Exactech Connexion GXL and conventional polyethylene liners were used in Exactech’s Novation and Alteon hip replacement systems. The liners were made with irradiated ultra-high molecular-weight polyethylene plastic, which was supposed to help them resist wear. However, polyethylene is susceptible to oxidation, a natural chemical process that occurs when materials are exposed to oxygen in the atmosphere.
After patients began to report problems with their hip implants, Exactech recognized that some of its plastic liners were wearing out sooner than expected. The company concluded that polyethylene liners manufactured since 2004 were packaged in out-of-specification vacuum bags that are oxygen resistant but do not contain a secondary oxygen barrier layer known as ethylene vinyl alcohol (EVOH), which enhances oxygen resistance. The use of non-conforming bags results in increased oxidation and premature degradation of the medical device.
Premature wear of the plastic insert of a hip replacement can lead to accelerated wear and bone loss and the device cracking or breaking. This can only be remedied with surgery to remove the faulty hip replacement and implant a new device.
