Patent Publication Number: US-10765526-B2

Title: Disk fusion implant

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. Pat. No. 10,039,647, issued Aug. 7, 2018 (U.S. patent application Ser. No. 14/191,954, filed Feb. 27, 2014), which is a continuation of U.S. Pat. No. 8,696,753, issued Apr. 15, 2014 (U.S. patent application Ser. No. 13/463,041, filed May 3, 2012), which is a continuation of U.S. Pat. No. 8,197,548, issued Jun. 12, 2012 (U.S. patent application Ser. No. 12/118,503, filed May 9, 2008), which is a continuation-in-part of U.S. Pat. No. 7,922,767, issued Apr. 12, 2011 (U.S. patent application Ser. No. 11/774,584, filed Jul. 7, 2007), all of which are herein incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     1. Field 
     The present invention relates generally to implantable prostheses and in particular to a spinal implant strip including a selectively applied bone growth promoting agent. 
     2. Description of Related Art 
     Spinal fusion implants have been previously proposed. In some cases, spinal fusion implants are embedded between adjacent vertebrae, partially or fully replacing the tissue disposed between the vertebrae. 
     One type of spinal fusion implant is the threaded spinal implant (commonly referred to as a spinal cage). This type of prosthesis is disclosed in Michelson (U.S. Pat. No. 6,264,656), the entirety of which is incorporated by reference. The threaded spinal implant is inserted between two adjacent vertebrae and is incorporated into the fusion of the bone along this portion of the spine. 
     Brantigan (U.S. Pat. No. 4,834,757) discloses plugs, used as spinal fusion implants, the entirety of which is incorporated by reference. The plugs are rectangular with tapered front ends and tool receiving rear ends. Generally, the plugs may be used in a similar manner to the spinal cages of Michelson. As with the spinal cages, the plugs may be inserted between adjacent vertebrae. The plugs may include nubs that behave like teeth, countering any tendency for the plugs to slip between the vertebrae. 
     Generally, the spinal fusion implants disclosed require invasive surgery for implantation. Furthermore, these spinal fusion implants rigidly fix two adjacent bones together and do not allow for any motion. There is a need in the art for a type of spinal fusion implant that may be implanted through a minimally invasive procedure. There is also a need for fusion implants that can potentially accommodate motion. 
     SUMMARY 
     Modifications for an implant strip for implantation is disclosed. In one aspect, the invention provides a spinal prosthesis, comprising: an implant strip configured for insertion between two vertebrae; the implant strip comprising a first portion having a first axial height and a second portion having a second axial height; and where the first axial height is greater than the second axial height. 
     In another aspect, the implant strip includes an edge that has a coiled shape selected from the group consisting essentially of a wedge shape, a convex shape, and a concave shape. 
     In another aspect, the first portion is associated with a crest of the implant strip. 
     In another aspect, the second portion is associated with a trough of the implant strip. 
     In another aspect, the second portion is a first end of the implant strip associated with an inner coil. 
     In another aspect, the first portion is a second end of the implant strip associated with an outer coil. 
     In another aspect, the first portion is a first end of the implant strip associated with an inner coil. 
     In another aspect, the second portion is second end portion of the implant strip associated with an outer coil. 
     In another aspect, the invention provides a spinal prosthesis, comprising: an implant strip configured for insertion between two vertebrae; the implant strip forming a first coil and a second coil; a separating portion disposed the first coil and the second coil; and where the separating portion contacts the first coil and the second coil. 
     In another aspect, the separating portion comprises a plurality of protrusions on a first surface of the implant strip. 
     In another aspect, the protrusions are associated with corresponding divots on an opposing second surface of the implant strip. 
     In another aspect, an opposing second surface of the implant strip is substantially smooth. 
     In another aspect, the separating portion is a polymer. 
     In another aspect, the thickness of the polymer varies over the length of the implant strip. 
     In another aspect, the invention provides a spinal prosthesis, comprising: an implant strip configured for insertion between two vertebrae; the implant strip comprising an edge; and where the edge includes a plurality of teeth. 
     In another aspect, the edge is an upper edge. 
     In another aspect, the edge is a lower edge. 
     In another aspect, a plurality of teeth is disposed on an upper edge and a lower edge. 
     In another aspect, the teeth have a configuration selected from the group consisting essentially of a saw-toothed shape, a rounded shape, a substantially dull shape, a substantially sharp shape, irregularly spaced teeth, and/or regularly spaced teeth. 
     In another aspect, the invention provides a spinal prosthesis, comprising: a dual implant strip configured for insertion between two vertebrae, the dual implant strip further comprising a first implant strip and a second implant strip; and a spacer portion is disposed between the first implant strip and the second implant strip and wherein the spacer portion is configured to attach the first implant strip to the second implant strip. 
     In another aspect, the spacer portion is made of a material different than a material of the first implant strip. 
     In another aspect, the invention provides a spinal prosthesis, comprising: a layered implant strip configured for insertion between two vertebrae, the layered implant strip further comprising a plurality of implant strips and a plurality of spacer portions; and where a spacer portion from the plurality of spacer portions is disposed between each pair of adjacent implant strips from the plurality of implant strips. 
     In another aspect, the invention provides a spinal prosthesis, comprising: an implant strip including a first shape and a second shape and wherein the first shape is different than the second shape; the implant strip having the first shape prior to insertion; and where the implant strip transforms from the first shape to the second shape following the application of a signal. 
     In another aspect, the signal is selected from the group consisting essentially of heat signals, chemical signals, mechanical signals, and electrical signals. 
     In another aspect, the invention provides a spinal prosthesis configured for insertion between two adjacent vertebrae, a first vertebrae and a second vertebrae, comprising: an implant strip including a lateral dimension extending from a first lateral side portion to a second lateral portion, and wherein the implant strip includes a longitudinal dimension extending down the length of the implant strip; and where the first lateral side of the implant strip is configured to engage the first vertebrae and wherein the second lateral side of the implant strip is configured to engage the second vertebrae; the implant strip having a pre-formed shape comprising a first longitudinal portion of the implant strip forming a first inner coil and a second longitudinal portion of the implant strip forming a second outer coil; and where the implant strip has the pre-formed shape prior to implantation. 
     In another aspect, the implant strip includes n coils and wherein n can be any real number greater than 1. 
     Other systems, methods, features, and advantages of the invention will be, or will become, apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description and this summary, be within the scope of the invention, and be protected by the following claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. 
         FIG. 1  is an isometric view of a preferred embodiment of a patient undergoing surgery; 
         FIG. 2  is a plan view of a preferred embodiment of an intervertebral disc; 
         FIG. 3  is a schematic view of a preferred embodiment of a healthy intervertebral disc and an intervertebral disc that has degenerated; 
         FIG. 4  is a plan view of a preferred embodiment of an implant strip; 
         FIG. 5-1  is a cross sectional view of a preferred embodiment of an implant strip with a bone growth promoting agent applied to the surface; 
         FIG. 5-2  is a cross sectional view of a preferred embodiment of an implant strip with a bone growth promoting agent that is selectively applied to the surface; 
         FIG. 6  is a plan view of a preferred embodiment of an intervertebral disc with a surgical tool and a dual catheter inserted; 
         FIG. 7  is a plan view of a preferred embodiment of an intervertebral disc with an implant strip being inserted; 
         FIG. 8  is a plan view of a preferred embodiment of an implant strip fully inserted; 
         FIG. 9  is a plan view of a preferred embodiment of an intervertebral disc including three implant strips; 
         FIG. 10  is a plan view of a preferred embodiment of an intervertebral disc with a corrugated implant strip inserted; 
         FIG. 11  is a schematic view of a preferred embodiment of an implant device in a pre-deflection state and a post-deflection state; 
         FIG. 12  is a schematic view of a preferred embodiment of an implant device undergoing bending; 
         FIG. 13  is a schematic view of a preferred embodiment of an implant device undergoing translation; 
         FIG. 14  is a schematic view of a preferred embodiment of an implant device undergoing twisting; 
         FIG. 15  is an isometric view of a preferred embodiment of an implant strip; 
         FIG. 16  is an isometric view of a preferred embodiment of an implant strip that has coiled; 
         FIG. 17  is an isometric view of a preferred embodiment of a coiled implant strip under axial force; 
         FIG. 18  is a plan view of a preferred embodiment of a section of an implant strip configured for axial deflection; 
         FIG. 19  is a plan view of a preferred embodiment of a section of an implant strip under axial load; 
         FIG. 20  is a plan view of a preferred embodiment of a section of an implant strip configured for axial deflection; 
         FIG. 21  is a plan view of a preferred embodiment of a section of an implant strip under axial load; 
         FIG. 22  is a plan view of a preferred embodiment of a section of an implant strip configured for axial deflection; 
         FIG. 23  is a plan view of a preferred embodiment of a section of an implant strip under axial load; 
         FIG. 24  is a plan view of a preferred embodiment of a section of an implant strip configured for axial deflection; 
         FIG. 25  is a plan view of a preferred embodiment of a section of an implant strip under axial load; 
         FIG. 26  is an isometric view of a preferred embodiment of an implant strip with slots; 
         FIG. 27  is a cross sectional view of a preferred embodiment of an implant strip with slots; 
         FIG. 28  is a cross sectional view of a preferred embodiment of an implant strip with slots; 
         FIG. 29  is an isometric view of a preferred embodiment of a coiled implant strip with slots; 
         FIG. 30  is a top view of a preferred embodiment of a coiled implant strip with slots; 
         FIG. 31  is an isometric view of a preferred embodiment of an implant strip undergoing axial deflection; 
         FIG. 32  is a plan view of two preferred embodiments of implant strips with slots with a differing number of slots; 
         FIG. 33  is a plan view of two preferred embodiments of implant strips with slots undergoing circumferential deflection; 
         FIG. 34  is a plan view of a preferred embodiment of an implant strip with different slots; 
         FIG. 35  is a schematic view of a preferred embodiment of an implant strip partially permanently deflecting; 
         FIG. 36  is a plan view of a preferred embodiment of a delivery device used for facilitating coiling of an implant strip; 
         FIG. 37  is a top down view of a preferred embodiment of a herniated intervertebral disc; 
         FIG. 38  is a top down view of a preferred embodiment of a herniated disc after partial discectomy; 
         FIG. 39  is a top down view of a preferred embodiment of a herniated disc with an implant strip inserted; 
         FIG. 40  is a plan view of a preferred embodiment of an implant strip with teeth disposed in a saw tooth pattern on an upper and lower edge; 
         FIG. 41  is an isometric view of a preferred embodiment of an implant strip coiled with a saw tooth pattern on an upper and lower edge; 
         FIG. 42  is a preferred embodiment of an implant strip with rounded irregularly spaced teeth disposed on an upper and lower edge; 
         FIG. 43  is an isometric view of a preferred embodiment of an implant strip coiled with rounded irregularly spaced teeth disposed on an upper and lower edge; 
         FIG. 44  is a plan view of an exemplary embodiment of an implant strip with protrusions; 
         FIG. 45  is a plan view of an exemplary embodiment of a coiled implant strip with protrusions; 
         FIG. 46  is a plan view of an exemplary embodiment of polymer applied to an implant strip; 
         FIG. 47  is a cross sectional view of an exemplary embodiment of an implant strip with an application of polymer; 
         FIG. 48  is an isometric view of an exemplary embodiment of a coiled implant strip with an application of polymer; 
         FIG. 49  is a cross sectional view of an exemplary embodiment of a coiled implant strip with an application of polymer; 
         FIG. 50  is a schematic view of an exemplary embodiment of an implant strip coiling in a kidney shape; 
         FIG. 51  is a schematic view of an exemplary embodiment of two coiled kidney shaped implant strips; 
         FIG. 52  is a schematic view of an exemplary embodiment of an implant strip coiling in an oval shape; 
         FIG. 53  is a schematic view of an exemplary embodiment of two coiled oval shaped implant strips; 
         FIG. 54  is a plan view of an exemplary embodiment of an implant strip with a curvilinear shape on an upper and lower edge; 
         FIG. 55  is an isometric view of an exemplary embodiment of a coiled implant strip configured with a wedge shape; 
         FIG. 56  is a cross sectional view of an exemplary embodiment of a coiled implant strip configured with a wedge shape; 
         FIG. 57  is a plan view of an exemplary embodiment of a tapered implant strip; 
         FIG. 58  is an isometric view of an exemplary embodiment of a coiled implant strip configured with a concave shape on a top and bottom surface; 
         FIG. 59  is a cross sectional view of an exemplary embodiment of coiled implant strip configured with a concave shape on a top and bottom surface; 
         FIG. 60  is a plan view of an exemplary embodiment of a tapered implant strip; 
         FIG. 61  is an isometric view of an exemplary embodiment of a coiled implant strip configured with a convex shape on a top and bottom surface; 
         FIG. 62  is a cross sectional view of an exemplary embodiment of coiled implant strip configured with a convex shape on a top and bottom surface; 
         FIG. 63  is a schematic view of an exemplary embodiment of a possible configuration of an implant strip using a plurality of provision sets; 
         FIG. 64  is a schematic view of an exemplary embodiment of a possible configuration of an implant strip using a plurality of provision sets; 
         FIG. 65  is a schematic view of an exemplary embodiment of a possible configuration of an implant strip using a plurality of provision sets; 
         FIG. 66  is an isometric view of an exemplary embodiment of an implant strip comprised of two implant strips and a spacer portion; 
         FIG. 67  is a top down view of an exemplary embodiment of a coiled implant strip comprised of two implant strips and a spacer portion; 
         FIG. 68  is a cross sectional view of an exemplary embodiment of a coiled implant strip comprised of two implant strips and a spacer portion; 
         FIG. 69  is an isometric view of an exemplary embodiment of an implant strip constructed with multiple materials; 
         FIG. 70  is a schematic view of an exemplary embodiment of an implant strip configured with distinct portions; 
         FIG. 71  is a cross sectional view of an exemplary embodiment of an implant strip configured with distinct portions; 
         FIG. 72  is an isometric view of an exemplary embodiment of a coiled implant strip with slots and an application of polymer; 
         FIG. 73  is a cross sectional view of an exemplary embodiment of a coiled implant strip with slots and an application of polymer; 
         FIG. 74  is an isometric view of an exemplary embodiment of an implant strip comprised of two implant strips, a spacer portion and an application of polymer; 
         FIG. 75  is a cross sectional view of an exemplary embodiment of a cannula with an implant strip comprised of two implant strips, a spacer portion and an application of polymer; 
         FIG. 76  is a top down view of an exemplary embodiment of a coiled implant strip comprised of two implant strips, a spacer portion and an application of polymer; and 
         FIG. 77  is a cross sectional view of an exemplary embodiment of a coiled implant strip comprised of two implant strips, a spacer portion and an application of polymer. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is an isometric view of a preferred embodiment of patient  1100  on operating table  1102 . In this embodiment, patient  1100  is experiencing a surgical procedure to insert a spinal prosthesis. In particular, back  1104  of patient  1100  preferably includes first incision  1106  and second incision  1108 . In a preferred embodiment, first incision  1106  includes first tube  1110  and second incision  1108  includes second tube  1114 . Preferably, first incision  1106  and second incision  1108  are both less than one inch long. It should be understood that the placement of incisions  1106  and  1108  may be moved further together or closer apart and the location of incisions  1106  and  1108  in the current embodiment is only meant to be exemplary. 
