End member for a bone fusion implant
An end member for use with a bone fusion implant is disclosed. The end member has a first portion, a second portion, and a shoulder connecting the two portions. The second portion is sized to fit within the interior of the bone fusion implant in such a fashion that the shoulder rests on the edge of the implant. The top surface of the first portion has at least one slot to receive a surgical instrument such as an inserter and/or distractor to facilitate implantation of the end member and bone fusion implant. The top surface may also have teeth to provide initial mechanical stability between the bone and end plate and promote bone fusion.
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This application is a continuation application of U.S. patent application Ser. No. 09/497,123 filed Feb. 3, 2000, from which priority of Provisional Application no. 60/118,806 filed on Feb. 4, 1999 is claimed under 35 U.S.C. § 119(e), both of which are incorporated by reference herein in their entirety.
FIELD OF THE INVENTIONThe present invention relates to a device for bone fusion, and in particular to an end member for a bone fusion implant.
BACKGROUND OF THE INVENTIONThe treatment and management of bone defects remains one of the most challenging aspects of orthopaedics. Bone defects occur in a wide variety of clinical situations. Restoring natural anatomical length and shape of any long bone with a bone defect is problematic. Additionally, whenever a vertebra has to be removed, it is necessary to insert a vertebral spacer to restore the natural length and curvature of the spine as well as to promote bone fusion. Restoring spinal anatomy and stability and promoting bone fusion are even more difficult in a corpectomy, a surgical procedure in which a section of one or several vertebrae is removed.
Many different implants have been developed for use with bone defects. So-called “mesh implants” have shown to be particularly effective. One such implant is the SynMesh™ available from Synthes (USA) of Paoli, Pa. The SynMesh™ is a titanium mesh cylinder which is provided with a plurality of uniformly-spaced apertures of uniform size distributed on its surface. In order to address the different clinical situations in which bone defects arise, the SynMesh™ is available in a variety of lengths and diameters. Commercially available allografts for treating-bone defects have recently become available.
Although the clinical results of mesh and allograft implants have generally been positive, one possible clinical complication is subsidence of the implant. Excessive sinking of the ends of the implant into the bone with which they contact is especially troublesome whenever the bone is extremely porous. From both a mechanical and physiological point-of-view, it would also be advantageous to increase the surface contact area between the implant and bone. U.S. Pat. No. 5,702,451 to Biedermann et al. discloses end rings that attempt to address these concerns. However, the end rings disclosed have no provisions for holding, insertion, and distraction instruments. Thus, implantation can be difficult. Furthermore, there can be excessive movement between the bone and the disclosed end rings after implantation. This may delay, and perhaps prevent bone fusion.
As the discussion above illustrates, there is a need for an improved end member for use with a bone fusion implant.
SUMMARY OF THE INVENTIONThe present invention relates to an end member for use with a bone fusion implant for fusing portions of bone. The end member has a first portion, a second portion sized to be inserted into the bore of the implant, and a shoulder between the first and second portions. When the second portion is inserted into the bore, the shoulder rests on an edge of the implant. The top surface of the first portion conforms in size and shape with the bone and has a channel or multiple channels for receiving a surgical instrument. When multiple channels are present, all the channels can run in the same direction, (e.g. the channels run in the anterolateral direction), or the channels can run in different directions, (e.g. a first channel runs in the anterior-posterior direction and a second channel runs in the lateral direction).
If the implant is made of metal, the end member is made of the same material in order to resist corrosion. The end member may also be made of allograft bone. The end member may have a wedge-shaped or spherical profile to restore the natural curvature of bone or to correct for a non-orthogonal osteotomy. One way to create the wedge-shaped profile is to have the first end of the first portion to be thicker than the second end.
The top surface can be made in any suitable cross-sectional shape, such as oval, oblong, or round, and may be annular or solid. The top surface can be a flat planar surface or can have a curvature that mimics the topography of the bone. The top surface may be provided with teeth or textured for interlocking with the bone. The teeth may have a pyramid or saw tooth shape.
In order to secure the end member to the implant, the second portion may have a hole for receiving a fastener. Alternatively, the exterior surface of the second portion may have protuberances that are sized to fit within the apertures of the implant. In an exemplary embodiment, the second portion comprises a plurality of tabs to secure the end member to the implant. These tabs may be resilient so that the tabs flex inward upon insertion of the second portion into the implant and flex back outward to create a friction fit that secures the end member to the implant. In another embodiment, the end member includes a projection hinged or pivotably connected to the first portion, a threaded bore in the second portion, and a set screw insertable into the threaded bore. Threading the set screw into the bore causes outward movement of the projection to thereby secure the end member to the implant.
In an alternative embodiment, an end member according to the present invention includes a top surface conforming in size and shape with the bone and a sleeve extending from the top surface and configured and dimensioned to receive an end of the implant. The end member further comprises first and second portions pivotable between and open position to facilitate receiving the end of the implant by the sleeve and a closed position to secure the end member to the implant. A locking element fixes the end member in the closed position.
