"Pes Planus or in vernacular "Flat feet" " (see related A)

Note: the foot is a very complex combination of parts able to sustain repeatedly the impact of the whole body weight. Apparently, "minor" alteration of the morphology and position of its component parts can result in major function disruptions (ambulation). Podiatry from podos=foot focuses on foot ailments and orthopedics (notion of "straight" and pedos as in pediatrics) on musculoskeletal pathologies.