EA001334B1 - Fusion implant device and method of use - Google Patents

Abstract

1. An intervertebral prosthesis comprising an implant member which is a bone graft implant member dimensioned for insertion within an intervertebral space defined between adjacent vertebrae, said implant member defining a longitudinal axis and having at least first and second longitudinal sections with respective first and second cross-sectional dimensions, said first cross-sectional dimension being greater than said second crosssection dimension to define a retaining surface of said implant member wherein upon insertion of said implant member between the vertebrae said retaining surface facilitates securement therewithin by corresponding engagement with surfaces of the adjacent vertebrae. 2. The intervertebral prosthesis according to claim 1 wherein said implant member is generally circular in cross-section. 3. The intervertebral prosthesis according to claim 2 wherein said second longitudinal section defines a diameter ranging from about 50% to about 95% the diameter defined by said first longitudinal section. 4. The intervertebral prosthesis according to claim 1 wherein said implant member is generally wedge-shaped. 5. The intervertebral prosthesis according to claim I wherein the implant member defines a single stepped region. 6. The intervertebral prosthesis according to claim I wherein said implant member includes multiple stepped regions. 7. The intervertebral prosthesis according to claim I wherein said implant member is a bone graft implant. 8. The intervertebral prosthesis according to claim 1 wherein said implant member comprises cancellous bone or cortical bone. 9. The intervertebral prosthesis according to claim 1 wherein said implant member defines an interior hollow cavity for accommodating bone growth inducing material. 10. The intervertebral prosthesis according to claim 9 including bone growth inducing material disposed in said interior hollow cavity, said bone growth inducing material including bone growth factors, glycerol, demineralized bone matrix (dbm), bone marrow, bone morphogenic protein (BMP-4). 11. The intervertebral prosthesis according to claim 9 wherein said implant member includes at least one opening extending through an outer surface in communication with bone growth inducing matcrial disposed within said hollow cavity. 12. An intervertebral prosthesis comprising an implant member of biocompatible material and being dimensioned for positioning between adjacent vertebrae, said implant member including first and second generally cylindrical sections, first cylindrical section defining a diameter greater than a diameter defined by the second cylindrical section, the juncture of said first and second cylindrical sections defining a retaining ledge such that upon insertion of said implant member between the adjacent vertebrae in a manner to prevent movement relative to the vertebrae thereby facilitating retainment therein. 13. The intervertebral prosthesis according to claim 12 wherein said first and second cylindrical sections are concentrically arranged about a longitudinal axis of said implant member. 14. The intervertebral prosthesis according to claim 12 wherein said implant member has a non-threaded exterior surface. 15. The intervertebral prosthesis according to claim 12 wherein said implant member includes a plurality of annular grooves formed on an exterior surface portion thereof. 16. The intervertebral prosthesis according to claim 13 wherein said implant member defines anterior and posterior ends, said first cylindrical section disposed adjacent said anterior end. 17. The intervertebral prosthesis according to claim 12 wherein said implant member comprises cortical bone. 18. The intervertebral prosthesis according to claim 12 wherein said implant member comprises cancellous bone. 19. A vertebral interbody fusion device comprising a bone graft implant member dimensioned to span an intervertebral space between adjacent vertebrae, said implant member having a non-threaded outer surface and first and second longitudinal sections, with respective first and second cross-sectional dimensions, the juncture of said first and second longitudinal section defining a retaining surface, said retaining surface facilitating retention of said implant member within said intervertebral space through cooperative engagement with corresponding surfaces of the adjacent vertebrae.

Description

Field of Invention

The present invention relates to a bone-forming interstitial splicable implantable device, in particular to a non-threaded intervertebral bone implant having a stepped shape that facilitates fixation of the implant in the intervertebral region.

Description of the Related Art

The spine is a flexible column formed by a series of bones called vertebrae. The vertebrae are hollow and are located one above the other, forming a strong hollow pillar to support the skull and trunk. The hollow core of the spine accommodates the nerves of the spinal cord and protects them. Different vertebrae are interconnected by articular processes and intervertebral fibrous cartilage spaces.

The intervertebral fibrous cartilage is also called the intervertebral disc, and they consist of a fibrous ring filled with fleshy material. Disks function as vertebral shock absorbers and also interact with synovial joints, facilitating movement and maintaining flexibility of the spine. When one or more discs degrade as a result of an injury or disease, nerves passing through the damaged area can be compressed and thereby irritated. As a result, chronic and / or debilitating back pain occurs. Various methods and devices have been developed to treat such back pain, both surgical and non-surgical.

