System and Method for Joint Resurface Repair

• US 20080172125A1
• Filed: 02/06/2008
• Published: 07/17/2008
• Est. Priority Date: 05/01/2000
• Status: Active Grant

• Current Assignee: Arthrosurface, Inc (Anika Therapeutics Incorporated)
• Original Assignee: Arthrosurface, Inc (Anika Therapeutics Incorporated)
• Inventors: Ek, Steven W.
• Granted Patent: US 8,177,841 B2
• Time in Patent Office: Days
• US Class Current: 623/14.12
• CPC Class Codes: A61B 17/1635 for grafts, harvesting or transplants
• CPC Class Codes: A61B 17/1764 for the knee
• CPC Class Codes: A61F 2/30756 Cartilage endoprostheses A61F2/3603 takes precedence
• CPC Class Codes: A61F 2/30942 for designing or making customized prostheses, e.g. using templates, CT or NMR scans, finite-element analysis or CAD-CAM techniques
• CPC Class Codes: A61F 2/3859 Femoral components
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• CPC Class Codes: A61F 2002/30112 Rounded shapes, e.g. with rounded corners
• CPC Class Codes: A61F 2002/30116 partial circles, i.e. circular segments
• CPC Class Codes: A61F 2002/30607 Kits of prosthetic parts to be assembled in various combinations for forming different prostheses
• CPC Class Codes: A61F 2002/3085 with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface
• CPC Class Codes: A61F 2002/30878 with non-sharp protrusions, for instance contacting the bone for anchoring, e.g. keels, pegs, pins, posts, shanks, stems, struts
• CPC Class Codes: A61F 2002/3895 unicompartimental
• CPC Class Codes: A61F 2002/4658 for measuring dimensions, e.g. length
• CPC Class Codes: A61F 2002/4663 for measuring volumes or other three-dimensional shapes
• CPC Class Codes: A61F 2230/0004 Rounded shapes, e.g. with rounded corners
• CPC Class Codes: A61F 2230/0006 circular
• CPC Class Codes: A61F 2250/0062 Kits of prosthetic parts to be assembled in various combinations for forming different prostheses

Abstract

An implant comprising a first, second, and third segment wherein the second and third segments partially overlap the first segment and define a load bearing surface comprising an anterior-posterior (AP) curvature including at least two tangential curves of the portion of the articular surface of the femoral condyle, the tangential curves having different radii of curvature. A drill guide comprises a body portion including a first, second and third bushing spaced along the body portion to establish a first, second and third axes, respectively. Each axis may be substantially normal to the articular surface at three different points along a curvature of the articular surface comprising the two tangential curves. A measuring device comprises a housing defining a longitudinally passageway and an outrigger. A guide pin may be received in the longitudinal passageway and a measuring device determines how far the guide pin is in the passageway.

Claims

1. An implant for replacing a portion of an articular surface of a femoral condyle comprising:

first, second, and third segments, wherein said second and said third segments partially overlap said first segment on opposing ends of said first segment, said first, said second, and said third segments comprise a bone contacting surface and a load bearing surface, said load bearing surface comprising an anterior-posterior (AP) curvature and a medial lateral (ML) curvature, wherein said AP curvature comprises at least two tangential curves of said portion of said articular surface of said femoral condyle, said tangential curves having different radii of curvature.

2. The implant of claim 1, wherein said first, said second, and said third segments each comprise a truncated, generally circular shape.

3. The implant of claim 2, wherein said first, said second, and said third segments each comprise a generally circular shape truncated along said AP curvature of said implant.

4. The implant of claim 2, wherein said first, said second, and said third segments each comprise a generally circular shape truncated along said ML curvature of said implant.

5. The implant of claim 1, wherein said bone contacting surface comprises at least one mounting feature configured to secure said implant to said femoral condyle.

6. The implant of claim 5, wherein said at least one mounting feature is configured to securely engage with a mounting screw.

7. The implant of claim 6, wherein said at least one mounting feature includes an opening configured to engage with a post of said mounting screw.

8. The implant of claim 2, wherein said first, said second, and said third truncated, generally circular segments comprise first, second, and third axes extending through respective centers of said segments, respectively, wherein said first axis is substantially normal to said portion of said articular surface.

9. The implant of claim 8, wherein said second and said third axes are substantially normal to said portion of said articular surface.

10. The implant of claim 9, wherein a first angle α

₁ between said first axis and said second axis and a second angle β

₁ between said first axis and said third axis are substantially symmetrical.

