MXPA00001054A - Cervical disk and spinal stabilizer - Google Patents

Abstract

A middle expanded, removable disk implant (22) for stabilizing adjacent cervical vertebrae (16, 18). The implant is substantially rectangular in cross-sectional shape with a niminal height (H) and a width (W) greater than the height. The implant is detachably mounted to an applicator for insertion into the anatomical region between two adjacent cervical vertebrae from which the intervertebral disk has been removed, and once inserted, is positioned by anterior-posterior movement in the disk space to the position in which both the expanded, larger width middle portion and the smaller diameter end portions of the implant engage the bodies of the adjacent vertebrae and the implant is then rotated to bring the sides of the rectangularly-shaped implant defining the width of the implant, with its larger dimension (W), into engagement with the bodies of the adjacent vertebrae. A lock, in the form of a stabilizer bar (29), is then secured to the implant to prevent further rotation thereof. The stabilizer bar includes structure which prevents relative rotation between the stabilizer bar and the implant and structure which protrudes into the space between the cervical vertebrae to prevent rotation relative to the vertebrae.

Description

Description The present invention relates to an intervertebral disc stabilizing implant for use in the cervical region of the spine and a method of stabilizing two adjacent cervical vertebrae. More specifically, the present invention relates to rectangular shaped disc implants that are expanded in the middle portion and are used for fusion of the cervical spine. The treatment of a herniated disc in the neck and lower back continues to be a challenging field of medicine. The classic treatment of a ruptured disk is the disquectomy, that is, the removal of the disc between the vertebrae. In this process, all or a portion of the intervertebral disc is removed, leaving a defect that can continue to bother patients throughout the rest of their lives. An additional ß procedure is to replace the disc space with a bone graft, usually bits of bone cut from the patient's iliac crest, causing fusion of the vertebrae above and below the disc, eliminating the empty space between the vertebrae. To date, no prosthetic disc has been shown to be safe and effective, so the best alternative treatment currently available is to fuse the adjacent "" • 2"vertebrae. However, the disked cytometry is not ideal, because the replaced bone does not have the function of the cartilaginous disc tissue, that is, it does not have a wrapping effect, and it has complications due to several factors. First, the conventional bone plugs used to pack the disc space do not conform to the disc space, because the disc bulges in the center. The space of the disc is wider in the middle and narrower in its front and back ends. For this reason, the different available commercial bone plugs have only four contact points, that is, in the front and in the back of the disc space, so that they are not as stable as would be desirable. Second, the access of the disc is from the side of the spine of the adjacent vertebrae, leaving a space that is "off center" in relation to the bodies of the vertebrae, in such a way that the stability of the implant is even more problematic than that could be seen by the limited contact resulting from the shape of the disk space. Another complication is the possibility of infection or other conditions that may require removal of the implant. Also, if the bone pieces do not fuse, they can eventually extrude out of the disc space, causing pressure on the nerve roots. The prosthetic disc plugs, or implants, are disclosed in the art, but all are characterized by limitations of not conforming to the shape of the disc space, in the scenarios, inability to be removed, and other inconveniences. For example, the Ufoi-Jps States patent No. 4,863,476 (and its European counterpart, EP-A-0260044), discloses a longitudinally divided elongated body with a cam device to increase the space between the two portions of the body once inserted in the disk space. However, this device is of a cylindrical shape, in such a way that the only points of contact with the vertebral bodies are in the front and in the back of the disc space, so that this device is characterized by the same instability as other disk plugs. The technique also discloses intervertebral disc prostheses (U.S. Patent Nos. 3,867,728, 4,309,777, 4,863,477, and 4,932,969, and French Patent No. 8816184), which may have more general contact with adjacent discs, but which they are not intended to be used in the fusion of discs. The technique also includes vertebral joint prostheses, such as are described in U.S. Patent No. 4,759,769, which are again not indicated for use when the preferred surgical procedure is fusion. The problem of maintaining separation between the vertebrae is particularly acute in the cervical vertebrae. The surgery itself is not as difficult as in the lumbar spine, because the access is from the front in the cervical spine, for example, ventrally to the patient. Because the bone pieces are not substantial enough to maintain the separation between the vertebrae, the accepted surgical method to maintain the separation between the adjacent vertebrae in the cervical spine is to remove the entire damaged disc, to drill a hole in the intervertebral space, and insert a plug of the patient's hole in the disc space. However, the cervical vertebrae are smaller than the vertebrae in the rest of the spine, so there is little tolerance for the anterior / posterior movement of the bone plug in the disc space, as it may occur before it is finished. the fusion. Due to the relatively small tolerances, almost any subsequent movement in the disk space endangers the nerves of the spinal cord, and the bone plugs do not have a structure to resist this movement. Accordingly, the hole into which the plug is inserted is of a size slightly smaller in relation to the plug, so that the ligaments on either side of the spine help to hold the plug in place by compressing the plug between the caps. vertebrae Even so, the plug can move in the intervertebral space, so there is a need for a spinal implant to stabilize the adjacent cervical vertebrae, which maintains sufficient space between the vertebrae to allow the spinal nerves to pass between the processes of the cervical vertebrae without being impacted by the vertebrae, and not allowing the anterior / posterior movement of the í¿ **? » * F implant in the disk space. In a similar manner, the bone chips packaged in the disc space around the plug can then be extruded against the spinal cord or the dorsal roots by compression provided by the ligaments that help hold the bone plug in place. Accordingly, there is a need for an implant that protects against the impact of the spinal cord and / or the nerves. There is also a need for a cervical implant that can be removed in the case ? of infection or other post-surgical complication. In the same way, there is a need for an implant to stabilize more than two vertebrae of the cervical spine without endangering the spinal cord and nerves, and without placing screws in the spinal bodies. These objects are provided by a cervical disc stabilizer constructed in accordance with the teachings of the present invention, which comprises an elongate member having a substantially rectangular cross-sectional shape for insertion between the adjacent cervical vertebrae, and a stabilizer bar for removably mounting to one end of the elongated member, to prevent relative rotation therebetween. An ear is formed on the stabilizer bar to be inserted between the adjacent cervical vertebrae, and because the stabilizer bar is mounted on the limb. elongated, in such a way that relative rotation is prevented, if the "^ elongate member begins to rotate in the space between the adjacent cervical vertebrae, the ear contacts one of the bodies of the adjacent vertebrae to prevent rotation of the elongated member. The stabilizer bar is elongated, and the long axis of the stabilizer bar is mounted orthogonally to the longitudinal axis of the elongated member. An implant comprised of an elongate member formed in multiple interconnected parts is also provided which, when assembled, provides the member with a substantially rectangular transverse sectional shape 10Oi to be inserted between the adjacent cervical vertebrae. A stabilizer bar is provided for detachably mounting to one end of the elongate member, to prevent relative rotation therebetween, with an ear formed thereon for insertion between the adjacent cervical vertebrae. Because the stabilizer bar is mounted on the elongated member in such a way as to prevent relative rotation, if the elongated member begins to rotate in the space between the adjacent cervical vertebrae, the ear contacts one of the vertebral bodies. adjacent to prevent rotation of the elongated member. The stabilizer bar is elongated, and the long axis of the stabilizer bar is mounted orthogonally to the longitudinal axis of the elongated member. If the implant must be removed, the stabilizer bar is removed, and the limb parts are dismantled. elongated in the disc space, in such a way that any , ~ f ,, ^, ^^.

