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What Factors Increase the Risk of Dislocation After Primary Total Hip Arthroplasty Using the Direct Anterior
Michael P Murphy1, Caitlin R Forti1, Henry Ho1
1Anderson Orthopaedic Research Institute, Alexandria, Virginia.
The Journal of Arthroplasty
|June 12, 2026
Summary
Women undergoing direct anterior approach total hip arthroplasty with smaller femoral heads face a higher dislocation risk. Precise acetabular cup positioning is crucial for minimizing this complication.
Area of Science:
- Orthopedic Surgery
- Arthroplasty Research
- Biomechanical Engineering
Background:
- Direct anterior approach (DAA) for total hip arthroplasty (THA) offers reduced dislocation risk but does not eliminate it.
- Dislocation after THA can be severely debilitating, necessitating identification of risk factors.
- Understanding DAA-specific dislocation predictors is vital for patient safety and surgical outcomes.
Purpose of the Study:
- To identify patient, surgical, and radiographic factors associated with dislocation risk in primary THA using the DAA.
- To analyze a large cohort of DAA THAs over a 15-year period.
- To provide evidence-based recommendations for reducing dislocation after DAA THA.
Main Methods:
- Retrospective analysis of 8,658 primary DAA THAs performed between March 2009 and May 2024.
- Cox proportional hazards regression to assess patient demographics and implant characteristics.
- Matched case-control analysis to evaluate radiographic parameters (cup orientation, offset, limb length, coverage).
Main Results:
- Overall dislocation rate was 0.5% (45/8,656).
- Women exhibited a higher dislocation rate (0.7%) compared to men (0.2%).
- Increased dislocation risk in women was associated with 28 mm (HR 7.5) and 32 mm femoral heads (HR 3.8).
- No significant differences in total offset or limb length change; however, controls had lower cup inclination variance (P=0.01).
Conclusions:
- Women using smaller diameter femoral heads (28mm, 32mm) are at significantly higher risk of dislocation after DAA THA.
- Precise acetabular cup positioning, indicated by lower inclination variance in controls, is critical for preventing dislocation.
- While DAA THA has a low dislocation rate, targeted risk factor identification can further improve patient safety.