Artificial Joint Element And Gripping Tool Equipped With The Same

• US 20080039949A1
• Filed: 11/30/2005
• Published: 02/14/2008
• Est. Priority Date: 12/03/2004
• Status: Abandoned Application

• Current Assignee: Aequos Endoprothetik GmbH
• Original Assignee: Aequos Endoprothetik GmbH
• Inventors: Nagerl, Hans, Meesenburg, Larissa
• Application Number:
  US11/792,049
• Publication Number:
  US 20080039949A1
• Time in Patent Office: Days
• US Class Current: 623/21.11
• CPC Class Codes: A61F 2/586 Fingers
• CPC Class Codes: A61F 2002/30245 Partial spheres
• CPC Class Codes: A61F 2002/30286 barrel-shaped
• CPC Class Codes: A61F 2002/30327 differing in diameter
• CPC Class Codes: A61F 2002/3065 Details of the ball-shaped head
• CPC Class Codes: A61F 2002/30665 Dual arrangement of two adjacent ball-and-socket joints
• CPC Class Codes: A61F 2002/4243 for interphalangeal joints, i.e. IP joints
• CPC Class Codes: A61F 2002/4251 for metacarpo-phalangeal joints, i.e. MCP or MP joints, e.g. knuckle joints
• CPC Class Codes: A61F 2230/0063 Three-dimensional shapes
• CPC Class Codes: A61F 2230/0071 spherical
• CPC Class Codes: A61F 2250/0039 differing in diameter

Abstract

The invention relates to an artificial joint element (1) for use in one or more single joints in a system of joints that consists of a combination of several kinematically coupled single joints, (series connection), in particular for use in one or more human finger joints. Said element comprises an essentially concave joint shell (2) and an essentially convex joint head (3). The aim of the invention is to obtain displacement characteristics for the artificial joint element (1), resulting from the additional degrees of freedom that are produced by incongruence, that mimic the natural behavior in an optimal manner. To achieve this, the joint element (1, 6) comprises at least four degrees of freedom and when used in the metacarpophalangeal joint, five degrees of freedom. For this purpose, the concave joint shell (2) comprises a curved contact line running over its surface with a first radius (R) and the concave joint head (3) has a contact line that is also curved running over its surface with a different second radius (r), which is smaller than the radius (R) of the contact line of the joint shell (2).

Claims

1. Artificial joint element (1, 6) for use of one or more individual joints in a joint system consisting of a combination of several kinematically coupled individual joints, especially for use in a human finger joint, each joint element (1, 6) being equipped with an essentially concave joint shell (2, 7) and with an essentially convex joint head (3, 8), characterized in that the joint element (1, 6) has at least four degrees of freedom.

2. The artificial joint element (1, 6) according to claim 1, wherein the joint element (1) for use in a metacarpophalangeal joint has five degrees of freedom.

3. The artificial joint element (1, 6) according to claim 1, wherein the concave joint shell (2, 7) has a first curved contact line which runs on its surface, with a first radius (R), and wherein the convex joint head (3, 8) has a second curved contact line which runs on its surface, with a second radius (r), the first radius (R) of the first curved contact line at least in a partial region between the extreme locations of the joint position being larger than the second radius (r) of the second curved contact line.

4. The artificial joint element (1, 6) according to claim 3, wherein the difference between the first radius (R) and the second radius (r) is at least 1 mm, especially between 2 mm and 4 mm.

5. The artificial joint element (1) according to claim 1, wherein the difference between the first radius (R) and the second radius (r) in the bent joint position is larger than in the extended joint position.

6. The artificial joint element (1) according to claim 1, wherein the artificial joint element (1) for replacement of the metacarpophalangeal joint (MCP) is made without concave regions.

7. The artificial joint element (6) according to claim 1, wherein the joint element (6) for replacement of the proximal interphalangeal joint (PIP) and/or distal interphalangeal joint (DIP) has a joint head (8) with two convex regions (condyles 13, 14) which are connected by a concave region (concavity 12).

8. The artificial joint element (1, 6) according to claim 7, wherein the joint head (6) and the joint shell (7) each have two contact surfaces which are situated in the convex region (condyles 13, 14) between the concave region (concavity 12) and the maximum distal extension.

9. The artificial joint element (1, 6) according to claim 1, wherein the surface normals of the contact surfaces have a common intersection point for each angle of flexion.

10. The artificial joint element (1, 6) according to claim 1, wherein the joint element (1, 6) is made as a thin molded part with a material thickness between 1 mm and 5 mm.

11. Gripping tool which is equipped with one or more artificial joint elements according to claim 1 and which can be actuated with a tension means which is connected by a drive unit, with an essentially concave joint shell and with an essentially convex joint head, the concave joint shell having a curved contact line with a first radius which is larger than the second radius of the second curved contact line of the convex joint head at least in one partial region.

12. The artificial joint element (1, 6) according to claim 2, wherein the concave joint shell (2, 7) has a first curved contact line which runs on its surface, with a first radius (R), and wherein the convex joint head (3, 8) has a second curved contact line which runs on its surface, with a second radius (r), the first radius (R) of the first curved contact line at least in a partial region between the extreme locations of the joint position being larger than the second radius (r) of the second curved contact line.

13. The artificial joint element (1, 6) according to claim 12, wherein the difference between the first radius (R) and the second radius (r) is at least 1 mm, especially between 2 mm and 4 mm.