What is it?

Mallet injury is an injury that causes a typical mallet deformity in the finger. The injury occurs from a sudden flexion force on the distal interphalangeal joint (DIP joint) of the finger. This causes a rupture of the extensor tendon or an avulsion fracture of the base of the distal phalanx.

Normal Finger	Ruptured Tendon	Avulsion Fracture

This frequently happens in basketball or volleyball, when the ball hits the point of the finger, causing it to flex forcibly at its tip.

What are the symptoms?

The patient presents with a crooked finger, bent at the last joint of the finger the so-called mallet deformity. If the tendon is ruptured, and there is no fracture, the injury is quite painless. However, the patient is unable to extend or straighten the DIP joint on his own.

What does your doctor do about it?

An X-ray will usually show if the mallet injury caused the extensor tendon rupture, or an avulsion fracture. In a young child, the avulsion fracture involves the growth plate, and is known as an epiphyseal plate injury.

In most cases, the treatment involves splinting the DIP joint with an aluminum splint (or a commercially made splint). The objective of splinting is to keep the DIP joint in hyperextension, thus allowing the ruptured ends of the extensor tendon to heal properly. In case of an avulsion fracture, hyperextension of the DIP joint will reduce the fracture back into position and allow it to heal properly. Six weeks of splinting is usually needed. Surgery is only needed in some cases.