Fig. 1From: Relationship between the presence of abnormal hallux interphalangeal angle and risk of ingrown hallux nail: a case control studyObliquity angle: A tangent was drawn to the articular surface of the proximal phalangeal head (a, b). A perpendicular line (c, d) was then extended from the longitudinal bisection of the proximal phalanx. Obliquity is the angular relationship between this perpendicular line and the mentionated tangentBack to article page