One of the ways, namely, the intermediate fusion, is that the spine is stretched to its natural position in order to increase the size of the channels of the nerve roots and to weaken or stop nerve irritation. The space between the vertebrae is held by fusion of the vertebrae in the damaged area at a fixed distance. Numerous prosthetic implants have been proposed to fill the void between the vertebrae. For example, US Pat. No. 4,936,848 describes an implant in the form of a spherical chamber made of metal or ceramic, which is inserted between adjacent vertebrae. The chamber has an internal cavity into which bone fragments are inserted. These bone fragments can be autogenous and are designed to stimulate subsequent bone growth and fusion of the vertebrae.

Another way to prevent vertebral contact is proposed in US Pat. No. 5,011,484, according to which a hairpin-shaped insert is inserted between two vertebrae in the longitudinal direction and fixed therein with a latch. US Pat. No. 4,309,777 describes an artificial intervertebral disc consisting of upper and lower discs interconnected by springs. An artificial disk is fixed between the vertebrae with the help of spikes that protrude from the disk into the vertebrae. US Pat. No. 4,743,256 describes a rigid porous insert that can be inserted between the vertebrae and secured in place using pins or screws. It is assumed that the porous structure of the liner will facilitate the growth of bone tissue into it.

Bone implantable insert for placement between the vertebrae is also described in US patent 4878915, in which, according to one design solution, an external thread is made outside the insert, which, when the insert rotates, will advance it into the prepared areas between the vertebrae. Part of the liner is provided with a groove, which includes the end of the key used to rotate the liner. US Pat. No. 5,105,255 describes a method for forming a canal between two adjacent vertebrae and setting up a transplanted medium, for example, small bone chips from cortical or cancellous bone. US Pat. No. 4,961,740 proposes a practically open, fusion chamber that is inserted between adjacent bone surfaces between the vertebrae by screwing the chamber into place. The chamber may be filled with bone chips or other substances causing bone growth, and when placed in the intervertebral space, there is immediate contact through the outer surface of the chamber between the bone-causing material contained in the chamber and the natural bone.

Ideally, a fused graft should stabilize the intervertebral space and fuse with adjacent vertebrae. In addition, while the fusion is in progress, the graft must have sufficient structural integrity to withstand the stress aimed at maintaining space, without significant deterioration or deformation, and also have sufficient stability to reliably stay in place until the actual bone ingrowth occurs. Therefore, the spliced graft must have some kind of attachment, as well as material that causes rapid bone growth and rapid coalescence of the implant with adjacent vertebrae. In addition, the material from which the spliced graft is made must be biocompatible and closely mimic the body’s natural bone tissue.

All implants described above are designed to support and preserve the appropriate intervertebral space. Unfortunately, these implants may not meet certain ideal criteria for an intermediate spliced implant. For example, many of these implants, in particular those described in US Pat. No. 4,936,848, are made of metal and ceramic and therefore do not have biocompatibility and do not provide a close imitation of the body’s natural bone tissue. US Pat. No. 5,015,255 describes a transplant in the form of bone chips, which can eventually grow between the vertebrae. In the case of adequate growth of bone chips, the final fused graft can closely mimic the body’s natural bone tissue. However, the bone chip after its introduction is not limited by anything and cannot remain enclosed between the vertebrae for a time sufficient for the corresponding fusion between itself and with adjacent vertebrae. The bone insert described in US Pat. No. 4,878,915 has a threaded outer surface to help place the implant between adjacent vertebrae. However, external threading compromises the strength of the implant. In addition, a threaded bone implant tends to extend from the prepared bone in the opposite direction.

Therefore, there is a need for improved intermediate spliced implants that are closer to the ideal spinal spliced implant.

SUMMARY OF THE INVENTION

Thus, the basis of this technical solution is the task of creating an intervertebral prosthesis. This prosthesis is an implantable element (preferably a bone), having the necessary dimensions for placement in the intervertebral space formed between adjacent vertebrae, and having at least the first and second longitudinal sections with the corresponding first and second cross-sectional dimensions. The first cross-sectional dimension of the first implant section is larger than the second cross-sectional size of the second implant section, thereby forming a stepped region having a locking surface. Therefore, after placing the implantable element in the receiving bed of the appropriate size, formed in adjacent vertebrae, the locking surface facilitates fixing in it due to the corresponding contact interaction with the surfaces of the receiving bed.

