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Metal-Free Hip Implant Incorporates New Combination of Materials to Provide High Durability

May 7, 2012 – 4:25 pm

A European Commission-funded project titled ENDURE focuses on developing a new type of hip implant that is metal-free and provides bone-like elasticity.

An international team of ten partners, which include companies, research organisations and universities, collaborated to develop a hip implant that demonstrated good wear resistance in initial tests. During the tests, a robot simulated various movements while wearing a prototype of the implant, according to a press release from Fraunhofer Institute for Manufacturing Engineering and Automation IPA.

Hip implants can provide great relief to patients with damaged hips, but researchers continue to search for a solution that does not need to be replaced every few years and does not contain metal. Metal-on-metal implants can raise ion levels in the blood when the metal ball rubs against its metal socket, releasing debris. While designed to improve durability compared to conventional implants, which need to be replaced every few years, the recent MoM hip implant scandal indicates that sometimes these implants actually need to be replaced more often. The new implant developed during the ENDURE project could potentially solve some of these issues, since it’s said to be more robust than other metal-free options.

The implant’s hip socket is made from carbon fibre-reinforced PEEK. Ceramic is used in the femoral head of the implant. A hydroxylapatite coating was added at the interface to the bone.

“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 in the Fraunhofer press release.

Fraunhofer Institute for Manufacturing Engineering and Automation IPA is one of the project partners. The other partners include Aurora Medical, Medicoat, Hunt Developments, Ala Ortho, CeramTec, Invibio, Biomatech and the Universities of Gothenburg and Southampton.

Besides the new combination of materials, the researchers made several other modification to the device compared to the way hip implants are typically designed. The prosthesis attaches to the bone without cement. Using a press-fit and an integral scaffold-type structure on the surfaces of the implant that contact the bone, the hemispherical ball and socket are tapped onto the femoral head and into the acetabulum and anchored in place. The researchers also developed a disposable tool that attaches the implant to conventional surgical instruments.