are provided for illustrative purposes, and that any other configuration and any other orientation relative to the interspinous process spacing device may be used. For example, according to one embodiment, tightening or clamping means similar to any of the securing means described, or any variation thereof, may be integrated with an insertion instrument and between the two arms. In this embodiment, after positioning an interspinous process spacing device to a patient&#39;s spinous processes, the tightening or clamping means may be used to tighten the device and secure it to the spinous processes, while other securing means on the device (e.g., those described, or simpler means, such as a set screw, ratchet, pin, screw, etc.) can be used to retain the device in its secured position. It is appreciated that, in some embodiments, clamping or tightening means integrated with a clamping instrument may differ from those described, and may include one or more screws, one or more ratchets, one or more levers, one or more geared mechanisms, and the like. 
     In addition, it may be advantageous to provide two different insertion instruments, one configured for an interspinous process spacing device being implanted in one orientation and the other configured for an interspinous process spacing device being implanted in the opposite orientation. According to some embodiments, as described herein, at least one arm of an insertion instrument may include features specifically designed to interface with a particular attachment side (e.g., the first retaining means  1162  configured specifically for retaining the second attachment side  142  and the second retaining means  1164  configured for retaining the first attachment side  140 , or the channel  1140  oriented to align with the worm gear screw of the securing means, etc.). Thus, without reconfiguring the orientation of these features and without changing the orientation of the handles, a physician would have to change sides of the patient when implanting devices having opposite orientations, which is very impractical and highly undesirable. For example, the screw driving the worm gear in the first and second interspinous process spacing devices are on one side, while the screw of the third interspinous process spacing device is on the opposite side. Accordingly, to prevent the physician from having to switch patient sides during implantation, a second insertion instrument can be formed as essentially the mirror image of the insertion instrument illustrated and described, such that the handles would be operated from approximately the same angle, but the features of the insertion instrument operably align with the device as designed. 
     However, in another embodiment, a universal insertion instrument may be provided, such that the retaining means extending from the distal ends of each arm of the instrument is configured to have substantially the same shape and orientation. Thus, the retaining means will integrate with either attachment side of an interspinous process spacing device, regardless of the device&#39;s orientation. For example, one way to achieve this universal fitment of the insertion instrument is with two pins extending from the distal ends of each attachment arm, the pins being configured the same on each arm. The first attachment side (e.g., the side that does not include the securing means, such as with a floating nut or other receiving member) can be configured with a complementary orifice for receiving one of the two pins while the other pin does not engage or interfere with the first attachment side. The second attachment side, however, can be configured with two complementary orifices such that the two pins are insertable into the two orifices. When installing the second attachment side, both pins are inserted therein, and when installing the first attachment side, only one pin is inserted while the other pin hangs free of the first attachment side. Thus, the operator need not switch between insertion instruments depending upon the orientation of the interspinous process spacing device being implanted. 
     The present invention also provides a surgical instrument for selecting an interspinous process spacing device, as exemplified in  FIGS. 21A-21D . The selection instrument  800  comprises a first arm  810  having a proximal end, an elongated central portion and distal end, wherein the distal end has a first interspinous process spacing measurement wing  814  extending therefrom comprising a first spinous process stop element  812  and a perpendicularly extending wing template  816 , a second arm  820  having a proximal end, an elongated central portion and distal end, wherein the distal end has a second interspinous process spacing measurement wing  824  extending therefrom comprising a second spinous process stop element  822  and a perpendicular wing template  826 . The first and second arms  810 ,  820  are pivotally attached about an axis  830  for positioning the first and second interspinous process spacing measurement wings  814 ,  824  to measure space between adjacent spinal processes. 
     The measurement device  800  can further comprise first and second wing templates  816 ,  826  adapted to overlap respective first and second adjacent spinal processes to determine space available on each spinous process for engaging an interspinous process implant. The instrument shown is adapted such that the proximal end of the second arm  820  has a measuring element  840  attached thereto with indicia to register length to the proximal end of the first arm  810 , wherein said length corresponds to space between adjacent spinal processes as measured by the first and second spinous process stop elements  812 ,  822 . Therefore, drawing the proximal ends of the arms  810 ,  820  together separates the wings  814 ,  824  to measure space between adjacent spinal processes. In one embodiment, the first or second wing template, or both, comprises a fastener template extending therefrom adapted to engage with a slot on an attachment side of an interspinous process spacing device previously implanted to determine space and orientation available for overlapping engagement of a link plate onto a base plate. 
       FIGS. 25A-25C  illustrate a rasping tool  1300  of the present invention for removing excess tissue from the interspinous space to prepare for insertion of an interspinous process implant. The rasping tool  1300  comprises a first arm  1310  having a proximal end, an elongated central portion and distal end, wherein the distal end has a first interspinous process stop element  1312 , extending therefrom, and a second arm  1320  having a proximal end, an elongated central portion and distal end, wherein the distal end has a second spinous process stop element  1322  extending therefrom. The first and second arms  1310 ,  1320  are pivotally attached about an axis  1330  for spreading apart the first and second interspinous process stop elements  1312 ,  1322  in order to remove successively larger areas of tissue from between adjacent spinal processes, in preparation for placing a spacer tray of the implant device therethrough. The tips of the interspinous process stop elements  1312 ,  1322  can be pointed and interface together in a split bullet configuration, as shown. The outside surfaces of the interspinous process stop elements  1312 ,  1322  can be configured with textured, abrasive, serrated, or sharpened features as shown for the removal of tissue by back-and-forth rasping movement of the tool  1300 . 
     As the proximal ends of the arms  1310 ,  1320  are brought together by the user, the interspinous process stop elements  1312 ,  1322  separate to create a larger rasping space. The rasping tool  1300  is also shown with the proximal end of the second arm  1320  adapted with a hinged latch and measuring element  1340  attached thereto with indicia to maintain and register the length to the proximal end of the first arm  1310 . The registered length on the hinged element  1340  corresponds to the space between adjacent spinal processes as measured by the outer surfaces of the first and second spinous process stop elements  1312 ,  1322 . The arms  1310 ,  1320  are maintained in position by the countervailing forces of a separation biasing element  1350  and the notched latch element  1340 . Therefore, drawing the proximal ends of the arms  1310 ,  1320  together separates the distal ends of the interspinous process stop elements  1312 ,  1322  to allow clearing and measurement of the space between adjacent spinal processes. When the desired interspinous space has been cleared by the rasp, the notched latch and measuring element  1340  can engage the arms  1310 ,  1320  together, and the numbered indicia on the element  1340  in turn corresponds to the suitable width size available from among the spacer trays provided by the invention, as shown in  FIGS. 6A and 6B , for optimization of indwelling implantation. 
