Abstract:
The implant device is a minimally invasive device for assisting in the fusing together of vertebral bodies of the spine. The implant device immobilizes the vertebral bodies by immobilizing the respective spinous process extending from the vertebral body. The implant device has at least one spacer and hook to immobilize adjacent spinous processes. The spacer and hook are fastened to connection rods. Each connection rod can individually traverse through a range of motion, allowing each hook to engage the respective spinous process.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority to United States Provisional Patent Application entitled SUPPLEMENTAL SPINE FIXATION DEVICE AND METHOD, filed Jul. 18, 2001, Serial No. 60/306,262 and is a continuation-in-part application of U.S. patent application Ser. No. 09/842,819, filed Apr. 26, 2001 and is a continuation-in-part application of U.S. patent application Ser. No. 09/579,039, filed on May 26, 2000 and entitled SUPPLEMENTAL SPINE FIXATION DEVICE AND METHOD, which is a continuation-in-part of U.S. patent application Ser. No. 09/473,173 filed on Dec. 28, 1999 and entitled SPINE DISTRACTION IMPLANT, now U.S. Pat. No. 6,235,030 issued May 22, 2001, which is a continuation of U.S. patent application Ser. No. 09/179,570 filed on Oct. 27, 1998 and entitled SPINE DISTRACTION IMPLANT, now U.S. Pat. No. 6,048,342 issued Apr. 11, 2000, which is a continuation-in-part of U.S. patent application Ser. No. 09/175,645 filed on Oct. 20, 1998 and entitled SPINE DISTRACTION IMPLANT, now U.S. Pat. No. 6,068,630 issued May 30, 2000. All of the above applications and patents are incorporated herein by reference.  
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention is directed to supplemental spine fixation devices and methods which are used as an adjunct to a primary spine fusion method and/or device, such as by way of example only, an inter-body fusion device. The present invention is also directed to a method and apparatus for engaging adjacent spinous processes without the use of a primary spinal fusion method or device.  
         BACKGROUND  
         [0003]    A common procedure for handling pain associated with degenerative spinal disk disease is the use of devices for fusing together two or more adjacent vertebral bodies. The procedure is known by a number of terms, one of which is inter-body fusion. Inter-body fusion can be accomplished through the use of a number of devices and methods known in the art. These include screw arrangements, solid bone implant methodologies, and fusion devices which include a cage or other mechanism which is packed with bone and/or bone growth inducing substances. All of the above are implanted between adjacent vertebral bodies in order to fuse the vertebral bodies together, alleviating associated pain.  
           [0004]    Associated with such primary fusion devices and methods are supplemental devices which assist in the fusion process. These supplemental devices assist during the several month period when bone from the adjacent vertebral bodies is growing together through the primary fusion device in order to fuse the adjacent vertebral bodies. During this period it is advantageous to have the vertebral bodies held immobile with respect to each other so sufficient bone growth can be established.  
           [0005]    Such supplemental devices can include hook and rod arrangements, screw arrangements and a number of other devices which include straps, wires, and bands, all of which are used to immobilize one portion of the spine relative to another. All of these devices generally require extensive surgical procedures in addition to the extensive procedure surrounding the primary fusion implant.  
           [0006]    It would be advantageous if the device and procedure for supplemental spine fixation were as simple and easy to perform as possible, and were designed to leave intact as much bone, ligament, and other tissue which comprise and surround the spine, as possible.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention is directed to providing a supplemental spine fixation device and method for alleviating discomfort associated with the spine and as an adjunct, if desired, to a primary spine fusion technique.  
           [0008]    The present invention provides for a method and apparatus for assisting in the fusing together of vertebral bodies of the spine. One of the features and purposes of the invention is to immobilize the vertebral bodies while spine fusion is accomplished. Fusion can require upwards of six months for bone cells from the upper and lower vertebral bodies to grow towards each other, generally through a primary fusion device.  
           [0009]    In order to assist in the fusing process, the supplemental spinal fixation device and method of the invention immobilizes the vertebral bodies by immobilizing the respective spinous processes extending therefrom. The present device and method of the invention is minimally invasive such that it does not add to the trauma of the primary fusion procedure, especially if the fusion procedure is from a posterior approach. With an anterior fusion approach, additional posterior incisions are required. However, these are minimal when compared to other devices and methods.  
           [0010]    It is also to be understood that the apparatus and method of the present invention can be used without spinal fusion in order to immobilize the spinous processes.  
