Radiological and Histological Examination of Gap Healing on Plasma Sprayed HA Coating Surface

Abstract

Bone formation on hydroxyapatite coatings in the presence of gaps is important for clinical applications. Samples of pure titanium and of this material coated with hydroxyapatite by plasma spraying were implanted in dogs. The implants were surrounded by gaps of 2mm, and the follow-up period was 12 weeks. Histological examination revealed that gaps could be bridged by bone if the hydroxyapatite coating was applied, and pure titanium implants were surrounded by fibrous tissue with no bone contact at all. In clinical trials, hip implants were HA-coated by plasma spraying and implanted in human femurs. There was a 2mm gap between host bone and implanted device on the top. After 1, 6, 12, 24 months, the hip implant was observed by radiological examination, and showed that one month after operation, part of the gap had been replaced by new bone. After 6 months, about 80% of gap was filled by new bone, and after 12 and 24 months, the percentage increased to over 90%.