Bone pedals that have fused in the disc space are not altered by removing the elongated member. Referring now to the figures, Figure 1 shows a perspective view of a cervical stabilizer constructed in accordance with the teachings of the present invention. Figure 2 is a side view of the human spine showing the cervical stabilizer of Figure 1 inserted into the intervertebral space, and having a portion of the adjacent vertebrae cut away to show the manner in which the stabilizer interacts with the vertebrae adjacent. Figure 3 is a top plan view of a single cervical vertebra showing the anterior-posterior placement of the cervical stabilizer of Figure 1 in relation to the body of the vertebra. Figure 4 is a schematic perspective view of the ventral aspect of the vertebral bodies of adjacent cervical vertebrae having the cervical stabilizer of Figure 1 inserted between each vertebra. Figure 5 is a partially schematic view of the adjacent cervical vertebrae, similar to the view shown in Figure 4, showing the two cervical stabilizers before connecting with a spinal stabilizer constructed in accordance with the teachings of the present invention. • $ 9.

Figure 6 is a partially schematic view of three adjacent cervical vertebrae similar to the view shown in Figure 4, and having a spinal stabilizer connecting the two cervical stabilizers Figure 7 is a perspective view of a second embodiment of a cervical stabilizer constructed in accordance with the teachings of the present invention Figure 8 is a perspective view of a third embodiment of a cervical stabilizer constructed in accordance with the teachings of the present invention Figure 8A is an elevated view end of an alternative embodiment of the cervical stabilizer shown in Figure 8. Figure 9 is a perspective view of a fourth embodiment of a vertical stabilizer constructed in accordance with the teachings of the present invention Figure 10 is a perspective view of a fifth mode of a vertical stabilizer built in accordance with the teachings of the present invention. Figure 11 is a perspective view of a sixth embodiment of a cervical stabilizer constructed in accordance with the teachings of the present invention. Figure 12 is a perspective view of a seventh embodiment of a cervical stabilizer constructed in accordance with the teachings of the present invention.

Figure 13 is a schematic perspective view of the ventral aspect of the vertebral bodies of adjacent cervical vertebrae, having an eighth embodiment of the cervical stabilizer constructed in accordance with the teachings herein, inserted between the second and third vertebrae. Figure 14 is a side elevational view of a ninth embodiment of a cervical stabilizer constructed in accordance with the teachings of the present invention. Figure 15 is an elevated end view of the cervical stabilizer of Figure 14. Figure 16 is a side view of a tenth embodiment of the vertical stabilizer of the present invention, having a portion of the adjacent vertebrae cut away to show how the which portions of the implant comprising the stabilizer, interact with each other. Figure 17 is a side view of the human spine, showing an eleventh embodiment of the vertical stabilizer of the present invention, inserted into the intervertebral space, and having a portion of the adjacent vertebrae cut away to show the manner in which the Stabilizer interacts with adjacent vertebrae. Figure 18 is a top plan view of a twelfth embodiment of the cervical stabilizer of the present invention. t% & -10- Referring now to the cervical stabilizer shown in Figure 1, the stabilizer is comprised of an elongated implant 22, a latch indicated generally in reference numeral 24, and an element for removably mounting the latch on one end 25 of the implant 22. In the embodiment shown, the mounting element takes the form of a screw, or a threaded post 26, which passes through a hole 28 in the stabilizer bar 29 comprising the safety 24, the threads of the post 26 being coupled with the threads of the nut 30 on the end of post 26. Implant 22 is an elongated member comprised of first and second sides 32, and third and fourth sides 34, which provide a cross-sectional shape of a substantially rectangular configuration. The height H of the section Cross section of rectangular shape is defined by sides 32, and width W is defined by sides 34. As can be seen by a comparison of H with, the height H of implant 22 is smaller than width W. As explained later, H is minimized to facilitate the insertion and placement of the implant 22 in the disc space from which all or a portion of the intervertebral disc 20 was removed, and W is maximized to provide the desired stabilization to the adjacent cervical vertebrae 16 and 18 (see Figure 2). The third and fourth sides 34 are arched from one end of the implant 22 to the other, for provide the intermediate implant portion 22 to the ranks that the width W "at the ends 2-5 and 36. Because the sides 32 of the implant 22 are substantially flat, and the sides 34 are arched from one end to the other. another, the implant 22 is characterized as a biconvex and biconvex implant.The biconvex sides 32 of the implant 22 are provided with teeth 38 for biting into the adjacent vertebrae 16 and 18, as explained below. form in a blunt, preferably flat, configuration to reduce the possibility of injuring the nerves during insertion into the disc space The implant 22 is provided with shims 40 formed integrally therewith: the shims 40 can be threaded on, or can be assembled in another way to the implant 22, in a manner known in the art.The shims 40 are diamond-shaped, and are oriented at an angle to the implant 22, such that the portion of the shoe 40 that contacts the body of the adjacent vertebrae, when rotated in the disc space as described below, is an acute front edge 42 for facilitating biting in vertebrae 16 and 18. From this description, will recognize that the wedge 40 can be made in the form of a hook, tip, beak, tooth, or can be formed in other configurations that perform the function of biting into the bone of the adjacent vertebrae to reduce the possibility of anterior / posterior movement of the implant 22 (in relation with the disk space. In a similar manner, the teeth 38 need not be configured as shown in FIG. 1 to reduce the possibility of anteplacement of the implant 22 in the disc space. The teeth 38 may have a tip, may be beveled to a point in opposite directions, or may be configured in another manner to increase the resistance to movement of the implant 22 relative to the bone comprising the adjacent vertebrae 16 and 18. 