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Background: The large-diameter metal-on-metal hip prostheses were expected to have low wear and reduced dislocation rate compared to the traditional metal-on-polyethylene implants. We compare 2 such prostheses, the ReCap resurfacing implant and the M2a-Magnum stemmed implant, with the C2a ceramic-on-ceramic stemmed implant as to clinical performance, serum concentrations of prosthesis metals, and the durability of the implants in a randomized, controlled clinical trial at 7 years of follow-up.Methods: All included patients had osteoarthritis. Preoperatively, the size of the implants was estimated from a magnetic resonance imaging (MRI) scan. Follow-up data included serum cobalt and chromium concentrations, Oxford and Harris Hip Scores, leg press and abduction force, 6-minute walk distance, WOMAC and SF-36 self-assessment scores, and from the 7th postoperative year also ultrasonography (US) examination of the soft tissue adjacent to the implant as well as MRI with metal artifact reduction sequence (MARS-MRI) when indicated.Results: One hundred fifty-two hips in 146 patients were included. The serum cobalt and chromium concentrations were significantly higher for the 2 metal-on-metal prostheses than for the ceramic-on-ceramic, with the M2a-Magnum as the highest. No significant difference was found between the groups concerning physical performance measurements and scores as well as dislocations and prosthesis survival. Five revisions were done and concerned all groups, for reasons of pain, high serum cobalt and chromium concentrations, cystic fluid collection around the joint, and infection. Metal concentrations, US, and MARS-MRI contributed to the decision making regarding prosthesis revision.Conclusion: Metal concentrations were significantly higher for the metal-on-metal prostheses than for the ceramic-on-ceramic. The clinical performance was good in all 3 prosthesis groups. Metal concentrations, US, and MARS-MRI findings were of use to identify hips needing revision. ID Number in ClinicalTrials.gov PRS: NCT00284674. [ABSTRACT FROM AUTHOR]

We perform a non-randomized, consecutive pilot study on the ASR and ReCap resurfacing hip implants and have completed 7 years follow-up. Forty-six non-osteoporotic patients with hip osteoarthritis and anatomical conditions suitable for resurfacing were divided into 2 equal groups and operated sequentially, starting with the ASR implants. Sixteen patients operated with ASR and 19 patients with ReCap have been followed-up. There were no significant differences between the two groups preoperatively as to physical function, pain, or femoral BMD. The serum concentrations of cobalt and chromium were higher in the ASR group from 1/2 to 7 years postoperatively. Five of 16 ASR implants have been revised, and none of the ReCap implants. BMD below the femoral component increased in both groups. [ABSTRACT FROM AUTHOR]