Dancers With Functional Ankle Instability

Ankle inversion sprains are the second most common cause of disability in both the dancing and the general populations5,8,12 causing symptoms of pain, swelling, decreased range of movement, and weakness at the ankle.15 Disabling symptoms of pain and swelling, feelings of instability and stiffness, and recurrent sprains continue to affect up to 60 % of people 12 months after simple sprain.4,10,34 Despite the high incidence of ankle sprain, the reasons that patients continue to experience ongoing symptoms of disability, particularly functional instability, are unknown. Those factors widely thought to account for chronic ankle instability (for example, impaired proprioception, weak peroneal muscles) have rarely been investigated during the common injuring mechanism, that is, during sudden ankle inversion while weightbearing on the plantar-flexed foot.27 The only factor that has been investigated under such conditions is muscle reaction time, mainly of the per-oneal muscles6,9,16,19,21,26,30 with inconclusive findings. The current study aimed to compare measures of senso-rimotor control of the ankle during quiet stance with these measures after an inversion perturbation in dancers with chronic ankle instability or healthy uninjured ankles. Sensorimotor control of the ankle was quantified by the amount of lateral oscillation occurring at the ankle during quiet standing and by the time taken to return to quiet standing after a sudden inversion perturbation. These measurements were made in two positions of the foot: the foot placed flat on the floor and the foot on demi-pointe (a ballet position in which the subject stands on the toes, that is, with the weight of the body resting on the metatarsals)