Lateral wedge insoles and their use in ankle instability

Abstract

The aim of the present study is to assess the immediate effects of applying lateral wedge insoles of different heights (0.00, 0.3, 0.4, and 0.6 cm) in patients with chronic ankle instability (CAI) in normal and supinated feet during a Star Excursion Balance Test (SEBT) and in the reflex response of Peroneus Longus (PL), Peroneus Brevis (PB), and Tibialis Anterior (TA) over a 30° inversion of the feet. The effects of the height of the wedges were assessed using a double-blind, crossover design. In total, 25 participants were allocated into two groups, depending on the foot posture (Normal = 12, Supinated = 13) and performed the tests in a random fashion. Reaction time (RT) of stabilizing muscles of the ankle was measured using superficial electromyography (EMG) and postural balance with the SEBT. Foot posture did not show any significant effects on the analyzed variables. Nonetheless, the use of a 0.3 cm external rearfoot wedge (PB p = 0.002; PL p = 0.066 and TA p = 0.006) and 0.6 cm (PB p = 0.043; PL p = 0.058 and TA p = 0.071) reduces RT in stabilizing muscles of the ankle and improves results in SEBT, except for the anterolateral direction, in subjects with CAI. Therefore, our results suggest that the use of lateral wedge insoles could reduce RT and improve dynamic balance in chronic ankle instability.

Keywords: SEBT; ankle instability; dynamic balance; lateral wedge; response time; surface electromyography.