JP4522637B2 - Vertebral implants to promote spinal bone fixation - Google Patents

Description

[0001]
[ Technical field ]
The present invention relates to an intervertebral spacer for treating spinal deformities. More preferably, the present invention relates to a metal or synthetic intervertebral spacer for embedding in a disc space prepared to promote spinal fusion and maintain the desired disc space height and / or spine orientation. Is.
[0002]
[ Background of the Invention ]
For degenerated, diseased or other damaged spines and vertebrae, all or part of the intervertebral disc is removed and an implant such as a spinal spacer is inserted into the intervertebral disc space to ensure normal disc height and spine It is known to treat these defects by restoring their orientation and repairing spinal defects. If desired, osteogenic material can also be embedded in the intervertebral space to facilitate joint fixation or promote spinal fusion between two vertebrae adjacent to the intervertebral space. A spacer selected to provide a cavity for receiving the bone forming material is formed.
[0003]
The spinal column exerts a very high force on the individual vertebrae and, consequently, on all implants implanted between the vertebrae. In the case of vertebrae that are poor or diseased, bone tissue at the center of the endplate, where the vertebral body is usually covered only by a thin cortical bone layer, is often weakened. The strength and completeness of the end plates can be compromised. Spacers inserted between these weakened bone tissues can sink or sink into the vertebral body. As a result, the desired disc space height cannot be maintained and the patient feels severe pain.
[0004]
In addition, it is recommended to perform an arthrodesis or fusion procedure on adjacent vertebrae to treat damaged intervertebral discs or diseased vertebrae. A spinal implant is typically made of a metal such as titanium or surgical steel. Although the choice of implant morphology and composition depends on a variety of conditions, it is often desirable to choose a material that does not stress shield bone ingrowth in the case of arthrodesis. While titanium and surgical steel provide the necessary strength to maintain accurate disc space height and orientation, these materials have been found to stress shield bone. Bone and the material obtained from bone can provide an acceptable material with similar strength and compressibility to native bone tissue. However, appropriate donor bone is rare. Strict adherence to further extensive testing and sterilization processes that can minimize the risk of transmission of actual or possible infections from donors to recipients.
[0005]
Next, the current technical state of the related art will be described.
Vertebral implants are described in International Application WO-95 / 08306, issued to Beckers (US Pat. No. 5,888,224). The intervertebral implant is made of titanium or a titanium alloy material, has a narrower width than its height, and has an elongated body with an essentially lens-shaped feature with or without an internal cavity. Implanting an implant requires distracting adjacent vertebral bodies, inserting the implant, and then rotating the implant about its longitudinal axis.
[0006]
Another vertebral implant is described in U.S. Pat. No. 4,834,757 issued to Brantigan. The vertebral implant has a parallelogram shape and has an outer surface completely covered with a protrusion or ridge embedded in a passage cut into the endplate.
[0007]
Intervertebral implants are described in international application WO 96/27348 (US Pat. No. 6,059,829) issued to Schlapfer et al. This implant basically consists of a frame around an internal cavity and comprises a longitudinal side wall with a hole portion therethrough. The frame is open without restriction at the top and bottom. The top and bottom surfaces are convex and connect the longitudinal side walls and the two end walls of the frame at sharp edges.
[0008]
Another implant is described in French patent 7/10664 issued to Liu et al. The metal implant includes an upper surface and a lower surface having a pair of protrusions that cut into the bone tissue of the opposing vertebral bodies and extend vertically from the upper and lower surfaces to pierce the bone tissue. The upper and lower surfaces also include multiple pairs of opposing bearing surfaces that contact the cortical bone portion of the vertebral body.
[0009]
In view of the above-mentioned problems of treating spinal defects, treatment of damaged or diseased spinal columns, improved implants, selection of appropriate materials from which implants can be formed, bones between adjacent vertebrae There is a constant need in the relevant fields for technological development, including the choice of methods to promote fusion. The present invention is such a technical development and provides a variety of advantages and advantages.
[0010]
[ Disclosure of the invention ]
The present invention relates to an intervertebral spacer, a method for manufacturing the same, and a method for using the same. The various aspects of the present invention are novel, non-obvious and offer various advantages. Although the actual nature of the invention described herein can be understood only by reference to the claims, specific features and actions are characteristic of the preferred embodiments disclosed herein. The part will be briefly described below.
[0011]
The present invention provides an intervertebral implant or spacer that is embedded within a prepared disc space. The intervertebral spacer can be made of metal or non-metallic materials such as polymeric materials, ceramic materials or reinforced composites. In one form, the intervertebral spacer includes an elongated body having an internal cavity. The cavity can act as a reservoir for osteogenic or spongy bone material so as to facilitate spinal fusion of vertebral bodies adjacent to the disc space. The spacer body is bounded by two longitudinal walls or side walls, and is bounded by two front walls or end walls arranged to face each other. Upper and lower surfaces extend laterally between the longitudinal walls. The top and bottom surfaces include openings into the internal cavities. An edge surface extending in the transverse direction of the end wall and the longitudinal wall defines a contact surface or bearing surface.
[0012]
In one preferred embodiment, the opposing front or end walls are formed thicker than the opposing pair of longitudinal walls, thereby extending the width of the cross edge extension surface. The cross end face is preferably formed as an integral part of the opposing end walls.
[0013]
In another form, the present invention provides an intervertebral spacer that is provided for implantation within an intervertebral disc space between adjacent vertebrae. The spacer includes an elongate body defining a longitudinal axis and at least one tissue receiving groove extending transversely to the longitudinal axis. The spacer is a cavity bounded by a first end wall and an opposite second end wall, the first end wall being opposite to the first bearing surface. A cavity defining a second bearing surface, a second end wall defining a third bearing surface and an opposite fourth bearing surface, a first end wall and a second An upper surface extending between the end wall of the first vertebrae and having an arcuate portion adapted to abut against the lower end plate of the first vertebra, the first end wall and the second end And a lower surface having an arcuate portion adapted to contact the upper end plate of the second vertebra. In a preferred embodiment, the first and second end walls have a first thickness that is greater than either the longitudinal wall thickness or the top and bottom surface thicknesses as measured along the longitudinal axis. have.
[0014]
In another form, the present invention provides a spacer that facilitates fusion between adjacent vertebrae. The spacer includes an elongated body having a through-opening that defines a longitudinal axis and extends transversely to the longitudinal axis. The main body includes a first support end wall that ends the main body at a first end, and an opposite second support end wall that ends the main body at a second end. The first and second support end walls are disposed generally transverse to the longitudinal axis and are adapted to abut against cortical bone tissue within opposing endplates of adjacent vertebrae; An opposite second side wall interconnects the first support wall and the second support wall, and the body includes at least one tissue receiving groove extending from the first side wall to the second side wall.
[0015]
In a preferred embodiment, the intervertebral spacer includes an end wall that is thicker than the longitudinal wall. The end wall ends with a cross edge or peripheral surface extending transversely to the longitudinal wall. The peripheral surface is wider than the cross edge surface of the longitudinal wall. The peripheral surface provides a wide contact or support surface that abuts the cortical portion of the adjacent vertebral body as seen within or around the cortical ring or epiphyseal ring structure. Cortical bone tissue is harder and / or denser than cancellous bone or sponge-like tissue found inside the vertebrae. The harder cortical bone tissue provides sufficient strength to transmit biomechanical forces applied to the spinal column to the spacer. The wide bearing surface or contact surface of the spacer can resist biomechanical forces and prevent the settlement of the implant into the vertebral body. This provides a spacer that can safely and permanently support the spinal column during normal patient activity and / or recommended motion.
[0016]
The longitudinal wall of the spacer can be narrow with a cross-sectional dimension measured perpendicular to the longitudinal axis. The spacer can be manufactured to minimize the longitudinal wall thickness but provide the necessary compressive strength to maintain the desired disc space height and orientation. This will provide a spacer having an enlarged cavity compared to an implant having a thicker longitudinal wall. Larger cavities can accommodate larger amounts of osteogenic material. On the other hand, this increases the success rate of spinal fusion and ultimately provides a stronger and more stable bone bridge between adjacent vertebrae.
