Unicondylar knee implants and insertion methods therefor

• US 20080015599A1
• Filed: 06/21/2006
• Published: 01/17/2008
• Est. Priority Date: 06/21/2006
• Status: Active Grant

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Inventors: Collazo, Carlos E., D'Alessio, Jerry
• Granted Patent: US 7,678,115 B2
• Time in Patent Office: Days
• US Class Current: 606/79
• CPC Class Codes: A61B 17/155 Cutting femur
• CPC Class Codes: A61B 17/157 Cutting tibia
• CPC Class Codes: A61B 17/1764 for the knee
• CPC Class Codes: A61F 2/4684 Trial or dummy prostheses
• CPC Class Codes: A61F 2002/3895 unicompartimental

Abstract

A method of preparing a knee joint for receiving a unicondylar knee implant includes preparing a first seating surface at a proximal end of a tibia, and providing a combination bur template and spacer block, the bur template having an upper end, a lower end and a curved surface extending between the upper and lower ends thereof that is adapted to conform to a femoral condyle of a femur and the spacer block extending from the lower end of the bur template and having top and bottom surfaces. The method includes flexing the knee joint so that the prepared first seating surface at the proximal end of the tibia opposes a posterior region of the femoral condyle and inserting the combination bur template and spacer block into the knee joint so that the top surface of the spacer block engages the posterior region of the femoral condyle and the bottom surface of the spacer block engages the first seating surface at the proximal end of the tibia. While the spacer block is maintained between the femur and the tibia, the knee joint is extended until the curved surface of the bur template engages the femoral condyle of the femur. The bur template is anchored to the femur and used to guide burring of the femoral condyle for preparing a second seating surface on the femur. After burring the distal end of the femoral condyle, the posterior region of the femoral condyle is resected.

Claims

1. A method of preparing a knee joint for receiving a unicondylar knee implant comprising:

preparing a first seating surface at a proximal end of a tibia;

providing a combination bur template and spacer block, said bur template having an upper end, a lower end and a curved surface extending between the upper and lower ends thereof that is adapted to conform to a femoral condyle of a femur and said spacer block extending from the lower end of said bur template and having top and bottom surfaces;

flexing said knee joint so that said prepared first seating surface at the proximal end of said tibia opposes a posterior region of said femoral condyle;

inserting said combination bur template and spacer block into said knee joint so that the top surface of said spacer block engages the posterior region of said femoral condyle and the bottom surface of said spacer block engages the first seating surface at the proximal end of said tibia;

while maintaining said spacer block between said femur and said tibia, extending said knee joint until the curved surface of said bur template engages a distal region of said femoral condyle;

anchoring said bur template to the distal region of said femoral condyle and using said bur template to guide burring of the distal region of said femoral condyle for preparing a second seating surface on said femur;

after burring the distal region of said femoral condyle, resecting the posterior region of said femoral condyle.

2. The method as claimed in claim 1, wherein the preparing a first seating surface includes resecting the proximal end of said tibia.

3. The method as claimed in claim 1, wherein said bur template and said spacer block are integrally connected together.

4. The method as claimed in claim 1, wherein said bur template and said spacer block are permanently connected together.

5. The method as claimed in claim 4, wherein said bur template and said spacer block form a single, rigid element.

6. The method as claimed in claim 1, further comprising:

determining a distance between the first seating surface on said tibia and the posterior region of said femoral condyle;

selecting one of a plurality of combination bur template and spacer blocks for inserting into said knee joint, the selected one having a spacer block thickness that matches the determined distance between the first seating surface on said tibia and the posterior region of said femoral condyle.

7. The method as claimed in claim 1, wherein said combination bur template and spacer block includes an alignment feature formed in a trailing end of said spacer block, the method further comprising inserting an alignment rail of a posterior resection guide locator into the alignment feature formed in the trailing end of said spacer block.

