Mallet finger is a deformity at the tip of the finger or thumb caused when the tendon that straightens the fingertip is damaged. The tendon is no longer able to straighten the finger.
Sometimes the tendon has torn away from the bone – this is called a tendinous mallet finger. Sometimes the force of the injury pulls a small piece of bone away, resulting in a small break in the bone (avulsion fracture) – this is called a bony mallet finger.
Causes of Mallet Finger
The most common cause of mallet finger is when a ball or other object strikes the tip of the finger forcing sudden bending of the finger tip. However, even simple day to day activities can cause this type of hand injury.
- Drooped fingertip or thumb tip that can not straighten on its own
- Pain in the finger may occur
- Swelling or bruising in finger may develop
- The finger may appear normal, except you can't straighten it
A Certified Hand Therapist can provide education on splinting options, exercises, and other therapeutic care.
A fingertip cast or splint can prevent bending of the fingertip, while allowing full motion of the other finger joints. The cast/splint is worn continuously for 6-8 weeks and must not come off or be removed for any reason. If the cast/splint comes off and the fingertip is left unsupported, the immobilization time starts over.
Instruction in exercises to maintain the mobility of uninvolved joints during the casting period.
When the continuous immobilization period is over and the tendon/bone has healed, your therapist will instruct you in additional exercises to gradually get the fingertip moving as well as provide a removable splint to wear for a few more weeks.
If the injury is severe or involves injury to the nail bed, surgery may be needed to prevent permanent deformity. Your hand surgeon can help decide the best treatment for you.
X-ray of mallet finger. Note dropped posture of fingertip. Figure 2 shows fracture fragments where the extensor tendon is attached