[0017]
The wide edge contact or bearing surface of the spacer supports most of the biochemical forces applied by the spinal column, so that a portion of cortical tissue can be removed from the vertebra endplate to expose the cancellous or spongy tissue. It is possible to remove. The implant is placed in the disc space and allows intimate contact between the bone forming material in the cavity and the exposed bone tissue of the opposite vertebra. This has the advantage of promoting vertebral arthrodesis.
[0018]
Furthermore, an integral implant design can be provided with minimal or no protrusions or protrusions extending from its outer surface. In one embodiment, the outer surface of the end wall is provided with a circular shape or a rounded edge on the outside. Furthermore, the edges where the longitudinal walls meet the upper and lower surfaces can be chamfered, beveled or rounded on the outside. These edges are easily mounted in the disc space prepared with the spacers formed without the risk of any protrusions, right-angled parts, edges, etc. tearing or biting into the surrounding tissue Which provides the advantage of minimizing accidental injury to adjacent tissue.
[0019]
The spacer has an internal cavity that functions as a reservoir for bone forming material. It is desirable to provide large internal cavities that allow large bone bridges or new bone growth to be achieved between adjacent vertebrae. In one form, the cavity can be provided to have a shape that substantially corresponds to the shape of the outer surface of the spacer. Thus, in one form, the basic internal shape of the cavity is also box-shaped and its dimensions are similar to the external dimensions of the body. Alternatively, the cavity may have a height that varies along the longitudinal axis. In the case of a wedge-shaped spacer, the internal dimensions of the cavity can also provide a wedge-shaped hollow interior. Similarly, when the outer profile of the spacer is generally lens-shaped, the inner chamber can be similarly lens-shaped. The internal cavity can be made larger in the present invention by reducing the thickness of either the longitudinal wall, the top wall, the bottom wall, or both. This can be achieved by making the end walls that support the biomechanical stress exerted by the spinal column a significant thickness. In another form, the height of the cavity is substantially uniform along the longitudinal direction to facilitate uniform loading of the osteogenic material within the cavity. In yet another form, the cavity cross-sectional area, measured in a plane approximately perpendicular to the longitudinal wall, is equal to or greater than the cross-sectional area of both the top and bottom openings of the spacer.
[0020]
The spacers can also be mass-produced efficiently, economically and easily while guaranteeing high quality over very specific tolerances regarding outer dimensions, compressibility and elastic modulus. The number of steps required to manufacture the spacer is significantly reduced, in particular the machining process and the milling operation are reduced. Small designs for implants include metal materials, synthetic materials, polymeric materials, ceramic materials, and a variety of materials such as composite materials including reinforcing materials, ie glass, fiber and / or carbon fiber reinforced material (CFRP). Often it is possible to provide the spacer body in a recurring material. These preferred materials for producing the spacers of the present invention reduce costs, extend the useful life and provide superior physiological compatibility. The material can be selected to be either a substantially permanent material, a biodegradable material or a bioerodible material. In addition, the spacer material can be provided to be radiopaque to facilitate monitoring bone ingrowth between the interior of the implant and the opposing endplates of adjacent vertebrae.
[0021]
The basic body has at least one groove. Preferably, at least one groove is formed in each of the transversely extending surfaces of the end wall. The grooves can extend laterally across the entire width direction of the spacer body. The groove can be easily formed as an integral working part in the implant body. The grooves can provide sufficient resistance to extrusion and / or movement within the disc space. Furthermore, the groove does not interfere with the penetration of the spacer into the disc space. The groove including the upper edge is located on the same plane as or below the outer surface of the spacer and extends inward. After the spacer is implanted in the prepared disc space, the spacer can be kept in the desired position by the pressure applied to the spacer by the spine. Push the tissue into the groove. Bone material serves to fill the spacer grooves and secure the position of the spacer within the disc space. The groove can also be engaged by bone tissue proximate to the epiphyseal ring under compressible biomechanical force applied by the spinal column to the contact surface of the implant.
[0022]
Furthermore, the outer surface of the spacer can include an anti-extrusion structure or working portion, but this is not essential. Such working parts include ridges and the like. These working parts can be provided through the milling and / or machining or shaping of the spacers. The anti-extrusion action portion prevents the implant from protruding from the disc space and / or prevents unwanted movement within the disc space. The entire outer surface of the implant can be roughened so that the surrounding tissue can engage or mechanically interlock with the roughened outer surface of the spacer.
[0023]
The longitudinal walls of the spacer are preferably formed to be substantially planar and parallel to each other. This provides significant advantages with respect to implant placement within the disc space, as will be described below. The thickness of the longitudinal wall can be chosen to be substantially less than the thickness of the end wall. For example, the thickness of the longitudinal wall perpendicular to the longitudinal axis can be one half of the end wall thickness measured substantially parallel to the longitudinal axis. More preferably, the longitudinal wall thickness ranges from about 0.5 to 0.4 times the end wall thickness. This ratio of other longitudinal wall thicknesses to end wall thicknesses is sufficient to accept the osteogenic material and yet provide a spacer that can support mechanical loads applied from the spinal column. A spacer having a sufficient internal cavity is provided.
[0024]
In selected embodiments, the spacer can be provided to have a generally convex shape. This can be achieved by providing upper and lower edges having a convex shape with respect to the longitudinal wall. The upper and lower surfaces of the longitudinal wall can have a maximum height disposed between the first end wall and the second end wall. In one form, a convex portion can be provided to engage within the natural concave surface portion of the opposing endplate. This shape has the advantage that a spacer can be easily attached to each vertebral endplate without requiring any previous machining or cutting process on the endplate.
[0025]
In other embodiments, the longitudinal wall defines a lordotic profile. In this configuration, the shape of the longitudinal wall is such that it can provide a spacer that conforms to the desired degree of lordosis or natural curvature of the spine.
[0026]
Both the top and bottom surfaces define an opening into the internal cavity. These openings ensure that the osteogenic material in the internal cavity contacts the bone tissue in the opposing vertebral endplate. Preferably, the top and bottom surfaces provide openings that are approximately the same as or corresponding to the cross-sectional area of the internal cavity. This makes it possible to maximize the degree of contact between the included osteogenic material and the opposing end plate.
[0027]
Preferably, an opening is formed in each of the two longitudinal walls so as to provide access to the internal cavity. This also allows blood and nutrients to penetrate laterally into the cavity holding the bone forming material. In addition, the lateral openings promote bone growth around the spacers between adjacent pairs of bone forming material, facilitating fusion of the spine from all lateral and vertical sides. Is acceptable. In a preferred embodiment, each longitudinal wall includes at least one large opening into the internal cavity. It will be appreciated that smaller openings may be formed in the longitudinal wall, each allowing access to the internal chamber. Preferably, each small opening has a small diameter compared to the height of the longitudinal wall. Preferably, a maximum of two large through holes are formed for each longitudinal wall. The diameter of each of the two large through holes corresponds to about one-half of the height of the longitudinal wall.
[0028]
It is preferable that the spacer main body includes a tool engaging portion provided at the rear end wall, for example, at one end of the spacer holder. Preferably, the tool engaging portion comprises an outer opening or hole formed in the middle of the rear end wall of the main body. The opening can have a threaded interior to accept a threaded pin or stud of the corresponding tool, but this is not essential. The tool engaging portion may also include a pair of opposed grooves formed in the lateral direction of the opening. The opening is arranged in line with the groove extending in the lateral direction. In a preferred form, the rear wall is substantially free of any further protrusions or shoulders. The mating portion of the tool can also include an intermediate position pin and an outwardly extending blade that engages a lateral groove formed in the end wall of the spacer. The pin can be engaged within the opening in the end wall and can be used to facilitate alignment of the spacer while securely securing and inserting the spacer into the tool. Alternatively, the tool may include a pair of opposing arms that can be opened and closed so that the spacer can be secured or gripped along a portion or top and bottom surfaces of opposing longitudinal walls. Preferably, the tool engaging portion is formed so that the spacer can be firmly attached to the tool in a relatively simple manner so that the tool can be used both as a spacer holding tool and as a penetration spacer into the disc space. To be.
