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Mallet Finger

By

Danielle Campagne

, MD, University of California, San Francisco

Last full review/revision Mar 2021| Content last modified Mar 2021
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In Mallet finger, the fingertip curls down and cannot be straightened. It is usually caused by a tendon injury.

Mallet finger usually results when the tendon that attaches bone to muscle in the fingertip is torn. This tendon (called the extensor tendon) is used to straighten the fingertip. Usually, the tendon is torn when a force causes the fingertip to bend more than it normally does. A common cause is a baseball that hits the fingertip and jams it. Thus, mallet finger is sometimes called baseball finger.

One or more fingers may be affected. Sometimes the joint is also dislocated.

When the tendon tears, it may pull a piece of bone from the finger (called an avulsion fracture). When an avulsion fracture occurs, the cartilage at the end of the affected bone (the joint surface) is also fractured.

Mallet Finger

People with Mallet finger cannot straighten the end of their finger.

Mallet Finger

Symptoms of Mallet Finger

The finger is usually painful, swollen, and bruised immediately after the injury. The joint remains bent. The person cannot straighten it. Occasionally, blood collects under the nail (called a subungual hematoma).

Diagnosis of Mallet Finger

  • Physical examination

  • X-rays to check for fractures

Doctors can usually diagnose mallet finger when they examine the finger.

X-rays are usually taken at several different angles to check for a fracture.

Treatment of Mallet Finger

  • A splint

Usually, doctors straighten the finger, then place a splint on it to hold it in a position that is bent slightly upward (in extension). The splint is worn for 6 to 8 weeks.

Rarely, when a fracture involves a large part of the joint surface or when the joint is dislocated, surgery is needed.

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