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The extensor tendons are located on the back of the hand and are attached to the muscles in the forearm. These tendons allow the straightening of fingers. Flat and thin in the fingers, these tendons lie very close to the bone and just under the skin, which leaves them more susceptible to injury.
Because of their location, extensor tendons easily lacerated with even a small cut. They can also be ripped from their attachment to the bone by jamming a finger. The most common types of extensor tendon injuries are Mallet finger, Boutonniere deformity and cuts on the back of the hand.
Mallet finger occurs at the terminal joint of the fingertip, when an extensor tendon is cut or pulled from its attachment to the bone. Occasionally, the tendon will pull off a piece of bone from the bone of the fingertip. The result is that the tip of the finger droops and cannot be straightened. Boutonniere deformity occurs when a laceration or tear of an extensor tendon causes the finger to remain bent at the middle joint of the finger. Cuts of the extensor tendons on the back of the hand can make it difficult to straighten the fingers from the large joint where the fingers meet the palm.
If after cutting a hand or a finger, or jamming a finger, a patient has trouble straightening all or part of the finger, then the tendon may be damaged and medical treatment should be sought.
If there is a fresh wound in the vicinity of a finger which will not fully straighten, then the diagnosis is fairly straightforward. Tendon ruptures can frequently be diagnosed just by the story the patient tells. Interestingly, mallet fingers can occur following surprisingly minimal trauma/injury, such as a mild blow to the tip of an extended finger against a filing cabinet. If a history of an injury is not present, then the examiner must make sure that the lack of finger motion is, indeed, due to a tendon disruption and not adjacent joint stiffness or a nerve injury.
Treatment for extensor tendon injuries depends on the location and severity of the injury, but almost always involves splinting in order to keep the healing ends of the tendons from separating. Sometimes the cuts may require stitches. Even with treatment, scar tissue may prevent regaining the range of motion. Therapy may be recommended to improve motion, and for those with seriously limited motion, surgery may be recommended to free the scar tissue.
For Mallet finger, the fingertip is kept straight with a splint until the tendon is healed--usually in about six to eight weeks depending on the severity and location of the injury. It is important to keep the splint on full time for the length of time recommended by your physician, or the fingertip may droop again. Until the tendon has healed, any bending of the fingertip may stretch at the healing tissue and preclude an excellent result.
For Boutonniere deformity, the middle joint of the injured finger is kept straight with a splint until the tendon is healed--usually in about four to eight weeks. Again, it is important to keep the splint on for the length of time recommended by your physician or the finger can bend even more and stiffen in this position.
For cuts on the back of the hand, the physician will usually stitch the ends of the tendon back together. Simple extensor tendon injuries may be repaired in the emergency room setting. More complex injuries usually require more formal surgery in an operating room. A splint for this type of injury may involve the wrist and part of a finger.