[0029]
The vertebral implant according to the present invention preferably comprises the following mechanical properties.
Static compression resistance in the height direction perpendicular to the longitudinal axis: about 15,000 N or more
Fatigue strength corresponding to this compression resistance: about 5,000 N or more
Implant torsional resistance in the longitudinal direction (torque inside (surrounding)): about 4 Nm or more
The spacers described above can be made from a wide variety of materials including metallic materials, synthetic organic materials, composites, ceramics and metals. Preferably, the implant is made of a synthetic non-metallic material. The implant of the present invention can be a nearly permanent implant that does not readily biodegrade. These implants can often remain in the intervertebral space and are incorporated into bone tissue. Alternatively, the implant may be biodegraded and substantially replaced by bone tissue.
[0030]
Examples of non-biodegradable polymer systems or low polymer materials include polyacrylates, polyethers, polyketones, polyurethanes and copolymers, alloys thereof and mixtures thereof. The use of the term copolymer is intended to include polymers formed with two or more characteristic repeating monomer units within the scope of the present invention. Such copolymers can include random copolymers, graft copolymers, block copolymers, radial blocks, diblocks, triblock copolymers, alternating copolymers, and periodic copolymers. Specific examples of non-biodegradable polymeric materials are: poly (vinyl chloride) (PVC); poly (methyl (meth) acrylate); acrylic, polyamide; polycarbonate; polyester; polyethylene terephthalate; And UHMWPE (ultra high molecular weight polyethylene); polyurethane; polyether, ie, epoxide; poly (ether ketone) (PEK), poly (ether ether ketone) (PEEK), poly (aryl ether ketone) (PAEK), and poly (ether) Ether ketone) (PEEKEK). A wide variety of suitable poly (ether-co-ketone) materials are commercially available.
[0031]
Alternatively, the implants of the present invention may be formed from materials that are either biodegradable or bioabsorbable. Typically, the biodegradable material is a polymeric material or a low polymer material, and the monomers are often connected via amide linkages as observed in poly (amino acids). It is also desirable to provide a biodegradable material (often referred to as creeping replacement) that degrades at a rate commensurate with the bone ingrowth characteristics of bone fusion when the implant is formed of a biodegradable material. It is more preferred to choose a biodegradable material that will remain in position and provide sufficient biomechanical support for the spine even after the bone bridge has grown and formed through the through-hole of the implant. . If an appropriate synthetic material is selected, the biodegradation rate of the implant can be changed. The biodegradation rate of the selected material can be further modified, for example, by increasing the degree of polymerization and / or increasing the degree of cross-linking between polymer chains can slow down the degradation rate. it can. Furthermore, it is not intended to limit the preferred materials only to substances that are partially or completely resorbed into the body. Substances that can decompose and ultimately drain from the body are intended to be included within the scope of the present invention.
[0032]
Examples of biodegradable polymers used with the present invention are poly (amino acids), polyanhydrides, polycaprolactones, polyorthoesters, polylactic acid, poly (lactide-co-glycolides), ie D, L of these components. And a copolymer of lactic acid and glycolic acid containing any of the D / L isomers. An example of a preferred biodegradable polymer for use with the present invention is a 70:30 poly (L, DL) copolymer commercially available from Boehringer Ingelheim.
[0033]
A particularly advantageous advantage provided by the present invention is that it is easy to produce suitable synthetic spacers. Spacers made of polymerized, low polymerized and composite materials can be manufactured using known manufacturing techniques, including extrusion, injection molding and blow molding. Further, the selected polymeric material is typically provided by the vendor in a form that can be readily molded and / or molded at high temperatures. A copolymer of D / L lactate is one specific example. This material can be obtained in a wide variety of forms including pellets or grains, plates, ingots. The material can be molded at a temperature of about 55 ° C. or higher so as to provide an implant of the desired shape and size. This material can be repeatedly heated to the required profile without any noticeable change in the material, ie its chemistry. In addition, the material can be easily cut using a cautery method so that the spacer easily adapts to the surface morphology of the bone. Even at low cautery temperatures, the material can be cut or shaped during the process.
[0034]
Examples of metallic materials include any metals and metal alloys that are known to be suitable for implantation in the body of animals, including humans. Examples include titanium, titanium alloys, and surgical steel.
[0035]
Specific examples of ceramic materials used with the present invention include glass, calcium phosphate, alumina, zirconia, apatite, hydroxyapatite and mixtures of these materials.
[0036]
Composite materials can also be used with the present invention. The composite can combine two or more of the desired materials so as to form an embedded spacer body. Examples of composites include reinforced ceramic, glass or polymeric materials. Preferred composites include fiber reinforced materials such as glass or carbon fiber reinforced organic polymers.
[0037]
The carbon fiber vertebra spacer of the present invention can be manufactured according to the following method. A fiber composite such as glass or carbon fiber composite (GFRP or CFRP, respectively) is first immersed in a liquid plastic, in particular a resin material such as an epoxy resin. The soaked fibers are wound on a winding mandrel as bundled fibers, particularly using a filament winding method. Thereafter, the plastic is cured. This is best done with a controlled temperature treatment. The wound material is formed into a simple rod-like shape, after which the elongated base body formed is provided with a cavity having a size and shape corresponding to the external form of the wound material. Since the end dimensions of the cavities are already formed of the winding material, some machining of the restrictive wall inner surface surrounding the cavities is required, but little is required. The soaked fiber material is wound on a winding mandrel until the body to be formed has an external dimension equal to or slightly less than the desired final dimension. Preferably, the soaked fiber is wound on a mandrel until the body to be formed reaches at least a selected minimum wall thickness relative to the maximum thickness wall or end wall so that subsequent machining steps are minimized. .
[0038]
The wound spacer body is machined according to the following steps. The wound mandrel is replaced with a receiving mandrel for centering within the chucking device so that the basic body can be precisely machined. The outside of the base body is machined to an intermediate configuration having an outer dimension that is smaller than the desired final dimension. Preferably, each of the surfaces of the intermediate form is smaller than the final form by an approximately equal amount. In other words, the basic body is machined so as to be in an intermediate form that substantially corresponds to the final form and is merely a miniaturized one. This intermediate form is in a compact form so that as little as possible material needs to be machined during the final machining process. Preferably, the winding / machining process provides an intermediate spacer having an outer dimension of about 90-98%, more preferably 95% of the final base body outer dimension.
[0039]
It should be understood that in the final form some walls are thicker than others so that the base body does not roll to the final dimensions on each outer surface. The chosen surface requires additional plastic to be wrapped around the mandrel. Milling, crushing and / or polishing methods are possible machining methods. During previous machining steps, different wall thicknesses of the longitudinal wall and the front wall are pre-formed in the spacer body by corresponding machining from a selected outer part of the basic body.
[0040]
In the next step, additional fibers are impregnated with resin and wound around the machined intermediate cavity body to form the sides to the desired thickness. The basic body that is formed approximates the desired outer dimensions. That is, the fiber and resin material are wrapped around the base body until the base body reaches at least the outer dimensions for each surface dimension of the implant. After re-inserting the winding mandrel, a second winding step is performed. In the last step, the basic body reaches its final outer dimension. With respect to the performance of the materials fiber and resin, this second machining step corresponds to the first machining step.
[0041]
This method provides a closed path of fibers on both the inner and outer surfaces of the spacer, taking full advantage of the strength enhancing properties of the fiber material. A completely closed independent path of the fiber is realized on the inner surfaces defining the cavities, since these surfaces are not machined after the winding process. Since two winding steps are used to manufacture the basic body, only a small amount of material has to be removed from the basic body after the second machining step. In this final machining step, few, if any, fibers are cut in the outer fiber winding. This form of the main roll in the wound state of the fiber is kept almost untouched.
[0042]
Optionally, in addition to the cavity, the base body is formed with holes and grooves by a corresponding machining process after the second winding process and after the plastic has hardened. In the vertebral implant according to the invention, these are the longitudinal and anterior wall through-holes, the receiving means groove, the free-edge surface groove extending in the transverse direction of the anterior wall.
