Abstract
The muscle strength of the peroneal muscles in foot and ankle disease as well as in a control group were analysed in 120 feet (60 cases) . Among the patient group, those with ankle and subtalar instability numbered 20 feet, and those with ankle and subtalar osteoarthritis numbered 41 feet. The control group consisted of 26 feet.
The average strength of peroneal muscles measured using an original apparatus with a strain gauge to measure the muscle strength at ankle eversion, was 4.4 kg±0.8 in the control group. Muscle strength was distributed from normal to weak in the instability group, and in the osteoarthritic group was less than 80 per cent of the control group. Muscle strength was found to be related to the term of disease, general joint laxity, clinical evaluation and radiographic stage.
The results revealed that pain in the foot and ankle and instability of the ankle and subtalar joint cause a weakness in the muscle strength of the peroneal muscles; therefore the patient experiences giving way and is conscious of an unstable feeling in the ankle. There are two factors involved in giving way in the foot; one is the static factor resulting from the degree of ligamentous instability, and the other is the dynamic factor resulting from weakness of the peroneal muscles.
