[Posterior tibial tendon dysfunction].
Posterior tibial tendon dysfunction is the most common cause of acquired flatfoot in adults. The posterior tibial tendon is the primary dynamic stabilizer of the medial longitudinal arch of the foot. Various histological alterations in the tendon substance disrupt the normal linear structure of the collagen fibers. As a result the tendon weakens, elongates, tears and its function is compromised. This in turn places the static stabilizers of the arch under excessive stress, which eventually leads to their collapse and formation of pes planovalgus deformity. Many etiologies have been proposed as an underlying cause of posterior tibial tendon dysfunction. The average age at the time of presentation is forty years and many of the patients are women, white, obese and suffer from hypertension. The diagnosis is mainly based on clinical findings and supported by radiographic findings. Posterior tibial tendon dysfunction was classified by Johnson and Strom according to the appearance of pes planovalgus deformity, its flexibility and the development of arthritic changes in the subtalar and ankle joints. In Stage I there is no deformity, in Stage II there is a flexible deformity, in stage III there is a rigid deformity and in stage IV there is an involvement of the ankle joint secondary to long standing rigid deformity of the hindfoot. The initial treatment for any stage should be non-operative and includes immobilization and anti-inflammatory drugs for the acute phase and different kinds of orthotics for the chronic phase. Failure of the non-operative treatment is an indication for surgery. The surgical procedures for the first stage include soft tissue debridement with or without tendon transfer. The surgical procedures for second stage include tendon transfer combined with various osteotomies or joint fusions. The surgical procedures for the third and fourth stages are triple arthrodesis and pantalar arthrodesis respectively.