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By Robert Trace
September 17, 2009

MANCHESTER – Researchers here reported that adverse soft tissue reactions
following metal-on-metal hip arthroplasty are typically due to increased wear of
the bearing surfaces, and patients with smaller femoral heads may be
particularly susceptible to these complications.

In an independent center study, David Langton, FRCS, and colleagues in the Joint
Replacement Unit at the University Hospital of North Tees in Stockton, England,
reviewed 155 Birmingham Hip resurfacings (BHR, Smith & Nephew) performed between
2002 and 2009 (mean follow-up, 60 months). They also studied 420 articular
surface replacements (ASRs) and 75 total hip replacements using ASR XL implants
(both DePuy Orthopaedics) with S-ROM stems (DePuy Orthopaedics) with a mean
follow-up of 35 months…

…There were 17 failures of this nature in patients with ASR implants (3.5%)
and no failures in the BHR group…

…Patients who had adverse reactions to metal debris (ARMD) had a mean femoral
size of 45 mm, a mean acetabular angle of 27° and a mean inclination angle of
53°. Among the asymptomatic patients, those numbers were 49 mm, 20° and 48°,
respectively…

…”I think we can say that the most important points are that increased wear
causes more complications, and all hip resurfacing systems are not the same,”
Langton said. “Also, we found that it is an issue of joint size and orientation,
rather than an issue of gender. And size does matter because men with femoral
components less than 49 mm have a 10% incidence of ARMD.”

Reference:
Langton D, Jameson S, Joyce T, et al. The incidence of adverse reactions to
metal debris (ARMD) following hip resurfacing with the articular surface
replacement (ASR) and Birmingham Hip Resurfacing systems (BHR). Presented at the
British Orthopaedic Association Annual Congress 2009. Sept. 15-18, 2009.
Manchester.