Blood metal ion levels help determine low-risk ARMD patients


A new study suggests that blood metal ion levels can determine patients who have a low risk of having adverse reactions to metal debris (ARMD).

Patients who receive metal-on-metal artificial hips tend to be at risk of having complications due to ARMD. However, researchers discovered that blood metal ion levels that are specific to the hip implant used could help predict who is at a lower risk of ARMD.

Implant surfaces sliding over each other on the artificial joint can cause patients to develop ARMD. It is recommended that patients have their levels of chromium and cobalt ions in the blood measured as part of their follow-up to help with early detection of ARMD. Doctors have not agreed whether specific blood metal ion levels should be a concern after metal-on-metal hip replacements. So, the researchers suggest that implant-specific thresholds could be a better indicator of patients who have a low risk of developing ARMD.

Researchers tested this method on 710 patients with 803 metal-on-metal hip replacements who received the Birmingham Hip Resurfacing (BHR) implant and the Corail-Pinnacle implant, two common metal-on-metal hip replacements. Implant-specific and fixed regulatory authority cutoff points for blood metal ions were tester for how well their numbers correlate with diagnosed ARMD. The researchers found that there was 12% after single-hip BHR replacement, 18% after double-hip BHR replacement and 7% after single-hip Corail-Pinnacle replacement.

Implant specific cutoff points were also a good indicator of patients who have and don’t have ARMD. The amount of patients who had ARMD and had ion levels above the implant-specific threshold ranged from 65% to 79% in three test groups. The percentage of patients who didn’t have ARMD and had ion levels below the threshold was 93% to 97% across the test groups.

The researchers suggest that overall, implant-specific cutoff points detected 97.2% of ARMD cases and fixed regulatory authority cutoff points missed up to 6.5% of cases.

The was done at Wolters Kluwer Health and was performed by Dr. Gulraj S. Matharu. It was published in the Journal of Bone and Joint Surgery.

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