11. A method of forming an implant for replacing a portion of an articular surface extending across at least two tangential curves of a femoral condyle, said tangential curves having different radii of curvature, said method comprising:

establishing a reference axis extending substantially normal to a point of origin on said portion of said articular surface;

establishing a reference plane that is parallel to a tangential plane extending through said point of origin on said articular surface;

measuring a first distance between said reference plane and a first point on said articular surface at a distance R1 along an anterior-posterior (AP) curvature of said portion of said articular surface from said reference axis;

measuring a second distance between said reference plane and a second point on said articular surface at a distance R2 along said AP curvature of said portion of said articular surface from said reference axis, wherein R1 is less than R2; and

providing an implant body having a load bearing surface, said load bearing surface comprising a first curvature approximating said at least two tangential curves of said portion of said articular surface based on said first and said second distances.

12. The method of claim 11, further comprising providing an implant comprising a first, second, and third segment, wherein said second and said third segments partially overlap said first segment on opposing ends of said first segment, said first, said second, and said third segments comprise said bone contacting surface and a load bearing surface.

13. The method of claim 12, wherein said first, said second, and said third segments comprise a first, a second, and a third axis extending through a center of a respective one of said segments, respectively, and wherein a first angle α

₁ between said first axis and said second axis and a second angle β

₁ between said first axis and said third axis are substantially symmetrical.

14. The method of claim 11, further comprising:

measuring at least two distances between said reference plane and a third and fourth point on said articular surface at a distance along a medial-lateral (ML) curvature of said portion of said articular surface from said reference axis; and

providing said load bearing surface comprising a second curvature approximating said ML curvature of said portion of said articular surface.

15. The method of claim 11, wherein said first curvature approximating said at least two tangential and different curves of said articular surface is determined based on only said first and said second distances taken at distances R1 and R2, respectively, from the reference axis.

16. The method of claim 11, comprising measuring two points at a distance R2 along said AP curvature of said portion of said articular surface from said reference axis, wherein one of said two points is taken at a point anterior from said reference axis and said other said two points is taken at a point posterior from said reference axis.

17. A drill guide for establishing a plurality of axes in an articular surface, said drill guide comprising:

a body portion comprising a generally arcuate shaped interior surface, wherein at least a portion of said interior surface is configured to be disposed on at least a portion of said articular surface; and

first, second and third bushings spaced along a length of said body portion and configured to establish first, second and third axes, respectively, wherein each of said first, said second and said third axes are configured to be substantially normal to said articular surface at three different points, respectively, along a curvature of said articular surface comprising at least two tangential curves, said tangential curves having different radii of curvature.

18. The drill guide of claim 17, wherein at least one of said first, said second and said third bushings are removably coupled to said body portion.

19. The drill guide of claim 17, wherein said second bushing is disposed along said body portion between said first and said third bushings, and wherein a first angle α

between said first axis and said second axis and a second angle β

between said second axis and said third axis are substantially symmetrical.

20. The drill guide of claim 17, wherein said second bushing extends generally outwardly from said interior surface of said body portion.

21. The drill guide of claim 20, wherein said second bushing comprises an outer diameter substantially corresponding to a diameter of hole formed in said articular surface.

22. The drill guide of claim 20, wherein said first and said third bushings extend generally outwardly from an exterior surface of said body portion.

23. A device for measuring a portion of an articular surface of bone, said device comprising:

a housing defining a longitudinal passageway extending from an open distal end, said housing further comprising an outrigger extending generally outwardly proximate said distal end a predetermined distance Rr from a longitudinal axis of said longitudinal passageway;

a guide pin configured to be at least partially received in said longitudinal passageway of said housing; and

a measuring device configured to determine how far said guide pin is received in said passageway.

24. The device of claim 23, wherein said measuring device further comprises a guide window disposed on said housing, said guide window comprising a plurality of indicia representing said distance measurements.

25. The device of claim 24, wherein said a proximal end of said guide pin is configured to align with at least one of said plurality of indicia to determine said distance measurements.

26. The device of claim 23, wherein a distal end of said guide pin comprises threads configured to engage with said articular surface.

27. The device of claim 26, wherein a distal end of said guide pin further comprises a tap including at least one fluted region and at least one cutting edge, wherein said guide pin is self-tapping.

28. The device of claim 24, wherein said guide pin further comprises indicia disposed a predetermined distance from said distal-most end of said guide pin corresponding to an insertion depth of said guide pin into said articular surface.