       FIG. 1  illustrates further detail of a top perspective view of embodiments of interspinous process spacing devices implanted in an overlapping fashion.  FIG. 1  shows a first interspinous process spacing device  130  having substantially flat attachment sides  140 ,  142 , which is illustrated in  FIG. 1  as being the one inferiorly located device, such as any of the interspinous process spacing devices illustrated in and described with reference to  FIGS. 2-12 . In addition, according to some embodiments of the invention, a second (and subsequent) interspinous process spacing device  132  is implanted on adjacent spinous processes, which includes attachment sides  144 ,  146  having a bent configuration. According to one embodiment, the bent configuration is created by having a substantially flat end  148 , which, when implanted, will lie along approximately the same plane as the entire attachment side of the adjacent inferior interspinous process spacing device (e.g., the attachment sides  140 ,  142  of the first interspinous process spacing device  130  per  FIG. 1 ), and an offset end  149 , which will overlap the adjacent end of the inferior (or superior, though not illustrated in this manner) interspinous process spacing device. The offset of the offset end  149  can be approximately equal to, or slightly larger or smaller than, the thickness of the anticipated adjacent attachment side (e.g., the thickness of an attachment side  140 ,  142  of the first interspinous process spacing device  130 ). 
     Accordingly, at least one end of each attachment sides  140 ,  142  of the first interspinous process spacing device  130  and the offset end  149  of the second interspinous process spacing device  132  includes an integration means for integrating an offset end  149  of the second interspinous process spacing device  132  with a respective attachment side of the first interspinous process spacing device. The embodiment includes an integration means having one or more apertures  240  formed in the outer surface to receive at least a portion of fasteners  220  extending from the inner surfaces of the offset ends  149  of the respective attachment sides  144 ,  146 . The fasteners  220  of the offset ends extending through the apertures  240  can be interlocking posts or be extended sharpened bone fasteners, such as spikes, for engaging a spinous process through the aperture. The apertures  240  permit the attachment sides  144 ,  146  of the second interspinous process spacing device  132  to integrate and interlock with the attachment sides  140 ,  142  of the first interspinous process spacing device  130 . 
     According to one embodiment, the number of apertures  240  in the first interspinous process spacing device  130  equals the number of fasteners  220  extending from the second interspinous process spacing device  132 . However, in other embodiments, there may be more apertures  240  than fasteners  220  to allow for selective adjustment of the relative orientation of the two interspinous process spacing devices  130 ,  132  by selecting from multiple positions created by the various aperture locations  240 . Apertures may be provided in an overlapping or inch worm pattern for finer adjustments of spacing and angles between each pair of spacing plates. Moreover, in one embodiment, the apertures  240  and corresponding fasteners  220  may have a turning/locking configuration, such that the fasteners  220  can selectively lock (e.g., by turning, snapping, etc.) within the apertures  240  when in position. In addition, the apertures  240  may be sized and shaped larger than the diameter of the corresponding fasteners  220 , to permit adjusting the position and orientation of the second interspinous process spacing device  132  relative to the already secured first interspinous process spacing device  130 . In other embodiments, however, the apertures  240  may be any configuration. Moreover, in one embodiment, slots may not be provided, and the offset ends  149  of the attachment sides  144 ,  146  may not include fasteners, but instead may include a rough surface, or other suitable means to secure the two attachment sides. Although only a first and a second interspinous process spacing devices  130 ,  132 , in other embodiments additional interspinous process spacing devices may be added to the second interspinous process spacing device  132  in a similar manner to connect additional spinous processes. Each subsequent interspinous process spacing device would be configured similar to the second interspinous process spacing device  132 , including offset ends  149  to overlap with the flat ends  148  of the adjacent interspinous process spacing device. To permit adding another interspinous process spacing device to the second interspinous process spacing device  132 , the outer surfaces of the flat ends  148  of the attachment sides  144 ,  146  also include apertures  240  to receive fasteners, like those shown on the first interspinous process spacing device  130 , or any other integration means. Any number of interspinous process spacing devices can be integrated together, permitting fusing a number of spinous processes and providing increased structural integrity over individually and un-integrated known spinous process spacing devices. 
     For example, in one embodiment in which three interspinous process spacing devices are attached. In this embodiment, the first interspinous process spacing device has substantially flat attachment sides, and the second and third interspinous process spacing devices have bent attachment sides with offset ends for overlapping adjacent devices. In this embodiment, the first interspinous process spacing device is implanted, after which the second and third interspinous process spacing devices are implanted such that each overlaps with a different end of the first interspinous process spacing device (e.g., one implanted superior to and the other implanted inferior to the first interspinous process spacing device). As shown, the second and third interspinous process spacing devices are oriented 180 degrees relative to each other to allow the offset ends of the bent attachment sides to overlap the attachment sides of the first interspinous process spacing device, depending upon whether being attached superior to or inferior to the first interspinous process spacing device. Thus, rotating the subsequent interspinous process spacing devices, if necessary, avoids having to manufacture two different interspinous process spacing device configurations—one for attaching superior to a flat device and one for attaching inferior to a flat device. Because the location of the securing means may differ when an interspinous process spacing device is rotated, different insertion instruments may be provided to accommodate the differing orientations of the device components. 
     In another embodiment, in which a stub implant is provided, instead of a first interspinous process spacing device. The stub implant simply consists of two stub sides proportioned to engage a single spinous process, and not intended to span two adjacent spinous processes. Accordingly, instead of attaching a second interspinous process spacing device to a first device, it is attached to a stub implant. In operation, the second interspinous process spacing device and the stub implant are likely implanted together, as the two stub sides are secured by the pressure exerted by the second interspinous process spacing device. Like the other interspinous process spacing devices, the stub sides can also include fasteners extending from their inner surfaces for securing to the spinous process, and apertures formed in their outer surfaces for receiving fasteners of the overlapping interspinous process spacing device, or any other integration means. This embodiment may serve to reduce the manufacturing costs, requiring only a single design for the interspinous process spacing device, and smaller, much simpler design for the stub implant. 
