Patients who present with tarsal coalitions have myriad presenting symptoms, but the most common include foot pain, foot deformity, and a history of an injury or multiple injuries to the ankle or foot. The orthopaedic surgeon must always be suspicious of a tarsal coalition in a teenager with multiple ankle sprains.

The history should alert the orthopaedic surgeon to the possibility of a coalition, but the physical examination will all but confirm its presence. A stiff flatfoot is the hallmark of a foot with a tarsal coalition. This is especially dramatic in presentation when the pathology is unilateral (Figure 1). The findings for a calcaneonavicular coalition are (1) restricted subtalar motion; (2) a palpable, often tender, bony ridge in the sinus tarsi; and (3) restricted plantar flexion of the affected foot compared with the unaffected side^1,2,3 (Figure 1, B). A patient with a talocalcaneal coalition may present with a (1) bony prominence around the sustentaculum tali (just below the medial malleolus)¹⁰ and, of course, (2) restricted subtalar motion. Any of these findings should prompt further diagnostic imaging, as discussed below.

In my opinion, nonsurgical treatment of a symptomatic tarsal coalition does not benefit the patient long term. Periods of immobilization may provide temporary relief but do not address the altered mechanics that can cause adjacent joint degeneration. I also believe that patients with coalitions are at risk for future foot/ankle injuries due to the coalitions. I recommend excision in all young patients of age 21 years and younger.

Much has been written about diagnostic imaging of tarsal coalitions. Both the calcaneonavicular and talocalcaneal coalitions have radiographic signs named for them: the anteater sign (Figure 2, A) and the C-sign (Figure 2, B), respectively.^2,9 Plain radiographs can be helpful screening tools, but I believe that all patients going to the operating room for resection of a coalition should have a CT scan of both feet and, if at all possible, three-dimensional reconstructions of those images. These images are extremely useful not only to delineate the extent of the coalition in three dimensions but also to ensure that multiple coalitions are not present. MRI may be useful for a patient
with stiff talar motion but no obvious evidence of a coalition on a CT. Sometimes MRI will show fibrocartilaginous coalitions not seen on CT scan.

The spectrum of each type of coalition as seen on diagnostic imaging is detailed in two articles. Upasani et al³ described calcaneonavicular coalitions (Figure 3), and Rozansky et al⁴ described talocalcaneal coalitions (Figure 4).