JP4126071B2 - Spinal fixation implants and insertion and modification tools - Google Patents

Description

  The present invention relates to a prosthetic implant that is placed in the space between vertebrae left after removal of a damaged spinal disc. More particularly, the invention relates to an implant that facilitates arthrodesis or fusion of adjacent vertebrae while maintaining or restoring normal spinal anatomy at a particular vertebral level.

  The number of spinal surgeries performed to treat the cause of lower back pain has steadily increased over the past few years. The cause of lower back pain is usually a spinal disc damage or defect between adjacent vertebrae. The spinal disc can form a hernia or be affected by various degenerative conditions, and in either case, the anatomical function of the spinal disc is temporarily lost. The most common surgical procedure for such a condition was to fix the two vertebrae surrounding the affected disc. In most cases, the entire disc, except the annulus, is removed using a discectomy. Because damaged disc material is removed, if nothing is placed in the space within the disc, the space may collapse and damage nerves that extend along the spinal column.

  In order to prevent such a disc space from collapsing and to stabilize the spine, the intradisc space is filled with bone or a substitute bone, and two adjacent vertebrae are fused or fixed together. In earlier techniques, bone material was simply placed between adjacent vertebrae, typically behind the vertebrae, so that the spinal column was stabilized by a plate or rod that spanned the affected vertebrae. . With this technique, once fixed, the hardware used to stabilize the part becomes unnecessary. In addition, the surgical procedure required to implant the rod or plate to stabilize the level during fixation is often required but lengthy.

  Therefore, fixing the vertebra between each end plate, optimally without the front and back plates, was considered to be the more optimal solution to stabilize the excised disc space. Attempts to develop an acceptable intradiscal implant that can be used to replace damaged discs and stabilize the interdisc space between adjacent vertebrae is at least a complete indirect fixation procedure It has been done countlessly until is achieved. These “interbody fusion devices” take a variety of forms. For example, one of the more common designs takes the form of a cylindrical implant. These types of implants are described in Bagby Patent 4,501,269, Brantigan Patent 4,878,915, Ray Patent 4,961,740 and Represented in US Pat. No. 5,055,104 and Michelson Patent No. 5,015,247. As represented by the aforementioned Ray, Brantigan and Michelson patents, these cylindrical implants are threaded on the outside of the cylinder to facilitate the insertion of the interbody fusion device. ing. In an alternative device, some of the fixation implants are configured to be driven into the intradiscal space and the vertebral endplate. These types of devices are represented by Brantigan's patents 4,743,256, 4,834,757 and 5,192,327.

In each of the above-listed patents, the cross-section of the implant is constant over the entire length of the implant and is typically in the form of a right circular cylinder. The cross sections of other implants developed for interbody fusion are not constant. For example, McKenna's Patent No. 4,714,469 discloses a hemispherical implant with an elongated ridge projecting into a vertebral endplate. Kuntz, U.S. Pat. No. 4,714,469, discloses a bullet-shaped prosthesis that provides a friction fit between the prosthesis and an adjacent vertebral body. The structure is optimized. Finally, the implant disclosed in Bagby US Pat. No. 4,936,848 is in the form of a sphere that is preferably centered between adjacent vertebrae.

  Interbody fusion devices can be divided into two basic categories as a whole: solid implants and implants designed to allow bone ingrowth. . This solid implant is represented by U.S. Pat. Nos. 4,878,915, 4,743,256, 4,349,921 and 4,714,469. The other patents mentioned above include certain aspects that allow bone to grow across the implant. It has been found that devices that promote natural bone ingrowth can achieve faster and more stable fixation. The device shown in the Michelson patent is representative of this type of hollow implant, which is typically filled with autologous bone before being inserted into the disc space. It is. The implant includes a plurality of circular openings that communicate with the hollow interior of the implant to allow tissue growth between the vertebral endplate and the bone or substitute bone in the implant. Is defined. In preparing the disc space, it is preferred that the adjacent end plates bleed the bone to facilitate the tissue growth described above. During fixation, it helps maintain the patency and stability of the moving part to which the metal structure provided by the Michelson implant is fixed. Furthermore, once fixed, the implant itself becomes a kind of fixed body or scaffold of solid bone mass.

  There are still a number of problems with currently available interbody fusion devices. While it is recognized that hollow implants that allow bone to ingrow into bones in or in bone substitutes are the best technique for achieving fixation, most prior art devices are at least It is difficult to achieve such fixation without the addition of certain stabilizers such as rods or plates to assist in the fixation. In addition, some of these devices do not have the structural strength to support the fixed vertebral level, i.e. the large loads and bending moments that are applied very frequently to the fixed vertebrae of the lower lumbar vertebrae. .

  There was a need to provide a hollow interbody fusion device that optimizes bone ingrowth capability but has sufficient strength to support the spinal portion until fixation is achieved. The inventors of the present invention have found that the opening for bone ingrowth plays an important role in eliminating the stress shield of autologous bone inserted in the implant. That is, if the size and shape of the ingrowth opening is inadequate, the autologous bone will not be able to withstand the loads typically required to ensure rapid and complete fixation. In this example, the bone inserted in the implant does not stop in the bone-like fixed mass, but simply absorbs or grows into the fibrous tissue, which makes the structure unstable as a whole. On the other hand, the bone ingrowth opening should not be so wide that the support area of the cage is insufficient to avoid sinking into the adjacent vertebra.

  Several disadvantages are provided by the bone graft material used in conventional metal cage fixation devices. Autografts are undesirable because existing structures cannot provide a sufficient amount of graft material. In addition, additional surgical procedures for extracting autografts may increase the risk of infection and reduce structural integrity at the donor site. In addition, many patients complain of significant pain some years after donor surgery. Allografts also have disadvantages due to the risk of disease transmission and immune response, although the restrictions on the supply of allograft material are not so severe. Furthermore, allogeneic bone does not have the potential to form autogenous bone, and therefore identification is less gradual and not significant.

Due to the above disadvantages, investigations have been made of bioactive substances that regulate a complex series of sequential interactions of bone repair cellular events. Such materials include bone morphogenetic proteins that are used as alternative or accessory graft materials. Bone morphogenetic proteins (BMPs), which are osteoinductive factors from a type of bone matrix, have the ability to induce osteogenesis when implanted into bone fracture sites or surgical bone sites. . Human bone morphogenetic protein-2 (rhBMP-2) resulting from genetic recombination has been demonstrated to be effective in bone regeneration in skeletal defects in several animal models. The use of such proteins requires the design of appropriate carriers and immobilization devices.

  To answer the above needs that cannot be solved by conventional devices, the present invention provides a hollow threaded interbody fusion device structured to restore normal angular relationship between adjacent vertebrae. Is provided. More particularly, such a fixation device includes an elongate body, the elongate body being tapered over substantially its entire length, defining a hollow interior and the size of the space between adjacent vertebrae. Has a larger outer diameter. The body includes an outer surface with opposed tapered cylindrical portions and a pair of opposed flat tapered side surfaces between the cylindrical portions. Accordingly, when viewed from the end view, the external appearance of the fixing device is a cylindrical body, and the side portion of the cylindrical body is truncated along the outer diameter string of the main body. The cylindrical portion is threaded to control insertion and engagement into the end plate of the adjacent vertebra.

  In another aspect of the invention, the outer surface is tapered at an angle along its entire length, and in one embodiment, is tapered at an angle corresponding to the normal anterior curvature of the lower lumbar vertebra. Yes. The outer surface is also provided with an angiogenic opening and a pair of elongated opposing bone ingrowth slots, the angiogenic opening being defined in the flat side and the pair of bone ingrowths. A slot is defined in the cylindrical portion. The lateral width of the bone ingrowth slot is preferably about half the effective width of the cylindrical portion in which the slot is defined.

  In another embodiment, the interbody fusion device retains the same tapered and truncated sidewalls and discontinuous external screws as in the previous embodiment. However, in this example, the implant is solid rather than hollow. Bone ingrowth is achieved by forming the solid, tapered implant with a porous high-strength material, while bone ingrowth is made into interconnected pores while sufficient New material is retained to ensure structural stability in the original position. In one preferred embodiment, the material is a porous tantalum composite.

In another aspect of the present invention, a hollow interbody fusion device is provided with an osteogenic material that optimizes the fixation. Such osteogenic materials comprise osteoinductive proteins in a suitable carrier.
In yet another embodiment, the interbody fusion device is solid rather than hollow and is constructed of a porous high strength material that allows bone ingrowth into the interconnected holes. In a preferred embodiment, such material is applied with an osteoinductive material.

  In another aspect, a cap is provided to close the opening in the fixation device and prevent the osteogenic material from being removed from within the device. The cap includes an obturator that closes the opening and an elongated anchor or anchor that secures the obturator within the opening. In some embodiments, the anchor includes a lip that is engageable with an opening in the wall of the closure.

  In yet another embodiment, a tool for operating a cap for an interbody fusion device is provided. In one embodiment, such a tool includes a pair of forks or prongs each having an opposing engagement surface that engages a locking device and a shaft slidably disposed between the prongs. The shaft has a cap engaging tip that engages a tool hole in the cap. The prong includes a pair of release members on each of the opposing engagement surfaces. The release member has a height and width that allows it to be inserted into an opening in the body wall of the fixation device to release the elongate anchor of the cap from the opening.

  For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe such embodiments. However, the scope of the present invention is not limited to the exemplary embodiments described using such terms, and the exemplary apparatus may be further modified and modified, and implementations illustrating the principles of the present invention may be illustrated. It will be apparent to those skilled in the art that applications other than examples are usually possible.

