Hydroxyapatite ceramic as a bone substitute.

We have used hydroxyapatite ceramic as a bone substitute for grafting in extensive bone replacement. Hydroxyapatite is composed of calcium phosphate and is incorporated into bone as a physiological mineral. It is not antigenic, carcinogenic or osteogenic. The material used in this study differs from other hydroxyapatite ceramics in that it is an interconnected porous system. Between 1981 and 1986 we used this material on forty five occasions in 44 patients. It was combined with autologous cancellous bone graft in 38 cases and used alone in a further seven. It was usually employed to fill defects after removal of bone cysts and for long fusions in patients with scoliosis. It was also used to fill bone defects after trauma, for non-union in the lumbosacral area, for anterior vertebral fusions, in limb sparing operations for malignant bone tumours, and in exchange operations after failed joint endoprostheses. We have not seen incompatibility or rejection of the implanted material. The rate of postoperative infection was higher than usual due to the selection of patients, but did not appear to be connected with the use of hydroxyapatite ceramic. We were able to review 36 patients up to sixty months after operation. The results are encouraging with no difference in progress compared with patients in whom simple autologous bone grafts had been used.