[Hydroxyapatite ceramics in clinical application. Histological findings in 23 patients].

Based on the histological findings of 23 patients who had received implants of the bovine hydroxyapatite ceramic Endobon for a period of up to 16 months, the biocompatibility, nature and extent of osseointegration as well as the resorption and degradation behaviour of the ceramic were investigated. The investigation material consisted mainly of small fragments that had been retrieved during revision operations that were indicated for other reasons. The results confirm the good tolerability and suitability that have been systematically investigated in experimental studies and described for hydroxyapatite ceramic as bone substitute in a vital cancellous bone bed that is not exposed to excessive strain (due to its brittle character). The importance of fulfilling certain requirements in order to achieve a successful result, such as stable implantation in a well vascularized, infection-free bone bed also with a minimization of the contact with local connective tissue has been further substantiated. Good success has been achieved by simultaneous loading with autogenous bone marrow as is practised by many ceramic users. In some cases a widening of intergrain boundaries as well as partial dissociation of superficial hydroxyapatite crystallites were observed in the implant surface.