The present evidence indicated the similar performance in survivorship among CoC , CoPc , CoPxl and MoPxl bearing implants , and that all likely have superiority compared with the MoM and MoPc bearing implants in THA procedures .
PURPOSE Although many  total hip bearing implants  are widely used all over the world , simultaneous comparisons across the numerous available bearing surfaces are rare .
The purpose of this study was to compare the survivorship of total hip arthroplasty ( THA ) with six available bearing implants .
Comparison of polyethylene wear associated with cobalt-chromium and zirconia heads after total hip replacement. A prospective, randomized study.
BACKGROUND A ceramic femoral head is an alternative to a metal femoral head for the bearing surface of total hip arthroplasty . The purpose of this study was to compare polyethylene wear in patients who had undergone bilateral total hip arthroplasty with implants that differed only with regard to the material used for the femoral head : a zirconia head was used on one side , and a cobalt-chromium head was inserted on the contralateral side . METHODS A prospect i ve , r and omized study was performed to evaluate the outcomes in fifty-two patients who had undergone sequential bilateral primary total hip replacement . A zirconia head was used in one hip , and a cobalt-chromium head was used in the other . There were forty-eight men and four women ; the mean age at the time of surgery was 44.2 years . The mean duration of follow-up was 7.1 years . Clinical and radiographic evaluations were performed preoperatively and at six weeks ; three , six , and twelve months ; and yearly postoperatively . Linear wear of the polyethylene liner was measured radiographically . Two femoral components with a zirconia head had aseptic loosening and were revised . The explanted heads were evaluated with use of interferometry , environmental scanning electron microscopy , and x-ray diffraction studies . RESULTS The mean polyethylene wear rate was 0.08 mm/yr in association with the zirconia heads and 0.17 mm/yr in association with the cobalt-chromium heads ( p = 0.004 ) . The mean amount of volumetric polyethylene wear was 350.8 mm3 in association with the zirconia heads and 744.7 mm3 in association with the cobalt-chromium heads ( p = 0.004 ) . With regard to surface roughness , the Ra values of the two explanted zirconia heads were 15.87 and 17.35 nm and the Rpm values were 153.86 and 156.18 nm . Two identical zirconia heads that had not been implanted had Ra values of 5.31 and 5.48 nm and Rpm values of 65.27 and 66.35 nm . Four unimplanted cobalt-chromium heads that were identical to the ones implanted in this study had Ra values ranging between 25 and 50 nm and Rpm values ranging between 262.6 and 525.2 nm . Little phase transformation was noted in the two revised zirconia heads . CONCLUSIONS The mean amount and rate of polyethylene wear were significantly lower in the hips with a zirconia head than they were in the hips with a cobalt-chromium head , presumably because the zirconia heads had a smoother articulating surface
The present evidence indicated the similar performance in survivorship among CoC , CoPc , CoPxl and MoPxl bearing implants , and that all likely have superiority compared with the MoM and MoPc bearing implants in THA procedures .
PURPOSE Although many  total hip bearing implants  are widely used all over the world , simultaneous comparisons across the numerous available bearing surfaces are rare .
The purpose of this study was to compare the survivorship of total hip arthroplasty ( THA ) with six available bearing implants .