The Association Between Hip Biometrics And Femoroacetabular Translation Evaluated With Dynamic Ultrasonography In Professional Ballet Dancers

PURPOSE: To examine the association between femoral rotation, ligamentous laxity and iliopsoas flexibility with dynamic ultrasound (US) measures of femoroacetabular translation in professional dancers. METHODS: A cross-sectional cohort study was performed on 90 dancers 18-38 years. Hip biometrics included Trochanteric Prominence Angle Test (TPAT) for femoral rotation and Beighton score. Anterior femoroacetabular US measures included: neutral (N), neutral-flexed (NF), extension-external rotation (EER) (d’Hemecourt PD et al, CORR 2019) and posterior measures: neutral (PN), flexion, adduction, internal rotation (PFADIR), stand-and-load (PStand) (Le H et al, Skeletal Radiol 2024). Femoroacetabular translation was calculated using the mean (mm) difference between NF and EER positions and PN and PFADIR positions, respectively. RESULTS: Table 1 presents descriptive statistics and table 2 the association between biometrics and US measures. 180 hips were evaluated, (1,080 images). The median Beighton score was 5 (3-7), median Thomas test for left hip 28 (25-30) and TPAT 12.3 ± 2.22; and median Thomas test for right hip 28 (25-30) and TPAT 11.7 ± 4.97. TPAT demonstrated correlation to PFADIR (left r = 0.23, right r = 0.27; p = 0.05) and posterior translation (left r = 0.24, right r = 0.29; p = 0.05). No other association was found for hip biometrics and US measures. CONCLUSION: Our study found no association between femoroacetabular translation measured using dynamic ultrasound and generalized laxity or iliopsoas flexibility in professional ballet dancers. Femoral rotation may be a factor in posterior hip translation.