  An interbody fusion device 10 according to one aspect of the present invention is illustrated in FIGS. The device is formed by a conical and robust load-bearing body 11, which is preferably formed from a biocompatible or inert material. For example, the body 11 can be constructed from medical grade stainless steel or titanium, or other suitable material having sufficient strength characteristics as described herein. The fixation device can also be composed of a biocompatible porous material, such as a porous tantalum composite material provided by Implex Corp. For reference purposes, the device 10 has an anterior end 12 and a posterior end 13, which corresponds to the anatomical position of the device 10 when the fixation device 10 is implanted in the intradiscal space. . The conical body 11 defines a chamber or hollow interior 15 delimited by a body wall 16 and closed at the rear end 13 by an end wall 17 (see FIG. 3). The hollow interior 15 of the fixation device 10 is structured to receive autograft bone or substitute bone material adapted to facilitate robust fixation between adjacent vertebrae and across the intradiscal space.

  According to the present invention, the interbody fusion device 10 is screwed into the end plate of the adjacent vertebra via a screw. In one embodiment of the invention, the conical body 11 defines a series of discrete outer threads 18 and a complete thread 19 at the tip of the implant. The complete screw 19 serves as a “starter” screw that screws the implant into the vertebra in the intradiscal space. Screws 18 and 19 can engage the vertebrae in a number of forms known in the art. For example, the cross section of the screw can be a triangle or a truncated triangle. Preferably, the height of the screw is 1.0 millimeter (0.039 inch) and is held firmly in the vertebra so that the high load on the spine does not push the fixation device 10 out of the disc space. To be. The thread pitch of a particular embodiment may be 2.3 millimeters (0. 2 mm) depending on the level of vertebrae to which the fixation device 10 is implanted and the amount of thread engagement required to hold the implant in place. 118 inches) or 3 millimeters (0.091 inches).

  In one aspect of the present invention, the cylindrical body 11, and in particular the body wall 16, includes parallel truncated sidewalls 22 that are most clearly illustrated in FIG. Preferably, the side walls are flat to facilitate insertion of a fixation device between the end plates of adjacent vertebrae and provide an area for bony fixation between the end plates. . The truncated side wall extends from the front end 12 of the anchoring device to a full screw 19 at the rear end 13. Thus, due to the truncated side wall 22, the appearance of the fixation device 10 in an end view is an incomplete circle with the sides of the device cut across a circular chord. In one particular embodiment, the anterior end diameter of the interbody fusion device 10 is 16.0 millimeters (0.630 inches). In this particular example, the truncated side walls 22 are formed along parallel chords spaced 12.0 millimeters (0.472 inches), and the removed arc of the circle is the fixing device's Each side is roughly at 90 °. Other advantages and effects provided by the truncated side wall 22 of the fixation device 10 will be described in more detail.

To facilitate fixation, the fixation device of the present invention can be provided with an opening defined through the body wall 16. The fixation device 10 illustrated in FIGS. 2-5 includes two types of body wall openings, namely, angiogenic openings 24, 25 and a bone ingrowth slot 27 as described below.

  The conical body 11 of the fixation device 10 includes angiogenesis openings 24, 25 defined through each of the truncated side walls 22. These openings 24 and 25 are adapted to be oriented laterally or laterally when the fixation device is implanted in the disc space. The opening is intended to provide a path for angiogenesis that occurs between the bone graft material in the hollow interior 15 and the tissue surrounding it. In addition, some bone ingrowth may occur through these openings. Openings 24 and 25 hold most of the structure of the conical body 11 and generate high axial loads that are transmitted across the intradisc space between adjacent vertebrae. It is sized to provide an optimal path for angiogenesis.

  The conical body 11 also defines opposing bone ingrowth slots 27, each of which is oriented at 90 ° to the truncated side wall 22. These slots 27 are preferably immediately adjacent to the vertebral endplate when the fixation device 10 is implanted. More particularly, as the fixation device screws 18 and 19 are screwed into the vertebral endplate, the vertebrae extend parallel into the slot 27 and are received within the hollow interior 15 of the fixation device 10. Contact bone implant material. As clearly shown in FIG. 5, the bone ingrowth slot 27 is shaped to provide maximum opening for bone ingrowth to ensure complete articulation and robust fixation. Has been. Preferably, the lateral width of the slot approximates the effective width of the threaded portion of the conical body.

  If the opening becomes small, there is a possibility of forming a pseudo-joint or generating fibrous tissue. Since the bone ingrowth slot 27 of the present invention directly faces the vertebra, it is not disposed in the portion of the fixation device that receives a high load. Instead, the truncated side wall 22 will support most of the load transmitted between the endplates via the discontinuous screw 18 and across the intradiscal space.

  In yet another feature, the front end 12 of the body wall 16 defines a pair of diametrically disposed notches 29 that are shaped to engage the implant driver tool described herein. ing. Furthermore, a tool engagement feature (not shown) is provided on the end wall 17 of the rear end 13 of the implant. For example, a hexagonal recess may be provided to accommodate the hexagonal driver tool, as will be described in more detail below.

  One important feature of the interbody fusion device of the present invention is that the body 11 is tapered or the body is conically shaped. That is, the outer diameter of the front end 12 of the main body is made larger than the outer diameter of the rear end 13. As shown in FIG. 3, the main body wall 16 is tapered at a constant angle A around the center line CL of the fixing device 10. The taper of the body wall 16 is adapted to restore a normal relative angle between adjacent vertebrae. For example, in the lumbar region, angle A is adapted to restore the normal lordosis angle and curvature of the spine in that region. In one particular example, the angle A is 8.794 °. It is also possible to provide the implant with a non-tapered portion if it does not interfere with the function of the tapered portion of the body.

The taper angle of the implant, along with the outer diameters of the anterior and posterior ends of the fixation device 10, is the amount that the adjacent vertebra expands at an angle when the implant is placed in place or screwed into place. Define. This feature is illustrated more clearly in FIGS. 6 and 7 and a preferred construction using a pair of fixation devices 10 is shown. In the illustrated construction, the fixation device 10 is positioned between the lower lumbar vertebrae L4 and L5, and the screws 18 and 19 are screwed into the end plates E of the two vertebrae. As shown in FIG. 7, when the fixation device 10 is screwed into the end plate E, it advances in the direction of arrow I toward the pivot axis P at the vertebral level. The pivot axis P is the nominal center of relative rotation between adjacent vertebrae of the moving part. As the tapered fixation device 10 is pushed further in the direction of arrow I toward the pivot axis P, the adjacent vertebrae L4 and L5 expand at an angle in the direction of arrow S. The maximum insertion angle L at which the insertion depth of the fixation device 10 is achieved between the two vertebrae is determined.

  In particular embodiments of the implant 10, the outer diameter of the front end 12 or the apex diameter of the thread may be 16, 18 or 20 millimeters and the overall length of the device may be 26 millimeters. The size of the device is determined by the level of vertebrae in which the device is implanted and the amount of angle at which the device is deployed.

  In another aspect of the present invention, the fixation device 10 is sized so that two such cylindrical bodies 11 can be implanted in one disc space, as shown in FIG. This allows bone graft material to be added between and around the device 10 in its original position. This aspect further facilitates fixation across the intradiscal space and more securely fixes the device between adjacent vertebrae to prevent removal of the device due to high axial loads on specific vertebral levels. Is done.

  In one particular embodiment of the interbody fusion device, the angiogenic opening 24 has a rectangular area having an overall area of 6.0 millimeters (0.236 inches) by 7.0 millimeters (0.276 inches). It is. Similarly, the angiogenic opening 25 is rectangular with an area of 4.0 millimeters (0.157 inches) by 5.0 millimeters (0.197 inches). Naturally, this opening is smaller because it is provided at the narrow rear end 13 of the fixing device 10. The bone ingrowth slot 27 is also rectangular with a lengthwise dimension of 20.0 millimeters (0.787 inches) and a width of 6.0 millimeters (0.236 inches). It has been found that these dimensions of the angiogenic openings 24, 25 and bone ingrowth slots 27 provide optimal bone ingrowth and angiogenesis. In addition, these openings are not so large that the structural integrity of the fixation device is compromised or that the bone graft material contained within the hollow interior 15 is easily eliminated during implantation. Nor.

  As can be seen in FIG. 7, when the fixation device is positioned between the vertebrae L4 and L5, the angiogenic openings 24 and 25 face to the side and contact the highly vascularized tissue surrounding the vertebrae. Further, as can be seen in FIG. 6, the bone ingrowth slot 27 is axially oriented to contact the vertebral end plate E.

  As shown in FIG. 8, in an alternative embodiment of the present invention, the interbody fusion device 30 is formed from a conical load bearing body 31. The body wall 34 defines a chamber or hollow interior 33 similar to the fixing device 10 of the previous embodiment. However, in this embodiment, the truncated sidewall 38 does not include any angiogenic openings. Further, the bone ingrowth slots 39 on the opposite sides of the fixation device 30 are made smaller than the fixation device 10 described above. This means that the length of extension of the discontinuous screw 36 outside the fixation device 30 around the implant is long. Use a porous material (eg, a porous tantalum composite) to add surface area to allow tissue to ingrow and settle in adjacent bone, or fix using a protein that promotes bone growth Such a design can be used to increase the rate. Also, the interbody fusion device 30 of this embodiment shown in FIG. 8 can be used at a certain vertebral level where the risk of the fixation device being eliminated is greatest. Therefore, the amount of screw contact can be increased to prevent such exclusion. Prior to insertion, the hollow interior 15 of the fixation device 10 is completely filled with bone or substitutes to facilitate such preloading.

