Tear of the posterior tibial tendon causing asymmetric flatfoot: radiologic findings.

Abstract

The purpose of this study was to describe the preoperative radiographic appearance of the acquired asymmetric flatfoot caused by a tear of the posterior tibial tendon. These radiographic changes reflect the loss of tendon function and the development of flatfoot deformity. Preoperative radiographs of 30 patients (mean age, 48 years) with surgically proved complete tears of the posterior tibial tendon were evaluated. Erect anteroposterior and lateral views of the feet were obtained in all patients and were frequently supplemented with anteroposterior views of the ankles to evaluate valgus tilt. Calcaneal plantar, talocalcaneal, and talometatarsal angles were measured on radiographs and compared with the measurements in normal control subjects. Additional osseous and soft-tissue abnormalities were also evaluated. Findings on preoperative radiographs of the foot were abnormal in 50% of patients. These abnormalities included decreased calcaneal plantar angle (50%), increased lateral talometatarsal angle (47%), increased anterior talocalcaneal angle (43%), and increased lateral talocalcaneal angle (13%). Bone and soft-tissue abnormalities included osteoporosis (37%), medial soft-tissue swelling (27%), tarsal osteoarthritis (20%), distal tibial proliferative changes (7%), and the presence of accessory navicular bones (17%). Multiple abnormalities of the intertarsal relationships are seen as a result of tears of the posterior tibial tendon with the development of hindfoot valgus, midfoot abduction, and forefoot pronation.