0? The latch 24 is comprised of a stabilizer bar 29 removably mounted on the end 25 of the implant 22, which resists the rotation of the implant 22 relative to the adjacent vertebrae 16 and 18 when the implant 22 is inserted therebetween. As shown in Figure 1, the stabilizer bar 29 is mounted on the implant 22 on a post 26 integrally formed with the end 25 of the implant 22. As described below, the end 25 of the implant 22 is placed anteriorly when insert the implant 22 between the • cervical vertebrae 16 and 18. The post 26 is screwed to receive a nut 30 to hold the stabilizer bar 29 thereon. An element is provided to prevent rotation of the stabilizer bar 29 relative to the implant 22 when the stabilizer bar 29 is mounted therein, in the form of the grooves 46 formed on the end 25 of the implant 22, to receive a key of a complementary form 48, formed on iltí • "a partee will recognize that the slot 46 can be located on the implant 22, and the key 48 can be located on the stabilizer bar 29, without any difference in the one in which these component parts operate. As best shown in Figure 3, the stabilizer bar 29 is elongated, and is mounted at the end 25 of the implant 22, such that the londinal axis of the stabilizer bar is positioned at an angle of approximately 90 ° C in 10i relation to the londinal axis of the implant 22. The ventral surfaces of the bodies of adjacent vertebrae 16 and 18 are rounded off when viewed along the axis of the spine, as shown in Figure 3, and to accommodate that rounded shape, the stabilizer bar 29 is also curved. stabilizer bar 29 is provided with an ear 44, preferably at or near both ends thereof, which projects into the disc space between the vertebrae 16 and 18, when the implant 22 is placed on which the stabilizer bar 29 is mounted between the cervical vertebrae adjacent. Each of the ears 44 protrudes into the space between the bodies of the adjacent vertebrae 16 and 18, and is provided with vertebral support surfaces 49 on its upper and lower surfaces. When the stabilizer bar 29 is mounted on the implant 22, which in turn stops at its place against the previous / subsequent movement through - -, "S &lbs 40 and teeth 38, support surfaces 49 prevent relative rotation between vertebrae 16 and 18 and implant 22. In this way, stabilizer bar 29 secures implant 22 in place between vertebrae 16 and 18. As noted above, the space around the implant 22 in the intervertebral space is preferably packed with bone chips (not shown), to facilitate fusion of the adjacent vertebrae, keeping the implant 22 the proper spacing between the vertebrae. Also as noted above, it is important to prevent the extrusion of the bone fragments posteriorly to a coupling with the spinal cord and / or the spinal nerves.To prevent this extrusion, the cervical stabilizer of the present invention is provided with elongated protectors of spinal cord 50, whose long axes extend from the implant 22 at an angle of approximately 90 ° C, for example, orthogonally to the long axis of the implant 22, as shown in Figure 3. The shields 50 extend orthogonally from the first and second sides 32 of the implant 22, i.e., laterally when the implant is implanted in the patient, inside the disc space , to close the posterior aspect of the disk space. In this way, the protectors 50 prevent, or at least reduce, the possibility of extrusion of the bone pieces packed in the disc space later, until a coupling with the spinal cord. As described in more detail below, the surfaces of the bodies of the vertebrae 16 and 18 adjacent to the disc space are slightly concave, such that the disc space is somewhat configured as the space between two inverted plates. Due to the shape of the disc space, the posterior opening of the disc space tapers near the edges of the vertebral bodies, and consequently, the proximal ends of the shields 50 are of a smaller vertical dimension (vertical with reference to the patient's spine when the implant is implanted, and the shields 50 in the manner described later) at their distal ends, than at the proximal ends 52 adjacent to the implant 22. Again, due to the shape of the disc space, it is inconvenient to insert the implant 22 in the disc space with the shields 50 in the position shown in Figure 3, ie, with the longitudinal axis of the shields 50 orthogonal to the axis of the implant 22. Accordingly, an element is provided for placing the protectors in that orthogonal position after the implant 22 is inserted into the disc space. As shown in Figure 1, the setting element takes the form of instantaneous adjustment posts 56 formed on each shield 50 to press fit into the complementary grooves 58 formed in the surface 60 of an end stop 62 integral with the end 36 of the implant 22. The surface 6 is oriented at approximately 90 ° with the surfaces 32 of the implant 22, and the posts 56 are formed on one of the iftdos 64 of the protectors 50, such that, when in the slots 58, the e's are long from the guards 50 are placed at the same orthogonal angle (relative to the longitudinal axis of the implant 22) as the surface 60. Referring now to Figures 4 to 6, a spinal stabilizer including the cervical stabilizer of the present invention is shown. The bodies of three adjacent cervical vertebrae 16, 18, and 66, are shown from the ventral side of the patient (the anterior or front part of the disc space) in Figure 4. A first cervical stabilizer 22 is inserted into the space between the first and second vertebrae 16 and 18, and a second stabilizer 22 'is inserted into the space between the second and third vertebrae 18 and 66. As shown in FIG.