In another embodiment using a porous material, the interbody fusion device 110 of FIG. 8A retains the tapered shape of the previous embodiment, but is solid rather than hollow. The fixing device 110 includes a load supporting body 111 having a taper. The outer diameter of the front end 112 of the load supporting body 111 is larger than the outer diameter of the rear end 113. The entire body 111 is solid, and the surfaces at both ends of the implant are closed surfaces such as surfaces 115. The securing device includes the discontinuous screw 118, starter screw 119 and truncated sidewall 122 of the previous embodiment. A drive tool slot 129 can also be defined in the end face 115. Alternatively, the starter screw 119 can be eliminated and the back end of the implant can be an unthreaded cylinder. Similarly, the drive tool slot 129 can take various forms depending on the design of the tool used to insert the fixation device 110 into the disc space.

  The advantages of the embodiment of the fixation device illustrated in FIG. 8A can be particularly appreciated by forming the solid body 111 using a porous high strength material. In a preferred embodiment, this material is a porous tantalum-carbon composite material, which is commercially available from Implex under the trade name HEDROCEL®, and Kaplan ( Kaplan), U.S. Pat. No. 5,282,861, the description of which is incorporated herein by reference. Due to the nature of the sludge cell material, the entire outer surface of the solid body 111 includes holes 130 interconnected through the entire body. The support of the sludge cell-tantalum composite is a glassy carbon skeleton or a reticulated open-cell carbon foam that defines a network of interconnecting pores. Such a support is infiltrated with a deposited metal film. Such metal thin film materials are Group 5 transition metals such as tantalum, niobium, or alloys thereof.

  The sledrocell is preferred because it eliminates the disadvantages of both metal and ceramic implants and provides the advantages of both. The sledrocell mimics the structure of the bone and has an elastic modulus close to that of the human bone, so it is well suited for the interbody fusion device of the present invention. The interconnected porosity promotes bone ingrowth and eliminates the deadlock that limits bone angiogenesis. The infiltrated metal film provides strength and rigidity without significantly increasing weight. The sledrocell implant has sufficient strength to maintain the normal curvature of the spine in the intervertebral space and in the moving part equipped with the instrument. At the same time, it is possible to dispense with stress shielding. This composite material is also advantageous because it does not require allografts or autografts.

  A further advantage of this material is that it is not reabsorbed. This prevents initial degradation and suppresses bone regeneration. Non-resorbable implants are also advantageous when complete bone ingrowth is not achieved. However, the disadvantages of permanent non-resorbable implants are avoided by the excellent biocompatibility and osteoconductivity of the composite material.

  Although sledrocell is preferred, it is conceivable to use any suitable high strength porous material. For example, ceramics such as alumina, zirconia, silicon nitride, carbon, glass, bran, hydroxyapatite, calcium sulfate, calcium ferric phosphate, calcium zinc phosphate, calcium phosphate phosphate, and calcium aluminate ceramic can be used. It is. If calcium phosphate esters such as hydroxyapatite, tricalcium phosphate esters and their biphasic ceramics can be produced to withstand high spinal loads, such calcium phosphate esters can be used.

  Other metal open cell support composites can also be considered. For example, the support may be another carbonaceous material such as graphite, or a ceramic such as tricalcium phosphate or calcium aluminate. Any suitable material is contemplated, but Group 5 elements such as tantalum, niobium and their alloys are preferred. Tantalum is particularly preferred because of its excellent mechanical properties and biological compatibility.

The interbody fusion device of the present invention can be implanted using the implant driver 50 illustrated in FIG. 9 according to one aspect of the present invention. The implant driver 50 includes a shaft 51 and a sleeve 52 arranged concentrically around the shaft 51. At one end of the shaft, a clamp or tong 54 for grasping and implanting the interbody fusion device 10 is formed. The tongue includes a tapered outer surface 55 and an opposing flat inner surface 56 adapted to engage the truncated side wall 22 of the interbody fusion device. The tapered outer surface 55 corresponds to the root diameter of the discontinuous screw 18 so that the tongue 54 essentially completes the complete cylindrical shape of the body wall 16. Since the tong tapered outer surface 55 rests in the internally threaded hole of the vertebra end plate, the fitting of the tong tapered outer surface 55 causes the interbody fusion device 10 to thread. It is made easy to do.

  Each of the tongues is provided with a driving protrusion 59 extending from the interlocking finger and the inner surface 56. The function of these components is more clearly illustrated in FIG. Referring to FIG. 9, the shaft 51 defines a hinge slot 62 that supports each of the pair of tongs 54. The hinge slot 62 is shaped to allow the tongue to be in a naturally biased position that is sufficiently widened and spaced apart to receive a tapered interbody fusion device 10 between the tongs. Yes. The shaft 51 defines a conical taper between the hinge slot 62 and each of the tongues 54. This conical taper mates with a conical surface 67 defined on the inner wall of the sleeve 53. Thus, as the sleeve 52 advances toward the tongue 54, it rests against the conical surface 67 and closes or compresses the hinge slot 62. In this manner, the tongues 54 are pushed toward each other, and are pressed by the interbody fusion device positioned between the tongues to be gripped and engaged with the fixation device.

  The shaft 51 and the sleeve 52 are provided with a threaded interface 65, which allows the sleeve 52 to screw up and down in the length direction of the shaft 51. In particular, the threaded interface 65 includes an outer thread on the shaft 51 and an inner thread on the sleeve 52, the outer thread and the inner thread having the same pitch, and the sleeve passes over the implant driver 50. It can be moved up and down easily. The shaft 51 is also provided with a pair of stops 69 that receive the interbody fusion device 10 by separating the tongs 54 over a sufficient distance from the rearward movement of the sleeve 52. Limit to the range necessary for

  The use of the implant driver 50 will be described with reference to FIGS. As can be seen in FIG. 10, the outer surface 55 of the tongue 54 is generally flat with the root diameter of the discontinuous screw 18. As can be seen in FIG. 11, interlocking fingers 58 are arranged to fit into each angiogenesis opening 24 of the truncated side wall 22. Similarly, the drive protrusion 59 engages the drive tool slot 29 at the front end of the conical body 11. The combination of interlocking fingers 58 and drive projections 59 firmly engages the interbody fusion device 10 so that it can be screwed into a tapered or non-tapered opening in the vertebra. It becomes possible.

  An alternative embodiment of an implant driver is illustrated in FIG. The implant driver 90 includes a shaft 91 that is long enough to reach from within the patient into the disc space. A head is coupled to the end of the shaft 91, which defines a pair of opposing tongues 93 such that each of the tongues is in flat contact with the flat truncated side wall 22 of the fixation device 10. It has a nice shape. Like the tongue 54 of the implant driver 50, the outer surface of the tongue is cylindrical and is adapted to correspond to the cylindrical threaded portion of the fixation device.

Unlike the implant driver 50, the implant driver 90 of the embodiment of FIG. 12 is adapted to securely grasp the fixation device 10 and insert it into the body using a deployment collet assembly. The collet 94 terminates in an annular flange 96 that is at least initially made slightly smaller than the inner diameter of the end 12 of the fixation device 10. An extension shaft or expander shaft 97 extends slidably through the collet hole and includes a flared tip 98 that is disposed adjacent to the annular flange 96. And extends slightly beyond the annular flange. The flared tip 98 of the expander shaft 97 begins with a diameter sized to slide within the collet hole, and gradually expands in a morning glory shape to a diameter larger than the collet hole.

  The implant driver 90 includes a pulling shaft or puller shaft 99 slidably disposed within a bore 100 defined in the shaft 91. The puller shaft 99 has a locking chamber 101 at its end, and the locking chamber 101 engages with a locking fence hub 102 formed at the end of the expander shaft 97. The puller shaft 99 projects beyond the end of the shaft 91 for access by the surgeon. When the puller shaft 99 is pulled, the expander shaft 97 is pulled away from the annular flange 96 of the collet 94 and the flared tip 98 engages in the collet hole 95 in stages. As the tip 98 is further advanced into the hole 95, the annular flange 96 extends from the initial diameter to the second expanded diameter and is in firm gripping contact with the interior of the fixation device 10. Once the fixation device is engaged as described above, it is possible to insert the fixation device 10 into the surgical site using an implant driver and then advance the expander shaft past the collet hole. Release of the flared tip results in release of the fixation device.

  In accordance with the present invention, there are two possible methods for implanting the interbody fusion device 10. First, referring to FIGS. 13 (a) to 13 (d), an approach from the front is illustrated. As a preliminary step, the appropriate starting point is positioned and the fixation device is preferably implanted bilaterally. In the first stage of the approach from the front, a dilator 75 is placed between the end plates E of the vertebrae to expand the disc space between the vertebrae L4 and L5. (Of course, this method can be applied at other vertebral levels.) In the second stage illustrated in FIG. 13 (b), an outer sleeve 76 is placed around the disc space. The outer sleeve 76 uses known designs to securely engage the anterior side of the vertebral body to firmly but temporarily fix the outer sleeve 76 in place. In essence, the outer sleeve 76 acts as an actuation channel in this laparoscopic approach. At this stage in FIG. 13 (b), a known design drill is used to extend through the outer sleeve to drill a circular opening in the adjacent vertebral body. The opening may be tapered to facilitate screwing of the fixation device, but this step is not necessary.

  In the next step, illustrated in FIG. 13 (c), the implant driver 50 is engaged with the fixation device 10 and the fixation device 10 is passed through the outer sleeve 76 until the starter screw 19 contacts the bone opening. Elongate. The implant driver 50 is then used to screw the fixation device into the internally threaded or unthreaded opening formed in the vertebral end plate E. At this stage, other suitable drive tools can be used, for example, a screwdriver type device can be used to engage the drive tool slot 29 with the front end 12 of the fixation device 10. I want to understand that. As described above, the amount of prone applied to or recovered from the vertebral level is determined by the degree of insertion of the fixation device 10. In the final stage, the implant driver is removed, leaving the fixation device 10 in place. Once implanted, the closed end wall 17 is directed toward the posterior side of the vertebra. The hollow interior 15 is open at the front end, but can be closed with plastic or metal material if desired.