[0043]
This method only provides a very stable vertebral implant from fiber reinforced material at low cost. Furthermore, the fibers can be oriented to wind in various directions, either in a single direction or alternatively.
[0044]
Alternatively, an implant formed of a fiber composite material can saturate individual fibers or fiber bundles with a resin, such as the polymeric material described above, and draw the resin saturated fibers through a die, It may be fabricated using a pultrusion process by providing the desired implant profile. The formed implant can be machined to a final configuration including a threaded outer surface, a chamfered surface and an opening, as described above. The implant produced by the pultrusion method as a whole has the fibers oriented in the same direction, for example, either axial or longitudinal.
[0045]
In yet another method, fiber reinforced composites can be fabricated using chopped fibers (or short fibers) embedded within a curable resin, such as, for example, one or more of the polymers described above. . The chopped fiber reinforced material can be cured, shaped and / or extruded according to techniques known in the art.
[0046]
The osteogenic composition used in the present invention can be obtained from other parts of the patient's body, such as, for example, cancellous bone in the vertebrae or other bone structures such as the tip of the iliac bone. In other embodiments, the osteogenic material can include a therapeutically effective amount of bone morphogenetic protein in a pharmaceutically acceptable carrier. Preferred osteoinductive factors include, but are not limited to, recombinant human bone morphogenetic proteins (rhBMPs) because these proteins can be supplied without limitation and do not transmit infectious diseases. Most preferably, the bone morphogenetic protein is rhBMP-2, rhBMP-4 or a heterodimer thereof. The concentration of rhBMP-2 is generally in the range of 0.4 mg / ml to about 1.5 mg / ml, preferably about 1.5 mg / ml. However, it is contemplated to use any bone morphogenetic protein, including bone morphogenetic proteins identified as BMP-1 through BMP-13. BMP is available from Genetics Institute, Inc. of Cambridge, Massachusetts and is produced by those skilled in the art as described in the following US patents: I can do it. US Pat. No. 5,187,076 to Wozney et al., US Pat. No. 5,366,875 to Warsney et al., US Pat. No. 4,877,864 to Wang et al. US Patent No. 5,108,922 to Wang et al., US Patent No. 5,116,738 to Wang et al., US Patent No. 5,013,649 to Wang et al., US Patent No. to Warsney et al. No. 5,106,748, International Patent Application WO 93/00432 to Warsney et al., International Patent Application WO 94/26893 to Celeste et al., And International Patent Application WO 94/26892 to Celeste et al. It is contemplated to use all osteoinductive factors, whether obtained as described above or isolated from bone. Methods for isolating bone morphogenetic proteins from bone are described in U.S. Pat. No. 4,294,753 to Urist and Ulist et al., 1984 81PNAS371.
[0047]
The selection of the carrier material for the osteogenic material is based on the desired application, biocompatibility, biodegradability and interface properties. The bone growth inducing composition can be introduced into the bone material pores by any suitable method. For example, the composition can be injected into the spacer space. Preferably, the osteogenic factor that is BMP is provided in lyophilized form and in a pharmaceutically acceptable liquid or gel carrier such as sterile water, physiological saline or any other suitable carrier. Be able to return to liquid. The carrier can be any suitable medium for supplying the protein to the implant. Preferably, the medium is assisted by a buffer solution as is known in the art. In one particular embodiment of the invention, rhBMP-2 is suspended or mixed in a carrier such as water, saline, liquid collagen or injectable bicalcium phosphate. In one most preferred embodiment, BMP is delivered into the pores of the graft and then lyophilized or freeze dried. The graft-BMP composition can then be frozen for storage and transport. Alternatively, osteoinductive protein may be added during surgery.
[0048]
Other osteoinductive protein carriers can be used to supply the protein. The protein carrier includes calcium sulfate, polylactic acid, polyanhydride, collagen, calcium phosphate, polymerized acrylic ester and demineralized bone. The carrier can be any suitable carrier that can supply protein. Most preferably, the carrier can be finally absorbed into the body. One preferred carrier is an absorptive collagen sponge sold by Integra LifeSciences Corporation under the name Ablistable Collagen Hemostatic Agent. It is. Another preferred carrier is an open cell polylactic acid polymer (OPLA). Other possible materials for the composition are biodegradable and chemically defined calcium sulfate, calcium phosphate such as tricalcium phosphate (TCP), and hydroxyapatite (HA), and also injectable Bicalcium phosphate (BCP) and polyanhydrides may be included. Other possible materials are those that are biodegradable and biologically obtainable, such as bone or dermal collagen. Further materials consist of pure proteins or extracellular matrix components. The osteoinductive material can also be a mixture of BMP and a polymeric acrylate carrier such as polymethylmethacrylate.
[0049]
One carrier is a biphasic calcium phosphate ceramic.
Hydroxyapatite // tricalcium phosphate ceramic is preferred because of its desirable biological activity characteristics and degradation rate in vivo. The ratio of hydroxyapatite to tricalcium phosphate ranges from about 1:99 to about 65:35. It is conceivable to use a ceramic carrier of any size or shape that fits within a cavity defined in the spacer. The ceramic block is the French B.C. P. It is commercially available from the Sofamor Danek Group of 4-62180 Langhe-de-Flyers and France, 31100 Truse 132 Route d: Espagne's Bioland. Of course, a rectangular shape and other appropriate shapes are also conceivable. The osteoinductive factor is introduced into the carrier by any suitable method. For example, the carrier can be immersed in a solution containing the factor.
[0050]
In order to prevent the hand tool from sliding out of the spacer, the rear wall receiving means is preferably formed to function as a holding means. The hand tool can be provided with, for example, a clamp, by which the spacer is held in tension, for example by engaging the inside of the groove, connected to the hand tool as a unit to which the spacer is connected, It may be possible for the surgeon to be easily maneuverable so that the spacer can be accurately positioned at a desired location within the disc space. In order to more accurately determine the position of the spacer with respect to the hand tool, a second penetration is formed in which the spacer opening extends through the rear wall and at the other end of the spacer this opening is formed in the opposite front wall. Can be aligned with the hole. The corresponding pin or shaft of the hand tool can be extended through the first through hole and into the second through hole, so that the center of the spacer is on the hand tool. The through hole in the front side facilitates access to the spacer cavity so that tissue ingrowth from the front side into the spacer can be facilitated.
[0051]
The intervertebral spacer according to the present invention can be embedded in an intervertebral disc space prepared from a variety of directions, including posterior, lateral posterior, anterior and lateral anterior directions. Prepare the intervertebral disc space before embedding it. Typically, a partial or complete disc incision is performed. The end plate is preferably cut so that the cancellous bone tissue can be exposed. Preferably, only the portion of the endplate directly opposite the embedded spacer opening is cut or scraped to expose the underlying cancellous bone tissue. This preserves the integrity of the endplate as much as possible so as to minimize the extent of the embedded spacer sinking into the endplate tissue (a scraper / chisel suitable for use in the present invention). Filed on Oct. 10, 1999, the entire contents of which are incorporated herein by reference, the “Spinal Implant Method and Cutting Attachment Method and Spinal Implant Method and Cutting Tool to Install Implant”. Tool Preparation Accessing The Implant ”), which is described in US patent application Ser. No. 09 / 420,622). The upper and lower surfaces of each longitudinal wall can engage non-cut portions of the endplate, while the bearing surface of the spacer abuts the thicker cortical bone tissue proximate to the epiphyseal ring. This preparation involves cutting the cortical bone of the endplate to provide openings within the disc space, and cutting or removing portions of the cortical bone tissue of the endplate to expose the cancellous bone tissue. Can be included, but this is not essential. If necessary, the vertebrae are distracted to provide sufficient clearance between opposing cortical edges of adjacent vertebrae so that spacers can be inserted. Thereafter, the intervertebral spacer is inserted into the prepared intervertebral disc space so that the upper surface and the lower surface are in contact with the opposed end plates, respectively, while the openings on the upper and lower surfaces are opposed to the cut portions of the end plates. The bearing surface is adjacent to the inner surface of the cortical margin around the vertebral body. After insertion of the spacer into the disc space, the vertebral bodies can be compressed together to reduce the disc space if necessary or desired. By compressing the intervertebral disc space, the surface of one or more spacers can be embedded in the cortical bone of the endplate. In one embodiment, the upper and lower surfaces of the spacer are previously embedded in the portion of the end plate that has not been cut. In addition, pedicle screws, plates and / or spinal rods or any other known fixation devices and techniques can be used to maintain disc space separation and spine orientation.