Figure 5, the stabilizer bars 29 and 29 'are mounted on each of the implants 22 and 22' on the posts 26 and 26 'of each implant, using the nuts 30 and 30', respectively, as described above. As shown in Figure 6, then the connector 68 is attached to the posts 26 and 26 'of the implants 22 and 22 'with nuts 70 and 70', to link the first and second implants 22 and 22 ', thereby supporting the fusion of the three cervical vertebrae, with all the advantages of the cervical stabilizer of the present invention. Figures 7 to 12 show alternative modalities of the vertical stabilizer of the present invention. Doing * 4C reference to Figure 7, one can see the reason why the connection between the shields 50 and the implant 22 is referred to as a positioning element. As shown in Figures 1 to 6, the positioning element comprises press fit connectors formed by the posts 56 and the slots 58 on the shields 50 and the end stop 62, respectively. In Figure 7, the positioning element takes the form of a piano hinge 72 connecting the shields 50 to the end stop 62. The implant 22 is inserted into the vertebral space with the 0, shields 50 in a first folded position, with axes • longitudinal protectors 50 substantially parallel to the longitudinal axis of the implant 22. After the rotation of the implant 22 along its longitudinal axis in the manner described above, the protectors 50 are pivoted from the first folded position to the second position extended, wherein the longitudinal axes of the shields are substantially orthogonal to the implant 22. To illustrate, the implant 22 shown in Figure 7 is shown with a shield 50 in the • first position folded, and the other in the second position 0 extended. As shown in Figure 7, the piano hinge 72 is formed on the end stop 62 near the point where the end stop 62 and the sides 34 intersect. In this way, the orthogonal surface 60 of the end stop 62 acts to provide a stop, in order to prevent the pivoting of the protectors from the first position through the first position, where the protectors extend in a substantially perpendicular manner from the first position. the longitudinal axis of the implant 22, and helps retain the protector 50 in the second extended position. In a third embodiment shown in Figure 8, the protectors 50 are pivoted from a first folded position to the second extended position on the piano hinges 74. In this embodiment, the piano hinges 74 that connect the shields 50 to the implant 22, are located on the end 36 of the implant 22, such that, when the guards 50 are pivoted to the extended position, the surfaces 50 at the proximal ends 52 abut, to resist further pivoting of the guards 50 passing through the second position. Also note that the ears 76 of the stabilizer bar 29 shown in Figure 8, are configured differently from the ears 44 shown in the embodiments shown in Figures 1 to 7. The ears 76 extend from the stabilizer bar 29 by a substantial distance, such that, when the stabilizer bar 29 is mounted on the implant 22, they project into the vertebral space, such that the engaging surfaces of the vertebrae 49 formed thereon, engage with the bone cortical hard on the edges of the bodies of the adjacent vertebrae 16 and 18, thus providing support for the vertebrae ? Í- ^ ÍÜÍÍ .. adjacent in a position located outwardly from the implant 22. Because its function is to contain the bone chips packed in the disc space on either side of the implant 22 (instead of maintaining the spacing between the adjacent vertebrae), the protectors 50 need not be comprised of the same material as the implant 22. The protectors 50, for example, may be comprised of a semi-rigid biocompatible polymer. When comprised of these materials, the vertical stabilizer of the present invention can be made in a configuration, shown in Figure 8A, which makes it possible to remove the disk space. In addition, unlike known intervertebral implants, the cervical stabilizer of the present invention can be removed after fusion of the bone chips around the implant. Removal is made possible by emptying or otherwise fabricating the shields 50 from a semi-rigid polymer with a spacer 77 as shown in Figure 8A. As shown in a raised view of the end 36 of the implant 22, with the shields 50 extended from the first folded position to the second extended position, the shields 50A and 50B are mounted on the corners of the end 36 of the implant 22, instead of the end surface 36 as shown in Figure 8. When it is mounted in the corners of the end 36, and it is * - ' -20 * pivots to the second extended position, a gap is left between the opposing rear surfaces 51 of the protectors 50A and 50B. However, as is the case in the embodiments shown in Figures 7 and 8 (and in Figures 9 to 12 described below), the implant 22 shown in Figure 8A is also provided with an element to restrict the pivoting of the guards 50 from the first folded position, passing through the second extended position. As shown in Figure 8A, the proximal end 52 of one of the shields (identified as 10A 50A in Figure 8A) is provided with an integral spacer 77, which extends at an angle from the surface 51 to abut the surface. opposite 51 of the proximal end 52 of the protector 50B, to resist the pivoting of the protectors 50A and 50B passing through the second extended position (ie, for preventing the protectors from pivoting through an angle that is approximately 90 ° relative to the longitudinal axis of the implant 22). If it is desired to remove the implant shown in Figure 8A, the stabilizer bar 29 is removed from the end 25 of the implant 22, and the implant 22 is held at the end 25, and is pulled anteriorly into the disc space (ventrally to the patient). When the implant 22 moves anteriorly in the disc space, the shields 50A and 50B are rotated through the orthogonal position described above, causing the separator 77, comprised of the same semi-rigid material as the former. protectors 50A and 50B, collapse between the opposite surfaces ^ - ^ g * t i .. < ~ 21-51, allowing this web to effectively pivot to one where once again they