Patients Following Revision Total Hip Arthroplasty With Modular Dual Mobility Components and Cobalt-Chromium Inner Metal Head are at Risk of Increased Serum Metal Ion Levels.

BACKGROUND

Modular dual-mobility (MDM) total hip arthroplasty (THA) is designed with a cobalt-chromium liner inserted into a titanium acetabular component. The purpose of this study is to investigate the potential risks for fretting corrosion at this junction, by measuring serum metal ions, after MDM acetabular revision.

METHODS

Thirty-seven patients with well-functioning revision THAs participated in a cross-sectional study at mean 5.1 (2-10) years after surgery. All received a trabecular titanium MDM acetabular component. The serum levels of cobalt and chromium were measured using mass spectrometry.

RESULTS

The mean values of chromium and cobalt were 2.08 μg/L (95% confidence interval 0.9-3.2, range 0.02-11.8) and 1.99 μg/L (95% confidence interval 0.81-3.17, range 0.07-16.05), respectively. Eleven patients (29, 7%) had ion levels above the normal range, with 6 (16.2%) above 5 μg/L and 5 (13.5%) between 1 and 5 μg/L. A significant correlation was found between an elevated serum metal ion level and University of California Los Angeles score (P = .016).

CONCLUSION

We conclude that serum metal level elevation may occur secondary to metal debris resulting from corrosion of the index MDM THA. This potential risk should be included in the decision-making process when dealing with revision arthroplasty in young and active patients.