Dual Mobility Versus Fixed Bearing Implants in Primary Total Hip Arthroplasty in Patients Under 55 Years of Age.

Introduction: Prosthetic dislocation after total hip arthroplasty (THA) is one of the most common causes of revision THA. Dual-mobility (DM) bearings were introduced to mitigate complications; however, there is minimal data on their performance in younger patients. This study compared results of patients who were under 55 years of age undergoing primary THA with DM or fixed-bearing (FB) implants.
Methods: A retrospective review of patients younger than 55 years who underwent primary THA with at least 2 years of follow-up between June 2011 and August 2019 was performed. Patients were stratified into two cohorts based on the implant they received (DM vs. FB). Primary outcomes were 90-day all-cause readmission, dislocation, all-cause revision, 90-day readmission and revision due to dislocation, and implant component survivorship. Demographic differences were assessed using chi-squared and independent samples t-tests. Outcomes were compared using multivariate linear and logistic regressions to control for confounding variables.
Results: A total of 803 patients were included (DM = 73, FB = 730). The DM and FB cohorts had similar rates of 90- day all-cause readmission (6.8% vs. 3.2%; p = 0.243) and 90-day readmission due to dislocation (4.1% vs. 0.8%; p = 0.653). At a mean follow-up of 4.42 ± 1.91 years, dislocation (4.1% vs. 1.1%; p = 0.723) and all-cause revision (5.5% vs. 4.9%; p = 0.497) rates between the DM and FB cohorts were similar. Kaplan Meier analysis yielded no significant differences in survivorship between groups for all-cause revision (95.1% vs. 94.5%; p = 0.923), revision due to dislocation (100% vs. 98.9%; p = 0.370), and acetabular component revision (97.3% vs. 98.6%; p = 0.418).
Conclusion: Dual mobility implants demonstrate similar dislocation rates and implant survivorship compared to FB in patients less than 55 years of age. Larger trials with long-term follow-up may be required to further elucidate the effects of DM bearings compared to FB inserts in younger patients undergoing primary THA.