boutonnièredeformitet

Boutonnière deformity is a condition affecting the finger, characterized by an abnormal bending of the finger at the middle joint, the proximal interphalangeal (PIP) joint, while the fingertip bends backward, towards the back of the hand. This results in a finger that resembles the eyelet of a buttonhole, hence the name.

The deformity typically arises from an injury to the extensor tendon at the base of the middle phalanx. This tendon is responsible for straightening the finger. When it is damaged, the central slip can tear, or the lateral bands that run along the sides of the finger can slip volarly (towards the palm). This disruption causes the PIP joint to become flexed and the distal interphalangeal (DIP) joint to become hyperextended.

Common causes of boutonnière deformity include direct trauma to the finger, such as a jammed finger, or inflammatory conditions like rheumatoid arthritis. In rheumatoid arthritis, the inflammation can weaken and damage the extensor tendon mechanism.

Symptoms include pain, swelling, and a characteristic loss of the ability to fully straighten the affected finger. The finger will appear bent at the PIP joint, with the tip extended. Diagnosis is usually made through a physical examination, observing the characteristic posture of the finger.

Treatment depends on the cause and severity of the deformity. For recent injuries, splinting may be used to hold the PIP joint in extension, allowing the injured tendon to heal. For older or more severe deformities, especially those associated with arthritis or stiffness, surgical intervention may be considered to realign the tendons or improve joint function. Rehabilitation with exercises to regain motion and strength is often a crucial part of the treatment process.