[0052]
The present invention may be modified as devised by those skilled in the art. The methods embodied in the present invention may be altered, rearranged, replaced, deleted, duplicated, combined or otherwise as devised by those skilled in the art without departing from the spirit of the present invention. Can be added. In addition, the various steps, processes, procedures, techniques, aspects and operations in these methods can be modified, rearranged, replaced, deleted, duplicated or combined as devised by those skilled in the art. All publications, patents, and patent applications cited herein are specifically as if each of their respective publications, patents or patent applications were individually and individually cited for reference. It is incorporated herein by reference for reference.
[0053]
BEST MODE FOR CARRYING OUT THE INVENTION
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated herein and specific language will be used for the description. It will be understood, however, that this is not intended to limit the scope of the invention in any way. Any changes and further modifications in the described processes, systems or devices, and further applications of the principles of the invention described herein, as would normally be devised by those skilled in the art to which the invention pertains. It is thought that it can be embodied.
[0054]
1 to 5 show an intervertebral spacer 1 according to the present invention. The spacer 1 is formed by an elongated body 2 that defines a longitudinal axis. A cavity 3 is formed in the main body 2. The cavity 3 is surrounded by two longitudinal walls 4, 5 and two end walls 6, 7 (rear wall 6 and front wall 7). The cavity 3 is formed so as to be able to penetrate and extend in the height direction H of the main body 2, and has a long and narrow rectangular shape in which a semicircular shape is added to the front side of the same in the plan view. Is provided. The cavity 3 has the same plan view over the entire height of the implant and is thus formed in the basic body 2 without an undercut region. The end walls 6, 7 are formed to be thicker than the longitudinal walls 4, 5 over their respective wall surfaces. In the illustrated embodiment, the walls 6, 7 are provided around the cavity 3 to be about 2.5 times the thickness of the longitudinal limiting walls 4, 5. In this case, the thickness of the center of each wall is used as the associated wall thickness.
[0055]
The main body 2 has bearing surfaces 8, 8 ', 9, 9' formed by the cross edge surfaces of the end walls 6, 7, and the cross edge surfaces 8, 8 ', 9, 9' , Having a width wider than the respective cross end edge surfaces 10, 11 formed by the lateral end edge surfaces of the longitudinal walls 4, 5.
[0056]
The surfaces 8, 8 ′, 9, 9 ′ are continuously extended and have no stepped portions and protrusions so as to be a substantially smooth surface. As is apparent from FIG. 13, the surfaces 8, 8 ′, 9, 9 ′ function as a contact surface and / or a support surface for the vertebral body W, and substantially reduce the compression force generated between the adjacent vertebrae W. Full support. For this reason, the vertebral body W comprises a harder cortical bone material K in the outer region near the cortical edge structure, while a more flexible, spongy or sponge-like bone material S is present in the vertebral body W. Is utilized. In this case, the peripheral outer skin or cortical edge of the vertebra W which consists of cortical bone tissue and to which the walls 6, 7 of the spacer 1 are attached via the bearing surfaces 8, 8 ', 9, 9' is sufficiently stable. It is possible to support the compressive force along the longitudinal direction of the spinal column and to transmit the compressive force to the spacer 1 adjacent to the bearing surfaces 8, 8 ', 9, 9'.
[0057]
Further, FIG. 2 shows the main body 2 when viewed in the width direction B (or side view) thereof, that is, parallel to the bearing surfaces 8, 8 ′, 9, 9 ′. The upper surface 24 and the lower surface 26 have a biconvex shape in the longitudinal direction, and a maximum height H is provided between the first end portion 20 and the second end portion 22. In the illustrated embodiment, the maximum height H of the main body 2 is arranged at a position close to the front end edge 31 of the opening 32 on the upper surface 24 (see FIG. 1). The lens-shaped design of the body 2 that is formed allows the body to be placed within the disc space and to restore and / or maintain the desired disc space height. This configuration keeps the upper surface 24 and lower surface 26 in contact with the exposed endplates of the vertebrae. As a result, the bone-forming material in the cavity 3 is pressed against the spongy or sponge-like bone tissue of the vertebra and promotes bone fixation. Furthermore, since the main body 2 is matingly engaged with the natural concave portion of the end plate, the possibility of being pulled out backward is minimized.
[0058]
FIG. 4 is a cross-sectional view taken along the intersecting line 4-4, that is, when viewed perpendicular to the bearing surfaces 8, 8 ′, 9, 9 ′. The spacer 1 is provided as a substantially elongated rectangular body having a substantially planar longitudinal wall. The corner 12 of the rectangular first end 20 is rounded to provide a generally tapered profile at the first end 20 with respect to the body 2. The corner 12 has a radius of about 1/3 of the width of the spacer 1. As can be seen from FIGS. 1 and 3, the longitudinal and anterior edges of the implant 1 are rounded so that it can be streamlined to facilitate the insertion of the spacer 1 into the disc space. The front of the shape. As a result, the spacer 1 can be inserted into the intervertebral disc space with minimal risk of tissue damage.
[0059]
In one alternative embodiment, the peripheral edge of the opening 32 through the top surface 24 into the cavity 3 is not provided with an upwardly rounded edge, thus forming an acute edge. This sharp edge creates a minimal risk of damaging tissue during spacer installation. Unlike the longitudinal and front spacer edges, the overall lens shape of the spacer 1 is from a maximum height portion proximate the front end edge 31 of the opening 32 to a lower height portion proximate to the second end 22. The peripheral edge of the opening 32 is further inwardly directed toward the central longitudinal axis. The bearing surfaces 9, 9 ′ extend substantially parallel to the longitudinal central axis of the spacer 1 when viewed in the lateral direction of the spacer 1.
[0060]
The grooves 13, 13 ′ extend in the transverse direction with respect to the longitudinal axis in the width direction B of the spacer 1. Grooves 13/13 ′ are formed in each of the contact surfaces 8, 8 ′, 9, 9 ′. The grooves 13, 13 ′ are provided such that the sides thereof are triangular grooves or ridges forming angles 28, 30 of approximately 90 ° with each other. However, other groove shapes such as rectangular or U-shaped are possible. The compressive force W from the two vertebrae pushes the tissue into the groove 13/13 'and further fixes the spacer 1 in the disc space.
[0061]
A hand tool or operating tool receiving means 14 is provided at the rear end of the basic body 2 (as shown at the right end of FIGS. 1, 2, 4, 5 and 7). The receiving means 14 includes a through hole 15 formed in the middle of the rear wall 7. The through hole 15 can be formed so as to be able to engage with a corresponding part of the hand tool. Grooves 16, 16 'of the second end 22 extend laterally from the through hole 15 so that they can engage the blade of the hand tool.
[0062]
A second through hole 17 aligned with the hole 15 is formed in the middle of the first end 20 of the basic body 2. The pen extension or stud corresponding to the counterpart of the hand tool can be engaged through the hole 17 to set the center of the spacer 1 relative to the tool. Thereafter, the through holes 17 and holes 15 allow bone material to grow into the spacer from the front and back sides.
[0063]
In the embodiment according to FIG. 1, two openings 18, 19 are formed in each of the longitudinal walls 4, 5 of the cavity 3. In an alternative embodiment, more than one opening is formed in each of the longitudinal walls 4,5. The diameter of each of the through holes 18 and 19 is equal to about one half of the maximum height H of the spacer 1. Bone material can grow laterally in the through holes 18, 19 and anchor the spacer 1 in the disc space.
