Ankle & hindfoot (question 15): a free FRCS (Tr & Orth) Section 1 question

This is the lateral talo-first metatarsal angle of Meary. On the normal weight-bearing view shown, a line along the axis of the talus continues along the shaft of the first metatarsal, so the angle is close to zero. When the medial arch collapses the talar head drops plantarwards and the two lines meet at an angle whose apex points to the sole, at the joint where the arch has given way, usually the talonavicular or naviculocuneiform joint. An apex pointing dorsally means a plantar flexed first ray, as in a cavus foot. The metatarsophalangeal joint lies beyond the measured segment, and the subtalar joint is not on the line of the medial column. The view must be weight bearing, as the deformity may correct when the foot is unloaded. Reference: Coughlin and Mann's Surgery of the Foot and Ankle 9e; Miller's Review of Orthopaedics 8e.