US 8,008,365 B2 · Crosslinking of polyethylene for low wear using radiation and thermal treatments

Abstract

The present invention discloses methods for enhancing the wear-resistance of polymers, the resulting polymers, and in vivo implants made from such polymers. One aspect of this invention presents a method whereby a polymer is irradiated, preferably with gamma radiation, then thermally treated, such as by remelting of annealing. The resulting polymeric composition preferably has its most oxidized surface layer removed. Another aspect of the invention presents a general method for optimizing the wear resistance and desirable physical and/or chemical properties of a polymer by crosslinking and thermally treating it. The resulting polymeric compositions is wear-resistant and may be fabricated into an in vivo implant.

Claims13

Dependent claims

A preformed polymeric composition comprising a polymer that is crosslinked without melting or annealing it, the crosslinked polymer is subsequently melted in ambient atmosphere, and the melted polymer is subsequently cooled to room temperature, and the most oxidized surface of the cooled polymeric composition is removed, said preformed polymeric composition is characterized by the following characteristics:

a degree of swelling of between about 1.7 and about 5.3;
a molecular weight between crosslinks of between about 400 and about 8400 g/mol;
and a gel content of between about 95% and about 99%.

Dependencies are inferred from the claim text.

Facts

Application

11/633,803Filed 4 Dec 2006 · continuation

Priority

9 Jul 1996

Published

US 2007/0100016 A13 May 2007

Granted

30 Aug 2011

Term ends

Not estimatedThe source records don’t support an estimate.

Classification33 codes

A61F 2/30767
Joints: special external or bone-contacting surface, e.g. coating for improving bone ingrowth
A61F 2/468
Special tools for implanting artificial joints: testing instruments for artificial joints
A61L 27/16
Macromolecular materials: obtained by reactions only involving carbon-to-carbon unsaturated bonds
B29C 71/02
After-treatment of articles without altering their shape; Apparatus therefor: thermal after-treatment

Family

Application60/017,852Us provisional application · filed 9 Jul 1996

Application60/025,712Us provisional application · filed 10 Sep 1996

Application60/044,390Us provisional application · filed 29 Apr 1997

PCT/US97/11947Parent of this continuation · filed 8 Jul 1997

Application09/795,229Parent of this continuation · filed 26 Feb 2001

US 6,228,900 B1Parent of this continuation · filed 8 May 2001

Application10/936,149Parent of this continuation · filed 7 Sep 2004

US 6,800,670 B2Parent of this continuation · filed 5 Oct 2004

US 2007/0100016 A1Pre-grant publication · published 3 May 2007

Application09/214,586Parent of this continuation

US 2002/0037944 A1Published application

US 2005/0048096 A1Published application

US 8,008,365 B2This patent

From the US filing history. Foreign family members aren’t listed.

Crosslinking of polyethylene for low wear using radiation and thermal treatments

Life of this patent

Crosslinking of polyethylene for low wear using radiation and thermal treatments

Life of this patent

Abstract

Claims13