           [0011]    Accordingly, an object of the present invention is to increase the rigidity and stability with respect to the adjacent spinous process and vertebral bodies in order to promote inter-body fusion between the vertebral bodies. A further object is to provide for such rigidity and stability without interbody fusion. For example the embodiment of the present invention can be used with an inventive spinous process distraction mechanism.  
           [0012]    It is yet a further object of the present invention to provide for an implant and method which does not require modification of the bone, ligaments, or adjoining tissues. In other words, it is an object of the present invention to provide for an implant and method which does not require that the bone be reshaped, notched, or in anyway modified. It is also an object that there is as little modification as possible to soft tissue and ligaments surrounding the bone.  
           [0013]    It is a further object of the present invention to provide for an implant and method which can be inserted from one side of adjacent spinous processes in order to immobilize the spinous processes and resultingly immobilize the adjacent vertebral bodies. By addressing the spinous processes from one side, the objects and advantages of a minimally invasive procedure with reduced trauma, can be accomplished.  
           [0014]    It is yet a further object of the present invention to provide for a device which has securing and/or hook elements which can easily and conveniently be secured about the spinous processes, which hook devices are preferably designed in order to accommodate the shape of the spinous processes and preferably swivel or pivot in order to accommodate the position and shape of one spinous processes relative to another.  
           [0015]    It is yet another object of the present of the invention to provide for a device which has several degrees of freedom in order to allow a portion of the device to be positioned between spinous processes in order to distract part the spinous processes and other portions of the device to engage the spinous processes in order to rigidly immobilize the spinous processes. These degrees of freedom allow the device to conform to the bones, ligaments, and tissues of each individual patient. Thus, the present device allows for adjustments along two and three axis in order to successfully immobilize spinous processes.  
           [0016]    It is yet another object of the invention to provide a device and method for securing together adjacent spinous processes which device is rigid and can keep the spinous processes aligned.  
           [0017]    Other aspects, objects and advantages of the invention are evident from the specification, the claims and the figures.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 is a perspective view of an embodiment of the present invention;  
         [0019]    [0019]FIG. 2 is a perspective view of an embodiment of the present invention of FIG. 1 illustrating the mobility of the connection rods;  
         [0020]    [0020]FIG. 3 is a front view of an embodiment of the present invention of FIG. 1;  
         [0021]    [0021]FIG. 4 is a front view of an embodiment of the present invention of FIG. 1 illustrating that the engagement members can individually rotate;  
         [0022]    [0022]FIG. 5 is a perspective view of yet another embodiment of the present invention illustrating two spacers;  
         [0023]    [0023]FIG. 6 is a perspective view of an embodiment of the spacer of the invention of FIG. 1;  
         [0024]    [0024]FIG. 7 is a perspective view of an embodiment of the rotatable engagement elements of the invention of FIG. 1;  
         [0025]    [0025]FIG. 8 is a perspective view of an embodiment of the present invention, illustrating the fastening bolts in an alternative arrangement and FIG. 8 a  is a side view showing a portion of this alternative embodiment;  
         [0026]    [0026]FIGS. 9 a  and  9   b;  FIG. 9 a  is a front view of an embodiment of the clamp of the present invention; FIG. 9 b  is a cross-sectional view of the clamp in FIG. 9 a  through line A-A; and  
         [0027]    [0027]FIGS. 10 a  and  10   b;  FIG. 10 a  is a top view of an embodiment of the connection rod of the present invention; FIG. 10 b  is a partial cross-sectional view of the connection rod in FIG. 9 a  through line A-A.  
         [0028]    [0028]FIG. 11 depicts the embodiment of the invention of FIG. 1 implanted between adjacent spinous processes.  
         [0029]    [0029]FIG. 12 depicts an alternative embodiment of the present invention used with an inventive spinous processes distractor. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0030]    Referring to FIGS.  1 - 4 , the implant device  100  has a spacer  102 , a first rotatable engagement element or hook  104 , a second rotatable engagement element or hook  106 , a first connection rod  108 , a second connection rod  114 , and clamps  110 . By way of example only, these elements may be manufactured from stainless steel, titanium or any other biologically acceptable material.  
