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Why Polyethylene Wear Should be Studied? (Review Article)

Wear debris of polyethylene (PE) is the main factor causing osteolysis and loosening. Wear depends both on intrinsic characteristics of the PE and on the extrinsic conditions. The extrinsic conditions are the forces acting on the material, the prosthetic design and the other constituents of the prosthesis. Early diagnosis of osteolysis is important to ensure easier revision surgery and more reliable results. The intrinsic characteristics are a result of the nature of the polymer resin (especially its molecular weight); the mode of manufacture of the component (extrusion; compression; and molding) and the sterilization method. The role that particulate polyethylene debris plays in loosening of total joint prostheses has come under increasing scrutiny. Despite these problems, polyethylene remains a super material for orthpaedic implants and is unlikely to be replaced by any new or better polymer in the near future. However, improvements in the polyethylene itself and in the design of components are necessary to decrease wear debris. Cross-linked UHMWPE (Ultra High Molecular Weight Polyethylene) has been recently approved by FDA for use in orthopaedic implants . The majority of commercially available UHMWPE orthopaedic components are cross-linked using gamma radiation.