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ANZ J Surg. 2015 Mar;85(3):164-8. doi: 10.1111/ans.12868. Epub 2014 Oct 7.

Two-year serum metal ion levels in minimally invasive total conservative hip resurfacing: preliminary results of a prospective study.

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Mater Clinic, Specialist Orthopaedic Group, Sydney, New South Wales, Australia.



Metal-on-metal (MoM) hip resurfacings have been associated with the potential development of metallic debris and its associated pathology. Serum cobalt and chromium levels are a reliable surrogate marker of wear rates in MoM bearings. The aim of the study was to examine the trend in serum metal ion levels in the initial 2-year post-operative period following implantation of the minimally invasive total conservative hip MoM hip resurfacing and to determine whether head size, acetabular component orientation, clinical outcome scores or post-operative range of movement would affect these levels.


In this prospective cohort study, serum cobalt and chromium ion levels were measured pre- and post-operatively in 25 patients who underwent minimally invasive total conservative hip MoM hip resurfacing. The results were correlated with acetabular component orientation, head size, outcome scores and post-operative range of movement.


The mean serum cobalt and chromium levels at 2 years were 1.2 ppb (0.4-4.4 ppb) and 2.1 ppb (0.7-5.7 ppb). The mean cup inclination was 43° (30°-60°) and anteversion was 18° (1°-47°). There was no clear relationship between serum ions and acetabular component orientation, outcome scores or range of movement. Patients with a head size ≤52 mm had significantly higher metal ion levels (cobalt P = 0.02, chromium P = 0.045).


Our preliminary results show all patients had cobalt and chromium levels below those indicating a high-risk implant, suggesting successful early outcome from minimally invasive total conservative hip resurfacing surgery.


chromium ion level; cobalt ion level; hip arthroplasty; metal-on-metal joint prosthesis

[Indexed for MEDLINE]

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