Mallet finger

What is it?

To the end bone of each finger (distal phalanx) is attached a tendon which extends or straightens the end joint of the finger. Due to an injury this tendon can tear off from where it joins to the bone, and the patient is not able to straighten the finger. The tip of the finger can be pushed straight, but the patient is unable to hold the position. The finger will drop, and this condition is known as a ‘Mallet finger’.
The tendon may tear off with a small fragment of bone in which case it is called a ‘mallet fracture’. Very rarely the bony fragment is large, resulting in the end joint partially dislocating.

Is it called by any other name?

Dropped finger; Mallet fracture

What is its cause?

Many causes are known such as if the finger catches ‘end-on’ during sport; if an object falls on the finger; during any household activity that reproduces the mechanism of the injury; or if the tendon is directly cut (open mallet finger).

Bony avulsion of the tendon leading to a dropped finger

What are the symptoms and how is the condition diagnosed?

Immediately following the injury, the main complaint is of pain and swelling. The patient is unable to straighten the tip of the finger. The area may become red.

Will further tests or investigations be needed?

An x-ray of the finger is usually recommended to rule out any fracture (as above).  

What is the treatment?

  1. The treatment for a closed mallet finger is splintage. The splint will keep the finger straight and needs to be worn continuously for 6-8 weeks.  If it is taken out for any reason (washing) the fingertip should still be held straight. After 6-8 weeks the splint can be weaned.
  2. If the mallet finger is the result of an open injury the wound needs to be cleaned and the tendon repaired if possible.
  3. If there is an associated avulsion fracture, the mallet finger can still be treated with a splint. However if the fragment is large (usually more than 1/3 of its joint surface) and the joint has partially dislocated, surgery that aims to reduce the fracture is advised. It is a technically demanding procedure as the bone fragment is small and difficult to fix. 

What happens if it is not treated?

If the condition is ignored the finger will not straighten by itself and it will become a permanent deformity. In some cases untreated deformity will lead to hyperextension of the middle knuckle joint (swan neck deformity).

What is the success of treatment?

In a majority of cases, treatment by a splint will result in normal function though a cosmetically perfect position may never be achieved. Surgery is rarely practiced except in cases of open injuries and large mallet fractures.

What are the complications of surgical treatment?

  1. Over zealous surgical intervention can cause nail growth deformities, scar formation, infection, implant failure and subsequent joint stiffness.
  2. Complex regional pain syndrome.
  3. Any surgical intervention has the risk of developing complications that are unpredicted. These complications may have the potential to leave the patient worse than before surgery.

Is there anything I can do to improve the outcome?

Use the splint continuously and do the prescribed exercises regularly to avoid stiffness. Do not let the splint and skin get wet as the skin may get broken and sore.

When can I do various activities?

Return to work depends on many factors including the nature of the job and hand dominance. Generally you will be able to return to a desk job soon afterwards as long as you take proper care of the splint. Manual work should be avoided for 6-8 weeks.

Driving should be possible with the splint. Before driving do check that you can manage all controls and start with short journeys.