       FIGS. 7A-7E  illustrate other example embodiments of an interspinous process spacing device that is configured for implanting at the L5-S1 vertebrae. As shown, an L5-S1 interspinous process spacing device  530  includes first and second attachment sides  540 ,  542 , each having an angled end  545  and an opposite flat end  547  with various spiked bone fasteners  525  extending inwardly. The angled ends  545  allow better fit with the anatomy of a patient&#39;s sacrum. In certain embodiments not shown, the angled ends may be further adjustable with respect to the central portion of the device to match the angle on the patient&#39;s sacrum. The L5-S1 interspinous process spacing device  530  may include any securing means, such as are illustrated in and described herein, and any integration means. Moreover, in a base plate embodiment such as that illustrated in  FIGS. 7A-7C  with apertures  550  in the flat end  547 , an additional interspinous process spacing link device can be implanted superior to the L5-S1 interspinous process spacing device  530  in an overlapping configuration by overlapping bent attachment sides of the superior interspinous process spacing device with the flat ends  547  of the L5-S1 interspinous process spacing device  530 . However, in a link plate embodiment such as that illustrated in  FIGS. 7D-7E , with fasteners  520  on an offset flat end  547 , the L5-S1 interspinous process spacing device  530  has bent attachment sides such that the ends opposite the angled ends  545  are offset and overlap flat ends of a superior interspinous process spacing device. In certain embodiments, the bone fasteners  525  extend from opposing plates toward the bone at different opposing points to reduce the risk of bone fracture. 
       FIG. 7B  illustrates a view of a second attachment side  542  of an L5-S1 interspinous process spacing device  530 . As shown, the angled end  545  of the second attachment side  542  may optionally include one or more apertures  550  for receiving one or more fastening means therethrough. Because the sacrum is typically more dense than spinous processes, one means to secure an L5-S1 interspinous process spacing device  530  to the sacrum includes fastening directly thereto through the one or more apertures  550 , such as via screws, set screws, and the like. In particular, an angled fastener  555  can be provided at an angle different from the angle at which other fasteners  525  extend. In some embodiments such as shown, the angled fastener  555  is a bone screw and the other bone fasteners  525  are bone spikes, although any combination of movable, immovable, or expandable bone fasteners can be used. 
       FIG. 7A  illustrates a side view of the interior surface of a second attachment side  542  of a L5-S1 interspinous process spacing device  530 . In this embodiment, one or more fasteners  525 , similar to the fasteners  225  described with reference to  FIG. 2A , extend from the interior of the angled end  545  of the L5-S1 interspinous process spacing device  530 . However, because of the orientation of the angled end  545  relative to the patient&#39;s sacrum, the fasteners  525  may extend at an angle other than 90 degrees (either acute or obtuse), such that they correctly engage the sacrum when tightening the two attachment sides together. It is appreciated that the second attachment side  542  is described and illustrated in detail by example, but that the first attachment side  540  may also include one or more apertures and one or more fasteners. 
     The integration means of certain embodiments includes a textured inner surface formed on the inner surface of the offset end and a textured outer surface formed on the outer surface of an adjacent flat end (on the same interspinous process spacing device or understood that the offset end of one interspinous process spacing device will overlap a portion of the flat end of an adjacent interspinous process spacing device). According to one embodiment, the textured inner surface has radially extending ridges arranged in a starburst or spoked pattern. Similarly, the textured outer surface can have one or more detents or nubs (or other surface patterns) approximately matching the radially extending pattern of the textured inner surface. The textured outer surface has multiple complementary detents to permit selective arrangement of the offset end in more than one position. It is appreciated that, while a radially extending pattern is described, any other textured surface may be applied to the inner and outer textured surfaces. 
     Moreover, according to one embodiment, the inner surface of the offset end may further include a pin extending inwardly, which can be at least partially inserted into one or more apertures formed in the outer surface of the flat end of the adjacent interspinous process spacing device. The pin can be positioned approximately in the center of the radially extending ridges and three apertures are formed in the flat end approximately in the center of the corresponding radial detents. It is appreciated that any number of pins and any number of apertures may be provided. Moreover, any other orientation of the pins and/or the apertures may be used. For example, according to another embodiment, the apertures may be formed in two dimensions to allow for both anterior/posterior and superior/inferior adjustment. 
     According to one embodiment shown in  FIG. 22A , an interspinous process spacing device is provided as a link wing plate with a first attachment side  2140  (and a corresponding second attachment side, not shown), whereby each attachment side includes an integrating extension fastener  2220 , or pin, extending inwardly therefrom. In this embodiment, the fastener  2220  is adjustably carried within an elongated fastener frame  2225  permitting movement from side-to-side to engage a slot in another interspinous process spacing device along a range of distances therefrom. In one embodiment, the fastener  2220  may be secured at a selected position within the fastener frame, such as by a set screw (not shown) on the outer surface thereof, and thereby at a selected distance away from an adjacent interspinous process spacing device.  FIG. 22B  is a side view of a base plate second attachment side  2142  with a single slot  2240  in each end thereof, such as for engaging an extension fastener  2220  of  FIG. 22A . 
     According to one embodiment shown in  FIG. 23A , an alternative interspinous process spacing device is provided as link wing plate with second attachment side  2342  (and a corresponding first attachment side, not shown), whereby each attachment side  2342  has an elongated slot  2340  to receive a fastener from an adjacent plate.  FIG. 23B  is a side view of an alternative base wing plate with second attachment side  2352  (and a corresponding first attachment side, not shown), whereby each attachment side  2342  has a pair of elongated slots  2340  to receive a fastener from an adjacent plate. In the embodiments shown in  FIGS. 23A and 23B , the slots  2340  are elongated to receive a fastener from a second interspinous process spacing device along a range of distances therein. Moreover, the slots  2340  may be narrowed by a clamping mechanism, such as an affixed advancing screw  2350 , and thereby tightened to secure a fastener received therein at a desired position. 