The implantable element preferably has a circular cross section, wherein the diameter of the second longitudinal section is from about 50 to about 95% of the diameter of the first longitudinal section. A single-stage implant is preferred, but a multi-stage option is also possible. The implantable element may also form an internal cavity to accommodate bone growth material. At least one opening may extend through the outer wall of the implantable member to provide communication with the bone growth promoting material located within the cavity to facilitate the fusion process.

A method for splicing adjacent vertebrae using the proposed prosthesis is also proposed.

Brief Description of the Drawings

The invention is further explained in the description of the preferred embodiments with reference to the accompanying drawings, in which FIG. 1 is a front elevational view of a stepped bone spliced implant according to the invention;

FIG. 2 is a general rear view of the spliced implant of FIG. one ;

FIG. 3 is a general view of the proposed implant cutting tool of FIG. 12;

FIG. 4 is a side cross-sectional view of the implant cutting tool of FIG. 3;

FIG. 5 is a sectional view of an implant cutting tool taken along line 5-5 of FIG. 4;

FIG. 6 is a perspective view with torn parts of an alternative embodiment of the implant cutting tool of FIG. 3;

FIG. 7 is a side cross-sectional view of the implant cutting instrument of FIG. 6;

FIG. 8 is a sectional view of an implant cutting tool taken along line 8-8 of FIG. 7;

FIG. 9 is a general view of the part of the cutting tool remote from the center with the implant cutting tool mounted on it, shown in FIG. 3-5;

FIG. 1 0 is a side view of a cutting tool with an implant cutting tool shown in cross section, illustrating the positioning of the tool near the bone mass with the penetration of the guide drill of the tool into the mass;

FIG. 11 is a view similar to that of FIG. 1 0, illustrating the penetration of a cylindrical knife of an implant cutting tool into bone mass;

FIG. 1 2 is a side view of a cutting tool with the removed parts of an implant cutting tool, illustrating a fully extended cylindrical knife for forming a stepwise spliced implant;

FIG. 1 3 is a view similar to that of FIG. 1 2 illustrating the removal of an implant cutting instrument with a stepwise spliced implant formed from bone mass;

FIG. 1 4 is a General view of a part of the spinal column, illustrating the receiving bed for the implant, formed in adjacent calls for receiving a stepwise spliced implant;

FIG. 15 is a view illustrating a lumbar expander mounted on adjacent vertebrae for diluting the vertebrae in order to facilitate the placement of a fused implant;

FIG. 16 is a view similar to that of FIG. 15 illustrating adjacent vertebrae diluted with a lumbar dilator;

FIG. 17 is a view illustrating the placement of a fused implant between the dilated vertebrae in the receiving bed for the implant;

FIG. 18 is a view illustrating a spliced implant installed in an implant receiving bed;

FIG. 19 is a sectional view of the spinal column illustrating the placement of two fused implants in the spinal column through posterior access;

FIG. 19A is a sectional view of the spinal column illustrating the placement of two fused implants in the spinal column through anterior access;

FIG. 20-25 are general views of alternative spliced implant embodiments of FIG. 12;

FIG. 26 is a perspective view of an alternative spliced implant in the form of a metal insert;

FIG. 27 is a cross-sectional view of a spliced implant in the form of a metal insert along line 27-27 of FIG. 26;

FIG. 28-29 are side and top views of another alternative embodiment of a spliced implant having a wedge-shaped shape; and FIG. 30 is a perspective view of the spliced implant shown in FIG. 28-29.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION The proposed interstitial spliced device for the spine is intended to be placed between adjacent vertebrae in order to correct the attenuating degeneration of the structure of the spine. In humans, this device can be used mainly in the lumbar spine, however, it can also be adapted for use in the thoracic and cervical regions. Being installed in place, the device maintains and maintains an appropriate distance between the vertebrae and causes the formation of bone tissue and its integration into a single whole with the device. Consequently, the intervertebral space is filled with its own bone tissue and forms a single rigid bone joint between adjacent vertebrae.