     Preferably, first tube  1110  and second tube  1114  may be inserted into an intervertebral disc disposed between two adjacent vertebrae. For the purposes of this application, “disc” and “disk” have the same meaning and may be used interchangeably.  FIG. 2  is a plan view of a single vertebra, shown generally at  1200 , and an associated intervertebral disc  1202 . (The anatomy shown in  FIG. 2  is generally that of a lumbar vertebra, although the anatomy of thoracic, lumbar, and cervical vertebrae is similar; therefore,  FIG. 2  can be considered to illustrate the basic principles of thoracic, lumbar, and cervical vertebral anatomy.) The spinous process  1206  of the vertebra  1200  extends dorsally and can typically be palpated and felt through the skin of the back. Also in the dorsally-extending portion of the vertebra  1200  are two transverse processes  1208  and two mammillary processes and facet joints  1212 . A spinal canal  1214  (i.e., an opening) is provided in the vertebra  1200 . The spinal cord and nerves  1216  extend through the spinal canal  1214  such that the spinal cord  1216  receives the full protection of the bony, dorsally-located spinous, transverse, and mammillary processes and facet joints  1206 ,  1208 ,  1212 . The vertebral body also protects the spinal cord and nerves  1216  ventrally. Periodically, nerves  1218  branch out from the spinal cord  1216  to innervate various areas of the body. The forward or ventral edge of the vertebral foramen  1221  is defined by the vertebral body (not shown in  FIG. 2 ), a bony, generally elliptical shelf in front of which the intervertebral disc  1202  rests.  FIG. 2  also illustrates the basic structure of the intervertebral disc  1202 , including the annulus fibrosis  1222  and the nucleus pulposus  1224 . 
     In some cases, an intervertebral disc  1202  may degenerate over time, requiring the need for a spinal disc implant.  FIG. 3  illustrates a preferred embodiment of degeneration. In this embodiment, healthy intervertebral disc  302  is disposed between vertebrae  304 . In this case, vertebrae  304  are separated by a distance D 1  because of support provided by disc  302 . Also shown in  FIG. 3  is unhealthy intervertebral disc  306 , which is disposed between vertebrae  308 . In this case, vertebrae  308  are separated by a distance D 2  that is much smaller than distance D 1  because of the degeneration of disc  306 . 
     If an intervertebral disc has failed or degenerated, a typical correction is a surgical procedure to remove some or all of the intervertebral disc. Following this, a spinal prosthesis may be inserted in order to facilitate fusion of the vertebrae adjacent to the failed intervertebral disc. In a preferred embodiment, surgery may be performed in a manner that limits the size of the incisions needed to insert a prosthesis. Preferably, a spinal prosthesis includes provisions for easy insertion via a small incision in the back. 
     In some cases, a vertebral body could also be fully or partially replaced using a spinal prosthesis. The following detailed description refers to the replacement of an intervertebral disc, however in other embodiments these same principles could be applied to a spinal prosthesis configured to replace a vertebral body. 
       FIGS. 4 and 5  illustrate a preferred embodiment of implant strip  1400 . Generally, implant strip  1400  may be a long thin strip. Preferably, implant strip  1400  has a length L 1  much greater than a width W 1 . Additionally, the thickness T 1  of implant strip  1400  is preferably small compared to both the length and the width of implant strip  1400 . In some embodiments, length L 1  may be between 1 cm and 100 m. In some embodiments, width W 1  may be between 2 mm and 20 cm. In some embodiments, thickness T 1  may be between 0.01 mm and 3 mm. It should be understood that if a vertebral body is being replaced, the thickness of implant strip  1400  could be much larger than the values discussed here. 
     As implant strip  1400  preferably has a relatively small profile, it may be inserted into smaller incisions, such as those shown in  FIG. 1 . However, to provide adequate support to the adjacent vertebrae, implant strip  1400  may preferably be packed tightly into intervertebral disc  1202 . In some embodiments, the packing of implant strip  1400  may be tight or loose depending upon mechanical properties of implant strip  1400 . For this reason, implant strip  1400  preferably includes provisions for conforming to a packed shape once it has been inserted into intervertebral disc  1202 . 
     Generally, implant strip  1400  may be constructed of a material including metal. In some embodiments, implant strip  1400  may be a shape memory alloy. In some embodiments, implant strip  1400  may be made of a titanium alloy. In other embodiments, implant strip  1400  may comprise a combination of one or more materials including, but not limited to, cobalt chrome (CoCr), stainless steel, Nitinol, polymers, biological matrices, ceramics, or any biocompatible material. In a preferred embodiment, implant strip  1400  may be made of a material including titanium. 
     In some cases, a stainless steel alloy may be used as a coiling spring. This arrangement is useful because such alloys low fatigue and high fatigue resistance. Additionally, these alloys may have a high return force. Additionally, using a stainless steel alloy allows for increased corrosion resistance. 
     Preferably, implant strip  1400  may include provisions for changing shape. In some embodiments, implant strip  1400  may be manufactured at an elevated temperature with a first shape. Following this, implant strip  1400  may be cooled and formed into a second shape. Finally, as implant strip is placed in temperature ranges of 90-100 degrees Fahrenheit, it may revert back to the first shape. In a preferred embodiment, the first shape is a spiral coil and the second shape is a long rectangular strip. 
     In some embodiments, implant strip  1400  may include provisions for promoting bone growth, once it has been inserted into the intervertebral disc region. In some embodiments, implant strip  1400  may include a bone growth promoting agent. In a preferred embodiment, implant strip  1400  preferably includes bone growth promoting agent  1402  disposed along the entirety of its length.  FIG. 5-1  is a cross sectional view of implant strip  1400  with bone growth promoting agent  1402  disposed along its entire outer surface  1401 . 
     In some embodiments, bone growth promoting agent  1402  may be selectively applied to one or more portions of implant strip  1400  or may not be applied at all. Preferably, as shown in  FIG. 5-2 , bone growth promoting agent  1402  may be applied to top surface  1403  of outer surface  1401 . Likewise, bone growth promoting agent  1402  may also be applied to bottom surface  1405  of outer surface  1401 . Generally, any type of bone growth promoting agent may be applied and in any pattern. Methods for selectively applying bone growth promoting agents have been previously disclosed in U.S. Patent Publication Number US 2008/0269893 (U.S. patent application Ser. No. 11/740,181, filed on Apr. 25, 2007, entitled “Prosthesis with a Selectively Applied Bone Growth Promoting Agent”), the entirety of which is hereby incorporated by reference. 
     Details of a preferred embodiment of a surgical procedure used to insert a spinal prosthesis of some kind are best understood with respect to  FIGS. 6-8 . The following embodiment comprises steps for inserting a spinal prosthesis using two tubes, however it should be understood that in other embodiments, a single tube may be used for discectomy and/or implantation. In this case, any parallel steps involving the use of two tubes simultaneously could be performed sequentially with a single tube. In particular, steps using a camera and/or light inserted through one tube and a spinal tool through a second tube may be accomplished by using a single tube incorporating a light and/or camera at the periphery of the tube or just outside of the tube. 
     In a first step, first tube  1510  and second tube  1514  may be inserted into intervertebral disc  1202 . Generally, one tube may be used for a surgical tool, while the second tube may be simultaneously used to insert a fiber optic camera into one of the incisions to give the surgeon a clear view of the intervertebral disc region. In some embodiments, first tube  1510  and second tube  1514  may be cannulae. The cross sectional shape of tubes  1510  and  1514  may be any shape, including oval-like, circular or otherwise round, as well as hexagonal or any polygonal shape. 
     Following the insertion of first tube  1510  and second tube  1514 , a series of instruments may be used to remove portions of intervertebral disc  1202  and score the endplates. In some embodiments, first surgical device  1540  may be inserted into first tube  1510 . First surgical device  1540  may be a brush, burr, rasp, or a shaver. In a preferred embodiment, first surgical device  1540  may include flexible shaft  1542  and wire brush tip  1544 . Preferably, wire brush tip  1544  spins, removing portions of intervertebral disc  1202 . 
     In some embodiments, dual catheter  1550  may be inserted into second tube  1514 . Preferably, dual catheter  1550  may include first channel  1552  and second channel  1554 . In some embodiments, first channel  1552  may include a fiber optic camera. With this configuration, the surgery may be visualized by the surgeon using the fiber optic camera. Additionally, second channel  1554  may be configured to inject water and/or provide a vacuum for removing debris. With this configuration, second channel  1554  may be used to clean out cavity  1560 , which is created as a portion of intervertebral disc  1202  is removed. Once the necessary portions of intervertebral disc  1202  have been removed, first surgical device  1540  may be removed from first tube  1510 . 
     Referring to  FIGS. 7-8 , implant strip  1400  may be inserted into cavity  1560  once a portion of intervertebral disc  1202  has been removed. As previously discussed, implant strip  1400  preferably has a material structure that allows it to change shape following insertion into cavity  1560 . In a preferred embodiment, implant strip  1400  is configured to coil as it is exposed to temperatures between 90 and 100 degree Fahrenheit. In other embodiments, implant strip  1400  could coil due to non-temperature dependent memory, such as occurs with a measuring tape. This could be achieved using a titanium implant strip, for example. 
     In this embodiment, first portion  1600  of implant strip  1400  has started to coil as it is inserted into cavity  1560 . Preferably, as implant strip  1400  is further inserted through first tube  1510 , the portion disposed within cavity  1560  may deform and coil as well. In a preferred embodiment, implant strip  1400  may be inserted in a manner that allows implant strip  1400  to coil around itself completely, as seen in  FIG. 8 . 
     Generally, implant strip  1400  may be configured to fill cavity  1560  of intervertebral disc  1202  completely. For illustrative purposes, implant strip  1400  is shown here to be coiled with large gaps between adjacent portions. However, in some embodiments, implant strip  1400  may coil tightly so that no gaps are seen. In a preferred embodiment, implant strip  1400  may coil loosely to provide space or gaps between adjacent, radially spaced coils. This arrangement may help to facilitate bone growth to occur between the coils. 
     In an alternative embodiment, multiple implant strips may be used. Preferably, each implant strip may include a coiled shape, similar to the shape of the previous embodiment. In some embodiments, each of the implant strips may be disposed against one another. In some embodiments, each of the implant strips may be associated with different heights in order to create lordosis. 
       FIG. 9  is a preferred embodiment including multiple implant strips inserted within cavity  1560 . In this embodiment, first implant strip  1802 , second implant strip  1804 , and third implant strip  1806  have been inserted into cavity  1560 . Preferably, each of the implant strips  1802 ,  1804 , and  1806  may be inserted in an identical manner to the method used to insert the implant strip of the previous embodiment. Generally, any number of implant strips may be inserted into cavity  1560 . 
     Preferably, each of the implant strips  1802 ,  1804 , and  1806  may be constructed of a shape memory alloy. In some embodiments, the shape memory alloy may be a nickel titanium alloy. In other embodiments, implant strips  1802 ,  1804 , and  1806  may comprise a combination of one or more materials including, but not limited to, cobalt chrome (CoCr), stainless steel, Nitinol, polymers, biological matrices, ceramics, or any biocompatible material. In a preferred embodiment, implant strips  1802 ,  1804 , and  1806  may be made of a material including titanium. 
     In other embodiments, the structure of an implant strip may be modified. In some embodiments, an implant strip may include a slightly different shape. In other embodiments, an additional material may be used in conjunction with the shape memory alloy of the previous embodiments. 
       FIG. 10  is a preferred embodiment of corrugated implant strip  1902 , which has been inserted into cavity  1560 . Preferably corrugated implant strip  1902  includes small bends along its length. Preferably, corrugated implant strip  1902  may be inserted into cavity  1560  in an identical manner to the method used to insert the previously discussed implant strips. As with the previous embodiments, it should be understood that a bone growth promoting agent may be applied to corrugated implant strip  1902 . This arrangement allows for greater mechanical strength as well as for facilitating increased bone growth into implant strip  1902 . By providing increased surface area, this arrangement may facilitate greater bone growth and more rapid bone healing. 
