Analysis of Muscle Strength and Gait after Excision of Hamstrings and Effect of an Ankle- foot Orthosis: A Case Report

Abstract

Background: Limb-sparing surgery is important for treatment of soft tissue sarcoma, but resection of major neurovascular bundles and/or muscles in the lower extremities causes motor and gait dysfunction. This case report documents the effect of an ankle-foot orthosis on muscle strength and gait in a 52-year-old woman who had limbsparing surgery for soft tissue sarcoma that removed the common peroneal nerve and hamstring muscles (biceps femoris, semimembranosus, and semitendinosus). Methods: The patient underwent knee flexor strength testing with and without the ankle-foot orthosis. Gait analysis was performed with and without the ankle-foot orthosis using a 3-dimensional motion analysis system, along with recording of the surface electromyogram and collection of ground reaction force data with a multicomponent force platform. Results: After surgery, the maximum torque of the knee flexor muscles was higher when the patient used the ankle-foot orthosis than without it. Gait analysis demonstrated improvement of knee flexion with the ankle-foot orthosis. The surface electromyogram showed that gastrocnemius activity was increased markedly by using the ankle-foot orthosis. Conclusions: Using an ankle-foot orthosis allowed gastrocnemius to act more effectively as a knee flexor after resection of the hamstrings. An ankle-foot orthosis may improve the gait of patients with hamstring resection.