Indications for Use of Dual Mobility Demonstrate Significant Differences in Subsequent Instability

Introduction: Dual mobility (DM) constructs are a well-established alternative to mitigate dislocations and instability following primary and revision total hip arthroplasty (THA).However, the effectiveness of DM constructs is hypothesized to vary markedly depending on the specific surgical indication.This study aimed to quantify the rates of subsequent dislocation in DM constructs across various primary and revision surgical indications.Methods: A retrospective cohort analysis was conducted on 488 consecutive THA procedures utilizing DM implants.Patients were stratified into three utilization groups: primary THA (n = 193), conversion THA (n = 55), and revision THA (n = 240).The revision group was further subdivided based on the index reason for revision, including instability, periprosthetic joint infection (PJI), aseptic loosening, periprosthetic fracture, and adverse reaction to metallic debris (ARMD).The primary outcome measure was postoperative dislocation.The influence of indication, surgical approach, patient demographics, anatomical factors, and comorbidity scores on dislocation risk was assessed using multivariable analysis.Results: With a mean follow-up of 36.1 months (zero to 148), the overall rate of postoperative dislocation was 4.7% (23 of 488).Dislocation rates differed across the main indications: 3.1% (six of 193) for primary THA, 0% (zero of 55) for conversion THA, and 7.1% (17 of 240) for revision THA (P = 0.05).Analyzing the revision cohort (n = 240) separately, the failure rate by etiology was 5.8% (four of 69) for PJI, 6.5% (four of 62) for aseptic loosening, 5.7% (three of 53) for instability, 0 (zero of 15) for periprosthetic fracture, and 25% (six of 24) for ARMD.Within the revision cohort, revision due to ARMD was strongly associated with failure on multivariable analysis (P < 0.001). Conclusions:The utility of DM constructs in mitigating dislocations varies substantially by indication.Revision THA for ARMD carries a disproportionately high risk of subsequent dislocation even with DM constructs, warranting patient counseling and more aggressive surgical strategies for obtaining stability in these high-risk groups.