In the second inventive method illustrated in FIGS. 14 (a) to 14 (d), an approach from the rear is performed. The first two steps of this approach from the rear are similar to the approach from the front described above, but the dilator 75, outer sleeve 76 and drill 77 are subsequently introduced into the instrumented area. It is different in point. This approach requires detachment or removal of the vertebra to receive the outer sleeve 76. In the third stage of the method, the fixation device 10 is inserted through the outer sleeve 76 into the expanded disc space. It should be understood that the disc space is expanded only to the extent necessary to accommodate the implant with a truncated side wall 22 that directly faces the vertebral end plate E. Accordingly, as illustrated in FIG. 14 (c), the bone ingrowth slot 27 is oriented laterally rather than coronally, as can be considered from its final implantation position. A suitable drive tool 80 can be provided to allow the fixing device 10 to penetrate the outer sleeve 76 and protrude into the disc space. In one embodiment, the drive tool 80 includes a note 81 shaped to engage a slot opening formed in the end wall 17 of the rear end 13 of the fixation device 10. An internal screw (not shown) can be used to secure the fixation device 10 to the driver 80.

  Once the fixation device 10 has been advanced into the disc space to an appropriate depth relative to the vertebral pivot axis P, the implant is rotated in the direction of the rotation arrow R shown in FIG. Is done. As the drive tool 80 is rotated, the fixation device itself rotates and the discontinuous screw 18 cuts and bites into the vertebra at the end plate E. In this way, the implant acts as a cam that separates adjacent vertebrae in the direction of the advancement arrow S shown in FIG. This cam approach provides a somewhat simpler insertion method in that the implant can be locked into the vertebra after one revolution. On the other hand, in the above-mentioned screwing technique, it is necessary to continuously turn the screw in order to put the fixing device in a predetermined position.

  With either technique, the position of the fixation device 10 relative to adjacent vertebrae can be ascertained by radiographic photography or other suitable technique to establish the angular relationship between the vertebrae. Alternatively, a suitable insertion depth of the implant can be determined in advance and measured from outside the patient once the implant is positioned between the vertebrae.

  It can be seen that the interbody fusion device 10, the implant driver 50 and the technique of the present invention provide significant advantages over the prior art. In particular, the fixation device 10 provides a hollow threaded implant that maximizes the potential for bony fixation between adjacent vertebrae while maintaining the integrity of the implant itself. . It should be understood that the spine can withstand significantly higher loads along its axis and that the fixation device supports the load until at least a robust fixation is achieved. The fixation device 10 also provides a means for causing angiogenesis and tissue ingrowth, increasing the fixation speed and increasing the strength of the fixed bony mass by the angiogenesis and tissue ingrowth. Another important point is that the tapered shape of the implant allows the surgeon to recover and maintain the proper curvature and relative angle between the vertebral bodies. This eliminates serious problems associated with conventional devices such as product deformation and spinal balance loss. Yet another advantage achieved with the device and implant driver of the present invention is that it allows insertion from the anterior or posterior side using laparoscopic techniques. Depending on the vertebral level, any suitable method can be taken, so it is important that the implant be able to be inserted from either direction. The insertion of the fixing device can be controlled by the screw-in technique used for insertion from the front side (as opposed to driving) and the sliding-in and cam method used for the insertion technique from the rear side.

  During the surgical implantation procedure, the surgeon can apply the osteogenic material to the fixation device 10 or 30 by filling the hollow interior 15 with the osteogenic material. Alternatively, in the case of a fixation device such as device 30 or 110, the osteogenic material can be applied by introducing an osteogenic composite material into the pores of the bone ingrowth material. Any suitable osteogenic or composite material is contemplated. The osteogenic composite material preferably comprises an osteoinductive element such as a bone morphogenetic protein in a therapeutically effective amount of a pharmaceutically acceptable carrier.

The osteogenic composite material can be any suitable carrier that provides a carrier medium for introducing the osteogenic material into the pores of the bone ingrowth material or the hollow interior of the device. Such carriers are known and commercially available. The carrier material is selected based on biocompatibility, biodegradability, mechanical properties and interface properties. The composite material of the present invention is appropriately formulated depending on its application. Any suitable carrier can be used provided it has the ability to deliver the bone morphogenic protein to the implant. Most preferably, the carrier is reabsorbed into the body. One suitable carrier is an absorbable collagen sponge marketed by Integra LifeSciences Corporation under the trade name Helistat®. Another suitable carrier is an open cell polylactic acid polymer. Other potentially usable substrates for the composite materials are biologically degradable and chemically defined calcium sulfate, tricalcium phosphate (TCP), hydroxyapatite (HA), biphasic TCP / HA ceramics, polylactic acid and polyanhydrides. Another potentially usable material is biologically degradable and chemically well defined bone or skin collagen. Another substrate is a pure protein or an extracellular component. The osteoinductive material can also be an additive of an osteoinductive cytokine and a polymeric acrylate carrier. The polymeric acrylic ester can be polymethylmethacrylate.

  In the hollow fixing device such as the device 101, the carrier can be provided in a strip shape or a sheet shape, and can be folded and matched with the hollow interior 15 as shown in FIGS. The carrier may extend out of the opening of the device, such as the angiogenic openings 24, 25, to facilitate contact of the bone forming material with the highly vascularized tissue surrounding the vertebra. Is preferred. In one embodiment, the osteogenic material 100 includes a polylactic acid polymer that functions as a carrier for bone morphogenetic proteins such as BMP-2. In this particular embodiment, the bone forming material 100 takes the form of a sheet 101, which is overlaid at a fold 102 in the hollow interior 15 of the fixation device 10. The length of the sheet 101 is preferably long enough to fill the hollow interior almost completely when folded within the device 10 and extend at least partially into the angiogenic openings 24 and 25.

  As shown in FIGS. 15 and 16, the sheet 101 is folded generally parallel to the truncated sidewall 22 so that the crease 102 of the sheet 101 is adjacent to a slot 27 in the threaded portion of the apparatus. It is supposed to be arranged. Alternatively, the sheet 101 is folded so that the layer between the folds is perpendicular to the side wall 22 as a whole.

  The bone forming material 100 can also be provided as several strips sized to fit into the hollow interior 15 of the fixation device 10. The strips (not shown) can be placed facing each other to fill the hollow interior. Similar to the folded sheet 101, the strip can be configured in several orientations in the device 10 to face the angiogenic openings 24, 25 or slots 27. The osteogenic material 100 may be provided in the form of a folded sheet, or in the form of a sheet that is folded in several layers and the length of the hollow interior 15 of the device 10. It is preferred to have a corresponding length and a width corresponding to the width of the device transverse to the longitudinal axis of the device.

  As stated in the Kaplan patent, open-cell tantalum material provides a highly interconnected three-dimensional porosity to promote bone ingrowth. The Kaplan type material facilitates bone ingrowth throughout the device and completes the fixation, while also eliminating the disadvantages of the metal such as stress shielding and incomplete fusion. Has strength. Another advantage of these porous materials is that a composition that induces bone growth can be introduced inside the pores. For example, in one embodiment, the composition includes a bone morphogenetic protein in a liquid carrier that is introduced into the pores to facilitate fixation. BMPs have been found to significantly reduce the time to achieve arthrodesis or fusion across the disc space to which the instrument is attached. Most preferably, the bone morphogenetic protein is BMP-2, such as human recombinant BMP-2. However, any bone morphogenetic protein containing bone morphogenetic proteins designated BMP-1 through BMP-13 is contemplated. BMPs are commercially available from Genetics Institute Inc. of Cambridge, Massachusetts, and U.S. Pat. No. 5,187,076 to Uzney et al. Patent 5,366,875, Wang et al. US Pat. No. 4,877,864, Wong et al. US Pat. No. 5,108,922, Wong et al. US Pat. No. 5,116,738 Uzny et al. US Pat. No. 5,106,748, Uzny et al. PCT Patent No. WO 93/00432, Celeste et al. PCT Patent No. WO 94/26893, and Celste et al. As described in No. WO94 / 26892, it can be made by those skilled in the art.

  BMP can be provided in lyophilized form and reconstituted in sterile water or another suitable medium or carrier. The carrier can be any suitable medium that can transport the protein to the implant. Such a medium is preferably supplemented with buffers known in the art. The composition that induces bone growth can be introduced into the pores by any suitable method. For example, the composition can be injected into the pores of the implant. In other examples, the composition is dropped onto the biocompatible material, or the biocompatible material is dipped into the composition. In one particular embodiment of the present invention, rhBMP-2 is suspended or added in a liquid carrier such as water or liquid collagen. The liquid is dropped into the device or the device is immersed in a suitable amount of the liquid, but in any case, interconnected holes in the entire pore material of the fixing device It is necessary to allow sufficient time for the liquid to enter all of the above.

  In some cases, a BMP-fixer is applied to the porous biocompatible material of the implant prior to introducing BMP so that the fixer can coat the pores of the device. The fixing agent is preferably a calcium phosphate ester composition. It has been discovered that the rate at which bone morphogenetic proteins are delivered to the fixation site can be controlled using such fixatives. The calcium phosphate composition is believed to bind to bone morphogenetic proteins and prevent premature dispersion of BMP from the device before binding occurs. Further, holding the BMP by the fixative allows the BMP to be leached from the device at a rate that is conducted to achieve complete and rapid bone formation and finally fixation across the disc space. Any suitable biocompatible calcium phosphate ester composition is contemplated. In the preferred embodiment, a layer of hydroxyapatite several microns thick is applied over the Kaplan material. Hydroxyapatite covers the ligament covered with the tantalum thin film while leaving the holes open. Also contemplated are tricalcium phosphate ceramics and hydroxyapatite / tricalcium phosphate ceramics.