are substantially parallel to the longitudinal axis of the implant 22, but extend in the opposite direction along that axis from the first folded position. . No parts of the protectors or the implant are broken, nor is any part of the implant or protector left behind in the space that is left by the removal of the stabilizer. In Figure 9 another embodiment of the cervical stabilizer of the present invention is shown. In this embodiment, the shields 50 are provided with a laminated edge 78 at the proximal end 52 thereof, which is snapped into a complementary shaped groove 80 formed in the orthogonal end stop surface 62. The orthogonal surface 60 provides both a stop against which the shield is placed when inserted into the disc space to conform to pressure in the groove 80, and resistance to the pivoting of the shield to an angle beyond approximately 90 ° from the longitudinal axis of the implant 22 in the manner described in relation to the embodiments shown in Figures 1 to 8. Also, the ears 82 of the embodiment shown in Figure 9, are configured and dimensioned to project more inwardly from the disc space than the ears 44. of the embodiments shown in Figures 1 to 7, to provide an additional vertebral surface against which the surfaces of "Xt vertebral support 49. In the embodiment shown in Figure 10, as in the embodiments of Figures 1 to 6 and 'the protectors 50 are assembled to the implant 22 after the implant 22 is inserted into the space In the embodiment shown in Figure 10, the proximal ends 52 of the shields 50 are provided with a key 84 for sliding in a key hole 86 that runs longitudinally along the length of the third and fourth faces 34 of the implant 22, until the protectors 50 abut the orthogonal surface 60 of the end stop 62, which comprises the element for resisting the pivoting of the guards 50 passing through the second extended position, as described above. leave the key hole 86 towards the end 25 of the implant 22, an elongated guard 88 is provided, configured to fit in, and slide toward, the key hole 86, such that, when the keeper 88 is inserted in the key hole 84, and the stabilizer bar 29 is mounted in the same, the keeper 88 prevents movement of the guards 50. In the embodiment shown in Figure 10, the vertebral support surfaces 49 on the stabilizer bar take the form of multiple pointed peaks 90. If there is insufficient space between the adjacent vertebrae so that the lugs 44 of the stabilizer bars 29 shown in FIGS.

J ^ "# * -23- Figures 1 to 9 between the bodies of the -vertebrae, or if for some other reason a stabilizer bar having ears formed thereon can not be used, the relative rotational movement between the vertebrae and the implant can be resisted by the tightening of the nut 30 to the point where the peaks 90 are propelled into the surfaces of the bodies of the adjacent vertebrae. In the embodiment shown in Figure 11, the relative rotation between the stabilizer bar 29 and the implant 22 is prevented by the interaction of the internal surfaces 92 of the arms 94 of the U-shaped latch 96 integrally formed with the stabilizer bar 29 and the surfaces 34 of the implant 22. The surfaces 92 of the latch 96 are provided with a slot 98 for receiving a key of complementary shape 100 on the implant 22, to facilitate the assembly of the latch 96 on the implant 22. It can be seen from from this description that slot 92 can be located on implant 22, and key 100 can be located on latch 96, with no difference in the way these parts operate. The latch 96 is provided with a hole (not shown) for receiving the post 26 when the slot 92 is aligned with the key 100 on the implant 22. In this embodiment, vertebral abutment surfaces 44 are provided on the ears 44 and on the shoulders. top and bottom of the insurance 96. In the modality shown in Figure 12, the protec- KSi .. ??? í: aM8Ss? SES?. TZi res 50 are provided with posts 102 similar to the posts 56 of the embodiment shown in Figures 1 to 6, to adjust to, X "pressure in the form slots Complementary 104 formed in the third and fourth surfaces 34 of the implant 22. When the posts 102 are instantaneously adjusted in the slots 104, the orthogonal surface 60 of the end stop 62 abuts the sides, or flat surfaces, of the shields 50, thus resisting the pivotal movement of the shields 50 in relation to the implant 22. In Figure 13 another embodiment of the vertical stabilizer of the present invention is shown in place between two adjacent cervical vertebrae 116 and 118. As the embodiment shown in FIG. Figure 8A, the embodiment shown in Figure 13 can be removed from the disc space, even after fusion of the bone chips packed in the disc space around the implant 122. As shown in FIG. Figure 13, the protectors 110, instead of articulating with the implant 122, and being comprised of metal or a semi-rigid polymeric material described in relation to the embodiment shown in Figure 8A, are cut and configured themselves from bone, to fit in, and close, the posterior opening of the disc space (the dorsal aspect of the vertebrae). The pieces of bone 110 shown in Figure 13 are effectively configured by the surgeon during surgery, so that they can wedge between adjacent vertebrae 116 and 118 during subsequent rotation of the implant 122 as described above, and before packing the space of the disc with the bone pieces, to close the posterior (dorsal) opening of the disc space. In the event that the implant 122 needs to be removed at a later date, so that the bone chips have been fused, the bone shields 110 will have fused with the bone chips, and the implant 122 simply removed without the shields 110. In the embodiments shown in Figures 14 and 15, the component parts of the implant 122 corresponding to the similar parts of the different implants 22 shown in Figures 1 to 12, are referenced by the same reference numerals preceded by a "1", that is, the teeth 38 are shown at 138 in Figures 14 and 15. The implant 122 is constructed to facilitate removal of the vertical stabilizer of the present invention after fusion of the bone chips in the disc