Lessons from 1st generation Ceramic on Ceramic THA
The alumina head on alumina cup combination was first implanted by Boutin in 1970 with Mittelmeier following with Autophor design in 1972. Such ceramic on ceramic bearing articulation have been used over 30 years and is being used more widely now. The clinical performance of these first generation alumina on alumina THA revealed very variable results between excellent to very poor. The unfavorable results of 1st generation alumina on alumina THA is not due to wear and wear related problems like as in metal-polyethylene THA but mainly due to mechanical failure. This high rate of mechanical failure was due to poor implant design and surgical technique, and most of ceramic articulation performed well and did not contribute to the unsatisfactory results. Some survived 1st generation ceramic THA without loosening shows excellent results without osteolysis. The reported wear rate of ceramic on ceramic combination is very low and is about one fortieth to eighties of wear rate of conventional metal-polyethylene. But some retrieved ceramic heads and sockets shows severe wear comparable to the conventional metal-polyethylene combination. These unexpectedly excessive wear is usually shown in the joints with high inclination of ceramic cup. Osteolysis which is the most common serious problems of metal-polyethylene articulation is extremely rare or minimal in ceramic on ceramic articulation. Even though early clinical use of 1st generation ceramic on ceramic combination was disappointing because of component loosening and fracture, previous data of 1st generation alumina ceramic bearings demonstrates much more wear resistance. These clinical proofs can give us belief that modern alumina ceramics which have a much lower porosity, lower grain size, and higher purity can provide more safe and durable joints.