Biomechanical Comparison of Pediatric Female Ballet Dancers With and Without Pain

Abstract

BACKGROUND: Across all genres of dance, studies have reported musculoskeletal injury in 20-84% of dancers with 95% reporting a history of musculoskeletal pain. Compared to other dance styles, ballet dancers specifically are most affected by musculoskeletal injuries. The purpose of this study is to compare movement patterns and muscle activity in pediatric female pre-professional dancers with and without self- reported pain, using the Patient-Reported Outcomes Measurement Information System pediatric numeric rating scale.   We hypothesize dancers reporting pain will exhibit compensatory strategies, such as asymmetrical movement patterns and muscle activity, across a series of ballet movements. METHODS: A total of 55 female ballet dancers who train en pointe were seen for testing (age 14.4±1.9 years), with 34 dancers (62%) self-reported pain in the 7 days preceding testing. Biomechanical testing, performed in pointe shoes, included performance of static (5 classical ballet positions) and dynamic ballet movements (développé, arabesqué and grand jeté) while instrumented with surface electromyography (EMG) to capture muscle activity and inertial measurement (IMU) dual sensors on the trunk and lower extremities to capture movement patterns. The experimental setup allowed for measurement of trunk and lower extremity muscle activity, as well as trunk, hip, knee, and ankle joint angles in the sagittal, coronal, and transverse planes. Student’s t-test was used to compare the pain and no pain groups across all variables with statistical significance set to α=0.05. RESULTS: Movement patterns and EMG differences were seen between groups.  During first and third positions, the right (non-barre sided) leg demonstrated less external knee rotation in the pain group (p≤0.05). In fifth position, the left (barre-sided) leg exhibited increased ankle flexion (p=0.048), reduced hip abduction (p=0.027), and reduced knee adduction (p=0.026) in the pain group. The pain group exhibited decreased trunk flexion/extension range-of-motion during the grand jeté (p=0.004), and increased trunk rotation range-of-motion when performing the arabesqué en pointe (p=0.034). Rectus femoris activation was reduced for the pain group on the left leg in fifth position (p<0.03). The up leg in the pain group during the développé (flat) showed increased hamstring activation (p=0.04). CONCLUSION: Ballet dancers with pain exhibited differences in movement patterns while performing certain ballet movements, notably during fifth position, grand jeté, and arabesqué (en pointe). Additionally, dancers with pain exhibited reduced rectus femoris activation in fifth position and increased hamstring activation on the working leg during the développé (flat). Future work should investigate how movement patterns and muscle activation in ballet dancers vary by location and severity of reported pain.