On physical examination she is five feet, seven inches tall, and weighs 165 pounds. With her heel held in neutral she has 10 degrees of forefoot varus. Radiographs demonstrate loss of the longitudinal arch with sag at the talonavicular joint on lateral and abduction on the AP with uncovering of the dome of the talus. Posterior tibial dysfunction is the most common cause of the acquired flat foot deformity in the adult. It does represent a spectrum of disease and ranges from mild tendinitis to complete rupture of the posterior tibial tendon and collapse of the medial longitudinal arch of the foot.
Advanced stages produce significant hindfoot valgus and excessive forefoot abduction.
Radiographically, this has been described by Hansen as representing peritalar subluxation where the calcaneus and navicular sublux around the inferior and anterior aspects of the talus. Historically, there have been multiple techniques described to reconstruct the ruptured posterior tibial tendon. Mann has popularized the transfer of the flexor digitorum longus and this has gained wide acceptance in the orthopaedic community. This technique preserves toe function by anastomosing the distal aspect of the flexor digitorum to the flexor hallucis longus. In that the majority of patients cannot wiggle their lesser toes independent of the great toe because of normal tendinous interconnections between these two tendons, there is generally no perceived donor deficit.