Next, a proposed spliced implant will be described with reference to FIG. 1-2. The implant 1 0 is an elongated body 12 made of cortical and / or cancellous bone. This bone may be of autogenous, allogeneic, or xenogenic origin and is preferably extracted from the humerus, tibia, femur and the like, as is known to those skilled in the art. As can be seen in the drawing, the elongated body 1 2 forms a longitudinal axis a and consists of the first and second longitudinal sections 14 and 16, respectively. The first and second longitudinal sections 14 and 16 are preferably cylindrical in shape and arranged concentrically along the longitudinal axis a.

The cross-sectional size of the first longitudinal section 1 4 is larger than the cross-sectional size of the second longitudinal section 1 6, as a result of which a step region 1 8 is formed at the junction of the two sections 1 4 and 1 6. As will be clear from the following description, the step region 1 8 forms a stop surface 20, which facilitates fixation of the fused implant 10 between adjacent vertebrae, for example, in a specially prepared bed created in adjacent vertebrae, and thereby ensures that the implant 10 does not move during treatment. In a preferred embodiment, the first longitudinal section 1 4 has a diameter of about 8 to 20 millimeters (mm), preferably 1 2 to 1 6 mm. The second longitudinal section 1 6 has a diameter of preferably 2 mm less than the diameter of the first section 1 4. The length of the elongated body 1 2 is about 10-35 mm, preferably about 15-30 mm.

In a preferred embodiment, the second section 1 6 has a higher density than the first part 14. Therefore, a smaller diameter of the second part 1 6 will not jeopardize the overall strength of the implant 1 0. A higher density of the second part 1 6 is achieved during the selection and formation of the implant. As will be explained in more detail below, when removing the implant from the tibia (for example, in the case of spongy inserts), the second section 1 6 is removed from the harder and denser proximal cartilage, and the first section 1 4 from the cancellous bone.

In FIG. 3-5, the proposed implant cutting tool for forming a step implant 10 according to the invention is illustrated. The implant cutting tool 1 00 is adapted to be mounted in a conventional rotary drill, as will be described below. The implant cutting tool 1 00 comprises an outer hollow drilling portion 1 02 with cutting teeth 1 04 and an inner hollow drilling portion 106 with cutting teeth 108. Typically, the outer drilling portion 1 02 is used to form the first longitudinal section 14 of the implant 10, and the inner drilling portion 106 - to form a second longitudinal section 16. The inner drilling portion 106 is located closer to the outer drilling portion 102, so that the teeth 108 of the inner drilling portion protrude to the inner Tenke drilled outer portion 102, as shown in FIG. 4-5.

As best seen in FIG. 5, the implant cutting tool 1 00 comprises a closely spaced inner threaded portion 110 that is articulated with a suitable drill design so that tool 1 00 can be mounted on the implant cutting drills. The implant cutting instrument 100 also includes a proximal flange 112 to facilitate handling of the instrument and its installation on drills.

In FIG. 6-8 show an alternative embodiment of the implant cutting tool of FIG. 3-5. The implant cutter tool 1 20 is similar to the tool 1 00, but has an internal drill part 1 22 with two diametrically opposed axial teeth 124. The diametrically opposed teeth 1 24 have transverse cutting edges 1 26 that cut the bone to form a second longitudinal section 16 of the implant. In all other respects, the implant cutting tool 200 is identical to the tool shown in FIG. 3-5.

In FIG. 9 shows an implant cutting tool 100 shown in FIG. 3-5, which is mounted at the far end of a conventional surgical drill 1,000 with a cannula. An implant cutting tool 1 00 is shown mounted with a fastener assembly 200, which is used to install an implant cutting tool 1 00 on drills 1000. This fastener assembly is disclosed in US Patent Application 08/404255, filed March 15, 1995, which is mentioned here for information. The fastening or cutting unit 200 described in the aforementioned application 08/404255 consists of a fastening element 202, a thrust rod 204 (Fig. 10) and a threaded clamping element 206. The fastening element 202 has a proximal end, the shape of which allows it to be installed in the drill cartridge 1 000 and a distal threaded shank 208 that is screwed into the internal thread 110 of the implant cutting tool 1 00 shown in FIG. 1 0, for installing the tool 1 00. The thrust rod 204 passes through an axial channel located in the fastening element 202, and passes towards the drill through the corresponding channel of the tool (as shown by the through image in Fig. 1 0) and from the drill through the tool 1 00 for implant excision. The abutment shaft 204 has a guide drill 210 provided at its distal end, which forms a control hole that helps guide the implant cutting tool 1 00 into the bone mass. The threaded clamping element 206 passes through the fastening element 202 and serves to selectively fix the thrust rod 204 in the desired longitudinal positions relative to the fastening element 202. Further information about the fastening unit 200 can be found in the application '255.

