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1522 |
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Wednesday, June 04, 2008, Room 05 1:40 PM Biomedical Coatings Coated implants offer a better life quality due to their superior osseointegration and longer life cycle |
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Ti-coating by VPS for carbon fibre PEEK implants
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Heiko Gruner* / MEDICOAT AG, CH Geoff Richards / AO Research Institute, Switzerland Ronald Wieling/ icotec ag, Switzerland |
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Carbon fibre reinforced (CF) PEEK is becoming more frequently used as implant material in orthopaedics and traumatology. The main advantage are the radiolucency, good fatigue behaviour and biocompatibility partially undermined by poor bone ongrowth on the surface of this thermoplastic composite. Responsible is a thin fibrous capsule rapidly formed around the CF PEEK device after the implantation. Therefore CF PEEK implants are until now only preferred for temporary implants with load bearing properties and designed for early and easy removal. Long-term implants, as used e.g. for spine surgery, require an intimate bone contact in order to improve the mechanical fixation and to secure functional outcomes during the life-time. After a careful adaptation of the process parameters, VPS-sprayed Ti-coatings are able to modify the surface of CF PEEK as required. Using adult female Swiss Alpine sheeps, Ti-coated and uncoated screws were tested in comparison. The improvement of bone formation is investigated and shown by histological methods and quantitative analysis of the screw-tissue interface. No soft tissue layer is visible between the Ti-coating and the host bone. Torque measurements during the removals of the screws as a function of the retention time show the significant increase of the torque moment by the Ti-coating compared to non coated screws. The mechanical stability of the bone/Ti-interface and the adhesion strength of the Ti-coating overpass the strength of the CF PEEK base material. |