Femoral sizing guide and method

• US 5,810,831 A
• Filed: 10/28/1997
• Issued: 09/22/1998
• Est. Priority Date: 02/16/1994
• Status: Expired due to Term

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Osteonics Corporation (Stryker Corporation)
• Inventors: D'Antonio, James A.
• Primary Examiner(s): Tucker, Guy V.
• Application Number:
  US08/963,127
• Time in Patent Office: 329 Days
• Field of Search: 606/88, 606/87, 606/89, 606/96, 606/102, 606/86, 606/79, 606/80, 606/82, 623/20, 623/18, 33/512, 33/511
• US Class Current: 606/88
• CPC Class Codes: A61B 17/155 Cutting femur
• 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

Abstract

A femoral sizing guide of the type in which a sizing guide block is located at the distal femur utilizing locator feet for engaging the posterior condyles to assist in the location of a femoral cutting guide of suitable size in the implant of a femoral knee prosthesis includes a coupling arrangement by which locator feet of selected size are independently coupled interoperatively with the sizing guide block for enabling a surgeon to compensate for conditions encountered at the implant site, during the implant procedure, and attain a stable placement of the femoral sizing guide at the distal femur for accurate sizing and location of the femoral knee prosthesis.

Claims

1. An improvement for facilitating the use of a femoral sizing guide in determining, interoperatively, the size of a femoral knee prosthesis to be implanted at a prepared distal femur of a femur extending in an axial direction within a recipient, the femoral sizing guide being arranged for location against the distal femoral surface and the posterior condylar surfaces of the prepared distal femur, the improvement enabling interoperative compensation for variations in the conditions encountered at the posterior condylar surfaces when determining the amount of bone to be removed from the posterior condyles, the posterior condylar surfaces including a medial condylar surface and a lateral condylar surface, the improvement comprising:

a femoral sizing guide block having a block locator surface extending in lateral and altitudinal directions for extending transverse to the axial direction when engaged with the prepared distal surface of the distal femur, and guide means for determining the location of a femoral cutting guide to be placed subsequently at the distal femur;

foot means for projecting in a longitudinal direction relative to the lateral and altitudinal directions of the block locator surface, the foot means including foot locator surfaces for engaging the posterior condylar surfaces when the block locator surface is engaged with the distal femoral surface, the foot means further including a medial foot having a medial locator surface for engaging the medial condylar surface, and a lateral foot having a lateral locator surface for engaging the lateral condylar surface; and

coupling means including an independent coupling arrangement for at least one of the medial foot and the lateral foot, such that said at least one of the medial foot and the lateral foot is selectively coupled with and is selectively uncoupled from the femoral sizing guide block, interoperatively, independent of the other of the medial foot and the lateral foot to enable the selection of said one of the medial foot and the lateral foot of predetermined size from a plurality of available foot means of different sizes for coupling with the femoral sizing guide block, the selected one of the medial foot and the lateral foot of predetermined size placing the corresponding one of the medial locator surface and the lateral locator surface in position relative to the other of the medial locator surface and the lateral locator surface to accommodate the conditions encountered at the posterior condylar surfaces and enable direct determination of the amount of bone to be removed.

2. The invention of claim 1 wherein:

the coupling means include an independent coupling arrangement for each of the medial foot and the lateral foot, such that either one of the medial foot and the lateral foot is selectively coupled with and uncoupled from the sizing guide block.

3. The invention of claim 2 wherein each coupling arrangement includes interengaging complementary sliding elements on the sizing guide and on each of the medial foot and the lateral foot, the sliding elements being selectively engaged and disengaged by relative sliding movement between the sizing guide block and the corresponding foot in a lateral direction between a fully-engaged position, wherein the corresponding foot is coupled with the sizing guide block, and a fully-disengaged position, wherein the corresponding foot is uncoupled from the sizing guide block.

4. The invention of claim 3 including securing means for securing each foot against movement relative to the sizing guide block when the foot is at the fully-engaged position.

5. The invention of claim 4 wherein the securing means includes a detent for releasibly securing each foot at the corresponding fully-engaged position.

6. The invention of claim 3 wherein the interengaging sliding elements include a groove extending in the lateral direction and having an altitudinal cross-sectional configuration, and a spline extending in the lateral direction and having an altitudinal cross-sectional configuration complementary to the corresponding cross-sectional configuration of the groove, the complementary cross-sectional configurations interlocking to preclude relative movement between the sizing guide block and each foot in altitudinal directions while enabling relative sliding movement in lateral directions for coupling and uncoupling the sizing guide block and each foot.

7. The invention of claim 6 wherein the complementary cross-sectional configurations are T-shaped.

8. The invention of claim 1 wherein:

the sizing guide block includes a further locator surface placed longitudinally opposite the block locator surface for enabling reversal of the sizing guide block to engage the further locator surface with the distal femoral surface; and

the coupling means includes a coupling configuration for enabling the foot means to be coupled with the sizing guide block so as to engage the posterior condylar surfaces when the further locator surface is engaged with the distal femoral surface.

9. The invention of claim 8 wherein:

the coupling means include an independent coupling arrangement for each of the medial foot and the lateral foot, such that either one of the medial foot and the lateral foot is selectively coupled with and uncoupled from the sizing guide block.

