MRI of lateral hindfoot impingement.

Lateral hindfoot impingement (LHI) is a subtype of ankle impingement syndrome with classic MRI findings. Biomechanically, LHI is the sequela of lateral transfer of weight bearing from the central talar dome to the lateral talus and fibula. The transfer occurs due to collapse of the medial arch of the foot, most commonly from posterior tibial tendon (PTT) and spring ligament (SL) insufficiency. Clinical features include lateral hindfoot pain, deformity, and overpronation on gait analysis. MRI changes continuously reflect the altered biomechanics as the syndrome progresses over time, including typical and often sequential changes of PTT and SL failure, increasing heel valgus, talocalcaneal and subfibular impingement, and finally lateral soft tissue entrapment. In addition to diagnosis, MRI is a useful adjunct to plan surgical treatment.