  Apply the calcium phosphate composition to the implant's porous biocompatible material, by plasma spraying or any suitable method such as chemical immersion in which the porous material is immersed in a slurry of the calcium phosphate composition. Is possible. Methods for applying a coating of a calcium phosphate ester composition are described in the following US patents: Constanz et al., US Pat. No. 5,164,187, Saita et al., US Pat. No. 5,030,474, Taylor et al., US Pat. No. 5,330,826, Cyta et al., US Pat. No. 5,128,169, Inoue et al., Re. 34,037, Kokubo et al. US Pat. No. 5,068,122, Konstanz US Pat. Nos. 5,188,670 and 5,279,831, which are incorporated by reference. Embedded in this book.

According to the present invention, the hollow spacer as shown in FIG.
A cap 300 (FIG. 17) is provided that prevents the inner graft material from being eliminated. (See FIG. 18) In a preferred embodiment, the cap 300 includes a closure 301 sized and shaped to contact and close the opening 15a and an elongated prong or anchor 310 protruding from the closure 301. Contains.

  In the embodiment illustrated in FIG. 17, the closure 301 includes an outer wall 304, an opposing inner surface 306, and a flange 307 that communicates with and is coupled to the outer wall 304. The flange 307 defines an engagement surface 308 that contacts the inner surface of the body wall 16 of the load bearing body 11 '. The flange 307 also prevents the cap 300 from entering the interior of the fixation device.

  The anchor 310 has a first end 311 attached to the closing body 301 and a second engaging means for engaging the opposing load support main body 11 ′ and holding the closing body 301 in the opening 15 a. End 312. In the preferred embodiment, the engagement means is a lip 315 that protrudes from a second end 312 that contacts the inner surface of the load support 11 '. The anchor 310 preferably has a length l that reaches from the closing body 301 to the opening of the main body wall when the cap 300 is inserted into the opening 15a. In FIG. 18, the lip 315 is engaged with the angiogenesis opening 24 '. In some embodiments, the outer wall 304 of the cap 300 is preferably flush or substantially flush with the opening 15a so as to have a low vertical cross-sectional shape, as shown in FIG. is there.

  The cap 300 illustrated in FIG. 17 also includes a second opposing elongated anchor 325 that projects from the closure 301. Of course, the number of anchors provided may be arbitrary. The anchor is preferably made of an elastic material, particularly when two or more anchors are provided. If it is an elastic material, the anchors 310 and 325 can be slightly displaced by the force F in the inward direction for insertion. Once the cap 300 has been inserted into the opening 15a, the forces applied to the anchors 310, 325 are released so that the anchors 310, 325 are normal relative to each of the anchors where the anchor 310 engages the load support 11 '. It becomes possible to return to the arrangement.

  The cap material of the present invention can be any suitable material such as a biocompatible metal or polymer. In one preferred embodiment, the cap is composed of titanium. In another preferred embodiment, the cap is made of, for example, polyethylene, polyvinyl chloride, polypropylene, polymethylmethacrylate, polycholin, and copolymers thereof, polyester, polyamide, fluorocarbon polymer, rubber, polyurethane, polyacetal, polysulfone and A polymer such as polycarbonate. Biologically degradable polymers including, for example, polymers based on glyloride, lactide and polycarbonate are also contemplated as cap materials. Such polymers are manufactured to degrade after incorporation / degradation into the graft material or substitute graft as scheduled. Polyethylene is particularly preferred because it is inert and has a smooth surface and no irritation. Another advantage is that polyethylene is radiolucent and does not interfere with radioangiogenesis. Other suitable materials include stainless steel and Hedrocell (registered trademark).

  The cap also preferably includes an osteogenic opening 305 sized through the outer wall 304 that is sized to allow bone ingrowth and protein withdrawal. The osteogenic opening 305 is particularly suitable when a material such as polyethylene is selected for the cap. Such biocompatible polymers are not known to be able to form bone bonds like other materials such as titanium. Thus, a solid plastic cap prevents bone formation in the cap area. The osteogenic opening may also be advantageous because it facilitates the control of the diffusion of bone growth proteins implanted in the chamber, facilitating fixation around the bone-like bridge and fixation device. The resulting fixation around the fixation device complements the device ingrowth fixation mass within the device, making the overall fixation more robust. Bone bridging around the device is also preferred because it better represents the success of such a method. While bone ingrowth within the device is difficult to evaluate radiographic using normal film, bone cross-linking outside the device can be easily seen. The size of the cap is arbitrary. The cap dimensions vary depending on the need to effectively close the opening of the fixation device. Referring to FIG. 17, the length L of the cap (the closure including the flange) is 13.7 millimeters (0.548 inches), and the length L 'of the closure without the flange is 12 millimeters (0.488 inches). ), Width W is 8.25 millimeters (0.330 inches), and height H is 9.4 millimeters (0.377 inches).

  The present invention also provides a tool for manipulating the cap of the interbody fusion device. Such tools include means for engaging the cap and means for engaging and securing the cap to insert and remove the cap. During the surgical procedure, the cap 300 is inserted into the opening 15a after the fixation device 10 'has been implanted and the chamber has been filled with osteogenic material. In some cases, it may be necessary to remove the cap during or after surgery to replace or remove the bone forming material in the chamber, or to access and fix the fixation device. The cap 300 illustrated in FIG. 17 includes a tool hole 320 for receiving an insertion or removal tool. The hole 320 is preferably threaded, but any engagement surface is conceivable, such as hexagonal inside the hole.

  One embodiment of the tool 400 of the present invention is illustrated in FIGS. The tool 400 includes a pair of forks or prongs 401 and a shaft 410, each of the prongs 401 having a proximal end 402 defining first engagement means for engaging a locking device, the shaft 410 has a first end defining a second engagement means for engaging the cap. The tool also includes means for slidably supporting the shaft 410 between the prongs 401. In one embodiment, the present invention includes a body or housing 420 that defines a passage therethrough. In this embodiment, the end 403 of the prong 401 is coupled to the housing. As shown in FIG. 20, the prong 401 can be attached to the housing 420 with a screw 404. Of course, any suitable fixing means is conceivable.

  The prong 401 can be used to fix the fixation device and the cap can be inserted, or the prong 401 can be used to engage the fixation device and / or cap to remove the cap. In the embodiment illustrated in FIG. 19, the proximal end 402 of the prong 401 includes an engagement surface 404 that engages an opposing fixation device. In the most preferred embodiment, a pair of release members 405 are disposed on each of the opposing engagement surfaces 404. Referring specifically to FIG. 21, the release member 405 has a height h and a width w so that it can be inserted into the opening 24 'of the fixation device 10'. It is possible to remove the cap 300 of the present invention using the tool shown in FIGS. 19 to 21, and the cap 300 is inserted into the opening 15a of the fixing device 10 ′ shown in FIG. Release member 405 is inserted into opening 24 'to apply pressure F to elongate arm or anchor 310 of cap 300 and deflect inwardly to anchor 310 to release cap 300 from interbody fusion device 10'. To do. In embodiments where the anchor 310 includes a lip 315 or other engagement means, a release member 405 is inserted into the opening 24 'to remove the lip 315 from the opening.

  The distance d between the proximal ends 402 of the prongs 401 is preferably adjustable to facilitate engagement with the securing device and / or part of the cap. In the preferred embodiment, this is accomplished by constructing the prong 401 with a resilient metal such as stainless steel. The adjustable feature can be sold by other means of attaching a hinge to the end 403 of the prong 401. Any other suitable means for adjusting the distance d is conceivable.

  Referring again to FIG. 19, the first end 411 of the shaft 410 defines a cap-engaging tip 415 that is configured to engage the tool hole of the cap. In the embodiment of FIG. 19, the cap engagement tip 415 defines a screw that engages a threaded tool hole in the cap 300 illustrated in FIG. Any suitable tool engagement means is contemplated, such as a hexagon that engages the hexagon inside the cap.

  In the embodiment shown in FIGS. 19 to 22, the shaft 410 is slidably disposed in the passage 421 of the housing 420. The shaft 410 is between the retracted position (FIG. 23) and the extended position (FIG. 24) where the first end 411 is adjacent to and between the proximal end 402 of the prong 401. Can be slid freely. To insert the cap into the fixation device, the prong 401 is used to engage the fixation device and hold the fixation device. The engagement end 415 engages the tool hole of the cap and slides the shaft 410 to the extended position (FIG. 24) to carry the cap to the locking device. If the engagement end 405 is threaded, after inserting the cap into the securing device, the shaft 410 is rotated within the housing 420 to rotate the shaft 410 and remove it from the cap. To remove the cap, first, the prong 401 is engaged with the fixing device. It is also possible to engage the prong 401 with the body wall of the fixing device. When used with a cap 300 as shown in FIGS. 17 and 18, a release member 405 is inserted into the opening 24 'to release the lip 315 and flex the anchors 310, 325 inward. I will. The shaft 410 is then moved from the retracted position (FIG. 23) to the extended position (FIG. 24) and then rotated to engage the tool engagement hole 320 of the cap. The shaft is then returned to the retracted position (FIG. 23) and the cap 300 is engaged with the engagement end 415.

