Orthopaedic applications of hydroxyapatite.

Hydroxyapatite (HA) has been used for more than six years. More recently we have used HA composites in clinical orthopaedics for spacing or filling bone defects. In this application the advantages of HA include lack of immuno-reaction and absence of postoperative morphological change or volume decrease. HA implants fixed with cement avoid problems from high density polyethylene wear particles. Other applications of HA include femoral plugs in total hip replacement and HA coating on metal components for cementless fixation. For rapid and strong cementless fixation porous metal surfaces are used; HA coating of porous metal gives improved results. We have also developed a technique for bioactive interfacial bone cementation by interposing fine HA granules between the bone and PMMA cement.