Peroneal muscle function in chronically unstable ankles. A prospective preoperative and postoperative electromyographic study.

In 33 patients with unilateral chronic ankle instability, peroneal muscle function was evaluated by surface electromyography (EMG) pre- and postoperatively. Twenty-six patients had a static reconstruction using the whole peroneus brevis tendon and seven patients had a dynamic one using only the anterior half of the tendon. At plantar flexion the peroneal EMG activity was markedly higher in men than in women, otherwise there were no differences between the sexes. Neither pre- nor postoperatively were there any significant differences between the patients' healthy and diseased legs. Postoperatively and after physiotherapy, there was a significant increased peroneal activity in both legs of the patients. The peroneal EMG activity was increased after operation, although the type of operation seemed to make no difference. A difference between the two types of reconstructions could only be shown at dorsal flexion, with the higher response in the dynamic reconstructed patients, because of the existing tension elicited of the remaining intact half tendon. This difference is probably not important for peroneal muscle function. Peroneal neuromuscular integrity was intact and independent of preoperative instability and the method of reconstruction.