New UHMWPE Promises Improved Hip and Knee Implants

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New UHMWPE material incorporates small, highly reactive molecules that cross-link at lower radiation doses than previous formulations.

A new family of ultrahigh-molecular-weight polyethylene (UHMWPE) from DSM Biomedical (Geleen, Netherlands) incorporates small, highly reactive molecules that cross-link at significantly lower radiation doses than previous formulations. This capability minimizes the adverse effects of radiation on the polymer's mechanical properties and will enable the fabrication of stronger hip and knee implants with improved long-term stability.Although UHMWPE has been used for more than 45 years in artificial joints, improvements in the material's wear resistance are required to prevent revision surgeries. While cross-linking by means of high radiation doses significantly improves wear resistance, it also affects the polymer's mechanical properties. The technique of incorporating highly reactive molecules that cross-link at lower radiation doses addresses this limitation. Considered a breakthrough, this development is the result of an R&D program that the company initiated in 2007 to improve the properties of UHMWPE for use in artificial joints."Nearly two million people receive artificial hips or knees each year, and the artificial joint market continues to grow in conjunction with trends associated with an aging population and increases in obesity," says Leo Smit, the company's business director for implants. "We believe that this platform will lead to more-stable implants and help reduce the number of revision surgeries needed."The company has filed a patent on this polymer platform and its application in total joint arthroplasty. In future work, it will also optimize the polymer's mechanical properties.