     According to one embodiment shown in  FIGS. 26A-H , an interspinous process spacing device  3130  is provided as a base plate with a first attachment side  3140  (and a corresponding second attachment side, not shown) for engaging either side of adjacent spinous processes. The first attachment side  3140  includes a spacer tray  3150  extending in a substantially perpendicular direction from the first attachment side  3140 . In use, the spacer tray  3150  may be received within a tray slot of the corresponding second attachment side, as described above with respect to other embodiments. The spacer tray  3150  is configured with surfaces to abut the spinous processes to maintain the spaced apart relationship of the spinous processes. Accordingly, the spacer tray  3150  acts to maintain a minimum distance between adjacent spinous processes to keep the vertebrae apart and relieve pressure on nerve tissue and/or facet joints. The first attachment side  3140  may include fasteners  3225 , such as teeth or barbs, for engaging the spinous processes and/or serving as integration means to engage the exterior surface of an adjacent interspinous process spacing device. The first attachment side  3140  also may include an integration means having one or more apertures  3240  formed in an outer surface to receive at least a portion of a fastener extending from an inner surface of a link plate type interspinous process spacing device. 
     The spacer tray  3150  is shaped to facilitate implantation between adjacent spinous processes and insertion into the tray slot of the corresponding second attachment side. For example, the spacer tray  3150  may have a reduced cross-sectional profile and a tapered width on the leading front edge, which eases insertion between the ligaments occupying the space between adjacent spinous processes. Accordingly, the spacer tray  3150  may be inserted between the ligaments without cutting due to its reduced, tapered, or flattened profile compared to larger, circular cross-sections of conventional devices. Moreover, as shown in  FIGS. 26C and 26H , the T-shaped cross section, with the bottom of the T extending medially or downward into the spine provides a supporting lift for the tip of the spacer tray  3150  off of the vertebrae and into the tray slot. Similarly, the tapering cross-section of the tip of the spacer tray into a rounded point facilitates insertion into the tray slot, as well as facilitating insertion through the ligaments. Finally, the arcuate longitudinal cross-section facilitates insertion when both attachment sides are engaged with an insertion tool and being drawn together in an arc. 
     The spacer tray  3150  also is configured to provide a robust connection between the first attachment side  3140  and the second attachment side to secure the desired relative orientation of the sides for fixation of the spinous processes. For example, the spacer tray  3150  may include a trough  3160  formed in a top surface of the spacer tray  3150 , and the trough  3160  may be able to receive part of a securing means extending through the second attachment side. As described above, the securing means may include a set screw extending through a central portion of the second attachment side and contacting the trough  3160  of the spacer tray  3150  received within the tray slot of the second attachment side. The trough  3160  may extend from a proximate end of the spacer tray  3150  adjacent the inner surface of the first attachment side  3140  to a distal end of the spacer tray  3150 . Additionally, the trough  3160  may be sloped upwardly from the proximate end toward the distal end, and the trough  3160  may run out toward the distal end. The sloped shape of the trough  3160  may be formed in a linear or arcuate manner. The trough  3160  may include angled sidewalls  3170  extending from the top surface of the spacer tray  3150  to the bottom of the trough  3160 . The angled sidewalls  3170  also may extend from the proximate end of the trough  3160  toward the distal end of the trough  3160 , and the angled sidewalls  3170  may taper inward as they extend toward the distal end of the trough  3160 . The trough  3160  further may include a plurality of grooves  3180  each extending along a width of the bottom of the trough  3160 . Accordingly, the grooves  3180  are perpendicular to the length of the trough  3160 . In some embodiments, the grooves  3180  may be formed by steps, graduations, serrations, or knurled ridges. 
     In use, the securing means extends through the second attachment side and is received partially within the trough  3160  of the spacer tray  3150 , which secures the first attachment side  3140  to the second attachment side. The angled sidewalls  3170  are configured to guide the securing means toward the bottom of the trough  3160 . Additionally, the angled sidewalls  3170  are configured to resist torsional and lateral loading of the connection between the securing means and the trough  3160 . Upon tightening of the securing means, the sloped configuration of the trough  3160  resists axial loading of the connection between the securing means and the trough  3160 . Therefore, the sloped configuration of the trough  3160  resists separation of the first attachment side  3140  and the second attachment side relative to one another. Finally, the grooves  3180  further increase the frictional resistance of the connection between the securing means and the trough  3160  and thus further resist separation of the first attachment side  3140  and the second attachment side relative to one another. Accordingly, the features of the trough  3160  provide a robust connection for securing the desired relative orientation of the sides for fixation of the spinous processes. 
     According to another embodiment shown in  FIGS. 27A and 27B , an interspinous process spacing device  4130  is provided as a base plate with a first attachment side  4140  (and a corresponding second attachment side, not shown) for engaging either side of adjacent spinous processes. As is shown, the first attachment side  4140  may be configured in a manner similar to the first attachment side  3140  described above and may include corresponding features, although certain differences in structure and function will be described below. The first attachment side  4140  includes a spacer tray  4150  extending in a substantially perpendicular direction from the first attachment side  4140 . In use, the spacer tray  4150  may be received within a tray slot of the corresponding second attachment side, as described above with respect to other embodiments. The spacer tray  4150  is configured with surfaces to abut the spinous processes to maintain the spaced apart relationship of the spinous processes. Accordingly, the spacer tray  4150  acts to maintain a minimum distance between adjacent spinous processes to keep the vertebrae apart and relieve pressure on nerve tissue and/or facet joints. The first attachment side  4140  may include fasteners  4225 , such as teeth or barbs, for engaging the spinous processes and/or serving as integration means to engage the exterior surface of an adjacent interspinous process spacing device. The first attachment side  4140  also may include an integration means having one or more apertures  4240  formed in an outer surface to receive at least a portion of a fastener extending from an inner surface of a link plate type interspinous process spacing device, as described above with respect to other embodiments. 