     Preferably, corrugated implant strip  1902  may be constructed of a shape memory material. In some embodiments, the shape memory alloy may be a nickel titanium alloy. In a preferred embodiment, corrugated implant strip  1902  may be made of a material including titanium. Generally, corrugated implant strip  1902  may be made of any of the materials discussed with respect to the previous embodiments of implant strips, including cobalt chrome (CoCr), stainless steel, Nitinol, polymers, biological matrices, ceramics or any biocompatible material. 
     Preferably, an implant device includes provisions for allowing for different kinds of motion that may occur in a spine. 
     In some embodiments, an implant device may include provisions to accommodate deflections in the axial direction. This may be a useful feature as axial forces may be applied to the implant strip by the adjacent vertebrae during normal activities such as walking, running, and bending of the spinal column. In other words, the implant strip may be configured to endure axial loads that are usually applied to spinal discs. Additionally, the implant device may be configured to accommodate bending, lateral (including shear forces), and twisting forces. 
       FIGS. 11-14  are intended to illustrate a generic embodiment of implant device  2200 . Generally, implant device  2200  may be any kind of device configured for implantation into the human body. In some cases, implant device  2200  may be configured to be implanted between vertebrae, functioning as a full or partial disc replacement device. In a preferred embodiment, implant device  2200  may be an implant strip. 
       FIG. 11  is intended to illustrate a general embodiment of implant device  2200  in a pre-deflection state  2210  and a post-deflection state  2212 . In this embodiment, implant device  2200  includes first portion  2202  and second portion  2204 . Preferably, first portion  2202  is relatively rigid compared to second portion  2204 . In other words, second portion  2204  is configured to deflect under axial forces before first portion  2202  would deflect. As shown in  FIG. 11 , second portion  2204  has a first height H 1  in a pre-deflection state  2210  and a second height H 2  in a post-deflection state  2212 . First height H 1  is preferably greater than second height H 2 . Additionally, first portion  2202  and second portion  2204  have a third combined height H 3 , in pre-deflection state  2210  and a fourth combined height H 4  in post-deflection state  2212 . Third combined height H 3  is preferably greater that fourth combined height H 4 . This preferred arrangement allows for some deflection of implant device  2200  without causing fatigue or failure. 
     In addition to deflection in the axial direction, a spinal implant device may also be configured to undergo bending, lateral and twisting motions. Implant device  2200  is seen in  FIG. 12  to undergo a bending motion due to bending forces  2209 . As bending forces  2209  are applied to first portion  2202 , second portion  2204  may bend. This preferred arrangement allows for some bending of implant device  2200  without causing fatigue or failure. 
     Implant device  2200  is seen in  FIG. 13  undergoing a lateral motion due to a lateral force  2208 . As lateral force  2208  is applied to first portion  2202 , second portion  2204  may be deflected laterally. This preferred arrangement allows for some lateral deflection of implant device  2200  without causing fatigue or failure. 
     Referring to  FIG. 14 , implant device  2200  is seen in undergoing a twisting motion due to a rotational force  2210 . As rotational force  2210  is applied to first portion  2202 , second portion  2204  may be twisted. This preferred arrangement allows for some twisting of implant device  2200  without causing fatigue or failure. 
     In each of these cases, first implant devices  2200  is provided with restoring forces via second portion  2204 . Additionally, although these different types of deflections (due to compressive, bending, twisting and lateral forces) have been shown separately, it should be understood that implant device  2200  may be configured to undergo any combination of or all of these various types of deformations simultaneously. 
     First portion  2202  may be made of any material, including both shape memory alloys and spring steel, as well as other types of materials, including previously discussed materials for implant strip  1400 . Second portion  2204  may be made of any material that may be less rigid than first portion  2202 . In addition, second portion  2204  may be designed to deflect and/or deform under various forces. Examples of such materials include, but are not limited to, elastomers, soft metals, plastics, polymers, wire meshes (made from materials such as Dacron or ceramics), as well as other types of materials. 
     Additionally, in some embodiments, first portion  2202  and second portion  2204  could be made of the same material. However, the rigidity of second portion  2204  could be modified by changing the structural properties of second portion  2204 . This configuration may be achieved by inserting holes or slots or modifying the structure of second portion  2204  in other ways. With these types of modifications, first portion  2202  may be more rigid than second portion  2204  even though they are made of the same material. 
     Preferably, the degree of deflection of implant device  2200  may vary. During the initial implantation, implant device  2200  may deflect or compress until the height of the implant device is about eighty percent of the initial height of the implant strip prior to implantation. This initial deflection is primarily due to normal stresses applied by the adjacent vertebrae when the spinal column is at rest. During motion, however, implant device  2200  may continue to deflect due to increased axial loads from the adjacent vertebrae. The degree of deflection may be between 15 and 25 percent of the initial height of implant device  2200 . It should be understood, however, that the degree of deflection is not limited and may vary according to properties of the various materials that are used. In some cases, the degree of deflection could be much larger than 25 percent or much less that 15 percent. By carefully selecting the material, size, design as well as other structural features of second portion  2204 , the deflection of implant device  2200  can be better controlled. The following embodiments illustrate ways in which the deflection of implant device  2200  can be achieved using different materials and structural features for second portion  2204 . 
       FIG. 15  is an isometric view of a preferred embodiment of implant strip  2000 . In some embodiments, implant strip  2000  may extend in a lateral direction from a first lateral side portion  2002  to a second lateral side portion  2006 . Preferably, first lateral side portion  2002  and second lateral side portion  2006  may be constructed of a similar material to the implant strips of the previous embodiments. In particular, side portions  2002  and  2006  may be made of a substantially rigid material that does not deflect much under axial loads. 
     In some embodiments, elastomer strip  2004  may be disposed between first lateral side portion  2002  and second lateral side portion  2006 . Elastomer strip  2004  is preferably made of a flexible material. In some embodiments, elastomer strip  2004  may be joined to first lateral side portion  2002  and second lateral side portion  2006 . In some embodiments, elastomer strip  2004  may encase perforated edges, teeth or roughed edges of first lateral side portion  2002  and second lateral side portion  2006  in order to ensure a positive mechanical connection. In this preferred embodiment, first lateral side portion  2002  and second lateral side portion  2206  may be associated with teeth  2007 . Using this configuration, teeth  2007  provide a point of attachment for elastomer strip  2004  to first lateral side portion  2002  and second lateral side portion  2006 . In other embodiments, other provisions may be used to fixedly attach elastomer strip  2004  to first lateral side portion  2002  and second lateral side portion  2006 . 
     In some embodiments, implant strip  2000  may include a bone growth promoting agent. In this embodiment, top portion  2003  and bottom portion  2005  are preferably coated with a bone growth promoting agent  2001 . Generally, any type of bone growth promoting agent may be used. Additionally, any type of pattern for a bone growth promoting agent may be used. Various bone growth promoting agents and patterns have been previously referenced. Using this configuration, implant strip  2000  may be configured to stimulate increased bone growth at adjacent vertebrae where implant strip  2000  is implanted. In some embodiments, such a configuration may be used in a manner similar to a spinal cage, which provides a means of fusing two vertebral bodies together. 
       FIGS. 16 and 17  are a preferred embodiment of implant strip  2000  after it has been coiled. Initially, implant strip  2000  has an axial height H 5 . As axial force  2012  is applied to flexible implant strip  2000 , elastomer strip  2004  may deflect in the axial direction, allowing first lateral side portion  2002  and a second lateral side portion  2006  to squeeze together. In this embodiment, flexible implant strip  2000  has a height H 6  that is less than height H 5  following axial deflection. Generally, elastomer strip  2004  has deformed and may slightly bulge outwards. This preferred arrangement allows implant strip  2000  to deflect under axial forces applied by adjacent vertebrae following implantation, which provides a similar function to a spinal disc. Also, using this configuration flexible implant strip  2000  may be configured as a flexible spiral coil that may not escape containment. Preferably, using this arrangement, the adjacent vertebrae may engage lateral side portions  2002  and  2006  of implant strip  2000  to lock it into place. 
     Referring to  FIGS. 15-17 , implant strip  2000  preferably is configured to be coiled in a manner that prevents contact between adjacent coils. In this embodiment, implant strip  2000  may include first longitudinal portion  2080  and second longitudinal portion  2081  extending in a longitudinal direction down the length of implant strip  2000 , as seen in  FIG. 15 . First longitudinal portion  2080  extends from first boundary  2082  to second boundary  2083 . Second longitudinal portion  2081  extends from second boundary  2083  to third boundary  2084 . Generally, the lengths of each longitudinal portion  2080  and  2081  are approximately equal to one 360 degree turn of a coil when implant strip  2000  is in a coiled state. In this embodiment, longitudinal portions  2080  and  2081  are adjacent to one another, however in other embodiments longitudinal portions  2080  and  2081  may not be adjacent to one another. 
     Preferably, first longitudinal portion  2080  is configured to form a first inner coil  2086 , as seen in  FIGS. 15-17 , as implant strip  2000  forms a coiled shape. Likewise, second longitudinal portion  2081  is configured to form a second outer coil  2087 . In a preferred embodiment, second outer coil  2087  is spaced radially outward from first inner coil  2086 . In some embodiments, first inner coil  2086  and second outer coil  2087  are spaced apart by a radial distance R 5  when first lateral side portion  2002  and second lateral side portion  2006  are not in motion (see  FIG. 16 ). Generally, distance R 5  may have any value and may vary from one embodiment to another. Using this preferred arrangement, first inner coil  2086  and second outer coil  2087  are spaced to prevent contact with one another. Preferably, first inner coil  2086  and second outer coil  2087  are also spaced apart when first lateral side portion  2002  and second lateral side portion  2006  are in motion, such as when implant strip  2000  is in a compressed or axially deflected state (see  FIG. 17 ). This arrangement helps to reduce or substantially eliminate particulate debris that may result from the rubbing of various portions together over the lifetime of implant strip  1400 . 
     Preferably, provisions for preventing contact between portions of an implant strip may be provided in other embodiments as well. The principles discussed here may be generally applied to any type of implant strip including a first longitudinal portion and a second longitudinal portion. In some embodiments, these implant strips may or may not include deforming portions. 
     In other embodiments, an implant strip may include different provisions for allowing deflection of the implant strip in the axial direction. In some embodiments, an implant strip may include perforated portions with large gaps or holes that reduce rigidity and thereby allow for some deflection of the implant strip. It should be understood that throughout these embodiments, illustrated in  FIGS. 18-34 , the various implant strips include portions of differing rigidity. Furthermore, in each of these embodiments, the portions of differing rigidity are joined together. 
       FIGS. 18-25  are preferred embodiments of sections of spinal implant strips that are configured for various types of deflection, including axial deflection. The spinal implant strips are also capable of accommodating other types of deflection, including bending, twisting, and lateral shear. Throughout these embodiments, it should be understood that the implant strips may be made of any material configured to coil or deflect in the circumferential direction. In some embodiments, these sections of implant strips may be made of a single material or comprise a combination of one or more materials including, but not limited to, cobalt chrome (CoCr), stainless steel, Nitinol, polymers, biological matrices, ceramics or any biocompatible material. In a preferred embodiment, these sections of implant strips may be made of a material including titanium. 
       FIG. 18  is a preferred embodiment of a portion of first implant strip  2020  prior to deflection. First implant strip  2020  preferably includes lower edge  2002  and upper edge  2006 . Lower edge  2002  and upper edge  2006  are preferably thin strips that form an outer periphery for first implant strip  2020 . 
     Additionally, first implant strip  2020  may include first deflecting portions  2024  that are disposed between lower edge  2002  and upper edge  2006 . Preferably, lower edge  2002  and upper edge  2006  are joined to first deflecting portions  2024 . For purposes of clarity, only a section of first implant strip  2020  is shown here, however it should be understood that first deflecting portions  2024  are preferably disposed along the entire length of first implant strip  2020 . Generally, the spacing and number of first deflecting portions  2024  may be varied in order to change the deflection properties of first implant strip  2020 . 
     In this embodiment, first deflecting portions  2024  may be elliptically shaped prior to deflection. In other embodiments, the shape of first deflecting portions  2024  may vary. Examples of other shapes that may be used include, but are not limited to, circles, diamonds, as well as any polygonal shape. Additionally, in other embodiments, the thickness associated with first deflecting portions  2024  could be changed. By varying these properties of first deflecting portions  2024 , the deflection properties of first implant strip  2020  may be modified. 
     In some embodiments, first implant strip  2020  may also include motion limiting features that prevent excessive deflection in the axial direction. In this embodiment, first implant strip  2020  may include motion limiting tabs  2026 . Preferably, motion limiting tabs  2026  may be disposed between edges  2002  and  2006 . Furthermore, motion limiting tabs  2026  may be disposed within deflecting portions  2024  and/or adjacent to deflecting portions  2024 . 
     Preferably, deflecting portions  2024  and motion limiting tabs  2026  may be formed by cutting or removing portions of first implant strip  2020 , which creates gaps within interior space  2022 . This cutting may be done using techniques known in the art, such as stamping, punching, laser fusion and/or water drilling, or any combination of techniques. In other embodiments, first implant strip  2020 , including deflecting portions  2024  and tabs  2026  may be formed using a die of some kind. These techniques are preferably used to create smooth edges in order to prevent burrs. Using this configuration, scar tissue due to burrs may be substantially reduced following implantation of first implant strip  2020 . In other embodiments, however, techniques used that leave burrs intact may be used so that the remaining burrs may facilitate in-growth of bone. 