Bone implant formation

Now, the formation of a bone implant 1 0 will be described using a tool 10 00 for cutting an implant in conjunction with a mounting unit 200 and a drill 1 000 with a cannula.

In FIG. 1 0-1 3 successively illustrates a preferred method for forming the bone spliced implant 1 0 shown in FIG. 1-3. First, as shown in FIG. 9, an implant cutting tool 100 is mounted using a mounting assembly 200 on a drill 1000, as described above. As seen in FIG. 1 0, after pressing the threaded clamping element 206 of the fastening assembly against the abutment shaft 204, the guide drill 210 is inserted into the bone mass b to form a control hole, as shown in the drawing. Bone mass L may be a tibia or iliac crest. A drill 1 000 is then actuated to transmit rotational movement to the implant cutter 1 00. The tool 100 is advanced into the bone mass b so that the cutting edge 1 04 of the outer drilling part 1 02 penetrates the bone mass b. After penetration of the cutting edge 104 into the bone mass b (as shown in FIG. 11), the drill 1000 is turned off. The threaded pressure member 206 is loosened to release the thrust rod 204 and thereby allow it to slide toward the center as the implant is formed, i.e. as the implant cutting tool 1 00 advances into the bone mass b.

In FIG. The 1 2 000 drill is again powered and continues to move the 1 00 tool for cutting the implant into the bone mass b. As you move forward, the cutting teeth 1 04 of the outer drill part 1 02 cut a column or cut the bone mass b, forming the first longitudinal section 14 of the implant. Further extension of the implant cutting tool 1 00 causes the cutting teeth 1 04 of the inner drilling part 1 08 to cut out the column or to cut the bone material received in the implant cutter 1 00, forming a second longitudinal section 1 6 of the implant. The implant excision tool 1 00 advances into the bone mass b until the flange of the implant excision instrument 100 abuts against the bone mass b. When drilling the tibia to the lowest implant 10, the external drilling portion 102 cuts out the column of the lower cancellous bone, forming a less dense first longitudinal section 14 of the implant, while the internal drilling section 108 cuts out the column of a denser cartilage to form a denser second longitudinal parts 16 of the implant 10.

After the bone implant 1 0 is fully formed, the 1,000 drill is turned off. The threaded clamping element 206 is again tightened on the abutment shaft 204, and the implant cutting tool 1 00 with the formed implant therein is removed from the bone mass b, as shown in FIG. 13. Thereafter, the bone implant 1 0 is removed from the implant cutting tool 1 00 by loosening the threaded pressure member 206 and moving the thrust rod 204 to the distal end to eject the implant 10 from the tool 100. In some cases, the bone implant cannot be removed from the tool 100. Then it can be removed by cross cutting using a standard reciprocating saw or other cutting device.

Spinal Fusion Procedure

Now, a process for setting up a spliced implant through posterior access for a lumbar incision and spinal fusion will be described. It is clear that other operative approaches can be used, for example, anterior, posterolateral, etc. to perform incision and implant placement 1 00.

First, they approach the spinal column through posterior access using appropriate retractors to remove adjacent muscle tissue, blood vessels and / or nerve tissue. After that, at least part of the degenerated disc is removed with the appropriate bone nippers or cutting tools. As shown in FIG. 14, the receiving bed g is formed, corresponding in shape to the fused implant 10, in opposite surfaces of adjacent vertebrae ν ₁ , ν ₂ . The receiving bed g can be prepared by drilling or opening with a chisel. These methods are well known in the field of surgery. The prepared sites should preferably be of sufficient size to extend to the central soft spongy bone material, including also the hard cortical bone of adjacent vertebrae VI, ν ₂ .

As shown in FIG. 15, a retractor c is installed on the front surfaces of the vertebrae VI and ν ₂ . One of the suitable retractors for this purpose may be a retractor of the brand Сlо \\ agb btbag baaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaay The retractor c has two levers that can be mounted on the posterior surfaces of the vertebrae with screws, as shown in the drawing. After the retractor has been properly installed, its levers move apart in order to part the adjacent vertebrae, as shown in FIG. 1 6, and to provide an appropriate clearance for introducing the spliced implant 100 into the receiving bed g. After that, the splicing implant 1 00 is inserted into the expanded space using appropriate tools (not shown), where it enters the receiving bed g, as shown in FIG. 17. After appropriate positioning of the fused implant 10 in the receiving bed, the retractor c is removed in order to return the adjacent vertebrae VI, ν ₂ to the normal position.

