Leg length discrepancy after total hip arthroplasty performed by direct anterior approach: a systematic review comparing surgical approaches and strategies for prevention

• Purpose: Leg length discrepancy (LLD) is a common complication following total hip arthroplasty (THA). The direct anterior approach (DAA) for THA is gaining popularity due to its advantages, but there is limited research on the incidence and size of LLD. This systematic review aims to explore the differences in LLD between DAA and other approaches, as well as the techniques to control LLD in DAA. • Methods: A comprehensive literature search was conducted to identify relevant studies comparing THA by DAA with other surgical approaches and investigating methods to control LLD in DAA, following PRISMA guidelines and a priori registration on PROSPERO (CRD42023412644). The quality of the included studies was assessed. Data on preoperative and postoperative LLD and other relevant outcomes were extracted and analyzed descriptively. • Results: In total, 29 studies were included in this systematic review. The majority (86%) were classified as level IV evidence. Comparisons between DAA and posterior approach (PA) or anterolateral approach (ALA) showed DAA had lower rates of LLD >10 mm compared to PA and ALA. Different pre- and intra-operative techniques were evaluated, but no consensus on the best method for preventing LLD in DAA was reached. • Conclusion: DAA shows comparable or superior results in the prevention of LLD compared to other surgical approaches. Supine patient placement, direct leg measurement, and the use of IF contribute to these outcomes. Intraoperative fluoroscopy with a grid and preoperative planning offers a good option, especially for training purposes, but its role in preventing LLD by experienced DAA surgeons needs further investigation.