The anatomical features of the lateral femoral cutaneous nerve with total hip arthroplasty: a comparative study of direct anterior and anterolateral supine approaches

Background: Lateral femoral cutaneous nerve (LFCN) injury after total hip arthroplasty causes patient dissatisfaction. This cadaveric study aimed to assess the risk for LFCN injury after the direct anterior approach (DAA) and anterolateral supine approach (ALS) with a focus on the anatomical variations of the LFCN. Methods: Thirty-seven hemipelves from 20 formalin-preserved cadavers (10 males and 10 females) were dissected to identify the LFCN, evaluate variations, and measure the distance from the LFCN to each approach. The LFCN was classified as classical, late, multi trunk, or primary femoral. Results: There were no significant variations in the LFCN between the sexes. The distance from the LFCN to DAA incision (10 [0–17.8] mm) was significantly less than that from the LFCN to ALS incision (27 [0–40] mm); moreover, 64.9% of DAA incisions crossed the LFCN. The classical type LFCN was closest to the DAA incision. The DAA incision most frequently crossed the LFCN at the proximal third, and the frequency of intersection of the LFCN and DAA incisions decreased by 25% by a 10-mm shortening of the DAA proximal incision. In contrast, 27% of ALS incisions crossed the LFCN. Multi trunk type LFCN was closest to the ALS incision. There were no significant differences between each approach and LFCN variations, and the frequency of intersection of the LFCN and ALS incisions decreased by 20% by a 10-mm shortening of the ALS proximal incision. Conclusions: The intersection rates between the LFCN and the DAA and between the LFCN and the ALS were approximately 65 and 30%, respectively. Approximately 20–25% of these injuries may be avoidable by a 10-mm shortening of the proximal incision.