No dislocation rate gap between single and two-stage revisions with a cementless Dual Mobility Cup

Introduction: A major complication of hip arthroplasty is dislocation. In revision, the rate of dislocation is even higher, especially among patients with hip prosthetic joint infection treated with two-stage surgery. The utility of a dual-mobility cup (DMC) in revision was already demonstrated but with a relatively low level of confidence due to the lack of direct comparison with other surgical techniques. We hypothesized that the dislocation rate for patients undergoing cementless DMC total hip arthroplasty (THA) would be similar between single and two-stage revisions. Methods: We conducted a single-center, retrospective, and case-control study from January 2011 through December 2020. During this period, 220 patients underwent a revision of their total hip arthroplasty. Among these, 40 patients experienced THA two-stage revision. This group constituted the cases in this case-control study. Each of the 40 cases was matched with 2 controls, single-stage surgery, on age, sex, and Paprosky grade, and we defined the groups according to primary endpoint: dislocation rate. Results: There was no significant difference in dislocation rate between two-stage and single-stage revisions (7.5% vs 3.8%, p = 0.40). In univariate analysis, auto-inflammatory disease and immunosuppressive agent use were risk factors for dislocation. There was no significant difference in dislocation-free survival (log-rank test, p = 0.40) or re-revision (log-rank test, p = 0.92) between single-stage and two-stage revision THA. At the end of follow-up, the mortality rate did not differ between the two groups. No chronic instability was noted at the last follow-up (80.4 ± 38.5 months) in both groups. Conclusion: The dislocation rate was similar between single and two-stage revision THA using DMC. Further studies are warranted to highlight the potential benefits of DMC in preventing dislocation in two-stage revision THA.