[Innovative materials in orthopaedics: the crosslinked polyethylene (XPE)].

More than 150.000 hip and knee arthroplasties are performed every year in Italy. More than 50% of the patients receive a polyethylene component (Ultra High Molecular Weight PolyEthylene, UHMWPE). Polyethylene abrasive wear induces over time in vivo a foreign-body response and consequently osteolysis, pain and need of implant revision. Furthermore, oxidative wear due to gamma-rays sterilization caused in the '90ies several and severe failures. To solve these problems, since then, the orthopaedics research has been addressed to: 1) develop new cross linked polyethylene with a higher molecular mass than UHMWPE and, consequently, a higher abrasive wear resistance; 2) avoid the oxidative wear induced by gamma-rays sterilization, by using other sterilization methods and by stabilizing UHMWPE by means of antioxidants such as Vitamin E. According to the most recent studies, performed on limited cohorts and mostly funded by manufacturers, cross linked polyethylene shows a better abrasive wear resistance if compared to the conventional polyethylene but no significant differences have been detected in the clinical outcomes. Clinical follow up of Vitamin E stabilized PE are not yet available. The organization of national arthroplasties registries, able to trace and characterize the implanted devices and based on the whole patients population, will facilitate the early detection of devices that show a performance inferior than the expected one. In Italy, the National Institute of Health has been entrusted by the Ministry of Health to organize the national arthroplasty registry.