The difference in clinical results between the direct anterior approach (DAA) and the anterolateral approach (ALA) for total hip arthroplasty (THA) is still unclear. The purpose of this study was to compare clinical results, including nerve injuries, between DAA and ALA in one-stage bilateral THA in a prospective, randomized controlled trial.
Thirty patients were recruited for primary bilateral THAs from 2014 to 2016. The left and right hips of each patient were randomly assigned to DAA and the others to ALA. We prospectively compared the clinical results, incidence of lateral femoral cutaneous nerve (LFCN) injury, and tensor fascia lata (TFL) atrophy considered to be related to superior gluteal nerve injury between both approaches.
No significant difference was found in the clinical results between both sides at postoperative 1 year. Temporary symptom of LFCN injury was observed only in DAA sides (7/30, 23.3%). The ratio of 3-month postoperative to preoperative cross-sectional area of TFL on computed tomography was significantly lower on the side subjected to DAA (DAA side, 78.8 ± 22.8%) than on the side subjected to ALA (ALA side, 90.7 ± 17.7%) (p < 0.01). In magnetic resonance imaging at postoperative 1 year, the mean grade of fatty atrophy of TFL by Goutalier classification was significantly higher in DAA sides (2.00 ± 1.6) than in ALA sides (1.1 ± 1.3) (p = 0.03).
Excellent clinical results for both DAA and ALA were achieved. LFCN injury was found only in DAA sides. Although TFL atrophy was found in both approaches, it was found significantly more in DAA sides. Our study suggested that ALA should be used rather than DAA in terms of the risk of nerve injuries.