Apparatus and method for aligning knee prostheses

• US 5,520,694 A
• Filed: 01/05/1995
• Issued: 05/28/1996
• Est. Priority Date: 06/21/1993
• Status: Expired due to Term

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Osteonics Corporation (Stryker Corporation)
• Inventors: Auchinleck, Geoffrey F., Dance, Mark N., Sims, Gordon C.
• Primary Examiner(s): Brown, Michael A.
• Application Number:
  US08/369,140
• Time in Patent Office: 509 Days
• Field of Search: 606/79, 606/80, 606/86, 606/87, 606/88, 606/96, 606/97, 606/98, 606/102
• US Class Current: 606/86.00R
• CPC Class Codes: A61B 17/154 for preparing bone for knee prosthesis
• CPC Class Codes: A61B 17/155 Cutting femur

Abstract

An apparatus for aligning a surgical instrument having a connection device attached to the femur in the vicinity of the knee joint at a point chosen to be on the mechanical axis. An adjustable vertical suspension device attached to the femur for counteracting the moment about the hip joint created by the weight of the femur. A vertical tension indicating device attached to the adjustable vertical suspension device.

Claims

1. Method for locating the mechanical axis of a femur in the medial-lateral plane for a supine patient, comprising the steps of:

(a) applying tension to the femur in the vicinity of the knee joint at a point chosen to be on the mechanical axis;

(b) allowing the femur to move freely into line with the applied tension; and

(c) using the axis of the applied tension to indicate the mechanical axis of the femur in the medial-lateral plane.

2. Method for locating the mechanical axis of a femur, comprising the steps of:

(a) applying a force to the femur to eliminate the moment about the hip joint caused by the weight of the limb;

(b) applying tension to the femur in the vicinity of the knee joint at a point chosen to be on the mechanical axis;

(c) allowing the femur to move freely into line with the applied tension; and

(d) using the axis of the applied tension to indicate the mechanical axis of the femur.

3. Method for locating the mechanical axis of a femur comprising the steps of:

(a) determining the suspension force required to suspend a femur in a selected location;

(b) applying tension to the femur in the vicinity of the knee joint at a point chosen to be on the mechanical axis;

(c) applying the suspension force to the femur to eliminate the effect of weight;

(d) allowing the femur to move freely into line with the applied tension; and

(e) using the axis of the applied tension to indicate the mechanical axis of the femur.

4. Apparatus for aligning a surgical instrument to the mechanical axis of the femur, comprising:

(a) connection means attached to a femur in the vicinity of the knee joint at a point chosen to be on the mechanical axis;

(b) adjustable vertical suspension means attached to the femur for counteracting the moment about the hip joint created by the weight of the femur;

(c) vertical tension indicating means attached to the adjustable vertical suspension means for indicating the tension in the vertical suspension means so that the tension in the vertical suspension means can be adjusted to a determined value;

(d) tension member means attached to the connection means for applying a tension to the femur; and

(e) a surgical instrument attached to the tension member so that vertical tension required to counteract the moment about the hip joint created by the weight of the femur can be recorded, tension can be applied to the femur with the tension member means and the adjustable vertical suspension means can be adjusted to apply a vertical tension equal to that recorded to align the surgical instrument with the mechanical axis of the femur.