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Metal-on-metal hip resurfacing yields component wear rates similar to modular THR
Matthies A. J Bone Joint Surg - Br. 2011; doi: 10.1302/0301-620X.93B3.25551.
Failed metal-on-metal hip resurfacing and modular total hip replacements have similar component wear rates, according to United Kingdom researchers. Both procedures are also linked to increased pre-revision blood levels of metal ions.
Ashley Matthies, BSc, and colleagues at Royal National Orthopaedic Hospital and Imperial College of London compared component wear rates and pre-revision blood metal ion levels in 240 failed metal-on-metal hip resurfacing and modular total hip replacement (THR).
They found no significant difference for either group in the median rate of linear wear for acetabular and femoral components. There was also no significant difference in the median linear wear rates when they compared failed hip resurfacing and modular THR of the same type (ASR [DePuy Orthopaedics, Inc.] vs. Birmingham hip resurfacing [Smith & Nephew]).
This study found no significant difference in pre-revision blood metal ion levels between hip resurfacing and modular THR, the authors wrote.
Although they saw edge loading in both groups, they found it was more common in the resurfacing group (67%) compared with the modular group (57%). This finding did not research statistical significance. “We attribute this difference to retention of the neck in resurfacing of the hip, leading to impingement-type edge loading,” the authors wrote. “This was supported by visual evidence of impingement on the femur.”