Comparison of Short-Term Outcomes and Survivorship of Three Modular Dual Mobility Implants in Primary Total Hip Surgery.

Background

Total hip arthroplasty (THA) is a common procedure, yet instability and dislocation remain leading causes of revision. Dual mobility (DM) acetabular constructs improve stability, but comparative data across modular DM systems are limited. This study compared the safety and efficacy of three modular DM implants in primary THA, focusing on acetabular revision and functional recovery.

Methods

We retrospectively reviewed 963 primary THAs performed from 2016-2024 using three modular DM systems. Patients with revision or bilateral THA, age < 18, or <2 years of follow-up were excluded. Outcomes included acetabular revision, 90-day readmission, and Hip Disability and Osteoarthritis Outcome Score for Joint Replacement (HOOS, JR). Kaplan-Meier analysis estimated 3-year implant survivorship for each implant, and non-inferiority of Implant A was tested against a combined "Dual Mobility Control" cohort (Implants B + C) using a prespecified -10% margin.

Results

A total of 297 patients met inclusion criteria (142 Implant A, 110 Implant B, 45 Implant C). Revision rates were 4.9% for Implant A, 6.4% for Implant B, and 8.9% for Implant C. HOOS, JR scores improved significantly in all cohorts with comparable 2-year outcomes. Kaplan-Meier analysis showed 3-year survivorship of 98.3% for Implant A, 98.4% for Implant B, and 96.9% for Implant C (log-rank p = 0.053). The Dual Mobility Control cohort survivorship was 98.0%, and the difference between Implant A and controls (95% CI: -2.19% to 2.69%) met the non-inferiority margin (log-rank p = 0.796).

Conclusions

Implant A demonstrated non-inferior 3-year survivorship and comparable short-term patient-reported outcomes relative to two other modular DM implants. Larger, multicenter studies with longer follow-up are warranted to confirm these findings.