The vertical mobility of the first tarsometatarsal joint during demi-plié with forced turnout in ballet dancers

Abstract

Abstract The forced turnout has a perceived risk of the development of hallux valgus (HV) in ballet dancers. We determined how the forced turnout affects the sagittal mobility of the first tarsometatarsal (TMT) joint, which is one of the pathogenic factors of HV development. Seventeen female ballet dancers were included and performed demi-plié in three conditions; control, functional turnout, and forced turnout. Ultrasound imaging synchronized with a three-dimensional motion analysis system was used for measuring the vertical locations of the first metatarsal and medial cuneiform (MC) to evaluate the first TMT joint mobility. Plantar displacement of MC and the first TMT joint mobility in the forced turnout was the greatest among the 3 conditions. Multiple regression analysis showed that the extent of the forcing angle was associated with the displacement of MC and the first TMT joint mobility. Evaluating the sagittal mobility of the first TMT joint in the forced turnout can assist in understanding the association between inappropriate techniques including the forced turnout and HV development in ballet dancers. Since the excessive mobility of the first TMT joint is one of the factors of HV development, the acquirement of adequate active turnout may have the potential to prevent HV development in ballet dancers.