Post-traumatic arthritis and avascular necrosis are common sequelae following acetabular fractures, often leading to conversion to total hip arthroplasty (THA). Traditionally, conversions to THA have been performed through posterior or direct lateral approaches, which navigate through scar tissue and previously placed implants. The direct anterior approach (DAA) is increasingly adopted for these conversions, as it accesses a 'virgin' surgical plane, potentially reducing the risks of infection and neurovascular injury. This study aims to compare clinical outcomes and complication rates between the DAA and traditional approaches in conversion THA after acetabular fracture fixation.

A retrospective review was conducted of acetabular fractures treated at a Level-I trauma center between 2008 and 2021. Patients were grouped by surgical approach (direct anterior (DA), posterior (P), or direct lateral (DL)). The study included patients with a minimum of one-year follow-up. Outcomes measured included Harris Hip Score (HHS), complications necessitating reoperation, infections, blood loss, surgical time, transfusions heterotopic ossification (HO) removal, acetabular implants encountered during reaming, and THA implants used.

Seventy-one patients were included: 30 in the DA group, 28 in the P group, and 13 in the DL group. The mean follow-up time was 51 months. No significant differences in demographics were found. The DA group had significantly higher HHS (90.1) compared to the P (70.5) and DL groups (84.8, p < 0.001). Blood loss was significantly lower in the DA (440 mL) and direct lateral (304 mL) groups compared to the posterior group (547 mL, p = 0.04). The DA group had no infections, the posterior group had 4 infections, and the DL group had one infection (p = 0.10). At final follow-up, the DA and DL groups had significantly higher HHS: 90.1 (DA) and 84.8 (DL) compared to 70.5 (P) (p < 0.001).

Conversion THA after acetabular fracture remains a high-risk procedure with significant complication rates. The DAA offers a safe and effective approach, with lower complication rates and superior functional outcomes compared to traditional approaches. This approach may reduce infection rates and neurovascular complications in straightforward cases. For complex cases involving extensive bone loss or acetabular defects, a more extensile approach may be necessary.