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The Biological Behavior of the Hydroxyapatite Ceramic Coating on a Titanium Stem of a Hip Prosthesis

J.F. Osborn

Category: Furlong Clinical Results

The First Histological Evaluation of Human Autopsy Material

Following a 7-week implantation period, a cementless IRI Furlong hydroxyapatite ceramic-coated total hip endoprosthesis made of TiA16V4 was examined by light and scanning electron microscopy. The undecalcified thin ground sections revealed that the intact hydroxyapatite ceramic coating (Osprovit) was almost invariably covered by newly formed bone, which revealed the maturity and mineral content of young lamellar bone. The obligatory gap between prosthesis and femur due to the trauma of insertion is obviously bridged by bilateral osteogenesis, i.e. by primary bone formation initiated from both the surface of the endosteal bone and the hydroxyapatite ceramic. This new bone shows a substantial intergrowth with the ceramic so that on no part of the interface is there any fibrous tissue. Bonding osteogenesis occurs both in the spongy as in the cortical bed – in contrast to the conventional form-fit – and establishes the basis for linear force transfer between the implant and bone. This fact, realised for the first time with the aid of a hydroxyapatite ceramic coating, inevitably requires a fundamental revision of the biomechanical concept of prosthesis anchorage to bone.