Mallet finger

What is a mallet finger?

A mallet finger describes a condition in which the end of a finger is bent (flexed) towards the palm and cannot straighten.

What causes a mallet finger?

The usual cause is an injury to the end of the finger. The injury tears the tendon that straightens (extends) the end of the finger.

It is sometimes called baseball finger, as it is a common injury when trying to catch a fast, hard ball. If the catch is missed slightly then the ball hits the straight finger. This may force the end of the finger to bend (flex) further than normal and tear the tendon. Without the use of this tendon, the finger stays bent (flexed).

Diagram of the hand showing mallet finger

Sports injuries are a common cause of mallet finger. However, any injury that forces the end joint of a finger to over-bend can cause it. (Sometimes the tendon does not tear but the injury causes a piece of bone to be pulled off the finger where the tendon is attached. The result is the same, as the tendon then cannot pull on the bone.)

What are the symptoms of a mallet finger?

After the injury, the end of your finger may become painful and swollen. The end of that finger will lie in a bent (flexed) position and you will not be able to straighten (extend) it at the end.

What is the treatment for mallet finger?

A splint is worn for 6-8 weeks to keep the finger straight with the end joint bent backwards slightly (overextended). It must be worn all the time, day and night. There are many different types of splints available. The type of splint given often depends on the size and shape of your finger. You must not take the splint off at any time during this treatment. If you have to take it off (for example, to wash) then you must keep that finger straight and not allow it to bend (flex). Keeping the finger straight constantly allows the two ends of the torn tendon or bone to stay together and heal. About three in four cases heal well with this treatment.

Surgery is needed to repair the torn tendon if the above fails. (Surgery may be advised straightaway if there is a cut to your finger; however, most injuries that cause mallet finger do not cut the skin.)

It may take several months for your finger to fully recover its function. Any redness, swelling and tenderness of your skin over the end of your finger may persist for the first few months after the injury. These symptoms will usually improve eventually.