         [0031]    The spacer  102  in FIG. 1 is substantially cylindrical in shape with an elliptical cross-section and a small diameter and a large diameter. The small diameter provides the height or distance between spinous processes. The small diameter of the spacer  102  is, by way of example only, 6 mm, 8 mm, 10 mm, 12 mm, and 14 mm. Additionally, the spacer  102  may consist of other shapes in cross-section such as, but not limited to, egg-shaped, oval or circular. In a preferred embodiment until locked in place by bolt  103 , the spacer  102  can rotate so that it may accommodate the shape of the spinous process it contacts.  
         [0032]    The spacer  102  also has a tapered front end, lead-in guide, or tissue expander  112 , a stem  113  and a threaded section  115  (See FIG. 6). As previously mentioned, the spacer  102  is placed between adjacent spinous process. Thus, the spacer  102  must be urged through the interspinous ligament. A physician will make an initial opening in the interspinous ligament to prepare the area for the spacer  102 . The tapered front end  112  minimizes the size of the initial opening a physician must make in the interspinous ligament. The tapered front end  112  can fit into the small initial opening and then distract the interspinous ligament to a height substantially equal to the small diameter of the spacer  102  as the spacer  102  is completely urged through the interspinous ligament. Thus, the tapered front end  112  minimizes trauma to the ligament tissue which promotes a faster recovery.  
         [0033]    The spacer  102  is attached with the first connection rod  108  and the second connection rod  114  by the bolt  103 . Until tightened, the bolt  103  allows the first and second connection rods  108 ,  114  to rotate relative to the spacer (see FIG. 2). This allows the hooks  104 ,  106  to engage a spinous process that are at different angles and distances relative to the spacer  102 .  
         [0034]    The first and second hook  104 ,  106  (FIG. 1) have an engagement element  116 , a tapered front end  118  and a stem  117  with a movement limiter  119  (FIG. 7). The tapered front end  118  is adapted for urging between adjacent spinous processes. Similar to the spacer  102 , the front end  118  includes a tip or pyramid. This tip or pyramid allows a physician to make a minimal initial opening in the interspinous ligament where the hook  104 ,  106  will be inserted. The front end  118  is urged into the initial opening and will distract the opening as the hook  104 ,  106  engages the spinous process. By creating a small initial opening, the tapered front end  118  allows the first and second hook  104 ,  106  to be inserted between adjacent spinous processes while minimizing the damage to the interspinous ligament tissue.  
         [0035]    Preferably, the engagement element  116  is U-shaped. One of ordinary skill in the art will appreciate that the engagement element  116  may comprise other shapes such as, but not limited to, rectangular and triangular. The engagement element  116  is intended to be positioned substantially around the spinous process (FIG. 11) such that the engagement element  116  will restrain the spinous processes from movement caused by bending forward. The shape of the first and second hook  104 ,  106  are such that the spinous processes do not need to be altered or cut away in any manner in order to accommodate the present invention. This is an improvement over the prior art because many prior devices require altering the spinous processes, such as cutting notches or grooves in the spinous processes. Further, the implant device  100  requires little if any altering to the ligaments and soft tissues surrounding the spinous processes. Generally, at most, ligaments would be pierced and/or urged apart. Altering the spinous processes in any manner can weaken the structure and can lead to complications in the future.  
         [0036]    The first and second connection rod  108 ,  114  have a first end  128  and a second end  132 . The first end  128  has a bore  130  extending through (See FIGS. 10 a  and  10   b  ). The spacer  102  is connected to both the first and second connection rods  108 ,  114 . To attach the spacer  102  with the first and second connection rod  108 ,  114 , the stem  113  (see FIG. 6) of the spacer  102  is inserted through the bore  130  of each connection rod  108 ,  114 . The spacer  102  is then secured to the first and second connection rod  108 ,  114  by engaging the bolt  103  with the threaded portion  115  of the stem  113 . With the bolt  103  fastened to the stem  115 , the first and second connection rod  108 ,  114  can pivot about the longitudinal axis of the spacer  102 . The spacer  102  can also rotate as indicated above. Fully tightening bolt  103  fixes the position of the spacer  102  and the connection rods  108 ,  114 .  
         [0037]    The first hook  104  is also connected with the second end  132  of the first connection rod  108 . The hook  104  is secured to the connection rod  108  by clamp  110 . As illustrated in FIGS. 9 a  and  9   b,  the clamp  110  includes clamping elements  109  and  111 , each of which has a channel  140  and a bore  142  extending through. The bore  142  has a limiting cavity  143 . The diameter of the two channels  140  is substantially similar to the diameter of the first connection rod  108 . The diameter of the bore  142  is substantially similar to the diameter of the stem  117  of the first hook  104 .  
