Reinforced polyethylene for articular surfaces

• US 5,609,638 A
• Filed: 11/29/1994
• Issued: 03/11/1997
• Est. Priority Date: 11/29/1994
• Status: Expired due to Term

• Current Assignee: Zimmer Technology Incorporated (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Zimmer Incorporated (Zimmer Biomet Holdings, Inc.)
• Inventors: Parr, Jack E., Price, Howard C., Hawkins, Michael E., Lin, Steve T.
• Primary Examiner(s): ISABELLA, DAVID J
• Application Number:
  US08/346,125
• Time in Patent Office: 833 Days
• Field of Search: 623/16, 623/18, 623/19, 623/20, 623/22, 623/23, 623/66
• US Class Current: 623/20.32
• CPC Class Codes: A61F 2/3094 Designing or manufacturing processes
• CPC Class Codes: A61F 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• CPC Class Codes: A61F 2/34 Acetabular cups
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2002/30009 differing in fibre orientations
• CPC Class Codes: A61F 2002/30276 frustopyramidal
• CPC Class Codes: A61F 2002/30685 Means for reducing or preventing the generation of wear particulates
• CPC Class Codes: A61F 2002/30934 Special articulating surfaces
• CPC Class Codes: A61F 2002/30971 Laminates, i.e. layered products
• CPC Class Codes: A61F 2230/0086 Pyramidal, tetrahedral, or wedge-shaped
• CPC Class Codes: A61F 2250/0028 differing in fibre orientations
• CPC Class Codes: A61L 2430/24 for joint reconstruction
• CPC Class Codes: A61L 27/16 obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: B29C 70/20 oriented in a single direction, e.g. roofing or other parallel fibres B29C70/083, B29C70/226 take precedence
• CPC Class Codes: B29K 2023/0683 UHMWPE, i.e. ultra high molecular weight polyethylene
• CPC Class Codes: B29K 2223/0683 UHMWPE, i.e. ultra high molecular weight polyethylene
• CPC Class Codes: B29K 2995/0087 Wear resistance
• CPC Class Codes: B29L 2031/7532 Artificial members, protheses
• CPC Class Codes: C08L 23/06 Polyethene

Abstract

An articular component has a fibrous structure wherein the fibers are oriented normal to the articular surface. Wear debris reduction is attributed to the increased strength of fibers over bulk material and to the abrasion resistance associated with abrading a fiber bundle on the fiber tips. This is similar to the abrasion resistance seen in a household broom which is subjected to abrasion across the tips of the broom bristles. Reduced cold flow is attributed to the increased strength and stiffness of fibers over bulk material.

Claims

1. An articular component of a prosthetic joint implant for the human body, the component comprising a body having an articular surface, the body including elongated fibers extending to and having terminating ends defining the articular surface, said fibers being oriented approximately normal to the articular surface.

2. The articular component of claim 1 wherein the fibers are consolidated to form inserts and said inserts are disposed in said body such that the fibers within each insert are oriented substantially normal to the articular surface.

3. The articular component of claim 1 wherein the component is a tibial component of a knee joint prosthesis for placement on a tibia and most of the fibers contained in the body are oriented parallel to one another such that the fibers are disposed parallel to the axis of the tibia when the component is placed on the tibia.

4. The articular component of claim 1 wherein the articular surface is non-planar and the component comprises a plurality of wedge-shaped segments, each segment comprising parallel consolidated fibers, the fibers of adjacent segments not being parallel, the segments being joined together to form said body which defines said articular surface wherein the fibers are approximately normal to the non-planar articular surface.

5. The articular component of claim 1 wherein said body is formed entirely from consolidated parallel fibers.

6. The articular component of claim 1 wherein the body has an articular component thickness measured normal to the articular surface and further wherein the fibers extend from the articular surface across the articular component thickness.

7. The articular component of claim 1 wherein the fibers are ultra high molecular weight polyethylene fibers which have been consolidated into a solid mass of fibers oriented approximately normal to the articular surface.