Extraarticular lateral hindfoot impingement with posterior tibial tendon tear: MRI correlation

Posterior tibial tendon dysfunction with secondary hindfoot valgus can lead to painful extraarticular, lateral talocalcaneal, and subfibular impingements, often necessitating surgical intervention. The purpose of this study was to correlate findings of lateral hindfoot impingement with grading of posterior tibial tendon tears and severity of hindfoot valgus on MRI.

MR images from 75 patients (45 women and 30 men) with MRI evidence of posterior tibial tendon tears were evaluated for grade of posterior tibial tendon tear, hindfoot valgus angle, osseous contact or opposing marrow signal changes at the talus-calcaneus or fibula-calcaneus, peroneal tendon subluxation-dislocation, and presence of lateral malleolar bursa. Statistical analyses were performed using Cochran-Armitage, Fisher's exact, and Mann-Whitney tests.

Twenty-eight cases (37%) of lateral hindfoot impingement were identified, including six talocalcaneal, eight subfibular, and 14 talocalcaneal-subfibular impingements. The prevalence of impingement was significantly increased with greater MRI hindfoot valgus angle (p < 0.001). The prevalence of talocalcaneal-subfibular impingement significantly increased with grading of posterior tibial tendon tear (p = 0.018). Peroneal tendon subluxation was present only with advanced hindfoot valgus (p = 0.010) and impingement (p = 0.004). There was no significant association between the presence of lateral malleolar bursa and hindfoot valgus severity.

Extraarticular lateral hindfoot impingement is associated with advanced posterior tibial tendon tears and increased MRI hindfoot valgus angle. Peroneal tendon subluxation likely represents an end stage of lateral impingement in patients with posterior tibial tendon dysfunction.