Swan neck deformity: What causes our hand to look like a swan’s neck
swan neck deformity of the hand of a 50 years old patient Swan neck deformity is described as fixed flexion of the distal interphalangeal (DIP) joint and extension of the proximal interphalangeal (PIP) joint . It is also described as hyperextension at the PIP joint with flexion at the DIP joint . This deformity is the reverse of the boutonniere or button-hole deformity. The mechanism for the development of swan neck deformity is linked to chronic synovitis. This chronic synovitis can lead to: Rupture or stretching of the extensor tendon on the dorsum of the DIP joint. Secondary to stretching of the volar plate at the PIP joint. Shortening of intrinsic muscles of the hands that exert tension on the dorsal tendon sheath, leading to hyperextension of the PIP joint. Swan neck deformity can occur in the fingers. It is a characteristic deformity that may develop with long-standing uncontrolled disease, specifically in the context of rheumatoid arthritis .