Hip arthroplasty trialing apparatus with adjustable proximal trial and method

• US 7,425,214 B1
• Filed: 03/03/2005
• Issued: 09/16/2008
• Est. Priority Date: 03/03/2005
• Status: Active Grant

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Inventors: DeMaria, Christopher, Cahayla, Jason R., McCarthy, Thomas F.
• Primary Examiner(s): Robert; Eduardo C.
• Assistant Examiner(s): Cumberledge; Jerry
• Application Number:
  US11/071,793
• Time in Patent Office: 1,293 Days
• Field of Search: 606/89, 606/91, 606/102
• US Class Current: 606/89
• CPC Class Codes: A61F 2/32 for the hip
• CPC Class Codes: A61F 2/34 Acetabular cups
• CPC Class Codes: A61F 2/36 Femoral heads ; Femoral endoprostheses
• CPC Class Codes: A61F 2/3662 Femoral shafts
• CPC Class Codes: A61F 2/4684 Trial or dummy prostheses
• CPC Class Codes: A61F 2002/3055 for adjusting length
• CPC Class Codes: A61F 2002/3611 Heads or epiphyseal parts of femur
• CPC Class Codes: A61F 2002/3625 Necks
• CPC Class Codes: A61F 2002/3631 with an integral complete or partial peripheral collar or bearing shoulder at its base

Abstract

Apparatus and method are described for interoperatively determining, during a trailing procedure conducted in connection with total hip arthroplasty, a combination of neck length and femoral head offset required in a femoral component for establishing appropriate hip mechanics in a prosthetic hip joint to be implanted at an implant site. A trial femoral head is coupled for selective movement relative to a femoral stem component to move the trial femoral head longitudinally and laterally relative to a predetermined direction among selected combinations of trial distance and trial offset to evaluate hip mechanics and determine interoperatively an appropriate combination of trial distance and trial offset corresponding to the combination of neck length and femoral head offset required in the prosthetic hip joint.

Claims

1. Apparatus for interoperatively determining, during a trialing procedure conducted in connection with total hip arthroplasty at an implant site, a combination of neck length along a predetermined direction and femoral head offset required in a femoral component to be engaged with an acetabular component in a prosthetic hip joint to be implanted at the implant site for establishing appropriate hip mechanics in the prosthetic hip joint, by selecting a combination of trial distance, along a predetermined direction, and trial offset between a trial femoral head and a femoral stem component placed at the implant site with the trial femoral head engaged with an acetabular component in a trial hip joint, the combination of trial distance and trial offset corresponding to the combination of neck length and femoral head offset required in the prosthetic hip joint, the apparatus comprising:

a trial femoral head component including a trial femoral head having a center of rotation;

an indexing arrangement coupling the trial femoral head component with the femoral stem component for selective movement relative to one another, during the trialing procedure, the indexing arrangement being dimensioned and configured such that the selective relative movement includes longitudinal movement of the trial femoral head along a longitudinal axis extending essentially parallel with the predetermined direction and lateral movement of the trial femoral head relative to the longitudinal axis for establishing a trial hip joint having a selected combination of trial distance and trial offset between the trial femoral head and the femoral stem component;

the indexing arrangement including a drive shaft extending along a drive axis essentially parallel with the predetermined direction and journaled for rotation about the drive axis, and a coupling arrangement coupling the trial femoral head component with the drive shaft for movement of the trial femoral head component along the longitudinal axis and for rotation of the trial femoral head component about the longitudinal axis in response to rotation of the drive shaft about the drive axis, the center of rotation of the trial femoral head being offset laterally from the longitudinal axis, the coupling arrangement including a lead groove and a follower engaged with the lead groove, the lead groove following a modified helical path and including segments for advancing the trial femoral head component along the longitudinal axis, and for moving the center of rotation of the trial femoral head to offset the trial femoral head laterally in response to rotation of the drive shaft such that movement of the trial femoral head component is among selected positions corresponding to selectable combinations of trial distance and trial offset; and

a drive mechanism dimensioned and configured for selectively driving the indexing arrangement to index the trial femoral head component among selected combinations of trial distance and trial offset, during interoperative trialing to evaluate hip mechanics in the trial hip joint, thereby determining interoperatively an appropriate combination of trial distance and trial offset, the appropriate combination of trial distance and trial offset corresponding to the combination of neck length and femoral head offset required in the femoral component for establishing the appropriate hip mechanics in the prosthetic hip joint.

2. The apparatus of claim 1 wherein the selected positions comprise predetermined selectable positions such that selection of a predetermined position determines the neck length and the femoral head offset required in the femoral component for establishing the appropriate hip mechanics in the prosthetic hip joint.

3. The apparatus of claim 1 including a trial proximal housing and wherein the lead groove is carried by the trial proximal housing and the follower is on the trail femoral head component.

4. The apparatus of claim 3 wherein the selected positions comprise predetermined selectable positions such that selection of a predetermined position determines the neck length and the femoral head offset required in the femoral component for establishing the appropriate hip mechanics in the prosthetic hip joint.

5. The apparatus of claim 4 including indicators for indicating placement of the trial femoral head component at corresponding selected predetermined positions.

6. The apparatus of claim 5 wherein the indicators comprise stops for holding the trial femoral head component at a corresponding selected predetermined position.

7. The apparatus of claim 4 including a number of segments, the number of segments providing combinations of trial distance and trial offset corresponding to combinations of neck length and femoral head offset available in a femoral component of selected size.

8. The apparatus of claim 7 wherein the combinations comprise six predetermined combinations corresponding to six combinations available in the femoral component of selected size.