BONE DEMINERALIZATION INDUCED BY CEMENTLESS ALUMINA-COATED FEMORAL STEMS

The biologic compatibility of ceramic materials has been widely demons trated, and alumina (Al2O3) has been used extensively in clinical appl ications for nearly 20 years. The authors examined the behavior of bon e tissue adjacent to the alumina coating in eight cementless hip prost hetic stems that appeared radiologically stable and were explanted bec ause of pain. Histologic evaluation demonstrated the presence of a con sistent layer of decalcified bone tissue in continuity with and parall el to the prosthetic interface. Based on laboratory findings, the auth ors attribute this demineralization phenomenon to a high local concent ration of aluminum ions with metabolic bone disease, which is histolog ically comparable to the osteomalacic osteodystrophy described in dial ysis patients. These findings must be carefully considered given the p otential long-term implications for alumina-coated implants.