Posterior Tibial Tendon Dysfunction

Posterior tibialis tendon dysfunction is the most common cause of acquired flatfoot deformity in adults. It is most commonly caused by chronic tendinopathy with subsequent functional impairment from elongation or rupture and it is most often seen in patients with obesity, diabetes mellitus, hypertension, and systemic inflammatory diseases. Degenerative tears occur most often distal and posterior to the medial malleolus in the critical zone of hypovascularity. There is a characteristic deformity consisting of hindfoot valgus, forefoot abduction, loss of the longitudinal arch, and, with increasing hindfoot valgus, a compensatory forefoot supination. The diagnosis is usually clinical. There is medial pain and swelling, pain or inability to perform a single heel rise, loss of the medial longitudinal arch, hindfoot valgus, and forefoot abduction identified by a positive “too many toes sign.” It is classified from stages I through IV based on the amount and flexibility of deformity. Radiograph findings are consistent with flatfoot deformity. Magnetic resonance imaging is not necessary for the diagnosis. Initial treatment should be conservative using cast immobilization for acute pain and dysfunction, and orthotics in the subacute and chronic cases. Surgery is indicated only when conservative measures fail, and the goal is restoration of normal foot alignment. Surgical decision making is influenced by the amount of deformity, as well mobility of the joints. Particularly important is the assessment of forefoot supination. Procedures include FDL reconstruction, calcaneus osteotomy, and arthrodesis, including isolated subtalar fusion, talonavicular fusion, double arthrodesis, and triple arthrodesis.