Clinical wear and simulator study of ceramic-ceramic THR to 20years and beyond

摘要

This study is the first report to grade the micro wear progress in clinical and simulator wear of ceramic on ceramic bearings to equivalent of 20years use. 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 retrieved in Vienna after 24 years. In SEM study wear severity was classified into 5 grades. In 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 (Grade 4). The peripheral gray stripe area had sever wear (Grade 5). 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 (Grade 4). 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 15-25 years by simulator studies and clinical studies.