  In the embodiment illustrated in FIG. 19, the first end 411 of the shaft 410 is a metal rod 412 attached to a plastic center rod 413 that can be autoclaved. Autoclavable plastics are selected for lightweight and reusable equipment. In one embodiment, a metal rod 412 is press fitted into a plastic center rod and further engaged with a pin 414.

  In one embodiment, the central rod 413 of the shaft 410 is slip fit into the passage 421 of the housing 420. Proximal and distal stop members are preferably provided to prevent the shaft 410 from sliding out of the housing 420. A proximal stop member is preferably disposed on the central rod 413 adjacent the first end 411 to prevent the first end 411 from entering the passage 421. As shown in FIG. 19, the stop member at the proximal end is an O-ring 430 engaged with the central rod 413 of the shaft 410. In one embodiment, the central rod 413 defines a groove 431 (FIG. 25) in which the O-ring 430 is seated. The groove 431 prevents the shaft 410 from moving beyond the retracted position illustrated in FIG. 23 when the O-ring 430 is seated in the groove, so that the first end 411 enters the passage 421. Has been to prevent.

The distal stop member 440 can be attached to the second end 416 of the shaft 410, the perimeter of the stop member being larger than the perimeter of the passage 421, so that the second end 416 enters the passage 421. It is possible to prevent this. As shown in FIG. 25, when the stop member 440 and the passage 421 are circular, the diameter D ₁ of the end stop member 440 is made larger than the diameter D _{2 of the} passage 421.

In the tool of the present invention, it is also preferable that a distal shaft operating member is attached to the second end 416 of the shaft 410 so that the shaft 410 slides and rotates in the passage 421. In the embodiment shown in FIG. 19, the operating member is a thumb wheel 441. Dimension or diameter _{D 1} of the said thumb wheel 441 is larger than the diameter _{D 2,} thus, is also end stop member 440.

  In order to more fully understand the present invention, the following specific examples are given. These examples are intended to illustrate the present invention and are not intended to limit the present invention in practice.

Example 1
Surgical Technique : Twenty-one grown female alpine goats were used in this study. The goat weighed between 42 and 62 kilograms. All goats were subjected to general anesthesia using intravenous barium and ketamine for introduction and surgical procedures were performed using inhaled halothane to maintain anesthesia. The anterior neck was sterilized to prepare for the surgical procedure, and the skin was incised longitudinally to access the cervical vertebra from the right anterior exterior. Fully developed longus coli muscle was dissected in the middle to expose the C2-C3, C3-C4 and C4-C5 disc spaces. The soft disc was first excised and each level of the anterior cervical disc was incised. Next, the 8 mm distraction plug positioned at the center of the post is lightly driven into the disc space to extend the disc space. A working tube was passed over the prongs at the end of the tube that was driven into the vertebral bodies above and below the post and disc space. These prongs maintained the disc space distraction when the center post and distraction plug were removed. The disc space and vertebral body / end plate were then expanded or reamed using a 10 mm reamer through the working tube. The bone waste generated when expanded was stored and used as graft material. The expanded channel was then threaded and a 10 mm diameter titanium BAK device (SpineTech, Minneapolis, Minnesota) was inserted. No attempt was made to remove the anterior longitudinal ligament or expose the spinal canal.

  The goats were divided into 3 treatment groups, each with 7 heads. Group I was equipped with devices filled with autogenous bone grafts harvested during the reaming at each level. Group II used a device coated with hydroxyapatite and filled with remnant autogenous bone waste as a graft. Group III used a device filled with 200 μg of recombinant BMP-2 (Genetics Institute, Cambridge, Massachusetts) with a collagen sponge injected. Prior to instrument installation, wounds were cleaned with a solution of normal saline, bacitracin (50 U / cc), polymyxin B (0.05 mg / cc) and neomycin (0.5%). The Longos coli muscle was then closed with a continuous suture. The subcutaneous tissue was reapplied with interrupted sutures, and the skin was reapplied with continuous sutures.

  After the operation, the goat was monitored until it completely recovered from anesthesia. Goats received 2 doses of Naxcell (ceftiofur), 500 mg intravenously before surgery and 500 mg intramuscularly after surgery. A soft bandage was wrapped around the goat's neck and the goat allowed free activities while observing it daily for several days in the barn.

  Clinical evaluation was performed every 3 weeks. Radiographic photographs of the lateral cervical vertebrae were taken immediately after surgery at the 3rd, 6th and 9th weeks. Fluorescent dye labels were applied at the 3rd, 6th and 9th weeks. The label at 3 weeks consisted of oxytetracycline (30 mg / kg IV), the label at 6 weeks consisted of alizarin complex oxytetracycline (30 mg / kg IV), and the label at 9 weeks consisted of DCAF (20 mg / kg IV). The goats were euthanized at 12 weeks by injecting Bethanasia intravenously. The cervical vertebra was then excised and all surrounding tissue was removed from the excised cervical vertebra. The specimens were then radiographed in the AP and lateral planes.

Biomechanical test was performed a biomechanical test brought to the biological Institute in the state of just give the spine specimen. Polyester resin for spine (Lightweight 3 in Cincinnati, Ohio)
Fiberglass-Evercoat (Lite Weight 3 Fiberglass-Evercoat, Cincinnati, Ohio) was used for mounting in C2 and C7 frames. Biomechanical testing was performed at a modified MTS Bionics 858 Servo-Hydraulic Material Tester (MTS Corporation, Minneapolis, Minnesota, Minnesota, Minnesota). The MTS machine can apply axial compressive and torsional loads around the longitudinal axis of the spine. This system allows a constant bending moment to be applied over the entire length of the spine, which allows pure sagittal bending and extension loads to be generated while maintaining axial loading and twisting to zero. .

  Separate tests were conducted for axial compression, twisting, flexion-extension, and lateral bending. An axial compressive load was circulated from 0 to 100N. Rotating or sagittal bending movements were allowed. The torsion was circulated from positive to negative 5 Nm and a 50 N compression preload was applied. Again, the connecting motion was allowed by leaving the axial load and sagittal bending under load control. A sagittal bend was circulated from flexion to extension with a uniform 2N-m bending moment under a 5N tensile preload. A 5N tensile preload was applied and the lateral bending was performed from left to right with a uniform 2N-m bending moment. In each test, 5 cycles of a sinusoidal load cycle of 0.1 Hz were performed. The specimens were conditioned in advance with data from the fifth cycle that was used for analysis during the first 4 cycles. Data was taken continuously for each test and stored in a computer data file.

  Axial compression data included axial load (N) and axial displacement (mm). Bend-extension, torsion, and lateral bending data included axial load (N), torque (Nm), and rotational displacement (degrees). Measurements of axial, flexion-extension, lateral bending, and torsional displacement were made simultaneously using extensometers attached across each of the operated disk levels. Data were analyzed by calculating the stiffness across each disk space for axial loading, flexion-extension, torsion and lateral bending.

Radiographic Analysis: 3 weeks, 6 weeks, all radiographic 9 weeks and 12 weeks were analyzed. Radiographs were analyzed for cage migration and the presence of glowing lines surrounding each cage. If a glowing line was observed in either the AP or the transverse radiograph, the cage was found to have a shine or lucency.

Histological analysis : Following the biomechanical test, the specimen was removed from the mounting grip and frame. The spine was cut through the middle axes of the C3-, C4 and C6 vertebral bodies into three individual specimens containing implants in the bone-disk space-bone block. The specimens were then cut into sagittal sections starting from the right side using an Isomet Plus precision saw (Buehler Instruments, Lake Bluff, Illinois), Lake Bluff, Illinois. . When the first sign of the cage appeared in the sagittal strip, two additional 2.5 mm strips were removed. These two pieces were then stored in 70 percent alcohol and awaited microradiographic analysis. The third sagittal piece was then removed and separated for fluorochrome analysis. The remaining specimens are stored in 70 percent alcohol.

  The first two pieces containing the cage were then processed for microradiography. Sagittal radiographs were obtained with a Hewlett Packard Faxtron device (Hewlett Packard, McMinnville, Oregon, Oregon), each sagittal micro radiograph. Two cage-vertebral body interfaces were included, each of which was graded separately and for the presence or absence of bone or fibrous tissue surrounding the cage, and then each interface was boned into the cage from the respective interface. Therefore, each inter-disc space-cage-end plate junction (1) has bone ingrowth and the cage is completely surrounded by bone (B- B), (2) Of the fibers There is growth or no ingrowth but the cage is completely surrounded by bone (BF / E), (3) there is fiber ingrowth and the cage is surrounded by fibers (FF) or (4) The cage was empty and could be classified as either (FE) surrounded by fibrous tissue.

  Successful joint fixation was determined from sagittal microradiography. If both disc space-cage-end plate interfaces are completely surrounded by bone, and the bone in the space is completely hardened, the level is considered to be firmly articulated. I did it. If both interfaces were surrounded by fibrous tissue and the cage was empty, the level of arthrodesis was considered to have failed. Level status if one interface is surrounded by bone and the other is surrounded by fibrous tissue, or if both interfaces are surrounded by fibrous tissue and the cage is filled with fibrous tissue Was considered to have obtained intermediate results.

  The third sagittal piece was placed in polymethylmethacrylate for fluorescent dye analysis. A 200 to 360 μm thick piece was obtained using an Isomet Plus precision saw. These pieces were then ground to 100 μm thickness using a Maruto ML-512D Speed Lapping Machine (Maruto Instruments, Tokyo, Japan, Tokyo). . Sagittal microradiographic photographs of specimens with a thickness of 100 μm were obtained to correlate with fluorochrome analysis. After obtaining this micro radiographic photograph, the piece was ground to a thickness of 40 μm and placed on a slide for dye analysis. The relative time frame of bone revascularization around and within the cage could be determined by the presence or absence of each marker around and within the cage.

