Degree of Hallux Valgus Is Associated With Dynamic Foot and Knee Kinematics in Ballet Turnout Movements.

Abstract

Hallux valgus (HV) is a common forefoot deformity that may compromise lower-extremity biomechanics, particularly during turnout movements in ballet. However, the kinematic consequences of dynamic high-load, turnout-specific dance tasks remain unclear. This study investigated the relationship between the degree of HV and lower-extremity joint kinematics in ballet dancers. Fourteen female ballet dancers with visible HV (mean HV angle: 26.5 ± 8.6 degrees) performed 3 tasks: <i>demi-plié, sauté</i>, and <i>grand jeté</i>. A 10-camera motion capture system and a force plate were used to assess foot and knee kinematics during task-specific peak-load phases. Across tasks, the mean medial longitudinal arch angle ranged from approximately 136 to 141 degrees. Significant positive correlations were observed between HV angle and midfoot-forefoot inversion during all tasks (<i>r</i> = 0.61-0.76, <i>P</i> < .05). During the <i>grand jeté</i>, a greater degree of HV was also associated with an increased medial longitudinal arch angle (<i>r</i> = 0.64, <i>P</i> = .04), greater knee valgus (<i>r</i> = 0.64, <i>P</i> = .04), and reduced hindfoot-midfoot inversion (<i>r</i> = -0.64, <i>P</i> = .04), reflecting a pronated foot posture and altered kinetic chain alignment. In this small case series, greater HV was correlated with altered foot and knee kinematics, particularly under high-load, single-leg conditions. These results underscore the importance of task-specific assessments in dancers. Level IV, case series.