[0064]
FIG. 7 is a perspective view of another embodiment of a spacer 80 used in the present invention. Like the spacer 1, the spacer 80 includes an elongated basic body 82 that defines a longitudinal axis 84. The basic body 82 has a substantially biconvex lens shape profile defined by a lower surface 86 and an upper surface 87. The upper surface 87 and the lower surface 86 are provided with a plurality of grooves 104. In addition, the base body 82 has an internal cavity 88 surrounded by first and second longitudinal walls 90, 92 and end walls 94, 96, respectively. End walls 94, 96 have a thickness approximately along the longitudinal axis that is greater than the thickness of either the first longitudinal wall or the second longitudinal wall 92. Each of the further end walls 94, 96 includes a cross edge surface defining a bearing surface 98, 98 ', 100, 100'.
[0065]
A plurality of grooves 104 extend across the bearing surfaces 98, 98 ', 100, 100'. Further, although the chosen groove can extend across the upper and lower surfaces 87, 86 perpendicular to the longitudinal axis, this is not essential. The selected groove is interrupted by the peripheral edge 108 of the opening 110 in the cavity 88. In other respects, the groove 104 extends laterally across the base body 82 from the longitudinal wall 90 to the longitudinal wall 92. The groove 104 can be provided as a recess cut in the lower surface 86 and the upper surface 87. Furthermore, the groove 104 defines a cut portion having a uniform curvature on the upper surface 87 and the lower surface 86. The groove 104 is formed so as to be substantially wider between the land portions 106 than the depth of the lower surface 86 or 87 of the groove.
[0066]
In the illustrated embodiment, pairs or adjacent grooves 107, 109 are separated by lands 106. The land portion 106 is provided so as to be substantially flush with the upper surface 87 and the lower surface 86.
[0067]
The basic body 80 includes a smooth hole 112 formed in the end wall 96. The smooth hole 112 can be used to place the insertion instrument before gripping the longitudinal walls 90, 92.
[0068]
FIG. 8 is a perspective view of one embodiment of a spacer holder 150 used in the present invention. The spacer holder 150 has an elongate shaft having a first end 154 adapted to receive a handle and a second end 156 at the other end provided with a head 158 for securing a vertebral spacer. 152 is provided.
[0069]
The head portion 158 includes a spacer fixing portion 160 that fixes one end of a spacer (not shown). The fixed portion 160 is a substantially concave surface or a U-shaped surface. The bottom portion 162 is provided as either a flat surface or a slightly convex surface so that it can abut against the end wall of the spacer. A pair of opposing overhangs 164, 166 project longitudinally from the bottom portion 162 and are spaced apart from each other by a selected distance so that they can engage the opposite longitudinal wall of the included spacer. The bottom portion 162 and the overhang portions 164, 166 define a U-shaped cavity 167 adapted to fit into and engage the first end portion and portion or side of the spacer. The bottom portion 162, in combination with the overhangs 164, 166, engages the spacer on three sides, straddles the spacer within the head portion 158 and embeds it in the disc space laterally. To control.
[0070]
A pair of blades 168 and 170 extend inwardly into the cavity 167. One blade 168/170 is provided so as to protrude radially inward from each of the overhang portions 164, 166. The blades 168 and 170 are provided so as to engage with the grooves 16 and 16 ′ of the spacer 1. It will be appreciated that the blades 168, 170 may be omitted from the portion 160 so that alternative embodiments of spacers according to the present invention may be secured.
[0071]
Centering pin 172 projects from bottom portion 162 into U-shaped cavity 167. In the illustrated embodiment, the centering pin 172 includes a tube 174 having a movable shaft extension 176 received therein. Either one or both of the tube 174 and the shaft extension 176 can be provided with a male thread. When the male thread portion is provided, the shaft extension 176 is rotatably received in the outer shaft 152 toward the first end 154, at which the shaft extension is a thumb operating screw or Connected to or engaged with the wheel, allowing the shaft extension 176 to rotate to either be pulled out or extended through the tube 174. In one form, the shaft 152 has an internal thread, while the axial extension has an external thread so that the shaft 152 can be moved longitudinally.
[0072]
The head portion 158 also includes a depth stopper 178 that projects laterally at at least one side. A depth stopper 178 is provided to contact the cortical edge of the vertebra adjacent to the disc space and constrain further movement of the mounted spacer into the disc space. The surgeon secures the spacer with the spacer holder 150, penetrates the disc space, and once in the disc space, the surgeon can place the secured spacer at a desired location in the disc space. During this time, the spacer remains fixed to the spacer holder.
[0073]
After preparing the adjacent vertebral endplates using the cutting tool 180 described with reference to FIGS. 9-12, a spacer according to the present invention can then be inserted into the disc space. The cutting tool 180 includes a cutting head 182, a shaft 184 that defines a longitudinal axis 186, and a handle engagement portion 188.
[0074]
The cutting head portion 182 is attached to the end of the shaft 184. The cutting head portion 182 includes a first arm 190 and a second arm 192 that extend substantially parallel to the longitudinal axis 186. Opposing first arm 190 and second arm 192 include two substantially smooth longitudinal surfaces 202,204. The surfaces 202, 204 are configured to facilitate the insertion of the cutting head 182 into the disc space and are substantially separated from each other by a distance D. The distance D is selected to be approximately equal to the width of the opening 3 in the spacer 1 or the width of the opening 88 in the spacer 80 when measured perpendicular to the longitudinal axis of each spacer.
[0075]
Each of the first arm 190 and the second arm 192 has a first arcuate cutting edge part 194 and an opposite second arcuate cutting edge part 196. Thus, the cutting head portion 182 has a total of four cutting edge portions. The first cutting edge portion 194 and the second cutting edge portion 196 are provided in a form that can substantially conform to the arcuate upper and lower surfaces of the spacers 1 and 80, respectively. Further, the first arm 190 and the second arm 192, and the first cutting edge portion 194 and the second cutting edge portion 196 included in the first arm 190 and the second arm 192 are adjacent to each other while substantially maintaining the natural concave curvature of the end plate. A portion of the cortical bone tissue at the opposing endplates of the vertebrae V1, V2 to be cut can be cut and removed. The cutting edges 194, 196 are of a length selected to avoid cutting the cortical edge, and preferably to avoid cutting the anterior and posterior portions of the endplate proximate to the epiphyseal ring. L. In this manner, the cavity prepared with the cutting tool 180 contacts the graft material in the implant 110 and the cancellous bone of the two vertebrae. The bearing surface of the implant 110 is positioned adjacent to the edge of the opening of the cortical endplate and abuts with other portions of the endplate to establish a strong load bearing relationship.
[0076]
The first arm 190 and the second arm 192 are generally opposite and define a cavity 198 therebetween to receive bone chips generated during the cutting operation. Bone chips collected from the cutting operation can be stored and filled in the openings 3 or 88 of the spacers 1, 80 to facilitate bone fixation. The proximal ends of the first arm 190 and the second arm 192 are attached to the distal end of the shaft 184. The other ends of the first arm 190 and the second arm 192 are attached to the non-cutting portion 200.
[0077]
The non-cutting portion 200 of the cutting head portion 182 is fixed to the ends of the first arm 190 and the second arm 192. Preferably, the non-cutting portion 200 has a first dimension perpendicular to the longitudinal axis that is approximately equal to the distance D and extends to approximately the same extent as the surfaces 202, 204 of the arms 194, 196. The non-cutting portion 200 is also adapted to facilitate the removal of equal amounts of cortical bone tissue from the adjacent vertebrae by aligning the surfaces 202, 204 an equal distance from the opposing endplate surfaces of the adjacent vertebrae. Further, the non-cutting portion 200 is adapted to prevent removal of cortical bone from the anterior cortical bone surface of the adjacent vertebra. Although the non-cut portion is illustrated as a cylindrical abutment, it is also understood that the present invention includes alternative forms. Such alternative forms include spherical, hemispherical, frustoconical, etc.
[0078]
Shaft 184 is rotatably received within sleeve 206. The sleeve 206 includes a stopper 208 that is adapted to come into contact with the vertebral body when the cutting blade portion is inserted into the intervertebral disc space. Preferably, the stopper 208 is adapted to prevent interference with the processes inside the intervertebral disc and the associated neural body. In one embodiment, the stopper 208 is adapted to engage a single vertebral body.
