Posterior Subtalar Facet Coalition with Calcaneal Stress Fracture

Abstract

2Present address: Hawkes Bay Hospital New Zealand, Private Bag 9014, Hastings, New Zealand. Address correspondence to D. C. Moe. arsal coalition is an abnormal union (fibrous, cartilaginous, or osseous) between two tarsal bones, with a reported incidence of 1–2%. Most (90%) occur at the calcaneonavicular and talocalcaneal joints [1]. Talocalcaneal coalition usually involves the middle subtalar facet. It rarely occurs at the anterior or posterior facet [2]. Diagnosis of talocalcaneal coalition can be made by radiographs, CT, or MRI. CT classically is held as the gold standard for imaging this entity [3]. However, MRI has been reported to be equally efficacious and often is the choice when other diagnoses are considerations [3]. In this article, we present a novel case of MRI-proven partial posterior subtalar facet coalition with associated medial and lateral calcaneal stress fractures. To our knowledge, this has never been reported. Case Report A 48-year-old woman presented to the Sports Medicine Clinic with 3 months of worsening left heel pain, without preceding accident or injury. Initially she had tenderness at the origin of the plantar fascia. Stretching and arch supports were prescribed for the treatment of presumed plantar fasciitis. However, over several months she continued to suffer from chronic medial calcaneal pain, at times severe. Initial hindfoot radiographs, consisting of lateral and Harris (axial) views, were interpreted as normal. In retrospect, the lateral radiograph of the foot shows a subtle osseous protuberance at the superior margin of the calcaneal tuberosity, creating an abnormal “humpback” appearance (Fig. 1A), which is readily apparent when compared with a lateral radiograph of a normal foot (Fig. 1B). The Harris view of the T