Central Slip Tear (Boutonniere Deformity)
A central slip tear, also known as Boutonniere deformity, is the name given to a rupture of the extensor tendon of the finger as it travels over the middle joint, or the proximal interphalangeal (PIP) joint, of the finger. It typically occurs as a result of direct injury to the finger by a solid object (eg. basketball or football) which causes the finger to flex (forward bend) beyond its intended limit, stretching the extensor tendon that attaches to the joint, resulting in extension tendon rupture. The result is a gradual deformity of the finger where an over bending of the DIP joint occurs while the PIP joint remains straight. This shape is referred to as a Boutonniere Deformity.