8. The method as claimed in claim 7, said posterior resection guide locator includes at least one pin opening that overlies said alignment rail of said posterior resection locator guide, wherein said at least one pin opening is aligned with said bur template when said alignment rail is inserted into said alignment feature formed in said spacer block.

9. The method as claimed in claim 8, further comprising insetting a pin through said at least one pin opening and anchoring said at least one pin in said femur.

10. The method as claimed in claim 9, further comprising disengaging said posterior resection guide locator from engagement with said combination bur template and spacer guide and sliding a posterior resection guide over said at least one pin in said femur.

11. A method of preparing seating surfaces in a knee joint for receiving a unicondylar knee implant comprising:

preparing a first seating surface for receiving a tibial component at a proximal end of a tibia;

flexing said knee joint so that said first seating surface opposes a posterior region of said femoral condyle;

providing a combination bur template and spacer block including said bur template having a curved surface extending between upper and lower ends thereof and said spacer block extending from the lower end of said bur template;

inserting said spacer block into said knee joint so that said spacer block engages the posterior region of said femoral condyle and said first seating surface on said tibia; and

while maintaining said spacer block between said femur and said tibia, extending said knee joint until the curved surface of said bur template engages a distal region of said femoral condyle.

12. The method as claimed in claim 11, further comprising using said bur template to guide burring of the distal region of said femoral condyle for preparing a second seating surface for receiving a femoral component.

13. The method as claimed in claim 12, after the preparing a second seating surface step, anchoring one or more alignment pins in the femoral bone at the second seating surface.

14. The method as claimed in claim 13, using the one or more alignment pins anchored in the femoral bone for aligning a posterior resection guide with the posterior region of said femoral condyle and using said posterior resection guide for resecting the posterior region of said femoral condyle.

15. A kit for preparing a knee joint for receiving a unicondylar knee implant comprising:

a combination bur template and spacer block comprising;

a bur template having an upper end, a lower end and a curved inner surface extending between the upper and lower ends thereof;

a spacer block extending from the lower end of said bur template, said spacer block having a top surface, a bottom surface, a leading end for insertion into a knee joint and a trailing end spaced from the leading end and adjacent the lower end of said bur template, wherein the trailing end of said spacer block includes an opening with an alignment feature that extends from the trailing end of said spacer block toward the leading end of said spacer block.

16. The kit as claimed in claim 15, further comprising a posterior resection guide locator including an alignment rail insertible into the opening at the trailing end of said spacer block.

17. The kit as claimed in claim 16, wherein the alignment rail is adapted to mesh with the alignment feature in the opening of said spacer block.

18. The kit as claimed in claim 16, wherein the alignment rail comprises an elongated projection and the alignment feature comprises an elongated groove that receives the elongated projection.

19. The kit as claimed in claim 17, wherein said posterior resection guide locator includes an alignment pin guide overlying said alignment rail, wherein said alignment pin guide includes at least one pin opening extending therethrough.

20. The kit as claimed in claim 19, wherein said bur template includes a guide rail extending around an outer perimeter thereof and a central opening surrounded by the guide rail, and wherein said at least one pin opening of said alignment pin guide is aligned with the central opening when said alignment rail is inserted into the opening of said spacer block.

21. The kit as claimed in claim 20, further comprising an alignment pin insertible into the at least one pin opening of said alignment pin guide.

22. The kit as claimed in claim 21, further comprising a posterior resection guide including an upper end, a lower end having an elongated opening for receiving a cutting tool and a pin opening between the upper and lower ends, the pin opening of said posterior resection guide being slidable over the alignment pin.

23. The kit as claimed in claim 19, wherein the pin opening includes a first set of pin openings and a second set of pin openings that is closer to the upper end of said posterior resection guide than the first set of pin openings.

24. The kit as claimed in claim 20, wherein the pin opening includes a third set of pin openings that is closer to the lower end of said posterior resection guide than the first set of pin openings.