Quantitative identification of ankle equinus with applications for treatment assessment

Abstract

A quantitative, objective technique has been developed to assist the clinician in the diagnosis and treatment of ankle equinus deformity. Gait patterns were analysed using a tibial nerve block (TNB) to assist in isolating the passive contributions to the ankle plantar flexor torque from the active. Kinematic and kinetic data were collected prior to and following a TNB, which were used to help identify the primary aetiology (i.e. spasticity or contracture) of equinus for each case. Several key gait parameters were investigated both for the subjects without foot deformities and those with equinus. The results demonstrated several statistically significant differences between the subjects with and without equinus. These differences involved: (1) the relative contribution of passive properties to internal ankle moment during walking, (2) the transfer of weight along the length of the foot, and (3) the angular displacement of the ankle from initial foot contact to early peak plantar flexion. Furthermore, two patients with ankle equinus were evaluated with this protocol both prior to and following surgical Achilles tendon lengthening procedures. Substantial changes in the walking patterns of these individuals were observed following surgery.