When you think about how much we use our hands, it's not hard to understand why injuries to the fingers are common. Most of these injuries heal without significant problems. One such injury is an injury to the distal interphalangeal, or DIP, joint of the finger. This joint is commonly injured during sporting activities such as cricket or netball but can occur after very minor injury too. If the tip of the finger is struck with the ball, the tendon that attaches to the small bone underneath can be injured. The extensor tendon is cut or torn from the attachment on the bone. Sometimes, a small fragment of bone may be pulled, or avulsed, from the distal phalanx. Untreated, this can cause the end of the finger to fail to straighten completely. This condition called mallet finger.
Initially, the finger is painful and swollen around the DIP joint. The end of the finger is bent and cannot be straightened voluntarily. The DIP joint can be straightened easily with help from the other hand. If the DIP joint gets stuck in a bent position and the PIP joint(middle knuckle) extends, the finger may develop a deformity that is shaped like a swan's neck. This is called a swan neck deformity.
Treatment for mallet finger is usually nonsurgical. If there is no fracture, then the assumption is that the end of the tendon has been ruptured, allowing the end of the finger to droop. Usually continuous splinting for eight weeks followed by two weeks of night time splinting will result in satisfactory healing and allow the finger to extend.
The key is continuous splinting for the first eight weeks. The splint holds the DIP joint in full extension and allows the ends of the tendon to move as close together as possible. As healing occurs, scar formation repairs the tendon. If the splint is removed and the finger is allowed to bend, the process is disrupted and must start all over again. The splint must remain on at all times, even in the shower. Splints that have been designed to make it easier to wear at all times.
In some extreme cases where the patient has to use the hands to continue working (such as a surgeon), a metal pin can be placed inside the bone across the DIP joint to act as an internal splint and allow the patient to continue to use the hand. The pin is removed at six weeks. Splinting may even work when the injury is quite old. Most doctors will splint the finger for eight to twelve weeks to see if the drooping lessens to a tolerable amount before considering surgery.
When the injury is new, the DIP joint is splinted non-stop in full extension for six to eight weeks. A mallet finger that is up to three months old may require splinting in full extension for eight to twelve weeks. The splint is then worn for shorter periods that include night time splinting for six more weeks. Skin problems are common with prolonged splinting. Patients should monitor the skin under their splint to avoid skin breakdown. If problems arise, a new or different splint may be needed. Nearby joints may be stiff after keeping the finger splinted for this length of time. Physiotherapy and exercise may be needed to assist in finger range of motion and to reduce joint stiffness.
Surgical treatment is reserved for unique cases. The first is when the result of nonsurgical treatment is intolerable. If the finger droops too much, the tip of the finger gets caught as you try to put your hand in a pocket. This can be quite a nuisance. If this occurs, the tendon can be repaired surgically, or the joint can be fixed in place. A surgical pin acts like an internal cast to keep the DIP joint from moving so the tendon can heal. The pin is removed after six to eight weeks.
The other case is when there is a fracture associated with the mallet finger. If the fracture involves enough of the joint, it may need to be repaired. This may require pinning the fracture. If the damage is too severe, it may require fusing the joint in a fixed position.
Finger Joint Fusion
If the damage cannot be repaired using pin fixation, finger joint fusion may be needed. Joint fusion is a procedure that binds the two joint surfaces of the finger together, keeping them from rubbing on one another. Fusing the two joint surfaces together eases pain, makes the joint stable, and prevents additional joint deformity.
Rehabilitation after surgery for mallet finger focuses mainly on keeping the other joints mobile and preventing stiffness from disuse. A hand physiotherapist may be consulted to teach you home exercises and to make sure the other joints do not become stiff. After the surgical pin has been removed, exercises may be instituted gradually to strengthen the finger and increase flexibility.