Subtalar instability of the foot. A review and results after surgical treatment.

Most subtalar ligamentous injuries occur in combination with ankle ligament injuries, but the exact aetiology and the true incidence remain unknown. The aim of this study was to review the problem, propose a definition and to analyze the results of an anatomic reconstructive surgical technique in the treatment of subtalar instability. Twenty-two patients suffering from chronic subtalar instability of the foot were operated with anatomical reconstruction. The cervical, the lateral talo-calcaneal and the calcaneo-fibular ligaments were imbricated and reinforced with the lateral root of the inferior extensor retinaculum. After a minimum of 2 years follow-up the functional results were excellent or good in 18 of 22 (82%) patients and fair or poor in 4 of 22 (18%). All of the patients with unsatisfactory results suffered from residual ankle pain, two of whom also had residual instability. No reoperations have been performed. Surgical complications were seen in three patients, all minor nerve injuries of the lateral branch of the superficial peroneal nerve. These complications had no bearing on the functional results, however. This procedure was found to be feasible in patients with chronic subtalar instability.