     As noted above, the first attachment side  4140  may be configured for contacting the adjacent spinous processes such that the fasteners  4225  engage and seed into the spinous processes for fixation of the associated vertebrae. In order to enhance such fixation, the wings  4155  of the first attachment side  4140  may have a medial-lateral thickness that varies along the height of the wings  4155  to accommodate the shape of the spinous processes. As is shown, each of the wings  4155  may have a substantially constant thickness along the upper portion  4160  of the wing  4155  and may have a lesser thickness along the lower portion  4170  of the wing  4155 . Specifically, along the lower portion  4170 , the inner surface of the wing  4155  may taper laterally toward the outer surface of the wing  4155  and away from the spacer tray  4150 . In this manner, the lower portions  4170  of the wings  4155  may accommodate the shape of the spinous processes which expand laterally about an interface with the lamina. In certain configurations, an angle α between the inner surface of the upper portion  4160  and the inner surface of the lower portion  4170  may be between 5 degrees and 15 degrees, between 15 degrees and 25 degrees, between 25 degrees and 35 degrees, between 35 degrees and 45 degrees, between 45 degrees and 55 degrees, between 55 degrees and 65 degrees, between 65 degrees and 75 degrees, or between 75 degrees and 85 degrees. It will be understood that the angle α of different configurations may be selected to match the angle of the vertebrae between which the interspinous process spacing device  4130  is implanted. 
     As is shown, some of the fasteners  4225  of the first attachment side  4140  may be positioned on the upper portions  4160  of the wings  4155 , and some of the fasteners  4225  may be positioned on the lower portions  4170  of the wings  4155 . Further, the fasteners  4225  positioned on the lower portions  4170  may be offset in the medial-lateral direction from the fasteners  4225  positioned on the upper portions  4160  to accommodate the shape of the spinous processes. Specifically, based on the offset of the fasteners  4225  and the shape of the spinous processes about the interface with the lamina, the wings  4155  may be configured such that the fasteners  4225  on the upper portions  4160  and the lower portions  4170  may engage and seed into the spinous processes at the same time. Accordingly, the wings  4155  of the first attachment side  4140  may be configured to achieve optimal fixation along the height of the spinous processes. 
       FIGS. 28A-28E  illustrate another embodiment of an interspinous process spacing device  4530  that may be configured for implanting at the lamina of the vertebrae or the sacrum. As is shown, the interspinous process spacing device  4530  may be generally configured in a manner similar to the interspinous process spacing device  530  described above and may include corresponding features, although certain differences in structure and function will be described below. The interspinous process spacing device  4530  includes first and second attachment sides  4540 ,  4542 , each having a first angled wing  4545  positioned on one end and a second angled wing  4547  positioned on an opposite end. As is shown, the first angled wing  4545  may be formed as a mirror image of the second angled wing  4547  across a midline of each of the first and second attachment sides  4540 ,  4542 . Alternatively, the first angled wing  4545  may be formed to have a first angle, and the second angled wing  4547  may be formed to have a second angle different from the first angle. The angled configuration of the wings  4545 ,  4547  may allow the first and second attachment sides  4540 ,  4542  to accommodate the shape of the patient&#39;s lamina or sacrum about the implantation site. In certain configurations, an angle β between the inner surface of the wings  4545 ,  4557  and the inner surface of the central portion of the attachment side may be between 5 degrees and 15 degrees, between 15 degrees and 25 degrees, between 25 degrees and 35 degrees, between 35 degrees and 45 degrees, between 45 degrees and 55 degrees, between 55 degrees and 65 degrees, between 65 degrees and 75 degrees, or between 75 degrees and 85 degrees. It will be understood that the angle β of different configurations may be selected to match the angle of the vertebrae between which the interspinous process spacing device  4530  is implanted. In certain embodiments not shown, the angled wings  4545 ,  4547  may be adjustable with respect to the central portion of the device to match the angle of the patient&#39;s lamina or sacrum and/or the spinous process of the L5 vertebra. 
     The interspinous process spacing device  4530  may include any securing means, such as are illustrated in and described herein, and any integration means. For example, various spiked bone fasteners  4525  may extend inwardly from each of the angled wings  4545 ,  4547 . In certain embodiments, the bone fasteners  4525  extend from opposing angled wings  4545 ,  4547  toward the bone at different opposing points to reduce the risk of bone fracture. As is shown, the bone fasteners  4525  may extend inwardly from the angled wings  4545 ,  4547  at an angle other 90 degrees (i.e., at an acute or obtuse angle), such that the bone fasteners  4525  seed into the sacrum and the spinous process of the L5 vertebra at an optimum angle to enhance fixation. Although in certain aspects, the embodiment shown in  FIGS. 28A-28E  has been described as being configured for implanting at the sacrum (i.e., the L5-S1 level), it will be appreciated that the interspinous process spacing device  4530  may be similarly configured to accommodate the shape of the vertebrae at other vertebral levels, including at the L3-4 and L2-3 levels. In this manner, such configurations may include angled wings  4545 ,  4547  and bone fasteners  4525  that are angled to optimize fixation at such levels. 
       FIGS. 29A-29C  illustrate yet another embodiment of an interspinous process spacing device  4730  that may be configured for implanting at the lamina of the vertebrae or the sacrum. As is shown, the interspinous process spacing device  4730  may be generally configured in a manner similar to the interspinous process spacing device  530  and the interspinous process spacing device  4130  described above and may include corresponding features, although certain differences in structure and function will be described below. The interspinous process spacing device  4730  includes first and second attachment sides  4740 ,  4542 , each having a straight wing  4745  positioned on one end and an angled wing  4747  positioned on an opposite end. As is shown, the straight wings  4745  may be fixed relative to the first and second attachment sides  4740 ,  4742 , respectively. In contrast, the angled wings  4747  may be movable relative to the first and second attachment sides  4740 ,  4742 , respectively. Specifically, as is shown in  FIGS. 29B and 29C , the angled wings  4747  may be configured to pivot in the medial-lateral direction about a pivot joint  4749 . In this manner, the pivotable configuration of the angled wings  4747  may allow the first and second attachment sides  4740 ,  4742  to accommodate the shape of the lamina or sacrum. In other embodiments not shown, both the straight wing  4745  and the angled wing  4747  may be configured to pivot in the medial-lateral direction about a pivot joint  4749 . In still other embodiments not shown, each of the first and second attachment sides  4740 ,  4542  may include a first angled wing  4747  positioned on one end and a second angled wing  4747  positioned on an opposite end, wherein both the first angled wing  4747  and the second angled wing  4747  may be configured to pivot in the medial-lateral direction about a pivot joint  4749 . 
