Ankle sprains are among the most common sport-related injuries and can lead to chronic ankle instability. Impaired sensorimotor function of the ankle musculature is often suggested as a cause. The current study sought to assess and compare the isokinetic performance and electromyographic patterns of evertor and invertor muscles in patients with chronic ankle instability and in a control group. Twelve patients with chronic ankle instability and twelve healthy subjects were included. Isokinetic eccentric and concentric testing at various angular velocities was performed for eversion and inversion movements. The corresponding myoelectric activities of the fibularis longus and tibialis anterior muscles were quantified from surface electromyographic recordings by computing average root mean square values. Patients had lower myoelectric activity of the evertor and invertor muscles than controls did; this difference could account for the eccentric weakness associated with ankle instability. Functional strength ratios revealed a dynamic strength imbalance in unstable ankle patients and that may contribute to recurrent injury. Our findings suggest that rehabilitation programs for unstable ankle patients must be focused on the motor control of eccentric contractions of the ankle evertors and invertors, to boost these muscles’ contribution to ankle stabilization.

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BACKGROUND: Information on altered foot pressures during ambulation would clarify how far limb deformities modify walking patterns in cerebral palsy (CP), and whether such data can inform prognosis and guide rehabilitation. OBJECTIVE: To compare patterns of plantar pressures during walking between children with CP and their able-bodied (AB) peers. METHODS: Twenty-five children/adolescents (10 with hemiplegia, 5 with diplegia, and 10 AB, respective ages 13.0 ± 1.9, 13.0 ± 0.6 and 14.0 ± 0.7 years) walked a 12 m line at a self-selected speed. Spatio-temporal parameters and peak in-shoe plantar pressures were recorded for both feet, using the Parotec analysis system. RESULTS: Walking speeds (m·s −1 ) differed significantly between groups (0.65 ± 0.13, hemiplegia, 0.93 ± 0.22 diplegia and 1.26 ± 0.05 AB), with shorter stride lengths in CP. Contact time, double support time and step duration were also shorter in hemiplegia. Plantar pressures differed substantially and consistently between AB and CP, with increased medial heel pressures in hemiplegia, and reduced hallux and lateral heel pressures but increased lateral, medial mid-foot and first metatarsal pressures in diplegia. CONCLUSIONS: Substantial alterations in spatio-temporal parameters (greater in hemiplegia than in diplegia) and plantar pressure distribution reflect attempts to compensate for poor stability of posture in CP. Further study of these adaptive changes holds clinical promise in providing data relevant to the design of orthotics, determinations of prognosis and the planning of neurorehabilitation.

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