As shown in FIG. 18, the fused implant 1 0 forms a spacer supporting and maintaining adjacent vertebrae ν ₁ , ν ₂ in a desired remote relative position. The optimal dimensions of the fused implant 1 00 are determined in practice, in part, by the size of the receiving bed g between adjacent vertebrae. The stepped region 18, formed at the junction of the first and second longitudinal sections 1 4, 1 6, prevents the backward extension or displacement of the installed implant due to the contact of the holding surface 20 with the surfaces 5 of the vertebrae formed by the receiving bed. Thus, the fused implant 10 is permanently fixed in the intervertebral space. As shown in the drawing, the second section 1 6 of the implant 1 0, having a smaller diameter, allows you to place it between the end plates of the vertebra. As noted above, the second section 1 6 of the implant is relatively dense, which provides adequate rigidity to support the vertebrae. Over time, the bodies of adjacent vertebrae grow into the implant 1 0, growing together with it into a continuous connection. In FIG. 19 shows two fused implants 10 located in the intervertebral space.

In FIG. 19A shows two fused implants 10 located in the intervertebral space using conventional anterior access. It is understood that anterior access can be easily used to position implants 10.

Alternative embodiments of the invention

In FIG. 20-25, alternative embodiments of a stepwise spliced implant according to the present invention are illustrated. The spliced implant 40 of FIG. 20 has a multi-stage shape formed by a plurality of alternating sections 42, 44 with different cross-sectional sizes. In particular, the implant section 42 has a first diameter that is smaller than the diameter of the second implant section 44. The junction of the first and second sections 42, 44 form stepped areas with retaining surfaces 46, which are in contact with the corresponding structure formed by the receiving bed in adjacent vertebrae. In FIG. 21 shows another multi-stage implant 50, in which sections 52, 54, 56, 58 have a successively increasing cross-sectional size from one end of the implant to the other end so that a plurality of locking surfaces 53, 55, 57 are formed. In FIG. 22 shows a single-stage splicable implant 60 similar to the implant of FIG. 1-3. However, in this constructive solution, the leading end will be the smaller section 62, i.e., when ν ₁ , ν _{2 is} inserted into adjacent vertebrae, the implant section with a smaller diameter will be introduced into the intervertebral space first, and the larger section 64 will follow it. The implant sections 62, 64 form a locking surface 66. In FIG. 23 shows another design, in which the implant has many steps with sections 72, 74, 76 located eccentrically relative to the axis a of the body of the implant.

In FIG. 24-25 shows another structural embodiment of the proposed spliced implant. This implant 80 is similar to the implant of FIG. 1-3, but contains an internal channel or cavity 82 for accommodating bone-causing materials 8. The outer wall of the implant 80 contains many holes 84 that communicate with the internal channel 82. When the implant is placed in the intervertebral space, the bone passes through the outer surface of the chamber into the internal cavity 82 and comes into contact with the material ₈ therein, causing bone growth. Materials that cause bone growth can be taken from the iliac crest, as is known in the field of surgery. One form of bone growth promoting material that can be used in conjunction with the proposed spliced implant is disclosed in co-assigned US patent application 08/191624, filed February 4, 1994, which is hereby incorporated by reference. The bone growth promoting materials disclosed in the '624 application include a flowable composition of osteogenic bone powder adjusted to the desired size in a flowable, biocompatible carrier.

In FIG. 26-27, another embodiment of the present invention is illustrated. The implant 90 is made of a metal material, such as titanium, its alloy or surgical steel. Alternatively, the implant 90 may be made of ceramic or a suitable rigid polymer material, or, as another alternative, bone, as described above. The shape of the implant 90 is similar to the shape of the implant 1 0 in FIG. 1 -2, but it additionally contains many alternating annular grooves and ribs 92, 94 with a stepped region 95. The grooves and ribs 92, 94 facilitate fixation in the intervertebral space by increasing the contact area of the surface of the implant 90 with the vertebral bodies.

