Dynamic simulation of flexor digitorum longus tendon transfer for flatfoot treatment

Tibialis posterior muscle dysfunction leading to adult acquired flatfoot deformity. Tibialis posterior muscle dysfunction is commonly treated with a flexor digitorum longus tendon transfer to the tubercle of navicular bone. In recent years, the dynamic computer modeling has been used to predict the results of surgical and treatment. The aim of this study was to provide a dynamic computer model of flexor digitorum longus tendon transfer for predicting the outcome of flat foot treatment. In this study the 3D model of ankle joint, which consists of 29 bones and 12 muscles was developed in OpenSim. Using software, ankle plantar flexion moment, metatarsophalangeal joints moment and inversion moment of subtalar joint were drawn. After flexor digitorum longus tendon transfer, there were decreases ankle plantar flexion moment (6.7%), metatarsophalangeal joints moment (45%) and inversion moment of subtalar joint (34%). Plantar flexion moment reduction caused no significant changes in the ankle joint, but reduction in metatarsophalangeal joints could limit heel lift during propulsive phase in walking or running. A decreased inversion moment at the subtalar joint could alter the biomechanics of lower extremities.