Engineering to extend the life of hip replacements

Hip implant for long-term use
Researchers at the Fraunhofer Institute for Manufacturing Engineering and Automation IPA in Stuttgart, partnering in an international team on an EC-funded project entitled "ENDURE" (Enhanced Durability Resurfacing Endoprosthesis), have now developed a new kind of hip implant that, unlike the conventional counterpart implants on the market today, provide a metal-free solution and bone-like elasticity. This is the result of a metal-free, high-tech composite: The hip socket is made of carbon fibre-reinforced PEEK – a high-strength, wear resistant, biocompatible polymer composite. For the femoral head, ceramic was used. In addition to this, a hydroxylapatite coating at the interface to the bone helps ensure that the bone tissue will fuse thoroughly with the surface structure of the implant. "The cobalt-chromium implants in use to date are very rigid, and the load transfer to the bone is non-optimal leading to potential adverse bone adaptation. Thanks to the new combination of materials, the transmission of force through the PEEK hip socket to the pelvic bone is modeled on natural conditions. And there are no metal ions released," notes IPA engineer Jasmin Hipp. The researcher and her team were able to confirm the good wear resistance in initial tests of the new hip replacement using a robot that simulated various series of movements such as walking or climbing and descending stairs. Eurekalert!