A review of tarsal coalition and pes planovalgus: clinical examination, diagnostic imaging, and surgical planning.

Pediatric pes planovalgus deformity may be classified as flexible or rigid. The rigid pes planovalgus is often a result of a tarsal coalition, which is typically characterized as a painful unilateral or bilateral deformity, frequently associated with peroneal spasm. However, many tarsal coalitions are asymptomatic and demonstrate no peroneal spasm or pes planovalgus deformity. Likewise, the severe pes planovalgus foot type can demonstrate some of the same clinical and radiographic features of a tarsal coalition, especially in the obese adolescent patient. Also, peroneal spasm may occur in the noncoalesced foot, making diagnosis and etiology more difficult to elucidate. The authors believe that many patients with a pes planovalgus deformity lie in this "gray zone": somewhere between the frank osseous coalition and the flexible pes planovalgus. The "step-forward Hubscher maneuver" is introduced as an effective means of evaluating the flexibility of a pes planovalgus foot by negating the effects of a gastrocnemius or gastrocnemius-soleus equinus. This article focuses on the clinical examination and findings of specific imaging studies to assist in an accurate diagnosis of these complicated patients. This will also help to reveal the various surgical options that are appropriate for the individual patient. Emphasis is placed on computerized tomography (CT) imaging and offers enhanced methods for ordering this test to specifically evaluate middle facet coalitions of the subtalar joint. The authors also introduce "lateral tarsal wedging," an image finding associated with severe deformities, the implications of this finding, as well as its impact on surgical planning.