Method of producing an endoprosthesis as a joint substitute for knee-joints

• US 5,735,277 A
• Filed: 09/20/1995
• Issued: 04/07/1998
• Est. Priority Date: 09/27/1994
• Status: Expired due to Term

• Current Assignee: Biomet Manufacturing, LLC (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Luis Schuster
• Inventors: Schuster, Luis
• Primary Examiner(s): Smith, Ruth S.
• Application Number:
  US08/530,829
• Time in Patent Office: 930 Days
• Field of Search: 128/653.1, 128/653.2, 623/16, 623/18, 623/20, 623/66
• US Class Current: 600/425
• 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 2/3877 Patellae or trochleae
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2002/30948 using computerized tomography, i.e. CT scans
• CPC Class Codes: Y10S 623/914 Bone

Abstract

In a process of producing an endoprosthesis as a joint replacement especially for knee joints, a reference image for determining contour differences on the femur and the tibia, which are obtained by comparing a corrected preoperative image of the damaged knee joint with a postoperative image, is used as the basis for preparing corresponding femoral and tibial components of the endoprosthesis.

Claims

1. A method of producing an endoprosthesis as a joint replacement for knee joints comprising:

preparing a preoperative tomographic image of the damaged knee joint;

preparing a healthy knee joint tomographic image by approximating the contours of at least the femoral bone and the tibia of the damaged knee joint to those of a healthy knee joint;

preparing a postoperative tomographic image of the damaged knee joint;

comparing and determining the differences between;

(1) the contours of at least the femoral bone and of the tibia of the healthy knee joint tomographic image; and

(2) the contours of at least the femoral bone and of the tibia of the postoperative tomographic image of the damaged knee joint, to prepare a tomographic reference image representing said differences; and

preparing at least a femoral component and a tibial component of an endoprosthesis based on the tomographic reference image.

2. The method of claim 1, wherein all of said tomographic images are prepared by a computed tomography.

3. The method of claim 1, wherein all of said tomographic images are prepared by a nuclear spin resonance tomography.

4. The method of claim 1, wherein the step of preparing said healthy knee joint tomographic image comprises manually altering said preoperative tomographic image.

5. The method of claim 1, wherein the step of preparing said healthy knee joint tomographic image includes preparing a mirror image of a healthy knee joint of the patient.

6. The method of claim 1, wherein the step of preparing said healthy knee joint tomographic image includes identifying an image of a healthy knee joint having contours of at least the femoral bone and the tibia comparable to the contours of the preoperative image of the damaged knee joint.

7. The method of claim 1, wherein the step of preparing at least a femoral component and a tibial component of an endoprosthesis includes digitizing the reference image and using said digitized reference image to prepare said femoral component and said tibial component according to a copying process.