     Following the insertion of first implant strip  2020  between two adjacent vertebrae, an axial force may be experienced as the vertebrae are compressed during motion of the spinal column. Referring to  FIG. 19 , first deflecting portions  2024  may be compressed under axial force  2028 . As first deflecting portions  2024  compress, lower edge  2002  and upper edge  2006  move closer together. As previously discussed, excessive axial deflection may be prevented using motion limiting tabs  2026 . Preferably, tabs  2026  are substantially rigid and therefore will not deflect or deform under axial force  2028 . Therefore, as tabs  2026  make contact, the compression of first deflecting portions  2024  may cease. In this embodiment, the height of implant strip  2020  has been modified from an original height H 3  to a modified height H 4  that is less than H 3 . Once axial force  2028  has been removed or reduced, implant strip  2020  may expand in the axial direction as deflecting portions  2024  uncompress. Using tabs  2026  helps to prevent fatigue failure of deflecting portions  2024  by limiting the range of motion. 
     Referring to  FIGS. 20-25 , an implant strip may include different types of deflecting portions. Additionally, an implant strip may or may not include motion limiting tabs. In a second embodiment, seen in  FIGS. 20-21 , second implant strip  2030  includes first deflecting ellipse  2032 , second deflecting ellipse  2034  and third deflecting ellipse  2036  disposed between edges  2002  and  2006  and within interior space  2038 . Preferably, ellipses  2032 ,  2034 , and  2036  are joined to edges  2002  and  2006 . As axial force  2028  is applied, deflecting ellipses  2032 ,  2034  and  2036  are compressed until they obtain a substantially circular shape. At this point, ellipses  2032 ,  2034 , and  2036  are disposed against one another, which may prevent any further deflection or deformation in the axial direction. 
     In a third embodiment, shown in  FIGS. 22-23 , third implant strip  2040  includes fourth deflecting ellipse  2042  and fifth deflecting ellipse  2046  disposed between edges  2002  and  2006  and within interior space  2048 . Preferably, ellipses  2042  and  2046  are joined to edges  2002  and  2006 . In addition, third implant strip  2040  preferably includes cross bar  2044  that is disposed between fourth deflecting ellipse  2042  and fifth deflecting ellipse  2046 . Cross bar  2044  preferably connects to both lower edge  2002  and upper edge  2006 . In a preferred embodiment, deflecting ellipses  2042  and  2046  as well as cross bar  2044  may all deflect under axial force  2028 . In particular, cross bar  2044  may experience column deflection. Preferably, cross bar  2044  only partially deflects, which limits the axial motion of lower edge  2002  and upper edge  2006 . 
     In a fourth embodiment, seen in  FIGS. 24-25 , fourth implant strip  2050  includes first curved portion  2052  and second curved portion  2056 . Preferably, curved portions  2052  and  2056  are joined to edges  2002  and  2006 . Fourth implant strip  2050  also preferably includes motion limiting tabs  2054 . As axial force  2028  is applied to fourth implant strip  2050 , curved portions  2052  and  2056  may deflect in the axial direction. Preferably, as tabs  2054  make contact, the deflection of lower edge  2002  towards upper edge  2006  may cease. Additionally, curved portions  2052  and  2056  may contact edges  2002  and  2006 , preventing further deflection. 
       FIGS. 26-28  illustrate another preferred embodiment of implant strip  2300  that is configured for axial deflection. Implant strip  2300  includes upper side  2304  and lower side  2306  that extend vertically. Protruding portion  2303  preferably extends outwards from, and is preferably joined with, upper side  2304  and lower side  2306 . In particular, protruding portion  2303  includes first sloped portion  2310  and second sloped portion  2312  as well as flat portion  2308 . Using this preferred arrangement, implant strip  2300  may be configured for slight deflections in the axial direction, as some slight compression of implant strip  2300  may occur at protruding portion  2303 . In particular, as axial loads are applied to implant strip  2300 , the angle of first sloped portion  2310  and second sloped portion  2312  with respect to upper side  2304  and lower side  2306  may vary. 
       FIG. 28  illustrates an alternative embodiment of a cross sectional view of protruding portion  2303 . In the embodiment shown in  FIG. 27 , first sloped portion  2310  and second sloped portion  2312  are straight portions. Alternatively, protruding portion  2303  could include first curved portion  2320  and second curved portion  2322 . Using an alternative shape for protruding portion  2303  allows for changes in the deflecting properties of implant strip  2300 . In other embodiments, the shape of protruding portion  2303  could be further modified to change the deflecting properties of implant strip  2300 . 
     Implant strip  2300  also preferably includes slots  2302 . In this embodiment, slots  2302  extend from upper side  2304  to lower side  2306  of implant strip  2300 . Slots  2302  preferably extend through protruding portion  2303 . The addition of slots  2302  to implant strip  2300  generally decreases the rigidity of protruding portion  2303 . Using this configuration, slots  2302  may provide increased deflection of protruding portion  2303 . 
       FIGS. 29 and 30  are a preferred embodiment of implant strip  2300  following implantation. As implant strip  2300  is coiled, implant strip  2300  is configured to deflect in the circumferential direction. In a preferred embodiment, the deflection primarily occurs at slots  2302 .  FIG. 30  illustrates the widening of slots  2302  during coiling. For example, first slot  2700  of implant strip  2300  is wider at first end  2704  than second end  2702 . 
       FIG. 31  is a preferred embodiment of outer ring  2332  of implant strip  2300  undergoing axial deflection. For purposes of clarity, inner rings  2330  of implant strip  2300  are shown in phantom. As an axial force is applied, protruding portion  2303  deflects. In particular, the angle between upper side  2304  and first sloped portion  2310  and the angle between lower side  2306  and second sloped portion  2312  may change as upper side  2304  and lower side  2306  are squeezed together. 
     In some embodiments, the number, shape, and size of slots associated with an implant strip may vary. By changing the number, shape, orientation, and/or size of slots of an implant strip, the axial loading characteristics of the implant strip may be controlled. Increasing the number of slots may increase the degree of axial deflection, as the rigidity of protruding portion  2303  is reduced with an increasing number of slots. Likewise, decreasing the number of slots may decrease the degree of axial deflection, as the rigidity of protruding portion  2303  is increased with a decreased number of slots. 
     Additionally, changing the number of slots may also increase the flexibility of the implant strip in the circumferential direction. Increasing the number of slots may generally increase the amount of deflection in the circumferential direction. Likewise, decreasing the number of slots may generally decrease the amount of deflection in the circumferential direction. 
       FIG. 32  is a preferred embodiment of first implant strip  2800  and second implant strip  2804 . First implant strip  2800  includes first slots  2802  and second implant strip  2804  includes second slots  2806 . Preferably, the number of slots comprising first slots  2802  is greater than the number of slots comprising second slots  2806 . 
     Referring to  FIG. 33 , first implant strip  2800  and second implant strip  2804  have different deflection characteristics since first implant strip  2800  has a greater number of slots than second implant strip  2804 . In this embodiment, first implant strip  2800  can deflect or curve more in the circumferential direction than second implant strip  2804 . In particular, first implant strip  2800  has a first radius of curvature R 1  than is smaller than a second radius of curvature R 2  associated with second implant strip  2804 . 
     By varying the radius of curvature of an implant strip in this manner, the tightness of coiling associated with an implant strip may be varied. Generally, a tighter coil provides more surface area over which to receive axial loads from adjacent vertebrae and thereby increases the strength of the implant strip in the axial direction. 
     In the previous embodiment, slots of different widths are used to modifying the deflecting properties of an implant strip. In other embodiments, the spacing between slots could vary. In still other embodiments, the orientation of the slots may vary as well. Additionally, in some embodiments, the slots could have different shapes such as oval, round, hexagonal or any type of polygon or irregular shape. These various shapes can be used singularly or in any desired combination. 
     In another embodiment, shown in  FIG. 34 , a portion of implant strip  3300  includes a variety of punched out shapes configured to change the deflecting characteristics of implant strip  3300 . In some embodiments, implant strip  3300  may include thin slots  3302  and wide slots  3304 . In this embodiment, the spacing between slots varies from spacing S 1  to spacing S 2 . In this exemplary embodiment, spacing S 1  is much larger than spacing S 2 . In other embodiments, the spacing between slots could be any length, and could vary over implant strip  3300 . 
     In some cases, the orientation of slots could be modified. In some embodiments, implant strip  3300  may include angled slots  3310 . Generally, angled slots  3310  may be oriented in any direction, including, in other embodiments, perpendicular to thin slots  3302 . 
     Additional shapes for cutouts are also illustrated in  FIG. 34 . In some embodiments, implant strip  3300  may include circular cutouts  3312 , triangular cutouts  3314 , or diamond cutouts  3315 . Furthermore, in some cases, the various shapes could be repeating or non-repeating, including various geometric patterns such as honeycomb-like cutouts  3316 . In this case, the remaining portions of implant strip  3300  may be configured as lattice  3318 . 
     The various shapes and patterns illustrated in  FIG. 34  are only meant to be exemplary. In some embodiments, a single size, shape and spacing for cutouts or slots may be used. In other embodiments, a variety of different shapes for cutouts or slots including regular or irregular spacing between shapes may be used. By using slots or cutouts of varying widths, sizes, orientations and various spacing between slots or cutouts, the deflection properties and the coiling properties of implant strip  3300  may be tuned. 
     Preferably, implant strips may be configured to permanently deflect in some situations. Generally, vertebrae are not completely symmetric and therefore the spacing between two adjacent vertebrae may vary. Using an implant strip that is configured to partially permanently deflect at some portions allows for a more natural fit of the implant strip. 
       FIG. 35  is a schematic view of a preferred embodiment of a portion of spinal column  3100 , including vertebrae  3102 . Implant strip  3104  has been inserted between vertebrae  3102  to replace a spinal disc. In this embodiment, the spacing between vertebrae  3102  varies. In particular, at front side  3106  of spinal column  3100 , vertebrae  3102  are separated by a height H 7  while at rear side  3108  of spinal column  3100 , vertebrae  3102  are separated by a height H 8  that is less than height H 7 . Preferably, implant strip  3104  has partially permanently deflected at rear side  3108 , allowing for a natural fit. It should be understood that implant strip  3104  has only partially permanently deflected at rear side  3108 . Generally, implant strip  3104  is configured to continue axial deflection under increased axial loads at front side  3106  and rear side  3108 . 
     Using the configuration described here, the shape of implant strip  3104  is preferably automatically customized. In some regions between adjacent vertebrae, such as the narrow region discussed above, the implant strip may plastically deform to adjust to natural contours of the adjacent vertebrae. In other regions, such as the wider region discussed above, the implant strip may remain extended or minimally deflected to fully fill in the spaces between vertebrae. In this manner, the implant strip preferably performs a similar function to a spinal disc. 
     Preferably, an implant strip may include provisions for facilitating coiling of the implant strip during implantation into a spine. In a preferred embodiment, a curved tube may be used to facilitate coiling of an implant strip. The following embodiment is intended to illustrate a provision for facilitating coiling of any type of implant strip. It should be understood that the following procedure may be used to facilitate the implantation of any of the various implant strips discussed earlier as well as other possible implant strips. 
       FIG. 36  is a preferred embodiment of implant strip  2110  being inserted into cavity  1560  of intervertebral disc  1202 . In this embodiment, the insertion of implant strip  2110  is facilitated by delivery device  2102 . Delivery device  2102  may be a catheter or similar tube configured for receiving implant strip  2110 . Preferably, distal end  2104  of delivery device  2102  is disposed just inside of cavity  1560  and includes curved deforming tip  2106 . 
     As implant strip  2110  is inserted, curved deforming tip  2106  helps facilitate some bending of implant strip  2110  in the circumferential direction. As insertion of implant strip  2110  continues, intermediate portion  2114  of implant strip  2110  is further coiled by inner curved portion  2108  of delivery device  2102 . This arrangement further facilitates the coiling of distal end  2112  of implant strip  2110  towards the center of cavity  1560 . Using delivery device  2102  allows for increased control of coiling of implant strip  2110  during implantation. 
     In some embodiments, a spinal implant strip may be used to repair a herniated intervertebral disc. This may be achieved by using similar techniques for removing the herniated portion of the disc. Following this, a spinal implant strip may be inserted into the removed portion of the disc. 
       FIG. 37  is a plan view similar to that of  FIG. 2 , illustrating a herniated or traumatized intervertebral disc  1202 . As shown, the nucleus pulposus  1224  is protruding from the intervertebral disc  1202  through a cut or flaw  1204  in the intervertebral disc  1202 . The protruding nucleus pulposus  1224  impinges on one of the exiting nerves  1218  as well as the spinal cord  1216  or cauda equina. 
     In cases where an intervertebral disc is herniated, such as is shown here, portions of nucleus pulposus  1224  may be removed, as seen in  FIG. 38 . This may be achieved using standard surgical techniques or techniques similar to those discussed in the previous embodiments illustrated in  FIGS. 6-8 . In some cases, a partial discectomy may be also performed through a single tube or double tube. At this point, recess  3702  is left open within disc annulus  1222 . 
     Preferably, implant strip  3802  may be inserted into recess  3702  to repair intervertebral disc  1202 , as seen in  FIG. 39 . This may be accomplished using similar techniques to those previously discussed for implanting a spinal strip illustrated in  FIGS. 6-8 . As noted in the embodiment shown in  FIGS. 6-8 , implant strip  3802  may be inserted using a single tube or double tube technique. Using this preferred arrangement, implant strip  3802  may be configured to replicate the mechanical properties of nucleus  1224 . 
