Declining Revision Burden of Metal-on-Metal Hip Arthroplasties

Background: Adverse reactions to metal debris (ARMD) have been a problem with metal-on-metal (MoM) hip systems for a decade. Unacceptably high revision rates have been described for both stemmed MoM total hip arthroplasties (THAs) and hip resurfacings. The aim of this study was to report survivorship and temporal trends of hip revisions in patients with MoM hips.

Methods: We identified 2520 patients with 3013 MoM hip arthroplasties performed at our institution. These included 1532 primary stemmed MoM THAs, 1262 MoM hip resurfacings, and 219 stemmed MoM THAs implanted in revision surgery.

Results: Revision surgery was performed on 551 (36%) primary stemmed MoM THAs and on 179 (14%) resurfacings. The most common reason for revision was ARMD both among primary MoM THAs (83%) and hip resurfacings (70%). The 15-year implant survivorship was 69% (95% confidence interval [CI] 67-71%) for the whole study group, 56% (CI 53-60%) for stemmed primary MoM THAs, and 84% (CI 82-87%) for hip resurfacings. Clear temporal peak in the number of revisions for ARMD was seen in 2011-2013, and the trend has been decreasing since.

Conclusion: After a decade since outburst of the ARMD problematics with MoM hips, a large proportion of them have gone through revision surgery at our single high-volume center. The peak years were 2011-2013, and thereafter, the number of ARMD revisions has decreased every year. With the threshold for revision remaining constant at our institution, it is not likely that large amount of new cases of ARMD will be seen. As these results are derived from a single center's data, similar studies from other institutions are needed to see whether our results represent a global trend.