Force transducer for a joint prosthesis

• US 5,360,016 A
• Filed: 03/22/1993
• Issued: 11/01/1994
• Est. Priority Date: 04/05/1991
• Status: Expired due to Term

• Current Assignee: NK Biotechical Engineering Company
• Original Assignee: NK Biotechical Engineering Company
• Inventors: Kovacevic, Nebojsa
• Primary Examiner(s): Pellegrino, Stephen C.
• Assistant Examiner(s): Tucker, Guy V.
• Application Number:
  US08/001,048
• Time in Patent Office: 589 Days
• Field of Search: 128/774, 128/782, 606/90, 606/91, 606/99, 606/61, 606/53, 606/102, 623/16, 623/17, 623/18, 623/20, 623/22, 73/862.042, 73/862.043, 73/862.044, 73/862.045, 73/862.632, 73/862.633, 73/862.627, 73/862.637, 73/862.636 , 73/862.68, 73/862.046, 73/862.541
• US Class Current: 600/595
• CPC Class Codes: A61B 90/06 Measuring instruments not otherwise provided for
• CPC Class Codes: A61F 2/38 for elbows or knees
• CPC Class Codes: A61F 2/3859 Femoral components
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• CPC Class Codes: A61F 2002/4632 using computer-controlled surgery, e.g. robotic surgery
• CPC Class Codes: A61F 2002/4666 for measuring force, pressure or mechanical tension
• CPC Class Codes: G01L 1/2231 the supports being disc- or ring-shaped, adapted for measuring a force along a single direction

Abstract

A force transducer for a joint prosthesis is disclosed. The transducer includes A f5RUw,V,central body having a plurality of cavities formed therein from a lower surface. Each cavity defines a flexure member. A plate is located on the side opposite the cavities and connect to each flexure member through support posts. The support posts localize three applied to the plate to each flexure member. Force sensing elements attached to each flexure member provide a signal corresponding to the force applied to the flexure member.

Claims

1. A transducer for measuring forces between two components of a joint prosthesis, the transducer comprising:

a central body having a plurality of spaced apart integral flexure members forming an upper surface of the central body wherein each flexure member is formed by a corresponding cavity of a plurality of spaced apart cavities;

a plate spaced apart from the upper surface;

a plurality of support posts connecting the plate to the central body wherein each support post is located within the perimeter edge of the plate and has a first end attached to only one of the flexure members, and a second end attached to the plate, the support posts localizing forces applied to the plate onto the flexure members; and

a force sensing element coupled to each flexure member, each force sensing element providing an output signal representative of the force applied to the corresponding flexure member.

2. The transducer as specified in claim 1 wherein each force sensing element comprises a strain gauge.

3. The transducer as specified in claim 2 wherein each strain gauge is resistive.

4. The transducer as specified in claim 1 wherein each support post is integrally connected to the plate and the corresponding flexure member.

5. The transducer as specified in claim 1 wherein each cavity is substantially cylindrical.

6. The transducer as specified in claim 5 wherein the plurality of cavities equals four.

7. The transducer as specified in claim 1 and a platform that is replaceably attached with locking means to an upper surface of the plate, the locking means aligning the platform on the plate and preventing both substantially perpendicular and lateral movement of the platform.

8. The transducer as specified in claim 7 wherein the locking means comprises a dovetail and notch interconnection to align the platform onto the plate and prevent substantial perpendicular movement of the platform from the plate.

9. The transducer as specified in claim 7 wherein the locking means comprises a depression termed in the upper surface of the plate and a protruding complementary element formed on a lower surface of the platform such that interaction of the protruding element with the depression prevents substantial lateral movement of the platform on the plate.