[Electromyographic analysis of the leg muscles in the hemiplegic patients with equinovarus deformity of the foot].

A series of EMG study of the leg muscles was carried out with a wire electrode in 86 hemiplegic patients of stroke to visualize the role of each muscle either in the development of equinovarus deformity of the foot or in correcting the deformity through tendon transfer. The muscles examined were anterior tibialis, posterior tibialis, gastrocnemius, soleus, flexor digitorum longus and peroneus brevis of the affected side. Tonic discharge of those muscles was recorded as the patients were elevating the affected leg in supine, sitting or standing posture or were standing on legs. On lifting up the affected limb, most patients showed electrical activity of anterior tibialis with or without simultaneous activity of other muscles, most frequently with that of flexor digitorum longus or gastrocnemius. When the patient stood on legs electromyographic discharge appeared most frequently in soleus. Varus deformity of the foot significantly correlated to the lack of the electrical activity of peroneus brevis. Both such abnormal activity of anterior tibialis and the lack of activity of peroneus seemed to be the main causes for the varus deformity. Postoperative EMG study in the patients who underwent Watkins-Barr procedure of anterior transfer of the posterior tibialis tendon, showed that the posterior tibialis was rather inactive both in elevating the leg and in standing on legs. Varus deformity was corrected independent of the discharge of posterior tibialis. The author concluded that the correction of the varus deformity after Watkins-Barr procedure was mainly obtained from the tenodesis effect. The tenodesis provides the checkline effect on the equinus and varus deformity, which reinforces the dorsiflexing action of anterior tibialis and attenuates its inverting action of the same muscle.