10. The invention of claim 9 wherein each coupling arrangement includes interengaging complementary sliding elements on the sizing guide and on each of the medial foot and the lateral foot, the sliding elements being selectively engaged and disengaged by relative sliding movement between the sizing guide block and the corresponding foot in a lateral direction between a fully-engaged position, wherein the corresponding foot is coupled with the sizing guide block, and a fully-disengaged position, wherein the corresponding foot is uncoupled from the sizing guide block.

11. The invention of claim 10 including securing means for securing each foot against movement relative to the sizing guide block when the foot is at the fully-engaged position.

12. The invention of claim 11 wherein the securing means includes a detent for releasibly securing each foot at the corresponding fully-engaged position.

13. The invention of claim 12 wherein the interengaging sliding elements include a groove extending in the lateral direction and having an altitudinal cross-sectional configuration, and a spline extending in the lateral direction and having an altitudinal cross-sectional configuration complementary to the corresponding cross-sectional configuration of the groove, the complementary cross-sectional configurations interlocking to preclude relative movement between the sizing guide block and each foot in altitudinal directions while enabling relative sliding movement in lateral directions for coupling and uncoupling the sizing guide block and each foot.

14. The invention of claim 1 wherein the distal femur includes an anterior cortex and the sizing guide includes:

a sizing stylus for mounting upon the sizing guide block for movement in anterior/posterior directions to enable engagement of the stylus with the anterior cortex of the distal femur when the block locator surface is engaged with the distal femoral surface; and

indicator means coupled with the stylus for providing an indication of the size of the femoral knee prosthesis to be implanted, based upon the anterior/posterior position of the stylus relative to the sizing guide block when the stylus is engaged with the anterior cortex.

15. The invention of claim 14 wherein:

the coupling means include an independent coupling arrangement for each of the medial foot and the lateral foot, such that either one of the medial foot and the lateral foot is selectively coupled with and uncoupled from the sizing guide block.

16. The invention of claim 15 wherein each coupling arrangement includes interengaging complementary sliding elements on the sizing guide and on each of the medial foot and the lateral foot, the sliding elements being selectively engaged and disengaged by relative sliding movement between the sizing guide block and the corresponding foot in a lateral direction between a fully-engaged position, wherein the corresponding foot is coupled with the sizing guide block, and a fully-disengaged position, wherein the corresponding foot is uncoupled from the sizing guide block.

17. The invention of claim 16 including securing means for securing each foot against movement relative to the sizing guide block when the foot is at the fully-engaged position.

18. The invention of claim 17 wherein the securing means includes a detent for releasibly securing each foot at the corresponding fully-engaged position.

19. The invention of claim 18 wherein the interengaging sliding elements include a groove extending in the lateral direction and having an altitudinal cross-sectional configuration, and a spline extending in the lateral direction and having an altitudinal cross-sectional configuration complementary to the corresponding cross-sectional configuration of the groove, the complementary cross-sectional configurations interlocking to preclude relative movement between the sizing guide block and each foot in altitudinal directions while enabling relative sliding movement in lateral directions for coupling and uncoupling the sizing guide block and each foot.

20. An improvement for facilitating the determination, interoperatively, of the size of a femoral knee prosthesis to be implanted at a prepared distal femur of a femur extending in an axial direction within a recipient, the determination including locating a femoral sizing guide against the distal femoral surface and the posterior condylar surfaces of the prepared distal femur, the improvement enabling interoperative compensation for variations in the conditions encountered at the posterior condylar surfaces when determining the amount of bone to be removed from the posterior condyles, the posterior condylar surfaces including a medial condylar surface and a lateral condylar surface, the femoral sizing guide including a femoral sizing guide block having a block locator surface extending in lateral and altitudinal directions for extending transverse to the axial direction when engaged with the prepared distal surface of the distal femur, guide means for determining the location of a femoral cutting guide to be placed subsequently at the distal femur, and foot means for projecting in a longitudinal direction relative to the lateral and altitudinal directions of the block locator surface, the foot means including foot locator surfaces for engaging the posterior condylar surfaces when the block locator surface is engaged with the distal femoral surface to determine the amount of bone to be removed from the posterior condyles, the foot means further including a medial foot having a medial locator surface for engaging the medial condylar surface, and a lateral foot having a lateral locator surface for engaging the lateral condylar surface, the improvement comprising the steps of:

selecting at least one of the medial foot and the lateral foot of predetermined size from a plurality of foot means of different sizes; and

coupling the selected one of the medial foot and the lateral foot with the femoral sizing guide block, independent of the other of the medial foot and the lateral foot, interoperatively, such that the selected one of the medial foot and the lateral foot is coupled to the femoral sizing guide block to place the corresponding one of the medial locator surface and lateral locator surface relative to the other of the medial locator surface and the lateral locator surface for location of the foot locator surfaces in position to accommodate the conditions encountered at the posterior condylar surfaces and enable direct determination of the amount of bone to be removed.

21. The invention of claim 20 wherein

the step of coupling the selected foot means with the femoral sizing guide block includes independently coupling each of the medial foot and the lateral foot with the femoral sizing guide block, such that either one of the medial foot and the lateral foot is selectively coupled with the femoral sizing guide block.