Abstract
Alumina all-ceramic implants were first used in 1970 by Pierre Boutin in France and around 1972/3 in the rest of Europe. Thus the European ceramic experience is approximately 30 years. In the early 1980’s, the so-called Mittelmeier THR was introduced into the USA but the clinical results were generally far from satisfactory. However, the survivors now provide a useful benchmark of about 15–18 years in the USA. Perhaps as a result, the FDA has still not permitted use of all-ceramic THR in the USA. However, there are a number of new materials recently approved for use, including the highly crosslinked polyethylenes (HCLPE) and CoCr on CoCr. In anticipation of all-alumina THR being approved in the near future, we have examined the types of wear seen long term. Implants were retrieved after 15–25 years of successful use and compare to 10 to 20 million cycle simulator studies. This report examines the ball and cup wear seen on 2 Mittelmeier retrievals in the USA with that seen on a conventional all-ceramic THR retIn retrieved implants gray coloring matter was deposited on load-bearing area. Gray stripe areas were observed on the periphery of the head The SEM analysis showed that the main bearing area had high wear. The peripheral gray stripe area had severe wear. EDAX showed that gray color was caused by transferred CoCr particles. In the simulator study the wear progress was most sever in main load-bearing area.
All-ceramic implants had minimal wear even after 24 years. The surface of retrieved implants had different types of wear. The contact zones showed normal wear and showed relatively mild. In the periphery of the contact zones, the stripe scars corresponded with the cup rim tracking and more sever wear. Such stripe wear was not observed in the simulator experiments. The gray wear areas were caused by the metal contamination from micromotion of stem against bone. Thus, ceramic bearings proved to be excellent after 15–25years by simulator studies and clinical studies.
The abstracts were prepared by Nico Verdonschot. Correspondence should be addressed to him at Orthopaedic Research Laboratory, University Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