[0079]
A handle engaging portion 188 is attached to the proximal end of the shaft 184. Handle engagement portion 188 is releasably engageable with a variety of handles (not shown) known in the art to facilitate rotation of shaft 184 and cutting head portion 182. . Alternatively, it will be appreciated that the cutting tool 180 may include a handle fixedly attached to the proximal end of the shaft 184.
[0080]
Next, various non-limiting embodiments of the spinal fixation or fusion method of the present invention will be described with reference to FIGS. One method is (a) cutting the vertebrae V1, V2 with a tool 180 to prepare for the implantation of the spacer 1 and / or 80, and (b) cutting the spacers 1 and / or 80 into the vertebral body V1 ′. , And V2 ′. Another detailed method of fusing two vertebrae together is described with respect to the following procedure.
[0081]
The surgeon exposes the vertebrae that need to be fused using known surgical techniques. The surgeon then separates the dura mater sleeve to form an extension of the bone marrow if the method is performed in the lumbar region, and then performs a disc incision to make room for the spacer within the disc space. provide. When inserting the spacer from the posterior side, the surgeon inserts two distractors known in the art between the two vertebral bodies V1, V2 from the posterior (posterior) side. The distractor can be inserted transversely to the cavity formed by the disc incision method and then rotated 90 ° to separate the vertebral bodies and restore the height of the disc space. If the anterior bay angle is desired, the distractor can include a tapered surface intended to establish the desired angle. Next, one of the distractors is removed. The surgeon then inserts the cutting tool 180 between the vertebral bodies V1, V2 so that the surfaces 202, 204 are in contact with the vertebral endplates as illustrated in FIG. When the cutting head 182 is correctly positioned in the central region of the cortical endplate, the stopper 208 abuts the outer surface of the vertebral body V1 or V2, and the non-cutting portion 200 is against the inner cortical bone wall of the vertebral bodies V1 and V2. Proximity. The surgeon then turns the handle 188 so that the cutting head 182 rotates about the longitudinal axis 186. Typically, the surgeon turns the handle 188 by a slight rotational angle to engage the cutting edges 194, 196 with the cortical bone of the adjacent end plate, and then changes direction to produce a rocking cutting action. . This cutting operation continues until the desired or proper amount of vertebral endplate has been removed. When the non-cutting portion 200 is accurately positioned between the inner cortical bone portions of the adjacent vertebrae V1, V2, the first cutting edge 194 and the second cutting edge 196 cut the end plates 244, 246 equally. To do. This forms an opening to both vertebral endplates 244, 246 and cuts a recess that is concave in both directions from the front to the rear and laterally. In a preferred embodiment, the maximum lateral dimension of the opening is chosen to be equal to the opening 3 of the spacer 1 or the opening 88 of the spacer 80. Other portions of the end plates 246 and 248 abut against the non-cutting portion 200 and the non-rotating shaft 206. Bone chips generated by cortical bone cutting are received in the cavity 198 between the first arm 190 and the second arm 192. The surgeon then pulls the cutting tool 180 out of the disc space. The bone chips remaining in the cavity 198 can then be collected and filled into the spacer 1 or 80. Next, the surgeon embeds spacer 1 (or spacer 80) previously filled with either osteogenic material or bone chips between vertebral bodies V1, V2 between end plates 244, 246. The spacer 1 is arranged as follows: the arcuate upper surface 24 and lower surface 26 engage adjacent to the cut portions of the end plates 244, 246 while adjacent to the cortical edges of the end plates 244, 246. It arrange | positions so that another non-cutting part may contact | abut to the bearing surface 8, 8 ', 9, 9'. The surgeon then removes the second distractor and repeats the previous procedure to place the second spacer 1 in a position substantially parallel to the first spacer 1 to thereby remove the second spacer. Install 1 (or 80).
[0082]
In FIG. 13, the vertebra W to which the spacer 1 is adjacent is shown. ² , W ^Three A cross-sectional side view of a portion of the spine is shown positioned between the two. From this figure it can be seen that the spacer 1 fits tightly within the disc space. The upper surface 24 and the lower surface 26 are in contact with opposing end plates substantially along the entire length in the longitudinal direction. The bearing surfaces 8, 8 ', 9, 9' abut against and support the epiphyseal ring structure of the individual vertebrae.
[0083]
FIG. 14 shows a state in which the pair of spacers 1, 1 ′ are arranged from both lateral directions over the profile of the upper end plate of the lumbar vertebra 220. The longitudinal dimension indicated by the reference line 222 of the spacer 1 is long enough to extend across the end plate and place the bearing surfaces 8, 8 ′, 9, 9 ′ opposite the epiphyseal ring 226. It is chosen so as to provide a space having a certain height.
[0084]
In other embodiments, the steps described above may be altered, deleted, combined, repeated, or reordered, as devised by those skilled in the art. As a non-limiting example, the method according to the present invention can utilize one or more different tools to prepare the spine for fixation by the implant of the present invention. In another example, the tool of the present invention can be utilized to prepare a surgical portion for implantation.
[0085]
While the invention has been illustrated in the drawings and described in detail in the foregoing description, this is by way of example only and should not be construed as limiting its features; only the preferred embodiments are shown and described. It is understood that it would be desirable to protect all changes and modifications that fall within the spirit of the invention.
[Brief description of the drawings]
FIG. 1 is a perspective view of one embodiment of an intervertebral spacer according to the present invention.
FIG. 2 is a side view of the spacer of FIG.
FIG. 3 is an end view of the intervertebral spacer of FIG.
4 is a cross-sectional view of the intervertebral spacer of FIG. 1 taken along the transverse line 4-4 of FIG.
5 is a cross-sectional view of the intervertebral spacer of FIG. 1 taken along the transverse line 5-5 of FIG.
FIG. 6 is a second end view of the intervertebral spacer of FIG.
FIG. 7 is a perspective view of one alternative embodiment of a spacer according to the present invention.
FIG. 8 is a perspective view of a spacer holder used with the present invention.
FIG. 9 is a perspective view of one embodiment of a cutting tool according to the present invention.
10 is a partial perspective view of a head portion of the cutting tool illustrated in FIG. 9. FIG.
11 is a side view, partially in section, showing a portion of the cutter of FIG. 9 received within an intervertebral disc space.
12 is a partial cross-sectional side view showing a portion of the cutter of FIG. 9 rotated 90 ° within the disc space of FIG. 11. FIG.
FIG. 13 is a type of cross-sectional side view of a portion of a spinal column with an intervertebral spacer disposed between a pair of adjacent vertebrae.
FIG. 14 is a top view of an upper end plate of a lumbar vertebra showing a state in which a pair of spacers according to the present invention are arranged from both lateral directions.