space. As shown in Figure 14, the implant 122 is comprised of the sections 122A, 122B, and 122C divided along the longitudinal axis of the implant 122. The sections 122A, 122B, and 122C are interconnected by the interlocking tabs 121 and the grooves 123, the tabs 121 being formed. on sections 122A and 122B, and grooves 123 formed on section 122C (Figure 15). The section 122C is provided with an element to selectively prevent relative movement of the sections 122A, 122B, and YYVY ^ nYY ^ - Y, 122C in the form of a pair of blind bags 127 (only one of which is shown in Fiura * J4), which have pins 131 placed therein, forcing each bolt 131 outwardly through a spring 133. The tabs "121 near each end of the sections 122A and 122B which, when assembled to the section 122C, comprise the end 136 of the implant 122, are inclined as in 137, such that the pins 131 travel upwardly along the incline 137 when each section 122A and 122B slides over the section of the implant 122C to fall into a stop 139 formed on the surface of the tab 121, to secure the sections 122A and 122B in place on the section 122 C. The detents 139 formed on the surfaces of the tabs 121 of the sections 122A and 122B are relatively shallow, such that, when sufficient force is exerted on the section 122C in a direction a what the At the same time as the longitudinal axis of the implant 122, such as when the implant 122 is to be removed from the disc space, the pins 131 are unable to remain in the position in which they are forced inwards from the detentions 139. Once it has been Removing the implant section 122C from between the sections 122A and 122B in this manner, then the sections 122A and 122B are dissected to be freed from the fused bone, and removed from the opening left by the removal of the section 122C. In an alternative embodiment, instead of making stops at the surface sections 122A and 122B, the pe of a material that breaks when subjected to a side grip, allowing the section 122C to be pulled between sections 122A and 122B . Figure 16 shows another three-piece implant 122 intended to facilitate the removal of disc space. Instead of the bolts and stops described in connection with the embodiment shown in Figures 14 and 15, the implant 122 shown in Figure 16 is provided with a central section 122C having a stop 141 formed near the end 136 thereof, such that, when the sections 122A and 122B are slid over the section 122C, their travel to the end 136 is restricted by the stops 141. To selectively prevent the movement of the sections 122A and 122B in a direction along the axis longitudinally of the implant 122, in a direction away from the stops 141, the section 122C is provided with a threaded slot 143 for receiving a screw 126 therein. When the screw 126 is inserted through the stabilizer bar 129 into the slot 143, and tightened, the screw 126 forces the two halves of the section 122C at the end 125 thereof to separate. The slots 146 formed in the end 125 of the implant 122 to receive the keys 148 on the stabilizer bar 129 are enlarged to allow relative movement between the two halves of the section 122C and the stabilizer bar 129. Because the sections 122A and 122B they become rigid by the shapes of the tongues 121, the * U? S2§af? &? T? A *% * ja lan when the halves of the section 122C are extended by the screw 126, causing the sections 122A and 122B to be linked with the section 122C, to prevent relative movement between them. To remove the implant 122 shown in Figure 16 from the disc space, the screw 126 is loosened to allow the halves of the section 122C to relax to their original shape, thereby allowing the section 122C to move relative to the legs. sections 122A and 122B, so that section 122C can be removed therefrom. In Figure 17 there is still another embodiment of a removable cervical stabilizer implanted between two adjacent cervical vertebrae 116 and 118. In this embodiment, the implant 122 is again comprised of three sections 122A, 122B, and 122C, and section 122C is provided. with stops 141 near its end 136. However, in the embodiment shown in Figure 17, the relative movement of the section 122C along the longitudinal axis of the implant 122 away from the stops 141 is selectively prevented by the stabilizer bar 129 which, when retained on the post 126 by the nut 130, traps the sections 122A and 122B against the stops 141. By a comparison of Figures 2 and 17, it can be seen that the stabilizer bar 129 is of a greater vertical dimension (with reference to the patient's spine) than the stabilizer bar 29 shown in Figure 2. As shown in Figure 17, bone inserts 110 are provided to prevent posterior extrusion (dorsal) of the bone chips packed in the disc space, but will recognize from this description , that the implant 122 shown in Figure 17 (or any of the implants shown in Figures 14 to 16), may also be provided with protectors of the type described above. FIG. 8A, or as described below in relation to FIG. 18. The implant 122 shown in FIG. 18 includes integrally formed shields 150 which, like the shields 50A and 50B described above in connection with FIG. 8A. , they take advantage of the fact that the protectors do not need to be as stiff and strong as the implant. As shown in Figure 18, the shields 150 are formed of the same material as the implant 122, but are relatively thin. When force is exerted along the longitudinal axis of the implant 122 to remove the implant 122 from the disc space, the thin shields 150 are bent at their respective junctions with the implant 122, to allow the implant and the shields 150 to be pulled from the implant. disk space. If necessary, the surface 164 of the shields 150 is provided with a plurality of regularly spaced apart vertical grooves, or markings, as shown at 165, to allow the shields 150 to continue to bend to "feed" through the groove in the boot. bone fused around implant 122, when the implant is pulled - <; -Y -30- 122 between the cervical vertebrae. Referring again to Figures 1 to 7, the method of the present invention will be described. Using extensors as disclosed