A highly crosslinked UHMWPE for CR and PS total knee arthroplasties.

X3 is a highly crosslinked ultrahigh molecular weight polyethylene (UHMWPE) produced by a sequential irradiation and annealing process. The sequential process results in a material with a free radical content that is 1% that of conventional UHMWPE gamma sterilized in nitrogen resulting in an oxidation resistance similar to that of virgin UHMWPE. Yield strength and ultimate tensile strength exceed American Society for Testing and Materials minimum rates for UHMWPE. Simulator testing of contemporary cruciate retaining (CR) and posterior-stabilized knee inserts (Triathlon) manufactured by the sequential process demonstrated 68% and 64% less wear, respectively, compared to conventionally processed inserts. The wear and mechanical integrity of sequentially processed posterior-stabilized inserts was unaffected by accelerated aging, whereas conventional UHMWPE exhibited increased wear, cracking, and delamination.