A flexural deformity is a stance or limb deviation that is visible from the side. It is caused by an incongruity between the length of a bone (in the limbs) and a tendon. If the tendon is relatively too long one speaks of a tendon laxity or a tendon hypoflexion: the most frequent example of this is the laxitiy of the digital flexor tendons in foals leading to hyperextension of the phalangeal joints and a 'toe-up' conformation. Relatively too short tendons also known as contracted tendons are also most commonly seen in the digital flexor tendons: a club foot is the result of a deep digital flexor tendon contracture, an extremely upright pastern (knuckling forwards at the fetlock) is the result of a superficial digital flexor tendon contracture.