     The interspinous process spacing device  4730  may include any securing means and any integration means, such as are illustrated in and described herein. For example, various spiked bone fasteners  4725  may extend inwardly from each of the straight wings  4745  and the angled wings  4747 . In certain embodiments, the bone fasteners  4725  extend from opposing straight wings  4745  and angled wings  4747  toward the bone at different opposing points to reduce the risk of bone fracture. As is shown, the bone fasteners  4725  may extend inwardly from the straight wings  4745  and the angled wings  4747  at an angle other 90 degrees (i.e., at an acute or obtuse angle), such that the bone fasteners  4725  seed into the lamina, the sacrum, or the spinous process at an optimum angle to enhance fixation. Although in certain aspects, the embodiment shown in  FIGS. 29A-29C  has been described as being configured for implanting at the sacrum (i.e., the L5-S1 level), it will be appreciated that the interspinous process spacing device  4730  may be similarly configured to accommodate the shape of the vertebrae at other vertebral levels, including at the L3-4 and L2-3 levels. In this manner, such configurations may include straight wings  4745 , angled wings  4747 , and bone fasteners  4725  that are angled and movable to optimize fixation at such levels. Moreover, in a base plate embodiment such as that illustrated in  FIGS. 29A-29C  with apertures  4750  formed in the straight wings  4745 , an additional interspinous process spacing link device can be implanted superior and inferior to the interspinous process spacing device  4730  in an overlapping configuration by overlapping bent attachment sides of the superior interspinous process spacing device with the straight wings  4745  of the L5-S1 interspinous process spacing device  4730 . 
     According to still another embodiment shown in  FIGS. 30A-30C , an interspinous process spacing device  4830  is provided as a link plate that may be configured for implanting at the lamina of the vertebrae or the sacrum. As is shown, the interspinous process spacing device  4830  may be generally configured in a manner similar to the link plate of the interspinous process spacing device  530  described above and may include corresponding features, although certain differences in structure and function will be described below. The interspinous process spacing device  4830  includes a second attachment side  4842  (and a corresponding first attachment side, not shown) for engaging either side of adjacent spinous processes. Moreover, as a link plate, the second attachment side  4842  is configured for attaching to a second attachment side of a superior interspinous process spacing device, such as the second attachment side  142  of the interspinous process spacing device  130 , as is shown. The second attachment side  4842  includes an angled wing  4845  positioned on one end and an offset flat wing  4847  positioned on an opposite end. The angled configuration of the angled wing  4845  may allow the second attachment side  4842  to accommodate the shape of the patient&#39;s sacrum. The offset configuration of the offset flat wing may allow the second attachment side  4842  to overlap the flat wing of the second attachment side  142 . 
     Similar to the link plate embodiments described above, the offset flat wing  4847  may include an integration means, such as a fastener  4820 , for integrating the offset flat wing  4847  with one of the apertures  240  of the second attachment side  142 . Upon integrating the fastener  4820  with one of the apertures  240 , the second attachment side  4842  may rotatable about the fastener  4820 . Accordingly, the second attachment side  4842  may be configured to rotate in the proximal-distal direction to allow the second attachment side  4842  to accommodate the shape of the sacrum. As is shown, the medial-lateral profile of the offset flat wing  4847  may be shaped to enhance the angle of rotation as compared to the offset flat wing  547  of the second attachment side  542  described above. Specifically, the top surface  4850  of the offset flat wing  4847  may have a greater taper angle such that the second attachment side  4842  may be rotated upward to a greater degree before contacting the center portion of the second attachment side  542 . In like manner, the bottom surface  4852  of the offset flat wing  4847  may have a greater taper angle such that the second attachment side  4842  may be rotated downward to a greater degree before contacting the center portion of the second attachment side  542 . Additionally, the bottom surface  4852  of the offset flat wing  4847  may define a notch  4854  to allow for an even further degree of downward rotation before contacting the center portion of the second attachment side  542 . In this manner, the second attachment side  4842  may provide greater flexibility in accommodating the shape of the lamina or the sacrum to achieve optimal fixation. Although in certain aspects, the embodiment shown in  FIGS. 30A-30C  has been described as being configured for implanting at the sacrum (i.e., the L5-S1 level), it will be appreciated that the interspinous process spacing device  4730  may be similarly configured to accommodate the shape of the vertebrae at other vertebral levels, including at the L3-4 and L2-3 levels. In this manner, such configurations may include angled wings  4845  and offset flat wings  4847  that are angled and rotatable to optimize fixation at such levels. Additionally, although the above-described embodiment has focused on the link plate second attachment side  4842  positioned inferior to the base plate, the features described also may be incorporated in a link plate first attachment side as well as an attachment side positioned superior to the base plate. 
       FIGS. 31A-31E  illustrate a rasp tool  4900  for preparing an implantation site for an interspinous process spacing device and also for selecting an appropriate size device to be implanted. The rasp tool  4900  includes a first arm  4910  having a proximal end, an elongated central portion and distal end, wherein the distal end has a first interspinous process spacing device measurement wing  4914  extending at a generally perpendicular angle therefrom. The rasp tool  4900  also includes a second arm  4920  having a proximal end, an elongated central portion and distal end, wherein the distal end has a second interspinous process spacing device measurement wing  4924  extending at a generally perpendicular angle therefrom. The first and second arms  4910 ,  4920  are pivotally attached about an axis defined by a pin  4930 . In this manner, the first and second interspinous process spacing device measurement wings  4914 ,  4924  may be positioned at an implantation site and separated by pivoting the first and second arms  4910 ,  4920  in order to measure a space between adjacent spinous processes. Based on this measurement, an appropriate size interspinous process spacing device may be selected. The rasp tool  4900  further may include biasing elements  4932 , such as leaf springs, configured to bias the first and second arms  4910 ,  4920  apart from one another such that he rasp tool  4900  is in a closed position. 