         [0038]    The clamp  110  is slidably attached with the first connection rod  108 . The stem  117  of the first hook  104  is inserted through the bore  142 . By inserting the stem  117  through the bore  142 , the limiter  119  fits within the limiting cavity  143 . The limiter  119  prevents the hook  104  from rotating completely around. The second end  132  of the first connection rod  108  is placed through the channel  140 . Without tightening the bolt  144  to the threaded portion  121  of the stem  117 , the clamp  110  can be moved to any position along the first connection rod  108 . Similarly, the clamp  110  can be rotated about the longitudinal axis of the connection rod  108  to any angle relative to the first connection rod  108 . Additionally, the first hook  104  can be rotated about the longitudinal axis of its stem  117 , until the limiter  119  contacts either edge of the limiting cavity  143 . It is to be understood that in another embodiment with the limiter  119  removed, the hook  109 ,  106  can rotate completely around until locked in position by bolt  144 .  
         [0039]    To secure both the clamp  110  to the connection rod  108  and the hook  104  to the clamp  110 , the bolt  144  engages the threadable portion  121  of the stem  117 . By tightening the bolt  144  the diameter of the channel  140  decreases causing and the clamp  110  to tighten around the connection rod  108 . The second hook  106  is attached with the second connection rod  114  in a similar fashion.  
         [0040]    Preferably, the hooks  104 ,  106  can be positioned at any angle and location along the connection rods  108 ,  114 . Preferably, the first and second hooks  104 ,  106  have three degrees of freedom. The separation between the spacer  102  and the hooks  104 ,  106  likely differs as the distance between each is dictated by the placement of the initial opening and the location of the spinous processes. Therefore, the hooks  104 ,  106  will likely be positioned at different locations along the connection rods  108 ,  114  and at different angles relative to the spacer  102  when the spacer is urged between spinous processes and with each hook  104 ,  106  engage the spinous processes.  
         [0041]    The embodiments described so far are intended to rigidly fix two spinous processes relative to one another. However, more than two vertebrae can be fused together. As illustrated by FIG. 5, the implant device  100  may contain two spacers  102 . With the exception of an additional spacer  102  and a third connection rod  99  which has a bore  130  at each end, the elements of this embodiment are substantially the same as the embodiments in FIGS.  1 - 4 . This embodiment also functions similar to the embodiment previously described above. The additional spacer  102  is connected to connecting rods  99  and  114 . One of the bores  130  of the connecting rod  99  is aligned with the bore  130  of the connecting rod  114 . The stem  113  of the second spacer  102  allows the bolt  98  to encircle the threaded portion  115 . Tightening the bolt  98  will fasten the second spacer  102  to both the connecting rods  109 ,  114 . Even though the remaining portion of this specification describes the present invention with only one spacer  102 , the description also applies to the embodiment with multiple spacers  102 .  
         [0042]    The device  100  is designed to be implanted via a minimally invasive procedure. In a preferred method, the patient is placed in a lateral decubitus position with maximum flection of the lumbar spine. The patient can be on his or her side to insure proper orientation of the implant device  100 . The implant device  100  will be preferably inserted between the spinous processes from the bottom or right side of the spinous processes to the top or left side of the spinous processes. This method permits easy visualization of the implant device  100  assembly.  
         [0043]    Once an incision has been made and the implant area is accessible, the physician will first urge the first hook  104  between spinous processes to engage the spinous process. The physician can adjust the position of the first hook  104  so that the engagement element  116  is properly secures around the spinous process. The physician can then urge the second hook  106  between adjacent spinous processes at the same time as, or after, the first hook  104  is inserted. Similarly, the second hook  106  can be positioned so that the engagement element  116  engages the spinous process, which spinous process would be below the spacer  102 . The physician can then urge the spacer  102  between adjacent spinous processes. At this point, preferably the connecting rods  108 ,  114  are connected to the spacer  102 . The physician can attach both hooks  104 ,  106  to the connection rods  108 ,  114 . This is the preferred method as the hooks should be more easily insertable about the two adjacent spinous processes prior to the spacer being inserted. This is because as the spacer is inserted between the two adjacent spinous processes, and thus generally distracts the adjacent spinous processes, the two adjacent spinous processes move closer to their respective adjacent spinous process, reducing the space where the hooks would be inserted. It is to be understood, however, that any combination of method steps of inserting and connecting together the spacer  102  and the hooks  104 ,  106  and the connecting rods  108 ,  114  fit within the spirit and scope of the invention. Thus, the hooks  104 ,  106  and the spacer  102  can be inserted prior to being attached to the connecting rods  108 ,  114 . Alternatively, the connecting rods  108 ,  114  can be attached to the hooks  104 ,  106  before the hooks  104 ,  106  are inserted and thereafter attached to the spacer  102  after the spacer  102  is inserted.  