     Using the various arrangements for a spinal implant strip discussed in this detailed description provide for improved utility over prior designs. Each of these designs is versatile since various types of implant strips may be used for replacing various kinds of spinal discs. Also, each of these arrangements provides for a single piece device that does not experience the wear or generate particulate debris that may be associated with multi-piece designs. Finally, using the materials and designs discussed in this detailed description, the implant strips are preferably configured to either remain rigid or maintain a general spring-like state without undergoing any fatigue or mechanical failure. 
     Embodiments of the present invention can provide for continuity of the spine. The term “continuity of the spine” generally refers to the concept of providing an actual mechanical bridge between two distinct vertebral bodies. In some embodiments, this implant device provides for a mechanical bridge, while also allowing motion between the two distinct vertebral bodies. This arrangement can approximate the natural biomechanics of the spine. 
     By applying principles or features of the present invention, a surgeon can implant a device to restore the original anatomical height of the disk, thereby restoring normal forces across the spine. The surgeon can also select an implant device that can provide decompression of the nerves in the vertebral foramen and canals. This implant device can provide a post-implantation height greater than or less than the original anatomical height of the disk. This implant device can also provide a post-implantation configuration that optimizes the relative position between two vertebrae. In some cases, this post-implantation configuration can be used to correct scoliosis or spondylolisthesis. 
     In some embodiments, a spinal implant strip may include provisions for embedding into adjacent vertebrae. A spinal implant strip with provisions for attaching to adjacent vertebrae may be useful in disc replacement procedures as well as disc fusion procedures. In other embodiments, an implant strip may include teeth on a periphery of the implant strip to assist in anchoring an implant strip to adjacent vertebrae. In some cases, teeth on a periphery of an implant strip may facilitate bone growth into the implant strip following implantation. By increasing the surface area on a periphery of an implant strip, teeth may facilitate bone growth into the implant strip. 
       FIGS. 40-43  are preferred embodiments of spinal implant strips with teeth disposed on a periphery of the implant strips. For the purpose of clarity, the implant strips are illustrated schematically. Typically, an implant strip will have a much greater length than the implant strips illustrated in these Figures. Preferably, the implant strips in these embodiments may be inserted in an identical manner to the methods used to insert the previously discussed implant strips of the previous embodiments. 
     Generally, teeth may be disposed on any portion of a periphery of an implant strip. In some embodiments, an implant strip may include teeth on a lower edge. In some cases, teeth may be disposed on a portion of a lower edge. In other cases, teeth may be disposed on an entirety of a lower edge. In other embodiments, an implant strip may include teeth on an upper edge. In a preferred embodiment, an implant strip may include teeth on an entirety of both a lower edge and an upper edge. Additionally, teeth may be disposed along an entirety of the length of an implant strip, or just a portion of an implant strip. By using different configurations of teeth along an implant strip, an implant strip can be embedded in various ways between two adjacent vertebrae. 
     Throughout the remainder of this detailed description and in the claims, the terms “upper edge” and “lower edge” generally refer to edges of an implant strip that extend in a longitudinal direction between a first end and a second end of the strip. In particular, the upper edge is configured to contact a vertebrae disposed above a coiled implant strip, while the lower edge is configured to contact a vertebrae disposed below a coiled implant strip. 
       FIGS. 40-41  illustrate an exemplary embodiment of implant strip  4000 . In these embodiments, implant strip  4000  includes lower edge  4002  and upper edge  4006 . Lower edge  4002  and upper edge  4006  form a portion of a periphery of implant strip  4000 . In this embodiment, lower edge  4002  and upper edge  4006  are configured with teeth  4010  disposed in a downward and upward direction, respectively. 
     Typically, teeth may be configured in any shape and size. For example, in some cases, teeth may have an approximately symmetrical shape. In other cases, teeth may have a saw tooth orientation. In still other cases, teeth may be rounded. 
     Various configurations of teeth may be included on an implant strip. In some embodiments, teeth may conform to a repeating pattern. In some cases, for example, smaller teeth may be interspersed between larger teeth. In other embodiments, teeth may be identical in size and shape. In other embodiments, teeth may be disposed in different shapes and sizes on a periphery of an implant strip without a recognizable pattern in an attempt to customize an implant strip to the anatomical shape of vertebrae adjacent to the insertion site. In still other embodiments, teeth may be configured in multiple patterns on a periphery of an implant strip. For example, teeth disposed on an upper edge of an implant strip may be identical, while teeth disposed on a lower edge may be a repeating pattern of smaller teeth interspersed between larger teeth. 
     In addition to teeth, embodiments of an implant strip may be configured with other provisions to encourage bone growth into the implant strip. These provisions may be applied to any desired portion of the implant strip. Generally, in any of the embodiments discussed in this detailed description, a combination of macroscopic holes and microscopic holes or other bone growth promoting surface treatments can be used. By using a combination of both features, bone growth can be encouraged at the surface of the implant strip so that the implant strip, on a surface level, integrates with the bone; and by using macroscopic holes, large scale or bulk integration of the prosthesis can occur, further solidifying the integration of the implant strip with the bone. Details of these provisions can be found in U.S. Patent Publication Number US 2009/0048675 (U.S. patent application Ser. No. 11/840,707, filed on Aug. 17, 2007, entitled “Spinal Fusion Implants with Selectively Applied Bone Growth Promoting Agent”), the entirety of which is incorporated by reference herein. 
     In the current embodiment, teeth  4010  are substantially identical with the same size and shape. In particular, teeth  4010  are configured in a saw tooth orientation. Specifically, teeth  4010  extend height H 9  from base to apex. Furthermore, teeth  4010  are regularly spaced on edges  4002  and  4006  and are separated by a distance D 3  between apexes of consecutive teeth  4010 . Generally, height H 9  and distance D 3  may have any values and may vary from one embodiment to another. In this embodiment, teeth  4010  are tightly spaced and distance D 3  is approximately the same as height H 9  of teeth  4010 . 
       FIG. 41  is an exemplary embodiment of implant strip  4000  after implant strip  4000  has been coiled. In some embodiments, implant strip  4000  may be pre-formed and coiled prior to implantation. Generally, any of the embodiments discussed in this detailed description may be coiled prior to implantation. For example, a surgeon may receive a preformed coiled implant strip for implantation in some cases. For example, an implant strip may be shaped into a preformed coil according to various particular features of a particular patient or the desires of the surgeon. In other embodiments, as discussed previously implant strip  4000  may coil as implant strip  4000  is implanted. 
     Upon implantation, teeth  4010  preferably extend upward and downward to engage adjacent vertebrae. Preferably, using this arrangement, teeth  4010  facilitate the in-growth of bone from adjacent vertebrae. In this manner, teeth  4010  may help embed implant strip  4000  into adjacent vertebrae. 
     Generally, teeth on a periphery of an implant strip may be regularly or irregularly spaced. In some embodiments, portions of a periphery may include teeth that are regularly spaced, while other portions of a periphery may include teeth that are irregularly spaced. In some cases, a surgeon may consider particular anatomical characteristics of a site where an implant strip is to be inserted when choosing an implant strip with regularly spaced or irregularly spaced teeth. 
       FIGS. 42 and 43  illustrate an exemplary embodiment of implant strip  4200  with teeth  4210  spaced irregularly. In this embodiment, a periphery of implant strip  4200  includes lower edge  4202  and upper edge  4206 . Teeth  4210  are disposed on the entirety of both edges  4202  and  4206 . In this embodiment, teeth  4210  are configured with a rounded shape. Furthermore, the rounded shape of teeth  4210  includes a relatively low profile with an approximate height H 10  at the apex. In some cases, the rounded shape of teeth  4210  may prevent burrs and shorten the healing time after the implantation of implant strip  4200 . 
     While teeth  4210  include a rounded shape on edges  4202  and  4206 , teeth  4210  are not identical due to irregular spacing. For example, apexes of consecutive first tooth  4211  and second tooth  4212  disposed on upper edge  4206  are separated by distance D 4 . In contrast, apexes of consecutive third tooth  4213  and fourth tooth  4214  on lower edge  4202  are separated by distance D 5  that is less than distance D 4 . In this embodiment, the spacing between teeth  4210  is irregular and varies between consecutive teeth. 
       FIG. 43  illustrates an exemplary embodiment of implant strip  4200  coiled. In some cases, implant strip  4200  may be pre-formed prior to implantation. In other cases, implant strip  4200  may coil as implant strip  4200  is inserted. Preferably, teeth  4210  on lower edge  4202  and upper edge  4206  provide increased surface area to engage adjacent vertebrae and augment bone growth. Additionally, by spacing teeth  4210  irregularly on a periphery of implant strip  4200 , top surface  4306  and bottom surface  4406  may be configured to present a desired shape to adjacent vertebrae as implant strip  4200  is coiled. In some cases, teeth  4210  may engage and provide support to adjacent vertebrae, while spacing between teeth  4210  may encourage the in-growth of bone and the attachment of implant strip  4200  to adjacent vertebrae. 
     Preferably, in the embodiments illustrated in  FIGS. 40-43 , teeth may be formed by cutting or removing portions of an implant strip. Cutting may be done using techniques known in the art, including, but not limited to, punching, laser fusion and/or water drilling, stamping, or any combination of techniques. In other embodiments, teeth may be formed using a die of some kind. Techniques are preferably used to create smooth edges on the teeth in order to prevent burrs. With this arrangement, scar tissue due to burrs may be substantially reduced following the implantation of the implant strips. In still other embodiments, however, techniques may be employed that leave burrs intact so that the remaining burrs facilitate in-growth of bone. 
     An implant strip may employ various provisions to prevent or limit contact between adjacent coils when the implant strip is coiled. In some cases, increasing the space between adjacent coils may reduce or substantially eliminate rubbing that may create particulate debris. In other cases, the creation of space between adjacent coils may enhance in-growth of bone into an implant strip. In still other cases, spacing of adjacent coils may allow a coiled implant strip to mimic the dynamic properties of an intervertebral disc. 
     Generally, an implant strip may be configured to coil in a manner that prevents or limits contact between all adjacent coils, a specific set of adjacent coils, or a portion of the coil of adjacent coils. In some embodiments, a coiled implant strip may be configured to prevent contact between a first set of coils, but allow contact between a second set of coils. In other embodiments, adjacent coils may be configured to be separated by a first distance on a first surface of an implant strip and separated by a second distance, different from a first distance, on a second surface of an implant strip. For example, in some cases, adjacent coils may be spaced apart on a top surface of a coiled implant strip, but adjacent coils on a bottom surface may coil tightly without space between adjacent coils. In a preferred embodiment, an implant strip may include identical spacing between all adjacent coils. 
       FIGS. 44-49  are exemplary embodiments of implant strips with provisions to prevent contact between adjacent coils. For the purpose of clarity, the implant strips in these embodiments are illustrated schematically. Typically, an implant strip will have a much greater length. Also, the implant strips in these embodiments may be inserted in an identical manner to the methods used to insert the previously discussed implant strips. In particular, the implant strips in these embodiments may coil during implantation or as previously discussed, may be pre-formed into a coil for implantation. Furthermore, the implant strips in these embodiments may include features discussed in any of the embodiments in this detailed description. 
     Generally, an implant strip may include one or more separating portions. The term “separating portion” as used throughout this detailed description and in the claims refers to any provision for separating adjacent coils of an implant strip. Separation portions may be configured on an implant strip in any manner known in the art. In some embodiments, separating portions may be integrally formed with an implant strip. In some cases, separating portions may be created by deforming portions of an implant strip. For example, separating portions may be formed by forcing portions of a first surface upward to create protrusions on an inner surface disposed opposite of the outer surface. Such a method of creating protrusions may also provide divots or recesses on a second opposing surface. In other embodiments, separating portions may be applied to an implant strip separately. In some cases, the separating portions could be integrally molded with the implant strip. In other cases, the separating portions could be bonded or attached to the implant strip. 
     Referring to  FIGS. 44-45 , implant strip  4400  is configured with protrusions  4410 . Protrusions  4410  are disposed on inner surface  4420  of implant strip  4400 . In particular, protrusions  4410  thrust outward from inner surface  4420 . In this embodiment, protrusions  4410  are substantially similar and shaped as half spheres. In addition, protrusions  4410  are irregularly and rather widely spaced. Specifically, the spacing between protrusions  4410  is relatively greater than diameter D 6  of protrusions  4410 . 
     Generally, protrusions may have different shapes such as oval, hexagonal, rectangular, or any type of polygon or irregular shape. These various shapes can be used singularly or in any desired combination. By using different shapes, size and spacing, the deflection properties and the coiling properties of an implant strip may be tuned. Typically, a tighter coil provides more surface area over which to receive axial loads from adjacent vertebrae and thereby increases the strength of the implant strip in the axial direction. 
     When implant strip  4400  is coiled, either prior to implantation or during implantation, protrusions  4420  create spacing between adjacent coils, as seen in  FIG. 45 . In particular, first inner coil  4501  and second outer coil  4502  are spaced apart by a radial distance R 6 . Generally, radial distance R 6  may have any value and vary from one embodiment to another. In this embodiment, radial distance R 6  is approximately equal to the height of protrusions  4410 . Furthermore, when implant strip  4400  forms a coil, all coils of implant strip  4400  will be separated by radial distance R 6 , since protrusions  4410  are identical. With this preferred arrangement, adjacent coils may not rub and create particulate debris. In addition, due to the spacing between protrusions  4410 , bone from adjacent vertebrae may grow between adjacent coils to secure implant strip  4400  in position. 
     In some embodiments, bone may be encouraged to grow between adjacent coils by the application of a material. Generally, any type of material may be applied including, but not limited to polymers, polymers embedded with biological matrices, bone growth promoting agent, or any biocompatible material. Furthermore, the material may be applied to an entirety or a portion of implant strip  4400  using any method known in the art. In some cases, biological matrices, bone growth promoting agent, or another biocompatible material may be applied in a sponge application. Also, the bone growth promoting agent could be applied in as a paste in, for example, a “peanut butter” type application. 