     As is shown, the first interspinous process spacing device measurement wing  4914  is formed as an elongated member including a sharp tip  4916  configured to ease insertion of the wing  4914  into the implantation site. The first interspinous process spacing device measurement wing  4914  also includes a cutout  4918  adjacent the sharp tip  4916  configured for receiving the second interspinous process spacing device measurement wing  4924  when the wings  4914 ,  4924  are in a closed position. Additionally, the first interspinous process spacing device measurement wing  4914  includes a plurality of grooves  4919  formed along an outer surface of the wing  4914  and configured for debriding and preparing the implantation site. The second interspinous process spacing device measurement wing  4924  is formed as an elongated member including a tapered tip  4926  configured for mating within the cutout  4918  of the first interspinous process spacing device measurement wing  4914 . The second interspinous process spacing device measurement wing  4924  also includes a plurality of grooves  4929  formed along an outer surface of the wing  4924  and configured for debriding and preparing the implantation site. In this manner, the wings  4914 ,  4924  may be used as a rasp for contouring bone and tissue about the implantation site to receive the interspinous process spacer device. 
     The rasp tool  4900  further may include a measurement element  4940  attached to the proximal end of the first arm  4910  and configured to engage the proximal end of the second arm  4920 . As is shown, the measurement element  4940  may be formed as a rack including teeth  4944  defined in a distal side of the measurement element  4940  and configured to engage the second arm  4920 . The measurement element  4940  also may include predetermined measurement indicia positioned on the proximal side of the measurement element  4940  and configured to correspond to a lateral spacing of the wings  4914 ,  4924  at a given position of the first and second arms  4910 ,  4920 . In this manner, as the first and second arms  4910 ,  4920  are pivoted relative to one another and the wings  4914 ,  4924  are separated or drawn together, the measurement element  4940  will indicate the lateral spacing or overall width of the wings  4914 ,  4924 . Accordingly, the rasp tool  4900  may be used to measure the width of the implantation site between adjacent spinous processes, and thus may be used to select an appropriate size interspinous process spacer device to be implanted. 
     According to another embodiment shown in  FIGS. 32A-E , an interspinous process spacing device  5130  is provided as a base plate with a first attachment side  5140  (and a corresponding second attachment side, not shown) for engaging either side of adjacent spinous processes. As is shown, the first attachment side  5140  may be configured in a manner similar to the first attachment side  3140  described above and may include corresponding features, although certain differences in structure and function will be described below. The first attachment side  5140  includes a spacer tray  5150  extending in a substantially perpendicular direction from the first attachment side  5140 . In use, the spacer tray  5150  may be received within a tray slot of the corresponding second attachment side, as described above with respect to other embodiments. The spacer tray  5150  is configured with surfaces to abut the spinous processes to maintain the spaced apart relationship of the spinous processes. Accordingly, the spacer tray  5150  acts to maintain a minimum distance between adjacent spinous processes to keep the vertebrae apart and relieve pressure on nerve tissue and/or facet joints. The first attachment side  5140  may include fasteners  5225 , such as teeth or barbs, for engaging the spinous processes and/or serving as integration means to engage the exterior surface of an adjacent interspinous process spacing device. The first attachment side  5140  also may include an integration means having one or more apertures  5240  formed in an outer surface to receive at least a portion of a fastener extending from an inner surface of a link plate type interspinous process spacing device, as described above with respect to other embodiments. 
     The first attachment side  5140  further may include fasteners  5235  configured for retaining a bone matrix  5300  (shown via phantom lines) or other bone-growth-promoting material and positioning the bone matrix  5300  during implantation of the interspinous process spacing device  5130  to promote bone growth between the adjacent spinous processes. The fasteners  5235  may be positioned about the inner surface of the first attachment side  5140  and configured for retaining the bone matrix  5300  against the inner surface. In this manner, upon implantation of the interspinous process spacing device  5130 , the bone matrix  5300  may be positioned at least partially between the adjacent spinous processes to promote bone growth. As is shown, the fasteners  5235  may be positioned about the inner surface of the central portion  5160  of the first attachment side  5140 . According to various configurations, one or more of the fasteners  5235  additionally or alternatively may be positioned about the inner surfaces of the wing portions  5155  of the first attachment side  5140 . The fasteners  5235  may be formed as hooks, spikes, teeth, or barbs configured for engaging the bone matrix  5300  and resisting migration of the bone matrix  5300  away from the first attachment side  5140 . 
     As is shown, the fasteners  5235  may include one or more upper fasteners  5240  and one or more lower fasteners  5245  configured for retaining at least a portion of the bone matrix  5300  therebetween. The upper fasteners  5240  may extend inwardly from the inner surface of the first attachment side  5140 , and the lower fasteners  5245  may extend upwardly from the top surface of the spacer tray  5150 . In this manner, the upper fasteners  5240  and the lower fasteners  5245  may define a space therebetween for retaining at least a portion of the bone matrix  5300 . According to this configuration, the spacer tray  5150  also may facilitate retention of the bone matrix  5300  by preventing downward migration of the bone matrix  5300 . As is shown in  FIGS. 32A-E , the upper fasteners  5240  may be formed as hooks including an angled tip portion pointing toward the spacer tray  5150 , and the lower fasteners  5245  may be formed as hooks including an angled tip portion pointing toward the first attachment side  5140 . According to another embodiment shown in  FIGS. 33A-E , the upper fasteners  5240  may be formed as hooks including an angled tip portion pointing toward the spacer tray  5150 , and the lower fasteners  5245  may be formed as angled spikes pointing toward the first attachment side  5140 . Other configurations of the fasteners  5235  are possible, such as where only the upper fasteners  5240  are included and opposing retention forces are provided by the top surface of the spacer tray  5150 , or where only the lower fasteners  5245  are included and opposing retention forces are provided by the inner surface of the first attachment side  5140 . Additionally, according to certain configurations, the first attachment side  5140  may include multiple sets of fasteners  5235  in addition to the upper fasteners  5240  and the lower fasteners  5245  shown. For example, additional sets of fasteners  5235  may extend from the inner surface of the first attachment side  5140  and/or from the top surface of the spacer tray  5150 . Such fasteners  5235  may include various combinations of hooks, spikes, teeth, or barbs. Further, although the fasteners  5235  are described herein with respect to the first attachment side  5140 , the second attachment side additionally or alternatively may include the fasteners  5235  configured in a similar manner for retaining the bone matrix  5300 . 
