• The patient is observed for an antalgic gait, characterized by a decreased stance phase on the affected extremity, and the position of the foot during stance phase is evaluated. Patients will often present with an out-toeing gait.

• Hindfoot and midfoot alignment is examined. Patients with a tarsal coalition will typically present with hindfoot valgus and abduction across the midfoot.

• The patient is evaluated for flattening of the medial longitudinal arch.

• A single-leg heel rise will assess the flexibility of the flatfoot deformity. Failure to reconstitute the arch of the foot is indicative of a rigid hindfoot and suggests the presence of some abnormality within the subtalar or transverse tarsal joints, such as a tarsal coalition.

• Point tenderness may be elicited plantar to the medial malleolus in the region of the sustentaculum tali.

• The hindfoot is inverted and everted while stabilizing the ankle joint, and compared to the contralateral side. Tarsal coalitions are associated with pain and limitation of subtalar motion.

• Anteroposterior (AP), lateral, and oblique views of the foot are obtained.

• The lateral view of the foot (Fig. 1A) is evaluated for a continuous C-shaped line between the posterior aspect of the talar dome and the posterior facet of the subtalar joint (C-sign).

• A Harris axial view may demonstrate a middle-facet talocalcaneal coalition (Fig. 1B), although commonly a computed tomography (CT) scan is necessary to adequately identify it.

• Standing AP, lateral, and Saltzman hindfoot alignment views may be used to assess alignment. A Saltzman view can be useful to quantify hindfoot valgus.

• A small bump may be placed on the contralateral hip to facilitate this position.