Is dual mobility associated with an increased risk of revision for infection? Matched cohort of 231 cases of dual-mobility cups and 231 fixed cups

We used a matched cohort of 231 cases of revision of primary dual-mobility cups (DMC) total hip arthroplasty (THA) and 231 cases of fixed cups (FC) THA, to determine whether (i) revision for infection was more frequent when using DMC-THA than FC-THA; (ii) Causes for revision were significantly different.

The French Society of Orthopaedics and Traumatology carried out a prospective multicentre study from 2010 to 2011. The inclusion criterion was an exhaustive collection of 1^st revision THA (at least 1 component revised, re-revision excluded). 2,044 1^st revision cases were prospectively collected; 251 (13.5%) were revision of DMC-THA and 1,793 were revision of FC-THA (87.7%). We defined a matching process (1:1) between the 2 cohorts. 231 DMC-THAs were eligible for comparison with 231 FC-THAs.

47 (20.3%) FC-THAs were revised for infection and 54 (23.3%) DMC-THAs. There was no statistical difference (p = 0.43). 41 (17.7%) FC-THAs were revised for dislocation, compared to 11 (4.7%) DMC-THAs (p<0.001).

The main finding of our study was that DMC was not associated with an increased risk of revision for infection compared to standard THA. THA revision for infection was not correlated to the type of cup used. It is mandatory to report on comparable types of patients when comparing outcomes. For similar patient profiles (i) DMC-THAs were not revised more often for infection than FC-THA (ii) FC-THAs were revised 4 times more for dislocation than DMC-THA.