     While this embodiment includes protrusions disposed on an inner surface of an implant strip, other embodiments may include protrusions or other provisions for spacing on an outer surface opposite of the inner surface. In some embodiments, provisions for spacing may be included on both an outer and inner surface of an implant strip. Generally, protrusions or other provisions for spacing disposed on both surfaces will increase the distance separating adjacent coils when an implant strip is coiled. 
       FIGS. 46-49  illustrate an exemplary embodiment of implant strip  4600  configured to coil in a manner that prevents contact between adjacent coils. Preferably, implant strip  4600  includes inner surface  4620  and outer surface  4630  disposed opposite of inner surface  4620 . In this embodiment, material  4640  is applied to a portion of inner surface  4620  and outer surface  4630 , as seen in  FIG. 47 . In particular, material  4640  is applied to cover regions on surfaces  4620  and  4630  between upper boundary  4606  and lower boundary  4602 . 
     Generally, material  4640  may have any desired thickness to provide a desired separation between adjacent coils. In this embodiment, material  4640  is applied with thickness T 2 . With this preferred arrangement, material  4640  creates space between adjacent coils when implant strip  4600  is coiled. 
     Any type of material may be applied to an implant strip, including, but not limited to, polymers embedded with biological matrices, bone growth promoting agent, or any biocompatible material. In addition, the material may be applied to an implant strip in any manner known in the art. In some embodiments, the material may be applied in a pattern. In some cases, the material could be applied in a regular pattern. In other cases, the material may be applied in an irregular pattern. Generally, a material may be applied with varying levels of thickness to any portion of an implant strip. In some embodiments, a material may be applied to produce a particular spacing between adjacent coils of an implant strip. 
     Referring to  FIG. 48 , implant strip  4600  may be pre-formed and inserted or coiled during insertion. By applying material  4640  on both surfaces  4620  and  4630 , coils of implant strip  4600  may be spaced apart a radial distance R 7 . Generally, radial distance R 7  may be related to thickness T 2 . In this embodiment, radial distance R 7  is two times thickness T 2 , since material  4640  is applied to both surface  4620  and  4630  of implant strip  4600 . Using this preferred arrangement, adjacent coils of implant strip  4600  are spaced to prevent contact with one another when implant strip  4600  is formed into a coil. 
     Preferably, portions of implant strip  4600  extend above and below upper boundary  4606  and lower boundary  4602 , respectively (see  FIG. 46 ). This arrangement provides for the upper and lower edges of implant strip  4600  to contact adjacent vertebrae directly. In particular, this arrangement may facilitate implantation of implant strip  4600  into adjacent vertebrae. In some cases, the lower and upper edges may also be modified to include teeth or similar provisions for facilitating implantation. 
     Furthermore, since material  4640  is not applied to the entirety of surfaces  4620  and  4630 , spaces or gaps may be created between adjacent radially spaced coils. In particular, portions of coiled implant strip  4600  above upper boundary  4606  and below lower boundary  4602  may include spaces, as seen in  FIGS. 48-49 . This arrangement may spur bone growth between the coils of implant strip  4600 . In other embodiments, boundaries  4606  and  4602  may be adjusted to alter the size of gaps or spaces between adjacent coils. This feature may be particularly useful during procedures involving disc fusion as well as disc replacement by engaging adjacent vertebrae and facilitating bone growth into implant strip  4600 . 
     Generally, a material may be used to help create separating portions for any type of implant strip. In the current embodiment, a material is applied to a substantially flat implant strip. However, in other embodiments, a material could be applied to other implant strips with different shapes. In some embodiments, a material can be applied to an implant strip with provisions for deflecting and/or deforming to endure bending, lateral, axial, and twisting forces. In some cases, separating portions may be applied to an implant strip to prevent the growth of bone into portions of the coiled implant strip. 
       FIGS. 72-73  illustrate an exemplary embodiment of coiled implant strip  7200 . In this embodiment, implant strip  7200  is configured to accommodate deflection in the axial direction. Preferably, implant strip  7200  is substantially similar to implant strip  2300  as seen in  FIGS. 26-31 . In particular, implant strip  7200  preferably includes protruding portion  7203  (a portion of which is shown in  FIG. 72  in phantom) that extends outward from, and is preferably joined with, upper side  7205  and lower side  7201 . With this arrangement, protruding portion  7203  may compress under axial loads. 
     In addition, implant strip  7200  may be configured with material  7240  that acts as a separating portion. In a similar manner to the previous embodiment, implant strip  7200  includes material  7240  that is applied to a portion of inner surface  7220  and outer surface  7230  of implant strip  7200 . Specifically, material  7240  is applied to cover regions of inner surface  7220  and outer surface  7230  between upper boundary  7206  and lower boundary  7202 . Preferably, protruding portion  7203  is disposed between upper boundary  7206  and lower boundary  7202 . In this manner, material  7240  may cover protruding portion  7203  and prevent the growth of bone into protruding portion  7203 . 
     In some embodiments, material  7240  may alter the deflection properties of implant strip  7200  when material  7240  covers protruding portion  7203 . In some cases, material  7240  may decrease the flexibility of protruding portion  7203 . In other embodiments, material  7240  may be configured with material properties that do not interfere with the deflection properties of implant strip  7200 . 
     Referring to  FIG. 72 , implant strip  7200  may be pre-formed in some embodiments. In other embodiments, implant strip  7200  may be coiled during insertion. In this embodiment, coils of implant strip  7200  may be spaced apart by radial distance R 10  by the application of material  7240  on inner surface  7220  and outer surface  7230 . Since material  7240  is not applied to the entirety of inner surface  7220  and outer surface  7230 , bone  7299  may grow into spaces between adjacent radially spaced coils above upper boundary  7206  and below lower boundary  7202 . This arrangement preferably facilitates the attachment of implant strip  7200  to bone. 
     Referring to  FIG. 73 , a cross section of coiled implant strip  7200  may be clearly seen with protruding portion  7203  providing a flexible core for implant strip  7200 . With material  7240  applied to implant strip  7200 , the growth of bone  7299  between adjacent coils is blocked at upper boundary  7206  and lower boundary  7202 . This arrangement prevents bone  7299  from contacting protruding portion  7203  and interfering with the deflection properties of protruding portion  7203 . 
     Generally, the thickness of an implant strip will impact the diameter of the coiled implant strip. Typically, a thinner implant strip will require a greater length to achieve the same diameter when coiled as a thicker implant strip. In other words, a thicker implant strip may have a shorter length but form a coiled shape with approximately the same diameter as a longer and thinner implant strip. In some cases, a thicker implant strip with a shorter length may be preferable because it does not require as many coils to achieve a coiled shape with a particular diameter. Furthermore, a thicker implant strip with a shorter length may be easier to store than a thinner implant strip with a longer length. 
     The thickness of an implant strip may be increased in any manner known in the art. In some embodiments, an implant strip may be constructed with a greater thickness. In other embodiments, an implant strip may be configured with greater thickness by adding distinct portions to an implant strip. In some cases, multiple implant strips may be layered together to create a single layered implant strip with an increased thickness over a single implant strip. Preferably, every pair of adjacent implant strips in a layered implant strip may be separated by a spacer portion. 
       FIGS. 66-68  illustrate an exemplary embodiment of dual implant strip  6600 . Although this embodiment is illustrated schematically, it should be understood that dual implant strip  6600  is configured with length L 5  that is shorter than the typical length of thinner implant strips. Furthermore, dual implant strip  6600  is configured with thickness T 6  that is greater than the typical thickness of longer implant strips. In order to achieve greater thickness T 6 , dual implant strip  6600  is configured with layered implant strips. 
     In particular, dual implant strip  6600  is comprised of first implant strip  6601  and second implant strip  6602 . In this exemplary embodiment, first implant strip  6601  is configured with thickness T 3 . Likewise, second implant strip  6602  is configured with thickness T 4 . In addition, first implant strip  6601  includes inner surface  6611  and first central surface  6612  disposed opposite of inner surface  6611 . In a similar manner, second implant strip  6602  includes second central surface  6621  and outer surface  6622  disposed opposite of second central surface  6621 . 
     Generally, multiple implant strips may be joined in any manner to create a thicker implant strip. In some cases, multiple implant strips may be attached directly to each other. In other cases, multiple implant strips may be joined with another material disposed between the implant strips. 
     In this exemplary embodiment, dual implant strip  6600  includes spacer portion  6603 . Spacer portion  6603  is disposed between first implant strip  6601  and second implant strip  6602 . Specifically, spacer portion  6603  attaches to first central surface  6612  of first implant strip  6601 . In a similar manner, spacer portion  6603  attaches to second central surface  6621  of second implant strip  6602 . With this arrangement, dual implant strip  6600  is configured with thickness T 6  that is approximately equal to the sum of thickness T 3 , thickness T 4  and thickness T 5  of spacer portion  6603 . 
     Generally, spacer portion  6603  may be constructed of any material discussed in this detailed description. In some cases, spacer portion  6603  may be constructed of a flexible plastic to provide flexibility to dual implant strip  6600 . In other cases, spacer portion  6603  may be constructed of shape memory alloy or shape-memory material to assist dual implant strip  6600  in coiling into a desirable shape following implantation. 
     Preferably, thickness T 6  and length L 5  of dual implant strip  6600  allow dual implant strip  6600  to form a coiled shape with fewer coils.  FIG. 67  is a schematic top down view of an exemplary embodiment of dual implant strip  6600  formed in a coiled shape. Due to thickness T 6  and length L 5 , dual implant strip  6600  forms two coils when shaped in a coil. In particular, dual implant strip  6600  is configured with first coil  6701  and second coil  6702 . For illustrative purposes, only two coils are shown here, however it should be understood that in other embodiments dual implant strip  6600  may form additional coils as well. 
     Referring to  FIG. 68 , a cross section of coiled dual implant strip  6600  may be clearly seen with spacer portion  6603  disposed between first implant strip  6601  and second implant strip  6602 . By forming a coiled shape with fewer coils, dual implant strip  6600  may be easier to implant than a longer thinner strip. Furthermore, the construction of dual implant strip  6600  with spacer portion  6603 , as well as first implant strip  6601  and second implant strip  6602 , provides opportunities to manipulate the coiling properties of dual implant strip  6600 . 
     In some cases, a dual implant strip may include provisions to facilitate bone growth into the implant strip. Generally, the growth of bone into a dual implant strip may be encouraged in any manner known in the art. In some embodiments, teeth may be disposed on edges of the dual implant strip to facilitate bone growth into the dual implant strip. In other embodiments, bone growth promoting agent may be applied to portions of the dual implant strip to assist bone growth into the dual implant strip. In still other embodiments, a coiled dual implant strip may be configured with recesses or gaps so that bone may grow into the recesses and anchor the dual implant strip. In some cases, a dual implant strip may be configured with a spacer portion and separating portions that create space for the growth of bone into the coiled implant strip. 
       FIGS. 74-77  illustrate an exemplary embodiment of dual implant strip  7400 . As discussed in the previous embodiment, an implant strip may be comprised of multiple implant strips to create a single thicker implant strip that requires fewer coils to achieve a coiled shape with a particular diameter. In this embodiment, dual implant strip  7400  comprises first implant strip  7401  and second implant strip  7402 . First implant strip  7401  and second implant strip  7402  may be configured with any width typical for an implant strip. In addition, first implant strip  7401  includes inner surface  7411  and first central surface  7412  disposed opposite of inner surface  7411 . Similarly, second implant strip  7402  includes second central surface  7421  and outer surface  7422  disposed opposite of second central surface  7421 . 
     Preferably, first implant strip  7401  is joined to second implant strip  7402  by spacer portion  7403 . Specifically, spacer portion  7403  attaches to a portion of first central surface  7412  of first implant strip  7401 . Also, spacer portion  7403  attaches to a portion of second central surface  7421  of second implant strip  7402 . In order to create space for the growth of bone, spacer portion  7403  preferably extends from upper boundary  7492  to lower boundary  7491  on first implant strip  7401  and second implant strip  7402 . In this manner, the upper and lower edges of first implant strip  7401  and second implant strip  7402  may contact adjacent vertebrae directly. 
     Generally, an implant strip comprising multiple implant strips may include separating portions. In some cases, an implant strip may be configured with separating portions to limit contact between adjacent coils when the implant strip is coiled. In other cases, an implant strip may include separating portions to create space between adjacent coils to encourage bone growth into an implant strip. 
     In this embodiment, dual implant strip  7400  includes material  7451  that acts as a separating portion. Material  7451  may be any material that may serve as a separating portion discussed in previous embodiments. Preferably, material  7451  is applied to a portion of inner surface  7411  of first implant strip  7401  and a portion of outer surface  7422  of second implant strip  7402 . In particular, material  7451  is applied to cover regions on inner surface  7411  and outer surface  7422  between upper boundary  7492  and lower boundary  7491 . This arrangement creates space for the growth of bone above upper boundary  7492  and below lower boundary  7491 . In addition, this configuration leaves the upper and lower edges of first implant strip  7401  and second implant strip  7402  free to contact adjacent vertebrae. 
     Spacer portion  7403  and material  7451  could be made of any material. In some embodiments, spacer portion  7403  and material  7451  could be made of similar materials. In other embodiments, spacer portion  7403  and material  7451  could be made of different materials. In a preferred embodiment, spacer portion  7403  and material  7451  are both made of a polymer of some kind. 
     Generally, material  7451  may be applied with any thickness necessary to achieve the desired width of coiled implant strip  7400 . In addition, the width of spacer portion  7403  may be greater or lesser than the width of a typical implant strip. Preferably, adjusting the width of material  7451  as well as adjusting the width of spacer portion  7403  may allow the diameter of the coiled dual implant strip  7400  to be fine tuned. 
