What is a mallet finger?
Fingers are usually kept in a fine balance by their tendons. The 'flexor' tendons run along the palm side of the finger, the 'extensor' tendons run along the back of the finger. It is the extensor tendons that are responsible for straightening the finger.
The extensor tendon runs up to the area near to where the nail starts. If the tendon breaks or is cut at near this insertion point, then the fingertip will 'drop', and the fingertip cannot be straightened. This is termed 'mallet finger'.
What causes mallet finger?
A cut across the back of the finger, near to the nail, can divide the tendon and cause a mallet finger. More commonly the injury is caused by blunt trauma, such as 'stubbing' the finger on a hard surface, or an object, such as a squash ball, hitting the end of the finger straight on. Sports, such as rugby, can also provide ample opportunity for trauma to fingers.
How is mallet finger treated?
If it has been caused by a cut, then an operation may be needed to stitch the tendon ends together.
If the mallet finger has been caused by blunt trauma, then treatment often depends on x-ray findings. If the tendon has wrenched a large fragment of bone with it, then the bone needs to be replaced for satisfactory healing. This may need thin wire to hold the bone in place, or a thin metal rod (a Kirschner or 'K' wire). The K-wire is left in place for 4-6 weeks.
If the x-ray shows that no bone has been pulled away (often the case), then the mallet finger can be treated with a simple splint. The splint keeps the fingertip straight, allowing the tendon ends to meet and fuse together again. The splint is worn for 6-8 weeks, and must be worn constantly or the mallet deformity could return.
What are the risks of mallet deformity?
Stiffness - it is very common to have a stiff fingertip joint after the splinting or procedure. This is due to the long period of splinting required and the nature of the injury itself. Physiotherapy helps to reduce the effects of this stiffness
Swan-neck deformity - if the mallet deformity is not corrected, then the finger tendons remain imbalanced. This can lead to the other finger joint (between the knuckle and fingertip) to hyperextend, causing problems with finger function
Other relevant SurgeryWise articles: fingertip breaks, broken knuckles, fractures, hand surgery, broken fingers
Any procedure involving skin incision can also result in unfavourable scarring, wound infection, or bleeding. This list of risks is not exhaustive, and you should discuss possible complications with your specialist. Whilst these risks will seem very worrysome, and indeed can be serious, it should also be borne in mind that many people have no postoperative problems whatsoever.
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