Results : All 21 goats were successfully operated and survived without problems during the experiment. No infection of cervical spine wounds occurred. There were no neurological complications.

Radiographic results : No cages moved from normal position in any group. In Group I, there were three cages with lucency. In Group II there were four cages with lucency. In Group II, none of the 21 cages showed lucency.

Microradiographic results : The results of grading each cage-endplate-interface junction are summarized in Table I. BMP filled cages have a very large number of interfaces surrounded by bone and a much greater amount of bone growth than either of the other two groups.

  The success rate of joint fixation was up to 95% in cages filled with BMP, followed by HA-coated (62%), and standard devices (48%). This difference was statistically significant (p = 0.002). The unsuccessful rate of joint fixation was 14% in both the HA-coated group and the standard group, and zero in the BMP-filled cage. The intermediate results were 38% for the standard cage, 14% for the hydroxyapatite cage and 5% for the cage filled with BMP.

Biomechanical data : Average biomechanical stiffness data for axial compression, twisting, bending, evolution and lateral bending are summarized in Table II for each group. There were no statistical differences between groups in any of the load mode tests. There was no statistically significant difference in stiffness in any load mode due to joint fixation results, but a cage with successful joint fixation was more axially compressed, twisted, bent, extended and lateral than a cage with failed joint fixation. There was a tendency for rigidity to be high in bending.

Fluorochrome analysis : In Group I, 10 cages showed bone formation all around the cage. Seven (70%) of these cages showed bone revascularization after the 3rd week injection and 3 (30%) showed bone revascularization after the 6th week injection. . In Group II, 13 cages showed bone formation all around the cage. Eight of these (62%) showed revascularization after 3 weeks of injection and 3 (23%) showed revascularization after 6 weeks of injection, 2 (15%) ) Showed revascularization after 9 weeks of injection. In Group III, there were 20 cages that showed bone formation all around the cage. Of these cages, 19 (95%) showed bone revascularization after the 3 week injection, and 1 (5%) showed bone revascularization after the 6 week injection.

  Of the 63 cages in the three groups, 21 showed bone growth in the cage. In Group I, one of six cages (17%) showed bone angiogenesis after the 6th week injection, and 5 cages (83%) showed bone angiogenesis after the 9th week injection. showed that. In Group II, all five cages showed bone angiogenesis after the 9th week injection. In Group III, 3 out of 11 cages (27%) showed revascularization after the 3rd week injection, 6 (55%) showed revascularization after the 6th week injection, Two (18%) showed revascularization after the 9th week injection. Thus, in general, cages filled with BMP showed early angiogenesis both around and within the cage compared to those of the other two groups.

CONCLUSION : BMP-filled intervertebral fusion cages result in significantly higher joint fixation rates, and autogenous interbody fusions with or without stabilization of devices or plates filled with autogenous bone Bone angiogenesis was faster compared to bone grafts.

Example 2
Design : A single level of intermediate lumbar interbody fusion was performed on 12 grown female sheep. All surgical dissections were performed under the same aseptic conditions. Following preparation of the anterior fixation site, the implant was inserted. A threaded interbody fusion device (TIBFD) comprising rhBMP-2 carried on a type I fibrillar collagen (Helistat) (n = 6) in a lateral orientation in a single cage. And treated in an approach approaching from behind the peritoneum. The extremities before the study (all n = 6) included TIBFD with autogenous bone plugs, autogenous bone plugs only, or simulated (empty) fixation sites. Sheep were allowed to eat grass immediately after the operation and did not get stuck outside. All sheep were slaughtered 6 months after surgery. Fourteen vertebrae taken from dead sheep were added to determine mechanical stiffness measurements between baseline vertebrae.

Materials : The interbody fusion cage developed and manufactured by Sofamor Danek, Inc., Memphis, Tennessee, was constructed of a Ti-6Al-4V alloy and designed as a closed cylinder. The device was 14 mm in diameter and included a screwed end cap that allowed placement of the graft material. As described by the manufacturer, the porosity of the device was 35% of the total hole to metal ratio and the porosity at the point of contact with the intervertebral body was increased. The yield mechanical load was reported as 80,000 Newtons (maximum human physiological load-10,000 Newtons). As a result of more than 5,000,000 cycles of cyclic compression loading from 800 to 9,680 Newton at 15 Hz, there was no observable minute damage or deformation.

  The dose of rhBMP-2 was 043 mg / ml. Proteins in the buffer were applied dropwise to commercial grade type I collagen (helistat). The composite material was then inserted into the cage chamber, after which the cage cap was attached. The device was then inserted into a suitable fixation site.

Surgical procedure : A 10 cm incision was made from the rostral part to the left abdomen of the tail part under aseptic conditions. Following the incision of the lateral fascia of the external abdominal musculature, the plane behind the peritoneum was identified. Proceeding through this plane, the soft tissue of the intervertebral disc between vertebral bodies L4 and L5 was removed. If no further exposure was needed, the segmental vessels were not tied up. The descending aorta was retracted to expose the anterior longitudinal ligament and anterior ring. A 2 mm guidewire was placed across the intervertebral disc that bisects the disc in the sagittal plane. A cannula punch with a cannula was used on the wire to create an annulotomy on the left side.

  A 7 mm diameter dilator with a rounded “bullet” shape was used on the same wire to expand the disc space and place a tensioned ring. An outer sleeve with four prongs was placed on the distractor and pushed to move the adjacent vertebral body. Side prongs in the disc space helped maintain the distraction. A bone cutting reamer was placed and used through the outer sleeve to drill a transverse hole through the disc space. Adjacent vertebral at least 3 mm end plates and subchondral bone were removed during the procedure. At this point, the device was prepared and implanted. External abdominal fascia, subcutaneous tissue and skin were closed normally.

Mechanical testing : All slaughtered sheep were mechanically tested after slaughter to determine fixation stiffness. In addition, spines taken from 14 untreated sheep corpses were similarly tested to establish baseline parameters for the L4-L5 motion segment. The L4-L5 intervertebral part (fixation site) was tested to determine the stiffness of all 18 sheep against the sagittal and coronal plane bending moments (flexion, extension, right bend, left bend). For baseline measurements, spines taken from 14 untreated sheep carcasses were also tested to determine the stiffness between L4-L5 segments in coplanar motion.

  After sacrifice, the spinal column from L3 to L6 was explanted. The intersegmental ligament tissue was retained. Lateral processing was eliminated to facilitate polymethylmethacrylate (PMMA) potting of L3 and L6 vertebrae. The PMMA potting did not include L3-L4 or L5-L6 discs.

  Non-destructive mechanical testing was performed using an MTS812 servo hydraulic tester. The specimen was mounted on the device so that it was oriented perpendicular to the axis of activation. One end of the specimen was fixed, the other was free to move, and placed directly above the actuator. A pure bending moment was applied using a device consisting of a cable and a pulley. A variable rotation differential transformer (RVDT) was attached to the vertebral body via a helical screw to measure the rotation of the L4-L5 moving part, and attached to the free end to measure each degree relative to the horizontal. Load displacement data was recorded.

  In each test, the maximum applied moment was about 10 Nm, and the load was applied by circulating 3 cycles of the second ramp of 5 per cycle. The test was performed in the order of bending, extension, right bending, and left bending. For all groups, the stiffness was calculated as the slope of the force diagonal displacement curve at 8 N-m.

Radiographic evaluation: immediately after the surgery, after two months, after four months, and in a state that took general anesthesia after 6 months, took the radiographic of the front and rear and side. Measurement of vertebral body height and disc height along the cervical vertebrae is performed at the intermediate sagittal line using a photo image analyzer (Ultra Fine Pitch Monitor, Image-1 / Atsoftware 1991) Was made. All measurements were made with true lateral radiographs. Since the measurement of the intervertebral disc height at the fixation site is obscured by the transplant material, an intervertebral body height index (IB index) was calculated to reflect the intervertebral distraction. This index was calculated as follows: The intermediate sagittal span from the L4 head end plate to the L5 tail end plate was measured as the “fixed height”. Since the vertebrae height is relatively uniform, the sum of the intermediate sagittal heights of the L3 and L6 vertebrae is used to determine the height of the L4 and L5 vertebrae excluding the intervertebral disc The total was estimated. Next, the sum of the L3 and L6 vertebrae was subtracted from the fixed height to confirm the “calculated interbody height”. In order to correct for the magnification difference, this value was expressed as a ratio to the average vertebra height and this value was defined as the IB index.

Results : Mechanical test results from one specimen transplanted with TIBFD + rhBMP-2 were excluded due to device error.

Mechanical test data results : The average standard displacement as a function of group is presented in Table III. Results from global and pairwise statistical comparisons are presented in Table IV. The average stiffness is significantly different between each mode of testing (p = 0.005, p = 0.0001, p = 0.0001, p = 0.0001) cogroup (control with 2 treatments and no surgery). there were.

  The body segments that received all the surgical procedures were significantly more rigid than the untreated body segments. That is, the site transplanted with TIBEF + rhBMP-2 or TIBFD + autograft is bent (p = 0.0001, p = 0.055), stretched (p = 0.0001, p = 0) compared to the untreated site. .0001), right bending moment (p = 0.0001, p = 0.0001) and left bending moment (p = 0.0001, p = 0.0001) showed extremely high rigidity. There was no stiffness difference between somites treated with TIBEF + rhBMP-2 and sites treated with TIBFD + autografts (comparison of tests in all modes was p = 0.05).

