Metal ion levels and revision rates in metal-on-metal hip resurfacing arthroplasty 2014
Complete Study Here:
http://www.ncbi.nlm.nih.gov/pubmed/24500833
Robinson PG1, Wilkinson AJ, Meek RM. April 2014
Abstract
Metal-on-metal (MoM) bearings in hip surgery are related to increased blood
levels of metal ions. The nature of the relationship between ion levels and
failure is still not fully understood.
This study compares three cohorts of patients, 120 patients in each cohort,
treated with a hip resurfacing arthroplasty, grouped by brand and diameter of
femoral component on average four years postoperatively: Birmingham Hip
Resurfacing ≥50 mm, Durom resurfacing ≥50 mm and Durom resurfacing <50 mm.
The median blood ion levels of cobalt and chromium were significantly lower
in the cohort with the large Durom resurfacing than the other two cohorts
(P<0.05). The large BHR and large Durom HRA had revision rates of 3.3%. The
small Durom HRA had a revision rate of 8.3%. Elevated blood ion levels can
indicate a failing MoM bearing.
The large BHR and large Durom HRA have similar revision rates yet the large
Durom HRA had significantly lower metal ion levels. When similar ion levels were
reported for BHR and small Durom the latter had significantly higher revision
rates.
This suggests ion levels do not absolutely predict the rate of HRA failure.
Since MoM generation of metal ions is not the sole reason of failure, regular
clinical and radiographic follow-up should also be in place for patients with
these joints.