In FIG. 28-29 illustrate side and top views, respectively, of another alternative embodiment of a spliced implant. In FIG. 30 shows a general view of an alternative embodiment. The implant 96 is almost wedge-shaped and consists of the first and second sections 97, 98 and stepped areas 99 formed at the junction of the longitudinal sections. The stepped regions 99 are preferably formed by removing the opposed peripheral parts 99a (shown by dashed lines) of the second section 98. It is also possible to form only one stepped region 99 instead of the two shown. The implant 96 is inserted into a canal of appropriate size, made in adjacent vertebrae, so that the stepped areas 99 are in contact with the surface of the vertebrae formed by a preformed receiving bed, similar to that described in connection with the embodiment shown in FIG. 12.

It is clear that various modifications of the above-described constructive embodiments of the invention can be made without going beyond the scope of the claims. The above description is not restrictive, it only gives examples of preferred embodiments of the invention. Specialists will be able to offer other modifications within the scope of the claims defined in the attached claims.

Claims (19)

CLAIM 1. The intervertebral prosthesis, which is a monolithic implantable element made of bone and having the necessary dimensions for placement in the intervertebral space formed between adjacent vertebrae, wherein the implantable element forms a longitudinal axis and contains at least the first and second longitudinal sections with the corresponding first and a second cross-sectional dimension, wherein the first cross-sectional dimension is larger than the second cross-sectional dimension, so that a stop surface is implanted ith element, which, after placing the implantable element between the vertebrae, facilitates its fixation in this place due to the corresponding contact with the surfaces of adjacent vertebrae. 2. The intervertebral prosthesis according to claim 1, in which the implantable element has an almost circular cross section. 3. The intervertebral prosthesis according to claim 2, in which the diameter of the second longitudinal section is from about 50 to about 95% of the diameter of the first longitudinal section. 4. The intervertebral prosthesis according to claim 1, in which the implantable element is almost wedge-shaped. 5. The intervertebral prosthesis according to claim 1, in which the implantable element forms one stepped region. 6. The intervertebral prosthesis according to claim 1, wherein the implantable element forms a plurality of stepped areas. 7. The intervertebral prosthesis according to claim 1, in which the implantable element is a bone transplanted implant. 8. The intervertebral prosthesis according to claim 1, in which the implantable element contains a trabecular bone or cortical bone. 9. The intervertebral prosthesis according to claim 1, in which the implantable element forms an internal cavity for placement of material that causes bone growth. 10. The intervertebral prosthesis according to claim 9, which contains material that causes bone growth located in the internal hollow cavity, which includes bone growth factors, glycerin, demineralized bone matrix (DMC), bone marrow, bone morphogenetic protein (MBK- 4). 11. The intervertebral prosthesis according to claim 9, in which the implantable element has at least one opening passing through the outer surface and communicating with the bone growth promoting material located in the hollow cavity. 1 2. An intervertebral prosthesis, which is a monolithic implantable element made of biologically compatible bone material, which has the required dimensions for placement between adjacent vertebrae, the implantable element includes the first and second practically cylindrical sections, the diameter of the first cylindrical section is larger than the diameter of the second cylindrical section, positioning, the junction of the first and second cylindrical sections forms a locking protrusion, which, after placing the implantable element between adjacent vertebrae ami prevents its displacement relative to the vertebrae thereby facilitating its fixation in place. 13. The intervertebral prosthesis according to item 12, in which the first and second cylindrical sections are concentric along the longitudinal axis of the implantable element. 14. The intervertebral prosthesis according to claim 12, in which the implantable element has a non-threaded outer surface. 15. The intervertebral prosthesis according to item 12, in which the implantable element has many annular grooves made on part of its outer surface. 16. The intervertebral prosthesis according to item 13, in which the implantable element forms the front and rear ends, while the first cylindrical section is located near the front end. 17. The intervertebral prosthesis of claim 12, wherein the implantable element contains a cortical bone. 18. The intervertebral prosthesis of claim 12, wherein the implantable element comprises a trabecular bone. 19. The vertebral intermediate spliced device, which is a solid, monolithic, bone, transplantable implantable element made of bone and having the necessary dimensions to cover the intervertebral space between adjacent vertebrae, the implantable element has a non-threaded outer surface and the first and second longitudinal sections with the corresponding the first and second dimensions of the cross section, the junction of the first and second longitudinal sections forms a locking surface that facilitates fixation an implantable element in the intervertebral space due to joint contact with the corresponding surfaces of adjacent vertebrae.