Is Dynamic Ultrasound Of Femoroacetabular Translation Increased In Female Dancers With Acetabular Dysplasia?

Abstract

BACKGROUND: Hip pain is common in dancers. A contributing factor to hip pathology in dancers may be the high prevalence of acetabular dysplasia. Dynamic ultrasound (US) of femoroacetabular translation has been shown as a reliable measure of femoroacetabular motion and may serve to assist in the evaluation of hip microinstability. Evidence regarding associations between acetabular dysplasia and femoroacetabular translation is unknown. PURPOSE: To investigate associations between acetabular dysplasia and dynamic US femoroacetabular translation in female dancers with hip pain. METHODS: Prospective cross-sectional study design. Dynamic US of femoroacetabular translation was performed in three positions: neutral (N), neutral with contralateral hip flexion (NF), and the apprehension position with contralateral hip flexion (EER flexed). Dysplasia was defined using radiographic measures: LCEA<25 or ACEA<20. Multivariable linear regression analysis was used to assess variation in femoroacetabular translation between dancers and non-dancers with and without dysplasia controlling for covariates. Independent variables included age, Beighton score, hypermobility (Beighton score≥5), BMI, and femoral version angles. P-values<0.05 were considered significant. RESULTS: The study included 64 female dancers and 92 non-dancer athletes. Dancers were younger (p=0.001), had a higher Beighton score (p=0.006), and were more likely to be hypermobile (p=0.005) compared to non-dancer athletes. Dynamic US femoroacetabular translation was not different in dancers with and without dysplasia (N, p=0.55; NF, p=0.78; EER flexed, p=0.93). Dancers showed greater dynamic US femoroacetabular translation when compared to non-dancer athletes in both the NF position (5.0±2.57 mm, 4.2±2.50 mm; p=0.04) and EER flexed position (6.0±2.53 mm, 5.2±2.41 mm, respectively; p=0.04). CONCLUSION: Acetabular dysplasia was not associated with increased dynamic US femoroacetabular translation in this cohort. Dancers showed increased US femoroacetabular translation compared to non-dancer athletes. This finding is likely related to increased ligamentous laxity and stretched ligaments inherent to dance training. Future research is warranted to collect data in asymptomatic dancers with and without acetabular dysplasia.