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Further investigation needed for assessment, treatment protocols of ASR implants
Among patients with Articular Surface Replacement metal-on-metal hip products, the relationship between MRI pathology, metal ion levels and acetabular inclination angles remains unclear, and further investigation is required for setting up protocols for assessment and treatment, according to researchers.
After the recall of the Articular Surface Replacement (ASR) system (DePuy International), the researchers compiled a database of 359 patients who had arthroplasties performed using this system from January 2005 until November 2009. MRI scans of 143 patients who had the ASR system in situ were reviewed.
Study results showed 59% of patients had cobalt values above the recommended blood levels and 44% of patients had chromium values above recommended blood levels. Cobalt and chromium ion levels were significantly higher among patients who had periprosthetic fluid collection, according to the researchers.
No relationship between the presence of a periprosthetic mass, bone marrow oedema or trochanteric bursitis and cobalt or chromium metal ion levels was observed, nor did the researchers find any association between greater levels of abductor muscle destruction and cobalt or chromium ions.
Levels of periprosthetic tissue reaction and acetabular inclination angle had no association with any of the pathologies identified on MRI, according to the researchers.
Disclosure: The authors have no relevant financial disclosures.