Is Hylamer adequate for use in alloarthroplasties?

In the present study ultrahigh molecular weight polyethylene (UHMWPE) implants from different manufactures were evaluated by differential scanning calorimetry (DSC), infrared spectroscopy (IRS) and wide-angle X-ray scattering (WAXS). With DSC measurements the crystallinity of all evaluated implants ranged between 58.2% and 73.2%. The highest crystallinity was documented in Hylamer with 73.2%. These results were checked and confirmed by infrared spectroscopy. According to WAXS studies Hylamer had an orthorhomboid phase as well as a monocline phase. After remelting the orthorhomboid phase was no longer detectable. We do not recommend using UHMWPE implants which have been secondarily modified. The product Hylamer clearly demonstrates how the original crystal structure of UHMWPE can be altered. The described changes in Hylamer implants will probably lead to an increased failure rate.