in the international application No. PCT / US95 / 00347, the reference of which is hereby incorporated in its entirety by this specific reference thereto, vertebrae 16 and 18 are distended to open the disc space . When the desired "extension" is achieved, an implant 22 having a height H and a width selected to fit in the disc space is mounted on an applicator (not shown), screwing the implant 22 onto the threads formed at the end. of the applicator, in the threads of the post 26. Then the implant 22 is inserted into the disc space using the applicator 52, with the implant 22 oriented, in such a way that its upper and lower parts, i.e., the first and second sides 32, engage the bodies of the adjacent vertebrae 16 and 18. Using the applicator, then the implant 22 is moved further inward (or outward) from the space of the disc in a anterior-posterior direction, to place the implant 22 in the The disc space is in a position in which the expanded middle portion and the smaller ends 25 and 36 of the third and fourth sides 34 of the implant 22 contact the respective lower and upper surfaces of the bodies of the vertebrae 16 and 18. when they rotate approximately 90 ° using the applicator. The respective upper and lower surfaces of the vertebral bodies are slightly larger, so that the mid-width portion of the implant 22 allows the implant 22 to be coupled substantially more with the respective surfaces of the implant. "vertebral bodies than conventional implants, thereby providing greater fusion stability once additional rotation of the implant 22 in the disc is prevented as described below.When placed to provide maximum stabilization, and rotated by approximately 90 °, in such a way that the "surfaces 32 of the implant 22 make contact with the bodies of the vertebrae 16 and 18, the implant applicator 22 is unscrewed, and is returned out of the disc space, then the protectors 50 are inserted into the disc space, and adjusted 5 in place in the grooves 58 formed in the orthogonal surface 60 of the end stop 62. In the case of alternative embodiments, wherein the element for placing the protectors 50 comprises hinges or other similar structure, the guards 50 pivot from the first position, where the 0 axis of the protector is substantially parallel to the axis of the implant 22, to the second position, where the axis of the protector is orthogonal to the axis of the implant The space inside the disc space on either side of the implant 22 is then packed with cancellous bone chips 5 After packing the disc space with chips 29 through the same incision, the ox $? ßi 4 'into the disc space from the "Hp & r" aspect of the disc space (the patient's ventral side). Then is X ß $ S $? the nut 30 on the 'Ja * post 26, and tightened to mount the stabilizer bar 29 on the implant 22, and stop the ears 44 in the disc space. Securing the stabilizer bar 29 in the implant 22 in this manner prevents relative rotation between the stabilizer bar 29 and the implant 22, while the lugs 44 of the stabilizer bar 29 protrude into the disc space between the bodies of the stabilizer bar 29. the adjacent vertebrae 16 and 18, in such a way that the bearing surfaces 49 prevent the rotation of the stabilizer bar 29 in relation to the vertebrae 16 and 18. The vertebral support surfaces 49 rest against the cortical end plates, which are comprised of non-cancellous bone, of the respective vertebral bodies which provide a hard and relatively smooth surface against which the surfaces 49 abut. If necessary, a small amount of a physiologically compatible adhesive of a type known in the art, on cancellous bone chips in the disc space, to close the opening in the disc space; the bone pieces begin to fuse before the opening narrows. The patient should be able to sit down and ambulate soon after the procedure is finished, due to the stabilization Implantity. The removal of the implant, if necessary, has been described above in relation to the description of Figures 8A and 13 to 18. Although described in terms of the modalities shown in the figures, these embodiments are shown to exemplify the invention, being able to Note that changes can be made to the modes shown without departing from the spirit of the present invention. These changes may include, for example, forming the implant 22 such that the first and second sides are substantially planar, but not parallel along their longitudinal axes. The wedge shape resulting from the implant facilitates the insertion of the implant into the disc space, reducing the rounded end to the possibility of injuring the nerves of the spinal cord during insertion into the disc space. In the same way, various combinations of placing elements, elements to prevent rotation, and ear shapes are described herein, and it will be recognized that these combinations can be used in any of several different combinations with equal efficiency. All these modifications, and other modifications that do not depart from the spirit of the present invention, fall within the scope of the following claims.

Claims (46)

1. -34- CLAIMS 1. A cervical disc stabilizer, comprising: an elongate implant having a substantially rectangular cross-sectional shape for insertion between adjacent cervical vertebrae; a protector for mounting on the end of said implant opposite said stabilizer bar; a stabilizer bar for releasably mounting on one end of said implant to prevent relative rotation therebetween; and a surface formed on said stabilizer bar for supporting against adjacent cervical vertebrae to prevent movement of said stabilizing bar relative to adjacent cervical vertebrae.
2. 2. The stabilizer of claim 1, wherein said protector extends outwardly from said implant at an angle of about 90 ° relative to the longitudinal axis of said implant.
3. 3. The stabilizer of claim 2, wherein the The longitudinal axis of said stabilizer bar is placed at an angle of about 90 ° relative to the longitudinal axis of said implant.
4. 4. The stabilizer of any of the preceding claims, wherein said protector is pivotally mounted. 25 on that implant.
