Mallet finger is the result of an injury to the tendon that extends or straightens your fingertip.
The extensor tendons of the fingers run from the muscles in the forearm, along the back of the hand and into the fingers. The action of the finger extensors straighten (extend) your fingers and thumb. The injury results in tearing or rupturing of the extensor tendon where it attaches to the bone, and results in the person being unable to straighten their fingertip.
The injury usually causes pain, swelling and tenderness over the distal interphalangeal joint (the finger joint closest to the tip of your finger), and the fingertip usually droops noticeably. It is known as mallet finger because the affected finger is said to look like a mallet. The person will be unable to actively straighten their fingertip
Mallet finger is usually caused by something striking the tip of the finger and forcibly bending it, such as a ball, hence it's sometimes called 'baseball finger'.
Most cases of mallet finger are ‘closed injuries’, which means that the skin is intact, however, a small number are ‘open injuries’, which means the skin has been broken (e.g. a laceration). If the skin is broken, it is important to see a doctor straight away, in case you have an underlying fracture (compound fracture).
In some cases, rather than the tendon tearing, the tendon may pull a small piece of bone off, and this is called an avulsion fracture.
What is the treatment for mallet finger?
First your doctor will examine you and will usually organise an X-ray to see if there is a fracture.
The treatment for most mallet finger injuries is splinting to hold the finger straight. The splint allows the torn ends of the tendon to come together so they can heal.
Usually, the splint will need to be worn constantly for at least 6 to 8 weeks. After this time, your doctor will assess whether the fingertip is straight, and what further splinting may be required.
Surgery is usually required if there is a compound fracture or a fracture involving a significant amount of the joint surface, or if treatment with splinting fails.