Hard-on-hard bearings showed advantages of reduction of wear rates, osteolysis and aseptic loosening in total hip arthroplasty (THA). A new combination of ceramic-on-metal (COM) was developed to compensate the disadvantages of MOM and COC. COM showed good short-term results in vitro and in vivo studies. There was no report of stripe wear and metal ion level elevation. Our study was designed to evaluate the wear pattern of this bearing in early loosening THA. During January 2009 to December 2010, 121 primary THAs were performed at our institution by single-surgeon, using the same acetabular component and same uncemented femoral stem with a 32-mm modular head. All patients received the information of the bearing couples and made their own decision to choose one of the following bearings: COM, MOP and MOM. The functional outcomes (Harris Hip Score), Serum Co and Cr levels and survival rates were compared between groups at 5 years. The retrievals were tested by optical microscopy and Raman spectroscopy to evaluate the wear pattern in the cases those need revision.Background
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