         [0044]    As previously mentioned, the spacer  102  and first and second hooks  104 ,  106  are inserted between adjacent spinous processes from only one side. Further, securing the spinous processes by first and second hooks  104 ,  106  with the engagement element  116  does not require altering the spinous process. Thus, this method minimizes the damage to surrounding body tissue and promotes a faster recovery than the typical method.  
         [0045]    The above methods use a small incision through which the pieces of the invention are inserted. However, yet another alternative method would be for the implant device  100  to be inserted through a larger incision, with the entire implant device  100  fully assembled. Prior to insertion, the bolts  103 ,  144  could be loosened so that the engagement portion  116  can be positioned around the spinous processes at about the same time that the spacer  102  is inserted between the spinous processes. Once this is accomplished, the spinous processes could be drawn down tightly around spacer  102 , with the engagement portion  116  finally positioned around the spinous processes. All the bolts would then be tightened.  
         [0046]    As indicated above, the implant device  100  can be implanted using a number of methods, preferably, once a primary spine fixation device is implanted between the vertebral bodies. It is to be understood, however, that this supplemented spine fixation device  100  of the invention can also be used by itself if it is desired to immobilize spinous processes relative to each other. Still alternatively as described below, another embodiment can be used with an independent spacer.  
         [0047]    As a further embodiment of the invention, the device of FIG. 1 can eliminate the body of the spacer  102  (FIG. 12) with the connecting rods  108 ,  114  still secured together with bolt  103  and a stem  115  with a threaded section connected to a small stop  121 , that is bigger than the bore  130  in the rods. This arrangement would keep the connecting rods  108 ,  114  together and allow them to rotate relative to each other until the bolt  103  is tightened. This device is used to limit the spreading apart of the spinous processes during flexion or forward bending. As can be seen in FIG. 12, this embodiment of the invention can be used, if desired with an inventive interspinous process distraction system  200  such as any of the variety of systems presented by the present assignee. These systems  200  are more fully described in the patents and patent applications referenced and incorporated herein under the cross-reference section.  
         [0048]    [0048]FIGS. 8 and 8 a  depict an alternative embodiment of the invention wherein the fastening and tightening bolts  103  and  144  are supplemented with alternative bolts such as bolt  182  in FIG. 8 a.  These bolts are mounted at approximate 90 degrees to the other bolts  103 ,  144  in order to allow the surgeon to tightened these bolts while looking at them head on, as opposed to looking at them from the side as would be the case with bolts  103 ,  144 . This is thus more convenient for the physician to assemble and tightened. As shown in FIG. 8 a,  for this arrangement, the clamp  110  includes an additional clamp element  180 . In this additional clamp element  180  another bolt as indicated above, bolt  182  is mounted. This bolt is essentially either a quarter or half turn bolt such that when the bolt is turned either a quarter or a half turn, a caming member  184  extends from the clamp member  180  in order to be urged against the adjacent clamp member, tightening that clamp member against the connecting rod  114 . In operation, the hook  106  and clamp  110  would be preassembled and then at the surgical site slid over the connecting rod  114 . After the hook  106  is positioned between spinous processes, the nut  182  can be turned in order to extend the caming member  184  from the clamp element  180  against the remainder of the clamp  110  in order to lock the hook  106  in place on the connecting rod  114 . It is to be understood that a similar arrangement can be accomplished with respect to the clamp mechanism which holds the spacer  102  to the connecting rods  108 ,  114 .  
         [0049]    As yet a further embodiment of the invention, the device of FIG. 1 can be modified to eliminate the second connecting rod  114  and the second hook  106  with the engagement element  116 . In this embodiment, the engagement portion  116  of the first hook  104  serves to keep the spacer  102  in place between adjacent spinous processes. So configured, the inventive device  100  aids to limit extension without inhibiting flexion or focused bending.  
         [0050]    The foregoing description of preferred embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations will be apparent to the practitioner skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications that are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalence.