Researchers set safe upper limit metal ion levels
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Researchers set safe upper limit metal ion levels for metal-on-metal hip resurfacings Orthopedics Today, July 2012 An award-winning study by researchers from Belgium identified safe upper limits of 4.6 µg/L for chromium and 4.0 µg/L for cobalt in unilateral metal-on-metal hip resurfacing arthroplasties and 7.4 µg/L for chromium and 5.0 µg/L for cobalt in bilateral procedures. “Levels higher than [these] established limits were significantly correlated with clinical symptoms, smaller component size, a smaller coverage arc, smaller contact patch to rim distance and a higher cup inclination,” Catherine Van Der Straeten, MD, said. “Females and small head sizes are more at risk of having problematic hips.” “These upper acceptable limits are lower than the recommended threshold by the Medicines and Healthcare Products Regulatory Agency [in the United Kingdom],” Van Der Straeten said. “But, we had low tolerance for what we call the clinically problematic hip.” |