A, Bilateral cornuate navicular and, on left, accessory navicular (white arrow) in 19-year-old woman. Note on left pronation of forefoot (evidenced by opening up of metatarsal-tarsal joint spaces), apparent widening of intermetatarsal spaces, and uncovering of fibular sesamoid compared with right foot. On standing lateral views of left foot, which had unilateral pes planus, talus is plantarflexed (B) compared with asymptomatic right foot (C). D, After excision of navicular flush with medial cuneiform, advancement of posterior tibial tendon distally, and lengthening of lateral column of foot with calcaneal opening wedge osteotomy (Evans procedure). Talonavicular joint reduced congruously but not with just advancement of posterior tibial tendon.