Compensatory tibial torsion as a component of turnout in professional ballet dancers

Purpose Classical ballet emphasizes external rotation (ER) of the hip joint as the primary mechanism of turnout, with ideal turnout being 90 degrees in each leg. Due to anatomical constraints, few dancers are able to achieve this ideal without compensating elsewhere in the kinetic chain. One mechanism of compensation for inadequate hip ER is tibial torsion. The purpose of this study is to determine the contribution of tibial torsion to turnout in a sample of professional ballet dancers. Methods The study sample consisted of five male and five female professional ballet dancers. Using motion capture technology, each dancer was filmed completing barre exercises at three times during the performance season. Rotational movement at the femoroacetabular, tibiofemoral and tibiotalar joints was approximated using motion markers. Results While the majority of external rotation during all movements originated at the femoroacetabular joint, females demonstrated 12-14 degrees of turnout originating at the tibiofemoral joint, and males demonstrated 15-17 degrees. Across all movements, females demonstrated more turnout originating at the hip joint than males. Conclusions According to classical ballet aesthetics, a turnout of 90 degrees is expected in each leg, with only 5 degrees of total turnout originating from each knee joint. The degrees of turnout originating from the knee in this sample exceed these values. Furthermore, the use of non-invasive motion-based testing such as motion capture allows for the creation of a three-dimensional model which may be used for performance tracking and injury prevention in dancers.