Interbody Height Measurement Interbody Height Index Results : Table V shows the results from mean standard displacement and global and pairwise statistical comparisons. There is no difference in interbody height index between TIBEF + rhBMP-2 and TIBFD + autografts at each time measurement (F (4.40) = 0.20 P = 94). In both groups, subsidence occurred mainly after the first 2 months after surgery (roughly 20% of the initial interbody disc height), but the interbody height reduction was not significant (F (2.20) = 0.19 P = 0.83)).

CONCLUSION : There was no mechanical or morphological difference between fixation caused by TIBEF + rhBMP-2 and fixation caused by TIBFD + autograft. The bending stiffness tended to be higher in TIBEF + rhBMP-2, but was not remarkable. Settlement tended to occur after the first two months in both groups. Although autogenous bone grafts were harvested, there is no advantage compared to using rhBMP-2 with Type I fibrillar collagen in this model.

Example 3
Open porous polylactic acid polymer (OPLA) is made into a sterile 12.0 mm x 6.5 mm x 30 mm strip package (2 strips in each package). Pure OPLA is sterilized by gamma irradiation. rhBMP-2 is lyophilized to a powder and reconstituted during surgery with sterile water and supplemented with buffered vehicle solution. rhBMP-2 is introduced into the carrier material and the carrier is placed in the hollow interior of the metal fixed cage device. The device is then implanted into the fixation site.

Example 4
A rhBMP-2 collagen implant is made from a Helicostat Absorbable Collagen Hemostatic Agent (Integra Life Science Corporation) and a rhBMP-2 hollow metal anchorage cage device. Place the device inside and implant the device into the fixation site.

By measuring the resistance of the end cap test reason rhBMP-2 for elimination by wet collagen sponge were tested were measured resistance for comparison with known urethane end caps.

Test A
Press-fit end cap extrusion test This test is required to remove a polyethylene press-fit end cap from the BAK® (Spine Tech, Minneapolis, Minnesota, Minnesota) equipment. The end cap was snapped into the BAK device and an axial load was applied to the end cap through the cavity of the BAK device. ) The load ranged from about 5.4432 to 16.7832 kgf (12 to 37 lbf).

Test B
Test Setup and Methods Five samples of a 12 mm end cap made of titanium (894-120, US Sofa Modeneck) (894-XXX, Sofa Modene, Memphis, Tennessee, USA), as illustrated in FIGS. 18 and 19 Each was placed in a 12 mm titanium Novos® LT (Safamodenek, USA) implant. A 12 mm implant was firmly secured to the base of a closed loop servo hydraulic tester. The actuator of the testing machine was attached to the end cap through an adapter screwed into the end cap. The end cap was withdrawn at a rate of 25 mm / min with an axial load until the end cap was completely removed from the 12 mm implant. Data including maximum load and displacement were recorded and plotted using Superscope II data acquisition software.

  All end caps were pulled out by elastic deformation of the two anchor prongs. The average draw load was 187 N (41.99 lbf). Table I shows the raw data of the withdrawal test.

Test C
The method of Test B was repeated for nine samples, but the load used was 12.5 mm / min at the withdrawal speed. The average draw load was about 13.87 kgf (30.57 lbf) on average.

  The value of 30.57 is sufficiently comparable to the value of test B, 41,99. The sample size for this test was 9, while the sample size for test B was 5.

Discussion and conclusions Test results show that the end caps of the present invention resist in vivo exclusion for two reasons. First, it is known that intervertebral discs are subjected to complex and complex loads. However, any load acting on the disc space does not act directly on the end cap of the implant and eliminate the end cap. The second reason is that a collagen sponge moistened with rhBMP-2 cannot exert a force of 177 N (41.999 pounds f) to eliminate the end cap.

  The anchor prong end cap of the present invention was easily inserted into the device by hand. In one example, the end cap was inserted via a servo hydraulic tester. The insertion load was measured and found to be about 1.45 kgf (3.2 lbf). This further supports a robust end cap engagement. The average rejection force is 13 times the insertion load.

  The anchor prong end cap of the present invention was sufficiently comparable to known polyethylene press-fit end caps. The pull-out load of the press-fit end cap was in the range of about 5.44 to 16.78 kgf (12 to 37 lbf), with an average of 25 pounds f. The anchor prong cap of the present invention exceeds the above value, the average of nine samples is about 13.86 kgf (30.57 lbf), and the range is about 5.67 to 21.15 kgf (12.5 to 46.f). 62 lbf).

  Although the present invention has been described in detail as above, such description is intended to be illustrative and the invention is not limited in its character by such description, but only in preferred embodiments. It is obvious that all changes and modifications can be made within the scope of the present invention.

FIG. 1 is a side view of a conventional fixing device. FIG. 2 is an enlarged perspective view of an interbody fusion device according to an embodiment of the present invention. FIG. 3 is a side sectional view of the interbody fusion device taken along line 3-3 in FIG. FIG. 4 is an end view of the interbody fusion device shown in FIG. 2 as viewed from the front end. FIG. 5 is a plan view of the interbody fusion device shown in FIG. FIG. 6 is a side view of AP as seen from the front side of the spine illustrating that the interbody fusion device according to FIG. 2 is inserted in the interbody space between two L4 and L5. FIG. 7 is a side view of the interbody fusion device inserted between L4 and L5 of FIG. FIG. 8 is a perspective view of an alternative embodiment of an interbody fusion device according to the present invention. FIG. 8A is a perspective view of another embodiment of the tapered interbody fusion device of the present invention. FIG. 9 is a plan view of an implant driver according to another aspect of the present invention. FIG. 10 is an enlarged perspective view of the end of the implant driver engaged around the interbody fusion device as shown in FIG. FIG. 11 is an enlarged partial side cross-sectional view illustrating an implant driver engaged with an interbody fusion device as illustrated in FIG. FIG. 12 is an enlarged partial side cross-sectional view illustrating an alternative embodiment implant driver adapted to engage the interbody fusion device 10. FIG. 13 (a) is a diagram illustrating four stages of a method for implanting an interbody fusion device, such as the device illustrated in FIG. 2, according to one aspect of the present invention. FIG. 13 (b) illustrates four stages of a method for implanting an interbody fusion device, such as the device illustrated in FIG. 2, according to one aspect of the present invention. FIG. 13 (c) illustrates four stages of a method for implanting an interbody fusion device such as the device illustrated in FIG. 2 according to one aspect of the present invention. FIG. 13 (d) illustrates four stages of a method for implanting an interbody fusion device, such as the device illustrated in FIG. 2, according to one aspect of the present invention. 14 (a) is a diagram illustrating the steps of a method for implanting an interbody fusion device such as the device illustrated in FIG. FIG. 14 (b) is a diagram illustrating the steps of a method for implanting an interbody fusion device such as the device illustrated in FIG. FIG. 14 (c) illustrates the steps of a method for implanting an interbody fusion device such as the device illustrated in FIG. FIG. 14 (d) illustrates the steps of a method for implanting an interbody fusion device such as the device illustrated in FIG. FIG. 15 is an enlarged perspective view of an interbody fusion device having an osteogenic material in an internal hollow according to an embodiment of the present invention. FIG. 16 is an end view of the interbody fusion device shown in FIG. FIG. 17 is a perspective view of a cap according to the present invention. FIG. 18 is a side perspective view of the fixing device of the present invention including the cap illustrated in FIG. 17. FIG. 19 is an elevational view of the cap operating tool of the present invention. FIG. 20 is a side view of the tool illustrated in FIG. FIG. 21 is a partially enlarged view of the tool of FIG. 22 is an elevational view of the tool of FIG. 19 engaged with a cap. FIG. 23 is an elevation view of the tool of FIG. 19 in a retracted position. FIG. 24 is an elevational view of the tool of FIG. 19 in the extended position. FIG. 25 is a partial end view of the tool of FIG.

Claims (10)

In a fixation device for facilitating joint fixation within the disc space between adjacent vertebrae,
Comprising a body of bone ingrowth material with porous biocompatible material having interconnected continuous pores;
The body includes a pair of opposing cylindrical portions extending along substantially the entire length of the body, each cylindrical portion having an outer surface defining an outer screw that engages an adjacent vertebra; And is tapered along a substantial portion of the overall length of the body,
Having a fixing agent applied on the main body, the fixing agent being applied in the continuous holes,
An anchoring device comprising a bone-forming material containing a bone morphogenic protein in the continuous pores of the porous bone ingrowth material.   The fixation device according to claim 1, wherein the bone morphogenetic protein is rhBMP-2, rhBMP-7, or a mixture thereof.   The porous bone ingrowth material is a composite material comprising a non-metallic rigid cell support formed by an interconnected network of carbonaceous materials defining interconnected continuous pores and a metal film covering the network The fixing device according to claim 1, wherein the fixing device is provided.   The fixing device according to claim 3, wherein the carbonaceous material is a carbon foam.   The fixing device according to claim 3, wherein the metal thin film is made of a Group 5 metal or an alloy of the Group 5 metal.   The fixing device according to claim 5, wherein the metal thin film is made of tantalum or an alloy thereof. The apparatus according to claim 1 , wherein the fixing agent comprises a calcium phosphate ester composition. The apparatus of claim 7 , wherein the calcium phosphate ester composition comprises hydroxyapatite. The apparatus of claim 8 , wherein the calcium phosphate composition further comprises a tricalcium phosphate ester, wherein the calcium phosphate composition is a two-phase ceramic. The body is elongated, has a constant length, a first diameter of the first end, and a larger second diameter of the second end opposite the first end; The first and second diameters are sized larger than the space between the adjacent vertebrae;
The outer surface of the body is tapered substantially continuously from the first end to the second end, and the outer thread extends on the outer surface along substantially the entire length of the body. The apparatus of claim 1.

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