     In some embodiments, dual implant strip  7400  may be pre-formed and inserted. In other embodiments, dual implant strip  7400  may coil during implantation. In a preferred embodiment, dual implant strip  7400  may coil following insertion with a cannula.  FIG. 75  illustrates a cross sectional view of an exemplary embodiment of cannula  7480  used for inserting dual implant strip  7400 . Preferably, dual implant strip  7400  can be inserted between adjacent vertebrae in a manner similar to the insertion of a single implant strip. The details of this method have been previously discussed. 
     Referring to  FIG. 76 , dual implant strip  7400  is coiled following insertion. Due to the thickness of dual implant strip  7400 , dual implant strip  7400  conforms to a coiled shape that includes first coil  7691  and second coil  7692 . In other embodiments, dual implant strip  7400  may be configured with more or less coils in a coiled shape. Furthermore, first coil  7691  and second coil  7692  are spaced a distance apart by material  7451 . Preferably, this spacing between first coil  7691  and second coil  7692  prevents undesirable rubbing of adjacent coils. 
       FIG. 77  is a cross sectional view of the exemplary embodiment of coiled dual implant strip  7400 . Preferably, the creation of space within coiled dual implant strip  7400  by spacer portion  7403  and material  7451  allows bone  7499  to grow into dual implant strip  7400 . In particular, bone  7499  grows between first implant strip  7401  and second implant strip  7402  into the spaces created by spacer portion  7403 . Additionally, bone  7499  grows into adjacent coils of coiled dual implant strip  7400 . Specifically, bone  7499  grows into spaces created between first coil  7691  and second coil  7692  by material  7451 . Furthermore, bone  7499  is blocked from growing between upper boundary  7492  and lower boundary  7491  of dual implant strip  7400  by spacer portion  7403  and material  7451 . With this arrangement, the upper and lower edges of first implant strip  7401  and second implant strip  7402  are free to contact adjacent vertebrae. This configuration allows dual implant strip  7400  to be anchored into place between adjacent vertebrae. 
     As previously discussed, an implant strip may be configured with distinct portions that are made of different materials. Different materials may have different material properties, including deflection and/or deformation properties. By constructing distinct portions of an implant strip with different materials, the deflection and/or deformation properties of an implant strip may be fine tuned. 
       FIG. 69  illustrates an exemplary embodiment of implant strip  6900 . In this embodiment, implant strip  6900  is comprised of first portion  6901  and second portion  6902 . First portion  6901  is constructed of a first material. Similarly, second portion  6902  is constructed of a second material. In this case, the first material and second material are different materials. Furthermore, the first material and second material have different deflection and/or deformation properties. Generally, the first material and second material may be any type of discussed in this detailed description. In this exemplary embodiment, the first material is a more elastic material and the second material is a more rigid material. 
     Generally, distinct portions may be disposed in various configurations to create an implant strip. In this exemplary embodiment, first portion  6901 , constructed of the more elastic first material, includes first region  6931  and second region  6932 . First region  6931  and second region  6932  extend in a longitudinal direction between first end  6951  and second end  6952  of implant strip  6900 . In particular, first region  6931  is disposed near upper edge  6920 . In a similar manner, second region  6932  is disposed near lower edge  6910 . 
     Second portion  6902  includes central region  6961  as well as upper edge  6920  and lower edge  6910 . This provides implant strip  6900  with rigid central region  6961  as well as rigid upper edge  6920  and rigid lower edge  6910 . Additionally, flexible first region  6931  and flexible second region  6932  are interspersed between central region  6961 , upper edge  6920  and lower edge  6910 . In this manner, implant strip  6900  may deform near upper edge  6920  and lower edge  6910  although upper edge  6920  and lower edge  6910  maintain a rigid shape. In some cases, this configuration may increase the strength of implant strip  6900  in the axial direction. Furthermore, this arrangement may assist implant strip  6900  in enduring bending, lateral, and twisting forces. 
     By selecting materials with particular deflection and/or deformation properties and incorporating those materials into distinct portions of an implant strip, the deflection and/or deformation characteristics of an implant strip may be fine tuned. For example, in an alternative embodiment of implant strip  6900 , the second material may be more flexible than the first material. In other words, upper edge  6920  and lower edge  6910  as well as central region  6961  may be constructed of a flexible material while first region  6931  and second region  6932  are constructed of a more rigid material. In some cases, the flexible material may allow upper edge  6920  and lower edge  6910  to deform with contact from adjacent vertebrae. However, the rigid material of first region  6931  and second region  6932  may limit the deflection and/or deformation. Also, central region  6961  may defect and/or deform to endure bending, lateral, axial, and twisting forces. Preferably, the deflection and/or deformation properties of an implant strip may be tuned by altering the materials as well as the sizes and shapes of distinct portions of an implant strip. 
     Distinct portions of an implant strip may be attached in various manners to create the implant strip. In embodiments where distinct portions comprising materials of differing flexibility are used, these embodiments can include provisions for facilitating attachment between the distinct portions. Preferably, these embodiments can include provisions to help prevent the distinct portions from detaching over time and with use. 
       FIGS. 70-71  illustrate an exemplary embodiment of a portion of implant strip  7000 . In this embodiment, implant strip  7000  includes three distinct portions. In particular, implant strip  7000  includes upper portion  7002 , lower portion  7001  and central portion  7003 . Upper portion  7002  preferably includes upper edge  7020  of implant strip  7000 . In addition, upper portion  7002  includes first bottom edge  7021 . In a similar manner, lower portion  7001  preferably includes lower edge  7010  and first top edge  7011 . Furthermore, central portion  7003  extends from second top edge  7052  to second bottom edge  7051 . In a preferred embodiment, central portion  7003  may overlap with first bottom edge  7021  of upper portion  7002  and first top edge  7011  of lower portion  7001 . 
     In different embodiments, the shape of first top edge  7011  and first bottom edge  7021  may vary. In some embodiments, first bottom edge  7021  and first top edge  7011  may have a wave like shape. In other embodiments, first bottom edge  7021  and first top edge  7011  could be generally straight. In this preferred embodiment, first bottom edge  7021  and first top edge  7011  have a wave like shape that varies in a periodic manner. This arrangement may provide periodically spaced portions that can facilitate attachment of upper portion  7002 , lower portion  2001  and central portion  7003 . 
     Generally, upper portion  7002 , central portion  7003 , and lower portion  7001  may be constructed from any material discussed in this detailed discussion. In this exemplary embodiment, upper portion  7002  and lower portion  7001  are constructed of a relatively rigid material. Additionally, central portion  7003  is configured of a relatively more elastic material. This configuration preferably allows implant strip  7000  to deform and endure axial loads from adjacent vertebrae. 
     Preferably, upper portion  7002  and lower portion  7001  include provisions to attach to central portion  7003 . In this exemplary embodiment, upper portion  7002  and lower portion  7001  include gaps  7050 . Gaps  7050  are disposed at intervals proximate to both first bottom edge  7021  and first top edge  7011 . In particular, gaps  7050  may be associated with crests of first bottom edge  7021  and first top edge  7011 . Although only a portion of implant strip  7000  is illustrated in  FIG. 70 , it may be assumed that gaps  7050  extend at intervals in a longitudinal direction between a first end and a second end of implant strip  7000 . 
     Referring to  FIG. 71 , gaps  7050  extend from inner surface  7081  of upper portion  7002  and lower portion  7001  to outer surface  7082  of upper portion  7002  and lower portion  7001 . Preferably, central portion  7003  may be configured to extend through gaps  7050  within upper portion  7002  and lower portion  7001 . With this arrangement, portions of upper portion  7002  and lower portion  7001  may be embedded within central portion  7003 . This configuration can assist in securely attaching central portion  7003  to upper portion  7002  and lower portion  7001 . 
     Central portion  7003  also preferably extends between first bottom edge  7021  and first top edge  7011 . As seen in  FIG. 71 , in a preferred embodiment, central portion  7003  may comprise a generally monolithic elastic material. This generally monolithic arrangement may provide increased structural stability for implant strip  7000 . In other embodiments, however, central portion  7003  could include any number of holes, gaps, voids, and/or channels. In some cases, holes, gaps, voids and/or channels can be used to modify the overall elastic properties of central portion  7003 . 
     The preferred arrangement illustrated in  FIGS. 70 and 71  may help to prevent separation between portions comprising distinct materials. In particular, upper portion  7002  is prevented from separating from central portion  7003  since central portion  7003  is disposed through gaps  7050  in upper portion  7002 . Likewise, lower portion  7001  is prevented from separating from central portion  7003  since central portion  7003  is disposed through gaps  7050  in lower portion  7001 . By substantially reducing the likelihood that distinct portions of implant strip  7000  may separate, the lifetime of implant strip  7000  can be substantially increased. 
     Generally, an implant strip may be configured to coil into any particular shape. In some embodiments, a coiled shape of an implant strip may be tailored to the replacement of an intervertebral disc or vertebral body of a patient. In some cases, an implant strip may be configured to coil into a particular shape to partially or fully fill a cavity of an intervertebral disc and provide increased support to the adjacent vertebrae. In other cases, an implant strip may conform to a particular coiled shape to replace a vertebral body. In other embodiments, a coiled implant strip may be configured to a particular shape to increase the effectiveness of a disc fusion procedure. In still other embodiments, an implant strip may be designed with a particular coiled shape to accommodate the insertion of multiple implant strips. 
       FIGS. 50-53  illustrate exemplary embodiments of implant strips configured to coil into a particular shape. These embodiments are not meant to be limiting, in other embodiments, implant strips may be configured to coil into additional coiled shapes. Preferably, the implant strips in these embodiments may be inserted in an identical manner to the methods used to insert the previously discussed implant strips. In particular, the implant strips in these embodiments may be pre-formed and inserted (see  FIGS. 51 and 53 ) or may coil during insertion (see  FIGS. 50 and 52 ). Additionally, delivery devices may assist in the insertion and configuration of the implant strips into particular coiled shapes. Furthermore, the implant strips in these embodiments may include all the features discussed in the previous and following embodiments. 
     Generally, the implant strips in these embodiments may be made of any material, including shape memory alloys and spring steel, as well as other types of materials, including materials discussed in other embodiments. An implant strip may be constructed from any suitable material that may be configured to assume a desired shape when formed in a coil. 
     In some embodiments, the shape of a coiled implant strip may be modified. In previous embodiments, the implant strips retain a generally cylindrical shape. In other embodiments, however, it may be desirable to modify the shape of the implant strip to adjust various loading properties of the coil. For example, using a kidney shaped coil may allow the surgeon to modify the axial loading properties along various portions between two adjacent vertebrae. 
     Referring to  FIG. 50 , implant strip  5000  may be configured to coil into a kidney shape. In this schematic illustration of the coiling of implant strip  5000 , distal end  5001  of implant strip  5000  preferably forms first curved portion  5003  and second curved portion  5004  to create a kidney shaped first inner coil  5005 . By following first inner coil  5005 , the remainder of implant strip  5000  may be configured to coil into a kidney shape. 
     When coiled in the kidney shape, implant strip  5000  has width W 2  and length L 2 , as seen in  FIG. 51 . In this embodiment, length L 2  is significantly greater than width W 2 . Generally, length L 2  and width W 2  may have any value and vary from one embodiment to another. 
     Furthermore, the kidney shape of coiled implant strip  5000  produces different radial distances between different portions of adjacent coils. In some cases, adjacent coils may be separated by greater distances on portions of coils disposed along the longitudinal axis of implant strip  5000  and separated by shorter distances on portions of the coils disposed along the latitudinal axis. For example, first outer coil  5101  and second outer coil  5102  may be separated by radial distance R 8  at first portion  5110 , disposed along the longitudinal axis of implant strip  5000 . At second portion  5111 , disposed along the latitudinal axis of implant strip  5000 , first outer coil  5101  and second outer coil  5102  are separated by radial distance R 9  that is less than radial distance R 8 . In general, the coiled shape of an implant strip may produce various spacing between portions of adjacent vertebrae. With this preferred arrangement, the in-growth of bone may be encouraged at particular portions of implant strip  5000 . 
     As previously discussed, multiple implant strips may be implanted simultaneously between adjacent vertebrae. In some cases, by modifying the shapes of one or more implant strips, a surgeon may implant multiple implant strips between adjacent vertebrae in different arrangements. 
     Implant strip  5000  may be implanted with second implant strip  5100 , as seen in  FIG. 51 . In this embodiment, second implant strip  5100  is identical in size and shape to implant strip  5000 . However, second implant strip  5100  is oriented as a mirror image of implant strip  5000 . In other embodiments, any number of implant strips configured with various coiled shapes and oriented in a variety of directions may be implanted with implant strip  5000 . In some cases, each implant strip may be associated with a different height to create Lordosis or correct scoliosis. Preferably, multiple implant strips may be inserted to fill a disc region and provide support to adjacent vertebrae. 
       FIGS. 52-53  illustrate a schematic view of an exemplary embodiment of implant strip  5200 . In this embodiment, implant strip  5200  is configured to coil in an oval shape. In particular, first distal end  5201  introduces first curved portion  5203  and second curved portion  5204  to create first inner coil  5205 . Preferably, by following first inner coil  5205 , the remainder of implant strip  5200  may be configured to coil into an oval shape. 
