Polyethylene in Orthopedic Implants: Recent Trends and Limitations

Joint replacements are prevalent surgical procedures performed for treating various skeletal disorders and injuries. In this procedure, the damaged part of the joints is replaced with an artificial design called an implant. Various biomaterials are commonly used in manufacturing orthopedic implants. “Ultra-high molecular weight polyethylene (UHMWPE)” has found extensive applications in various joint replacements as a bearing material at the articulating surface of the replaced joints. The overall clinical performance of polyethylene has been reported to be good; however, some concerns remain associated with its use. Wear particles generated from the polyethylene causes osteolysis, affecting the longevity of the implant. To improve its wear properties, polyethylene has undergone several development stages over the last five decades, including cross-linking and incorporation of vitamin E. In this article, a summary of the use of different grades of UHMWPE in various joint replacements is presented. Historical development of UHMWPEs and their state-of-the-art processing techniques are highlighted. The evaluation of both clinical and pre-clinical performances of UHMWPE used in major orthopedic implants, correlation of material properties with the failure mechanisms, and the limitations and the future scope of improvement of UHMWPE have been discussed.