Iatrogenic tensor fascia lata damage during direct anterior approach total hip arthroplasty: a prospective study of frequency, timing, and risk factors

The tensor fascia lata (TFL) muscle is prominent during the direct anterior approach (DAA) for THA and can be injured. This study aimed to determine patient or procedure-related risk factors for damage. One hundred consecutive THAs from November 2024 through March 2025 performed by a fellowship-trained surgeon were prospectively observed. Patient demographics and intraoperative data including choice of femoral fixation, and amount, location, and timing of TFL damage were collected. Femoral neck-shaft angle, femoral neck length, and iliac wing width relative to the femoral intramedullary canal were measured using preoperative radiographs. Iatrogenic TFL damage was classified as none (0%), minimal (< 10%), moderate (10–20%), and severe (> 20%). A multivariate linear regression determined if patient demographics, operative variables, or pelvic anatomy correlated with damage. Ninety-two of 100 cases (92%) demonstrated minimal to no TFL damage. Seven (7%) cases had moderate and one (1%) had severe damage. Five (71%) of the moderately damaged TFLs occurred during femoral exposure/preparation, while the other two (29%) occurred during femoral neck cut/head removal. The one severely damaged TFL also occurred during neck cut/head removal. A varus femoral neck-shaft angle ( P = 0.006), wide iliac crest ( P = 0.001), and choice of cemented femoral fixation ( P < 0.001) were associated with TFL damage (R 2 = 0.326, F(7, 92) = 5.72, P < 0.001). Severe TFL damage was uncommon in this exploratory single-surgeon series using a careful protective technique. A wide iliac wing, varus femoral neck-shaft angle, and cemented femoral stem were associated with increased risk of TFL damage.