     The bone matrix  5300  or other bone-growth-promoting material used with the interspinous process spacing device  5130  may be formed of natural bone or various synthetic materials having osteoconductive and/or osteoinductive properties to promote bone growth. For example, the bone matrix  5300  may be a demineralized bone matrix or a synthetic bone graft substitute, such as a bone putty. The bone matrix  5300  may be substantially malleable and thus may conform to the features of the interspinous process spacing device  5130 , such as the fasteners  5235 , to facilitate retention of the bone matrix  5300  during implantation of the interspinous process spacing device  5130 . Further, the bone matrix  5300  may conform to the geometry of the adjacent spinous processes and may fill voids between the interspinous process spacing device  5130  and the spinous processes. The fasteners  5235  may engage the bone matrix  5300  by penetrating corresponding surfaces of the bone matrix  5300 . Specifically, the upper fasteners  5240  may penetrate the outer side surface of the bone matrix  5300 , and the lower fasteners  5245  may penetrate the bottom surface of the bone matrix  5300 , as is shown. The size of the bone matrix  5300  may be selected depending upon the size of the interspinous process spacing device  5130  as well as the geometry of the vertebrae between which the interspinous process spacing device  5130  is implanted. According to certain configurations, the bone matrix  5300  may have a height substantially equal to the distance from the top surface of the spacer tray  5150  to the top surface of the central portion  5160  of the first attachment side  5140 . As is shown, the bone matrix  5300  may have a width substantially equal to the width of the spacer tray  5150 , for example, between 5 mm and 20 mm. Further, the bone matrix  5300  may have a depth in the medial-lateral direction between 5 mm and 20 mm. 
     According to certain configurations, surfaces of the interspinous process spacing device  5130  may be formed in a manner to promote bone growth thereabout. For example, surfaces of the first attachment side  5140  and the second attachment side may roughened, scored, etched, or otherwise textured to promote bone growth between and around the features of the surfaces. Such surface texturing may be present on the inner surfaces of the attachment sides, the spacer tray  5150 , the fasteners  5225 , and/or the fasteners  5240 , according to various configurations. 
     The interspinous process spacing devices and any associated components may be made of any suitable biocompatible material, including, but not limited to, metals, resorbable ceramics, non-resorbable ceramics, resorbable polymers, non-resorbable polymers, and/or any combination and/or alloys thereof. Some specific examples include stainless steel, titanium and its alloys including nickel-titanium alloys, tantalum, hydroxylapatite, calcium phosphate, bone, zirconia, alumina, carbon, bioglass, polyesters, polylactic acid, polyglycolic acid, polyolefins, polyamides, polyimides, polyacrylates, polyketones, fluropolymers, and/or other suitable biocompatible materials and/or combinations thereof. 
     In use, an example method of implanting at least two interspinous process spacing devices can be understood with reference to  FIGS. 1-23 . In one embodiment, after gaining access to the surgical implantation site, and removing all necessary tissue, the second attachment side  142  of a first interspinous process spacing device  130  is attached to a securing means  1162  of the first arm  1132  of an insertion instrument  1130  prior to attaching the second arm  1134  to the insertion instrument  1130 . The first arm  1132  is used to position the second attachment side  142  against one side of two adjacent spinous processes. Because of the reduced profile of the securing means, such as the threaded member  451  used in a worm gear securing means, the second attachment side  142  may be more easily inserted from a lateral direction through ligaments existing between the two spinous processes (although, the device may also be inserted by removing all or a substantial portion of the ligaments and inserted directly from the posterior direction). The second attachment side  142  may further be seated by striking a flattened surface of the insertion instrument  1130  with a mallet or tamp. The first attachment side is then attached to the securing means  1164  of the second arm  1134  of the insertion instrument  1130 , and the second arm  1134  is pivotally attached to the first arm  1132 . The physician then squeezes the handles of the insertion instrument  1130  to pivot the first attachment side  140  in place against the opposite side of the same two spinous processes, inserting the spacer tray  150  through the ligaments and aligning with its tray slot  210  on the second attachment side  142 , while also operably aligning the securing means extending from the second attachment side  142  with the corresponding receiving member on the first attachment side  140 . In one embodiment, a punch instrument may first be used prior to inserting either or both of the first and second attachment sides,  140 ,  142  to remove a portion of the ligaments to facilitate insertion and alignment of the attachment sides  140 ,  142 . The punch instrument may operate in a manner similar to the insertion instrument  1130 , but include a punch (or may simply dilate) that laterally passes through and removes the ligaments when the handles are squeezed together. The two attachment sides  140 ,  142  are pushed together enough to engage the securing means (e.g., worm screws meshing with the worm gearing, screws through a threaded collar, or shaft and gear meshing with the gearing/rack, etc.). Then, to tighten the attachment sides  140 ,  142  relative to each other, the operator can operate the securing means (e.g., turn the screw to operate the worm drive mechanism). Because of the ability of each attachment side  140 ,  142  to pivot relative to the other, the interspinous process spacing device  130  can be tightened against the spinous processes, irrespective of the possible varied thicknesses of each spinous process. Once in a tightened configuration, a set screw assembly may optionally be set to secure the second attachment end  142  to the spacer tray  150 . It is appreciated that other insertion instrument embodiments may be used to position and implant an interspinous process spacing device, such as one in which a securing means (e.g., gearing, worm gear, screw, ratchet, etc.) is integrated as part of the insertion instrument, instead of, or in addition to, being integrated with the interspinous process spacing device. Thus, in this embodiment, the tightening can at least partially be achieved by operating securing means of the insertion instrument instead of on the device to both tighten and loosen the insertion instrument. 
     To implant a second (or subsequent) interspinous process spacing device  132 , the same steps are repeated with the exception of aligning the integration means (e.g., fasteners, apertures, domes, pins, etc.) on the inner surfaces of the offset ends  149  (or a straight member) with the outer surfaces of the respective attachment ends of the adjacent interspinous process spacing device  130 . 
     Modifications and variations of the devices and methods described herein will be obvious to those skilled in the art from the foregoing detailed description. Such modifications and variations are intended to come within the scope of the appended claims and the example inventions described herein.