Ultra high molecular weight polyethylene articles and methods of forming ultra high molecular weight polyethylene articles
The present invention generally provides implantable articles and methods of forming implantable articles from a crosslinked ultrahigh molecular weight polyethylene (“UHMWPE”) blend stabilized with Vitamin E. The crosslinked UHMWPE blend may be prepared by combining the UHMWPE material and vitamin E prior to irradiating the UHMWPE blend with electron beam radiation at a sufficient radiation dose rate to induce crosslinking. The crosslinked UHMWPE blend may be incorporated into a variety of implants, and in particular, into endoprosthetic joint replacements
1. An article comprising a blend of ultrahigh molecular weight polyethylene and vitamin E, in which the vitamin E is present in a substantially uniform distribution throughout the ultrahigh molecular weight polyethylene, in which the blend has a swell ratio of less than about 3.5 after crosslinking, in which the blend is prepared by a process comprising
combining the vitamin E and the ultrahigh molecular weight polyethylene;
blending the vitamin E and the ultrahigh molecular weight polyethylene until a substantially uniform distribution of vitamin E is present throughout the ultrahigh molecular weight polyethylene to provide a blend;
crosslinking the blend using electron beam radiation at an absorbed dose of at least about 95 kilo Grey and a dose rate of at least about 15 MegaGrey per hour; and
annealing the crosslinked blend at a temperature up to about 200° C.
2. The article of claim 1 , in which mechanical annealing is used to anneal the crosslinked blend.
3. The article of claim 1 wherein the blend further comprises at least one additional polymeric material.
4. The article of claim 1 further comprising an additional component joined to the article to form an implant.
5. The article of claim 1 wherein the article comprises at least portions of an artificial hip, hip liner, knee liner, disk replacement, shoulder, elbow, foot ankle, finger, mandible or bearings in artificial heart.
6. The article of claim 1 , in which the vitamin E is presently between 0.02 w/w % and about 2.0 w/w %.