In another alternative embodiment, the end member includes an outer ring having a prong with a ramped surface and an inner ring rotatable with respect to the outer ring. The inner ring has a protrusion which contacts the ramped surface of the prong upon rotation to thereby urge the prong radially outward.
BRIEF DESCRIPTION OF THE DRAWINGSPreferred features of the present invention are disclosed in the accompanying drawings, wherein similar reference characters denote similar elements throughout the several views, and wherein:
Second portion 14 is also shown having a round shape. As was the case for top surface 18, second portion 14 can have any suitable shape. Preferably, the shape of second portion 14 matches the shape of the bone fusion implant used with the end member. As best seen in
Referring back to
For each of the end members shown in
As seen in
As previously discussed,
While various descriptions of the present invention are described above, it should be understood that the various features can be used singly or in any combination thereof. Therefore, this invention is not to be limited to only the specifically preferred embodiments depicted herein.
Further, it should be understood that variations and modifications within the spirit and scope of the invention may occur to those skilled in the art to which the invention pertains. Accordingly, all expedient modifications readily attainable by one versed in the art from the disclosure set forth herein that are within the scope and spirit of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is accordingly defined as set forth in the appended claims.
Claims
1. An end member for use with an implant for fusing bone comprising:
- a first portion having a first top surface having a plurality of teeth and a first channel;
- wherein at least a portion of the plurality of teeth have a base located at the first top surface;
- wherein the first channel is at least partially located at a depressed location relative to at least a portion of the first top surface;
- a second portion configured and dimensioned to be inserted into a bore of the implant; and
- a shoulder joining the first and second portions and sized to rest on an edge of the implant when the second portion is inserted in the bore of the implant.
2. The end member of claim 1, wherein the first portion further comprises a second channel.
3. The end member of claim 2, wherein the first channel and the second channel are substantially perpendicular to each other.
4. The end member of claim 1, wherein the first portion has a substantially wedge-shaped profile.
5. The end member of claim 1, wherein the first portion further comprises a second top surface, and wherein the first top surface and the second top surface are at least partially separated by the first channel.
6. The end member of claim 1 wherein the first portion is substantially circular.
7. The end member of claim 1, wherein the first portion is substantially oval-shaped.
8. An end member for use with an implant for fusing bone comprising:
- a first portion having a first top surface adapted and configured to engage a bone surface, an outer perimeter edge, an inner perimeter edge defining a central opening, and at least a first channel;
- wherein the first channel extends from a first point on the outer perimeter edge to a second point on the outer perimeter edge such that the first channel divides the first portion into two substantially identical portions;
- wherein the width of the first channel at the first point on the outer perimeter edge is substantially equal to the width at the second point on the outer perimeter edge;
- a second portion configured and dimensioned to be inserted into a bore of the implant; and
- a shoulder joining the first and second portions and sized to rest on an edge of the implant when the second portion is inserted in the bore of the implant.
9. The end member of claim 8, wherein the first top surface comprises a plurality of teeth.
10. The end member of claim 8, wherein the first portion further comprises a second channel.
11. The end member of claim 10, wherein the first channel and the second channel are substantially perpendicular to each other.
12. The end member of claim 8, wherein the first portion has a substantially wedge-shaped profile.
13. The end member of claim 8, wherein the first portion further comprises a second top surface, and wherein the first top surface and the second top surface are at least partially separated by the first channel.
14. The end member of claim 8, wherein the first portion is substantially circular.
15. The end member of claim 8, wherein the first portion is substantially oval-shaped.
16. An end member for use with an implant for fusing bone comprising:
- a first portion having a first top surface adapted and configured to engage a bone surface, a continuous outer perimeter edge, a continuous inner perimeter edge defining a central opening, and a first channel extending from a first point on the outer perimeter edge to a second point on the outer perimeter edge;
- a second portion configured and dimensioned to be inserted into a bore of the implant; and
- a shoulder joining the first and second portions and sized to rest on an edge of the implant when the second portion is inserted in the bore of the implant.
17. The end member of claim 16, wherein the first portion further comprises a second channel.
18. The end member of claim 17, wherein the first channel and the second channel are substantially perpendicular to each other.
19. The end member of claim 16, wherein the first portion has a substantially wedge-shaped profile.
20. The end member of claim 16, wherein the first portion further comprises a second top surface, and wherein the first top surface and the second top surface are at least partially separated by the first channel.
21. The end member of claim 16, wherein the first portion is substantially circular.
22. The end member of claim 16, wherein the first portion is substantially oval-shaped.
23. The end member of claim 16, wherein the first top surface comprises a plurality of teeth.
Type: Application
Filed: Jun 8, 2005
Publication Date: Oct 27, 2005
Applicant:
Inventors: Dominique Messerli (West Chester, PA), David Paul (Phoenixville, PA)
Application Number: 11/149,093