Mallet finger is an injury involving the distal interphalangeal joint (DIP) which is the last joint of the finger. It is caused either by an injury to the extensor tendon or to the bone where it inserts. The extensor tendon straightens the last joint of the finger.
The most common type of injury is one which causes forced flexion of the DIP joint. This could be caused, for example, by getting hit by a ball on the tip of the finger, causing the tip of the finger to be bent down suddenly and forcefully.
Most people with a mallet finger experience pain at the time of injury. Swelling often occurs at the DIP joint. This injury results in a person being unable to actively fully extend the finger at the DIP, causing the tip of the finger to droop. However, it is usually possible to passively extend the DIP joint. The inability to straighten the affected finger might not occur until several hours or days after the injury.
Mallet finger is diagnosed by a physical exam by a doctor. X-rays will also be performed in order to evaluate the bones of the finger and to see if any displacement or avulsion (breaking off of a piece of bone) has occurred.
Usually, Mallet finger can be treated with splinting. The splint stabilizes the joint so that the tendon and/ or bone can heal. Only the DIP joint will be immobilized in the splint. Many different types of splints can be used – they can be placed on the top of the finger, the bottom of the finger, or on either side of it. The finger is held in extension so that the DIP joint is held in a straight position, or in mild hyperextension so that the DIP joint is curled slightly upwards.
The splint will need to be in place for six to eight weeks. It is very important that the DIP joint never be allowed to bend during this time, even if the splint is being changed. The tip of the finger must be held while the splint is off so that there is no flexion or bending of the DIP joint. If a fracture has occurred or the finger cannot be passively extended, surgery may be necessary for healing.
Your doctor will let you know when your child may return to play. It is best to avoid contact sports during the first 6-8 weeks of splinting so that the joint is not re-injured. Depending on the sport that your child plays, it may be possible to return to play immediately. However, it will be necessary to continue to wear the splint at all times, including while playing.
Mallet finger can be prevented by avoiding injuries which cause forced flexion of the DIP joint. The riskiest activities are ball sports. There are no exercises, braces or equipment that will prevent mallet finger.