       FIG. 53  illustrates a schematic view of an exemplary embodiment of coiled implant strip  5200  implanted with second implant strip  5300 . Preferably, implant strips  5200  and  5300  are coiled in identical oval shapes. In particular, implant strip  5200  has length L 4  and width W 4  that is less then length L 4 . In a similar manner, second implant strip  5300  has length L 3  and width W 3 . Lengths L 3  and L 4 , as well as widths W 3  and W 4 , are substantially identical in this embodiment. Generally, lengths L 3  and L 4 , as well as widths W 3  and W 4 , may have any value and vary from one embodiment to another. In this embodiment, the oval shape of implant strips  5200  and  5300  produces approximately similar radial distances between adjacent coils. 
     Additionally, in this embodiment, implant strips  5200  and  5300  are inserted in opposite orientations. Specifically, implant strips  5200  and  5300  are inserted so that second end  5202  of implant strip  5200  and second end  5302  of second implant strip  5300  are disposed opposite of each other. Preferably, the insertion of implant strips  5200  and  5300  provides spinal continuity. 
     Typically, vertebrae are not completely symmetric and so the spacing between adjacent vertebrae may vary. A coiled implant strip that presents a particular shape at the top and/or bottom surface of the implant strip may allow for a more natural fit of the implant strip between adjacent vertebrae. In particular, an implant strip that presents different portions with differing axial heights can provide for a better fit between a coiled implant strip and adjacent vertebrae. With this arrangement, an implant strip may fit the natural contours of the adjacent vertebrae and perform a similar function to a spinal disc. 
     In some embodiments, a coiled implant strip may provide a particular contour on a top surface, while presenting a flat profile on a bottom surface. In other embodiments, a coiled implant strip may provide a particular contour on a bottom surface, although a top surface of the coiled implant strip is generally flat. In still other embodiments, a coiled implant strip may provide a first contour on a top surface and a second contour, different from the first contour, on a bottom surface. In a preferred embodiment, an implant strip may include symmetrical surfaces on a top and bottom surface when coiled. 
     Preferably, in these embodiments, contours of a top and/or bottom surface of a coiled implant strip may be formed by shaping a top and/or bottom edge of an implant strip. The shape of a top and bottom edge of an implant strip may be created by cutting or removing portions of an implant strip. Cutting may be done using techniques known in the art, including, but not limited to, punching, laser fusion and/or water drilling, stamping, or any combination of techniques. In other embodiments, a shape on an edge may be formed using a die of some kind. 
       FIGS. 54-62  illustrate schematic views of exemplary embodiments of implant strips that present particular contours on the top and bottom surfaces of the implant strips when coiled. For the purpose of clarity, the implant strips in these embodiments are illustrated schematically and are typically much longer. Preferably, the implant strips in these embodiments may be inserted in an identical manner to the methods used to insert the previously discussed implant strips. In some cases, the implant strips in these embodiments may be pre-formed prior to insertion. In other cases, the implant strips in these embodiments may coil during insertion. Also, the implant strips in these embodiments may include any other features discussed in other embodiments in this detailed description. 
       FIGS. 54-56  illustrate an exemplary embodiment of implant strip  5400 . Implant strip  5400  includes upper edge  5406  and lower edge  5402 . In this embodiment, upper edge  5406  and lower edge  5402  are configured with a symmetrical curvilinear shape, including interspersed crests and troughs. Specifically, the shape on edges  5406  and  5402  is configured to provide implant strip  5400  with maximum height H 12  at first crest  5411  disposed on upper edge  5406  and corresponding second crest  5412  disposed on lower edge  5402 . In addition, implant strip  5400  is configured with minimum height H 11  at first trough  5421  disposed on upper edge  5406  and corresponding second trough  5422  disposed on lower edge  5402 . Furthermore, the crests and troughs on edges  5406  and  5402  confer intervening heights between maximum height H 12  and minimum height H 11  on implant strip  5400 . In particular, successive crests on edges  5406  and  5402  are separated by a distance approximately equal to one 360 degree turn of a coil when implant strip  5400  is in a coiled state. In a similar manner, successive troughs on edges  5406  and  5402  are separated by a distance approximately equal to one 360 degree turn of a coil when implant strip  5400  is in a coiled state. 
     When implant strip  5400  is coiled, the curvilinear shape on edges  5406  and  5402  preferably creates a wedge shape, as seen in  FIG. 55 . In particular, coiled implant strip  5400  has maximum height H 12  at first portion  5501  and minimum height H 11  at second portion  5502 . With this preferred arrangement, upper edge  5406  creates an inclined plane on top surface  5506 . In a similar manner, lower edge  5402  provides an inclined plane on bottom surface  5590 .  FIG. 56  is a cross sectional view of the exemplary embodiment of implant strip  5400  in a coiled state. 
     In some cases, a wedge shaped implant strip may be used to correct scoliosis or spondylolisthesis. In other cases, a wedge shaped implant strip may assist in providing lordosis to a vertebral column. In particular, in some embodiments, a coiled implant strip with a wedge shape may be inserted to orient a portion of the coiled implant strip with a maximum height to the anterior and a portion of the coiled implant strip with a minimum height to the posterior of a patient. In other embodiments, the orientation of an implanted wedge shaped coiled implant strip may be tailored to a specific patient. For example, a wedge shaped coiled implant strip may be oriented to correct scoliosis in a patient. 
     In some embodiments, an implant strip may be tapered to create a concave shape on a top and/or bottom surface when the implant strip is coiled.  FIGS. 57-59  illustrate an exemplary embodiment of implant strip  5700  tapered from second end  5702  to first end  5701 . In particular, second end  5702  extends maximum height H 14  and first end  5701  extends minimum height H 13 . Generally, maximum height H 14  and minimum height H 13  may have any values and may vary from one embodiment to another. In addition, in the current embodiment upper edge  5716  and lower edge  5712  smoothly decline from second end  5702  to first end  5701 . In other embodiments, edges  5716  and  5712  may decline in another manner. 
     Referring to  FIG. 58 , implant strip  5700  is coiled with first end  5701  disposed on an inner coil. Second end  5702  is disposed on outer coil  5810 . With this arrangement, coiled implant strip  5700  presents a generally concave shape on top surface  5806 . Likewise, a generally concave shape is disposed on bottom surface  5802 .  FIG. 59  provides a cross sectional view of the exemplary embodiment of implant strip  5700 . Minimum height H 13  may be clearly seen at the center of coiled implant strip  5700  in this Figure. Using this configuration, adjacent vertebrae may be supported and in-growth of bone into implant strip  5700  may assist in anchoring implant strip  5700  in position. 
     In other embodiments, an implant strip may be configured to create a convex shape on a top and/or bottom surface of the coiled implant strip.  FIGS. 60-62  illustrate an exemplary embodiment of implant strip  6000 , including first end  6001  and second end  6002 . In this embodiment, implant strip  6000  is tapered with upper edge  6016  and lower edge  6012  smoothly declining from first end  6001  to second end  6002 . In particular, first end  6001  is configured with maximum height H 15 . In a similar manner, second end  6002  is configured with minimum height H 16 . Generally, maximum height H 15  and minimum height H 16  may have any values and may vary from one embodiment to another. 
     With this arrangement, implant strip  6000  is coiled with first end  6001  disposed at the center of the coiling, as seen in  FIG. 61 . Also, second end  6002  is disposed on outer coil  6010 . Preferably, upper edge  6016  of coiled implant strip  5700  creates a generally convex shape on top surface  6106 . Likewise, lower edge  6012  creates a generally convex shaped on bottom surface  6102 . A cross sectional view of the exemplary embodiment of implant strip  6000  is illustrated in  FIG. 62 . The convex shape on top surface  6106  and bottom surface  6102  with maximum height H 15  disposed at the center of the coiling of implant strip  6000  may be clearly seen in this Figure. This preferred arrangement may provide spinal continuity and encourage bone growth, in particular, on a periphery of coiled implant strip  6000 . 
     Preferably, the different provisions of implant strips discussed in this detailed description may be combined to create a spinal implant strip that maximizes the utility of the implant strip for a particular patient. Furthermore, a bone growth promoting agent may be applied to a portion or an entirety of an implant strip in concert with any other provisions described in this detailed description. Generally, a surgeon or medical expert may assess a patient and configure a spinal implant device based on factors specific to the patient. In some cases, for example, a surgeon or medical expert may consider the location of the damaged tissue, size of the vertebrae, and anatomical shape of the vertebrae or spinal disc as factors in the design choice of an implant strip. In other cases, a particular combination of provisions of an implant strip may be chosen to correct scoliosis or spondylolisthesis. In still other cases, an implant strip may be configured to alleviate compression of the nerves in the spinal foramen and canal. Generally, an implant strip may be configured with particular provisions to approximate the natural biomechanics of the spine and provide for spinal continuity. 
       FIGS. 63-65  illustrate a schematic representation of an embodiment of various provisions associated with implant strips and exemplary combinations of those various provisions to create implant strips. In this embodiment, these provisions are arranged into various provision sets, grouped with common properties. In other embodiments, these provisions may be arranged differently. In this embodiment, a first row includes teeth set  6301  with a choice of teeth disposed on an upper and lower edge of an implant strip. Additionally, a second row contains spacing set  6302  with a choice of spacing features that may be disposed on an implant strip. In a similar manner, a third row contains deflection set  6303  with provisions for the deflection of an implant strip. Also, a fourth row includes shape set  6304  that includes various shapes configured on the top and bottom surfaces of implant strips. 
     Furthermore, the first choice in each set  6301 - 6304 , notably first column  6311 , provides the option for not selecting the feature associated set. For example, first implant strip  6321  of teeth set  6301  has no teeth on an upper or lower edge. However, second implant strip  6322  of teeth set  6301  includes teeth disposed in a saw tooth pattern on an upper edge and lower edge. Teeth set  6301  further includes third implant strip  6323  with irregularly spaced rounded teeth disposed on an upper and lower edge. In some embodiments, additional elements with other provisions may be added to sets  6301 - 6304 . In some cases, for example, an implant strip with regularly spaced rounded teeth disposed on an upper edge may be added to teeth set  6301 . Also, in other embodiments, additional sets with other provisions may be considered when selecting features for an implant strip tailored for a particular patient. 
       FIG. 63  illustrates a schematic view of an exemplary embodiment of a selection of provisions for implant strip  6350 . In this embodiment, a saw tooth pattern for teeth is selected from second implant strip  6322  of teeth set  6301 . Additionally, first option  6350  with no spacing is chosen from spacing set  6302 . Also, second option  6352  of an implant strip with provisions for axial deflection is selected from deflection set  6303 . Finally, wedge shape  6354  is chosen from shape set  6304 . With this combination of features, implant strip  6356  is created and preferably tailored to different properties of a deformation of a spine of a particular patient. 
       FIG. 64  illustrates a schematic view of the selection of features for a second exemplary embodiment of spinal implant strip  6450 . In this embodiment, first option  6321  with no teeth disposed on an upper and lower edge from teeth set  6301  is selected. Next, protrusion option  6452  is chosen as spacers from spacing set  6302 . In a third choice, an elastomer strip option  6354  is selected from deflection set  6303 . In a fourth choice, convex shape option  5356  with a convex top and bottom surface is chosen from shape set  6304 . With this combination of selections, implant strip  6450  may be constructed and preferably be tailored to conditions in a spine of a specific patient. 
       FIG. 65  illustrates a schematic view of the combination of features for a third exemplary embodiment of spinal implant strip  6550 . In this embodiment, saw tooth option  6322  for teeth is selected from teeth set  6301 . In a second choice, no spacing provisions are selected from spacing set  6302 . Additionally, no deflection provisions are selected from deflection set  6303 . Finally, no modified shape provisions are chosen from shape set  6304 . This combination of provisions yields implant strip  6550 . With this preferred arrangement, implant strip  6550  includes features to embed into adjacent vertebrae following insertion. 
     In addition to the combinations of implant strips that have already been described, it is also possible to form other combinations. If there are three distinct elements in a teeth set, three distinct elements in a spacing set, four distinct elements in a deflection set, and four distinct elements in a shape set, then there are one hundred and forty-four distinct implant strips that can be formed. As the number of distinct feature sets and the number of elements within feature sets increases, the total number of possible implant strips grows. A larger number of distinctly configured implant strips allows a medical expert or surgeon to make more subtle adjustments to an implant disc to increase the ability of an implant strip to mimic the dynamic properties of a disc and/or provide for the continuity of a spine. 
     As discussed previously, an implant strip may include provisions to change shape. In some embodiments, an implant strip with provisions to change shape may be constructed of a shape-memory material. An implant strip constructed of a shape-memory material may be configured in a first shape prior to implantation. After implantation, the implant strip may assume a second shape that is different from the first shape. 
     In some cases, a signal associated with implantation may trigger the implant strip to transform to the second shape. Generally, the signal associated with implantation may be any type of signal including, but not limited to, heat, light, a local chemical environment, or mechanical or electrical stimulation. For example, when an implant strip is implanted, the body temperature of a patient may trigger the implant strip to transform into a second shape. 
     Generally, an implant strip constructed of shape-memory material may form various types of second shapes following implantation. In some cases, the second shape may be an oval shape. In other cases, the second shape may be any desired shape, including a circular shape or a kidney shape. Preferably, incisions to implant an implant strip constructed of shape-memory material may be smaller because the implant strip may assume a second shape without assistance from a surgeon. 
     It is also possible that an implant strip constructed of a shape-memory material may expand in size following implantation. Preferably, this may allow an implant strip to be constructed with a smaller size than necessary. With this arrangement, an implant strip may be constructed with a first size. Following implantation, the implant strip may expand to a second size that is larger than the first size. In this manner, smaller incisions may be made to implant the implant strip. This can provide reduced trauma and faster healing rates following implantation of an implant strip constructed of shape-memory material. 
     While various embodiments of the invention have been described, the description is intended to be exemplary, rather than limiting, and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims.