Posteromedial Ankle Impingement Caused by Hypertrophy of Talocalcaneal Coalition: A Report of Five Cases and Introduction of a Novel Index System

Ankle impingement syndromes are common disorders that can be attributed to many factors. To the best of our knowledge, posteromedial ankle impingement syndromes caused by talocalcaneal coalition have never been previously reported. The present report describes 5 patients with posteromedial ankle pain and inversion limitation. The physical examination, radiographic, and magnetic resonance imaging findings suggested posteromedial ankle impingement syndrome and talocalcaneal coalition. The 5 patients underwent surgery after conservative treatment had failed. A novel index system, namely the angle and thickness of the medial talocalcaneal facet, was introduced. The talocalcaneal coalitions protruded medially and impinged on the malleolus medialis. The medial facet of the talus and calcaneum had a wider angle and thickness than normal. Pain relief was noted, and good long-term outcomes were achieved after resection of the medial prominence and coalition in all 5 patients. Talocalcaneal coalition can cause posteromedial ankle impingement syndrome when the coalition is hypertrophic. The angle and thickness of the medial talus facet could be a simple index to diagnose this disorder.