(HealthDay News) – Elevated blood cobalt concentrations are associated with an increased risk of early joint failure in metal-on-metal (MoM) hip resurfacings secondary to the development of an adverse local tissue response, according to a study published online March 12 in BMJ Open.

David J. Langton, from University Hospital of North Tees in the United Kingdom, and colleagues retrospectively analyzed the clinical course of 278 patients with “no pain” or “slight/occasional” pain and a Harris Hip Score ≥95 at the time of venesection. A blood metal ion screening program was initiated in 2007 for all patients with Articular Surface Replacement (ASR) and Birmingham MoM hip resurfacings. Annual assessment was used unless symptoms presented earlier. Ultrasound scan and joint aspiration was utilized in symptomatic patients.

The researchers found that blood cobalt concentration was a positive and significant risk factor (z=8.44) for joint failure. The Birmingham Hip Resurfacing posed a significantly reduced risk for revision by 89% (z=-3.445). Men had a 66% lower risk of joint failure than women (z=-2.29419; P=0.0218).

“The results suggest that elevated blood metal ion concentrations are associated with early failure of MoM devices secondary to adverse reactions to metal debris,” the authors write.

Several authors disclosed receiving payments for travel, testimony, or product endorsements from pharmaceutical companies.

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