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The occurrence of pseudotumours following metal-on-metal hip resurfacing arthroplasty (MoMHRA) has been associated with high serum metal ion levels and consequently higher than normal bearing wear. Measuring ground reaction force is a simple method of collecting information on joint loading during a sit-to-stand (STS). We investigated vertical ground reaction force (VGRF) asymmetry during sit-to-stand for 12 MoMHRA patients with known serum metal ion levels. Asymmetry was assessed using two methods: a ratio of VGRF for implanted/unimplanted side and an absolute symmetry index (ASI). It was found that subjects with high serum metal ion levels preferentially loaded their implanted sides. The difference between the two groups was most apparent during the first 22% of STS. VGRF ratio showed significant and strong correlation with serum metal ion levels (Spearman's rho = 0.8, p = 0.003). These results suggest that individual activity patterns play a role in the wear of MoMHRA and preferential loading of an implanted limb during the initiation of motion may increase the wear of metal-on-metal hip replacements.

Original publication

DOI

10.5301/hipint.5000115

Type

Journal article

Journal

Hip international : the journal of clinical and experimental research on hip pathology and therapy

Publication Date

22/01/2014

Volume

24

Pages

20 - 26

Addresses

1 Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS), University of Oxford, Oxford - UK.

Keywords

Hip Joint, Humans, Foreign-Body Reaction, Prosthesis Failure, Metals, Gait, Arthroplasty, Replacement, Hip, Reoperation, Follow-Up Studies, Hip Prosthesis, Movement, Stress, Mechanical, Aged, Middle Aged, Female, Male, Mass Spectrometry, Biomechanical Phenomena