Claims (47)

A vertebral implant mounted in an intervertebral disc space, comprising a box-shaped elongate basic body defining a longitudinal axis formed with a cavity extending transverse to the longitudinal axis;
The cavity is bounded by two longitudinal walls arranged at positions facing each other and two end walls arranged at positions facing each other,
An edge surface extending in the transverse direction of the cavity functions as a contact surface between the vertebra and the vertebra implant;
The two end walls of the cavity are formed thicker than both of the longitudinal walls, thereby increasing the width of the edge surface extending in the transverse direction;
The implant is made of synthetic material,
A vertebral implant, wherein the basic body has a shape curved outward in the longitudinal direction when viewed parallel to the edge surface.   The vertebral implant of claim 1, wherein a groove is formed in each of the transversely extending edge surfaces of the end wall, the groove extending transversely to the longitudinal axis of the base body.   The vertebral implant of claim 1, wherein both end walls are formed with a thickness at least twice that of the longitudinal wall.   The vertebral implant of claim 1, wherein at least one through hole is formed in each longitudinal wall.   2. The vertebral implant of claim 1, wherein the base body comprises receiving means at one front end portion for receiving a hand tool, whereby the receiving means can apply a rotational moment about the base body longitudinal axis to the base body. Vertebra implants.   6. The vertebral implant according to claim 5, wherein the receiving means is formed on the side of the hole at the end wall of the basic body and the outwardly open hole formed in the middle of the end wall of the basic body. A vertebral implant comprising one groove and the hole opening outward.   7. The vertebral implant of claim 6, wherein the receiving means hole is formed as a threaded hole.   The vertebral implant of claim 1, wherein the synthetic material retains elongated carbon fibers.   The vertebral implant of claim 1, wherein the synthetic material carries an x-ray contrast agent. An intervertebral spacer provided to penetrate into an intervertebral disc space between adjacent vertebrae and defining a longitudinal axis;
At least one tissue receiving groove extending transversely to the longitudinal axis;
A cavity bounded by a first end wall and an opposite second end wall, the first end wall defining a first bearing surface and an opposite second bearing surface. Defining the cavity, wherein the second end wall defines a third bearing surface and an opposite fourth bearing surface;
An upper surface extending between the first end wall and the second end wall, the upper surface having an arcuate portion adapted to engage the lower end plate of the first vertebra. When,
Opposite lower surface extending between the first end wall and the second end wall and having an arcuate portion adapted to engage the upper end plate of the second vertebra A lower surface on the opposite side,
A first longitudinal wall extending between the upper surface and the lower surface;
An opposite second longitudinal wall extending between the upper surface and the lower surface;
Each of the longitudinal walls is substantially planar and arranged to be substantially parallel to each other;
Each of the longitudinal walls connect the upper and lower surfaces with rounded edges on the outside ;
An intervertebral spacer , wherein the first end wall and the second end wall are formed thicker than the first longitudinal wall and the second longitudinal wall .   The spacer according to claim 10, wherein the spacer is made of a metal material.   The spacer according to claim 10, wherein the spacer is made of a synthetic organic material.   The spacer of claim 12, wherein the synthetic organic material comprises a biodegradable polymeric material.   The spacer of claim 12, wherein the synthetic organic material comprises a non-biodegradable polymeric material.   13. The spacer of claim 12, wherein the synthetic organic material comprises a reinforcing material selected from the group consisting of continuous fibers, short fibers, plates, particles and mixtures thereof.   The spacer according to claim 12, wherein the synthetic organic material comprises glass fiber, ceramic fiber, or carbon fiber reinforced polymer material.   13. The spacer of claim 12, wherein the synthetic organic material is poly (vinyl chloride); poly (methyl (meth) acrylate); polyacryl; polyamide; polycarbonate; polyester; polyethylene terephthalate; A spacer selected from the group consisting of ether ketone) poly (ether, ether ketone) poly (aryl ether ketone) poly (ether ether ketone ether ketone) and mixtures thereof.   The spacer of claim 12, wherein the synthetic organic material is selected from the group consisting of poly (amino acids), polyanhydrides, polycaprolactone, polyorthoester polylactic acid, poly (lactide-co-glycolide) and mixtures thereof. Spacer.   The spacer of claim 10, wherein the spacer is made of a ceramic material.   The spacer of claim 10, wherein the first and second end walls each have a first thickness sufficient to maintain a desired disc space height when measured along the longitudinal axis. Having a spacer.   21. The spacer of claim 20, wherein the top surface has a third thickness measured transverse to the longitudinal axis, the third thickness being less than the first thickness.   21. The spacer of claim 20, wherein the body comprises a first longitudinal wall and an opposing second longitudinal wall, each of the longitudinal walls measured at a right angle to the longitudinal axis. A spacer having a thickness, wherein the second thickness is less than the first thickness.   The spacer of claim 10, wherein each of the top and bottom surfaces comprises at least one groove extending transversely to the longitudinal axis.   The spacer of claim 10, wherein each of the first bearing surface, the second bearing surface, the third bearing surface and the fourth bearing surface comprises at least one groove extending transversely to the longitudinal axis. Spacer.   11. The spacer of claim 10, wherein the upper and lower surfaces comprise one or more grooves, ridges and combinations thereof. In a spacer that promotes fusion between adjacent vertebrae,
An elongate body defining a longitudinal axis, the elongate body having an opening extending transversely to the longitudinal axis, the body comprising:
A first support end wall that terminates the body at a first end;
A second support end wall opposite the end that ends the body at a second end, the first and second support end walls being disposed substantially transverse to the longitudinal axis. And can abut against cortical bone tissue at opposing endplates of adjacent vertebrae,
A first side wall connecting the first support end wall and the second support end wall to each other and a second side wall opposite to the first side wall; and the main body extends from the first side wall to the second side wall. Having at least one tissue receiving groove extending to
Each of said first and said second side wall, Ri Owa at the upper arcuate edge and an opposite lower arcuate edge in a direction along the longitudinal axis,
The spacer, wherein the first support end wall and the second support end wall are formed thicker than the first side wall and the second side wall .   27. The spacer of claim 26, wherein the body is made of a metallic material. 27. The spacer of claim 26, wherein poly (vinyl chloride); poly (methyl (methacrylic acid) ) ; polyacryl; polyamide; polycarbonate; polyester; polyethylene terephthalate; polysulfone; A spacer formed of a synthetic organic material selected from the group consisting of ether, ether ketone) poly (aryl ether ketone) poly (ether ether ketone ether ketone) and mixtures thereof.   27. The spacer of claim 26, formed of a synthetic organic material selected from the group consisting of poly (amino acids), polyanhydrides, polycaprolactone, polyorthoester polylactic acid, poly (lactide-co-glycolide) and mixtures thereof. Spacer.   27. A spacer according to claim 26, wherein the body is made of a biodegradable polymeric material.   27. A spacer according to claim 26, wherein the body is made of a non-biodegradable polymeric material.   27. The spacer of claim 26, wherein the body is made of a reinforced composite material.   33. The spacer of claim 32, wherein the reinforced composite material comprises glass fiber, ceramic fiber or carbon fiber reinforced polymeric material.   27. The spacer of claim 26, wherein the body is made of a ceramic material.   27. The spacer of claim 26, wherein each of the first and second support end walls has a thickness sufficient to maintain a desired disc space height when measured along the longitudinal axis. Spacer.   27. The spacer of claim 26, wherein each of the first side wall and the second side wall has an opening into the opening.   27. The spacer of claim 26, wherein the first support end wall terminates at a first end of the first tissue engaging surface and at the other end of the second tissue engaging surface, the first and first A spacer, wherein each of the two tissue engaging surfaces comprises a groove extending transversely to the longitudinal axis.   27. The spacer of claim 26, wherein the first support end wall terminates at a first edge of the bearing surface and at an opposite edge of the second bearing surface, the first and second bearing surfaces being Spacers, each comprising a tissue receiving groove.   39. The spacer of claim 38, wherein the first bearing surface and / or the second bearing surface are substantially planar and are positioned at an angle with respect to the transverse axis.   40. The spacer of claim 38, wherein the first and second tissue engaging surfaces are adapted to matably engage within opposing epiphyseal ring portions of adjacent vertebrae.   27. The spacer of claim 26, wherein the first and second sidewalls define a forward profile.   27. The spacer of claim 26, comprising an upper surface and an opposite lower surface, wherein the upper surface and the lower surface extend between the first and second support end walls.   43. The spacer of claim 42, wherein at least one of the upper or lower surface comprises a tissue engaging structure comprising a groove, a ridge and combinations thereof. In the spacer holder fixed so that it can penetrate into the disc space which prepared the spacer of any one of Claims 1, 10, 26,
An elongate shaft defining a longitudinal axis and having a first end engaging the handle and an opposite second end having a spacer anchoring head;
A head portion extending from the second end portion, the head portion having a concave surface defining a gripping portion of the spacer, and the gripping portion of the spacer having a centering pin extending in a longitudinal direction from the concave surface A spacer holder.   45. A spacer holder according to claim 44, comprising a pair of blades with concave surfaces extending radially inward.   45. The spacer holder of claim 44, wherein the concave surface comprises an axis that can extend in a direction parallel to the longitudinal axis.   45. The spacer holder of claim 44, wherein the shaft has a male thread.

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