5. 5. The stabilizer of claim 4, wherein said protector pivots from a first folded position against Y and said implant to a second extended position, extending orthogonally from said implant. - The stabilizer of claim 5, wherein said protector is provided with a plurality of slots vertically aligned to allow said protector to pivot from said first to said second position by bending along the length of the protector. 7. The stabilizer of claims 4, 5 or 6, Wherein said protector is pivoted from a first folded position to insert said implant into the space between adjacent cervical vertebrae and a second position extending outwardly of said implant at an angle relative to the longitudinal axis of said implant to close the aspect dorsal of space between adjacent cervical vertebrae. The stabilizer of claims 4 or 5 or 6 or 7, further comprising means for restraining the pivoting of said protector from the first folded position plus 0 beyond said second extended position. The stabilizer of claim 8, wherein said restricting means is capable of being broken so as to allow said protector to pivot past said second extended position to a third position approximately 180 ° from said first folded position. 4 < - 36 - X 10. The stabilizer of claim 1, wherein said stabilizer bar is mounted on said implant so that the respective axes of said stabilizer bar and said implant are orthogonal. The stabilizer of any of the preceding claims, wherein said stabilizer bar is curved to approximate the shape of the ventral aspect of the adjacent vertebrae. The stabilizer of any of the preceding claims, further comprising a connector for releasably mounting to said implant when implanted between adjacent cervical vertebrae. The stabilizer of claim 12, wherein said connector is mounted on a second implant. The stabilizer of any of the preceding claims, further comprising means formed on said implant to prevent movement of said implant toward or away from the space between two adjacent cervical vertebrae when inserted therebetween. 15. The stabilizer of any of the preceding claims, wherein said implant is formed into movable sections with respect to each other. 16. The stabilizer of claim 15, further comprising means for selectively preventing relative movement of the sections of said implant. 17. Apparatus for stabilizing two adjacent cervical vertebrae, comprising: an elongate implant having a width dimension greater than the height dimension; a stabilizer bar having an ear formed therein configured to fit in the space between two adjacent cervical vertebrae; means formed at the first end of said implant for removably mounting said stabilizer bar therein, with the axis of said stabilizer bar approximately • perpendicular to the longitudinal axis of said implant; and a spine guard for positioning at the second end of said implant to close the space between two adjacent cervical vertebrae when said implant is inserted therebetween. The apparatus of claim 17, wherein the sides of said implant forming its height dimension are provided with means for biting the bone when said implant is inserted into the space between two adjacent cervical vertebrae. The apparatus of claim 17 or 18, wherein said mounting means comprises means for preventing the rotation of said implant relative to said implant. The apparatus of any of claims 17 to 19, wherein said spine guard comprises first and second elongate members positioned in said implant at an angle of the longitudinal axis thereof. The apparatus of any of claims 17 to 19, wherein said spine protector comprises first and second elongate members positioned on said implant and movable from a first folded position against said implant to a second position extending substantially perpendicularly. from the longitudinal axis of said implant. The apparatus of any of claims 17 to 21, further comprising a connector mounted on said implant at the same end as said stabilizer bar to extend along the spine to stabilize the spine. 23. A cervical stabilizer, substantially as disclosed herein, with reference to the description and the drawings. 24. A method of stabilizing adjacent cervical vertebrae, comprising the steps of: inserting an implant having a width dimension greater than the height dimension in the space between adjacent vertebrae with the width dimension oriented at approximately 90 ° with the axis of the axis of the spine; rotate the implant approximately 90 ° so that its width dimension is aligned with the axis of the spine; and pivoting a spine guard connected to the implant from a first position folded against the implant to a second position extending approximately 90 ° from the implant. The method of claim 24, further comprising packing bone chips in the space between adjacent vertebrae after pivoting the spine guard from the first folded position to the second extended position. 26. The method of claim 25, further comprising removing the implant from the space between adjacent vertebrae without removing the bone chips packed therein. The method of claim 24, further comprising resisting the pivoting of the guard of the first folded position more than about 90 ° beyond the second extended position. The method of claim 24, further comprising connecting a first implant inserted into the space between adjacent vertebrae with a second implant inserted into the space between a third adjacent vertebra. 29. The method of stabilizing adjacent cervical vertebrae, substantially as described herein with reference to the description and the drawings. 30. A cervical disc stabilizer, comprising: an elongate implant having a substantially rectangular cross-sectional shape for insertion between adjacent cervical vertebrae; a stabilizer bar for releasably mounting on one end of said implant to prevent relative rotation therebetween; an ear on said stabilizing bar projecting towards the adjacent space between vertebrae and having a surface formed therein to support against adjacent cervical vertebrae to prevent movement of said stabilizing bar relative to adjacent cervical vertebrae; '• tes. 31. The stabilizer of claim 30, which further comprises a shield for mounting to the end of said implant opposite said stabilizer bar. 32. The stabilizer of claim 31, wherein said guard extends outwardly from said implant at an angle of 90 ° relative to the longitudinal axis of said implant. The stabilizer of claim 32, wherein the longitudinal axis of said stabilizer bar is positioned at an angle of about 90 ° on the longitudinal axis of said implant. 34. The stabilizer of claim 31, wherein said protector is pivotally mounted on said implant. 35. The stabilizer of claim 34, wherein the guard is adapted to pivot from a first folded position against said implant to a second extended position extending orthogonally from said implant. 36. The stabilizer of claim 35, wherein • said protector is provided with a plurality of slits aligned vertically to allow said protector to pivot from the first to the second position by bending along the length of the protector. 37. The stabilizer of claims 35 or 36, wherein said protector is pivoted from a first folded position for inserting said implant into the space between adjacent cervical vertebrae and a second position extending outwardly of said implant at an angle relative to the longitudinal axis. of said implant to * close the dorsal aspect of the space between adjacent cervical vertebrae. 38. The stabilizer of claims 35, 36 or 37, further comprising means for restraining the pivoting of said protector from the first folded position beyond the second extended position. 39. The stabilizer of claim 38, wherein Said restraining means are capable of being broken so as to allow said protector to pivot beyond said second extended position to a third position approximately 180 ° of said first folded position. 40. The stabilizer of claim 30, wherein 25 said stabilizer bar is mounted on said implant so s * • "sfíSt -42"* s that the respective axes of said stabilizing bar and said implant are orthogonal 41. The stabilizer of any of claims 30 to 40, wherein said stabilizer bar is curved to approximate the shape of the ventral aspect of the adjacent vertebrae. 42. The stabilizer of any of claims 30 to 41, further comprising a connector for releasably mounting said implant when implanted between two adjacent cervical vertebrae 43. The stabilizer of claim 40, wherein said connector is mounted in a second implant 44. The stabilizer of any of claims 30 to 43, further comprising means formed in 15 said implant to prevent movement of said implant toward or away from the space between two adjacent cervical vertebrae when inserted therebetween. 45. The stabilizer of any of claims 30 to 44, wherein said implant is formed into sections 20 movable together. 46. The stabilizer of claim 45, further comprising means for selectively preventing relative movement of the sections of said implant. fc * «f» * Se