Thumb injuries commonly occur during sports participation and other activities. Because the thumb enables you to grip, pinch, and do other important hand functions, injuring it can be extremely disabling. One of the most commonly occurring thumb injuries is damage to the ligaments, the tissue that connects the bones. This injury is called skier's thumb because it frequently occurs when you fall on your hand while holding a ski pole.
The two bones that meet in the knuckle joint of the thumb (metacarpophalangeal joint) are held together and supported by ligaments. The ulnar collateral ligament, which is one of these supportive ligaments, is located on the inner side of the thumb. When high stress is placed on the knuckle joint, the thumb is forced away from the palm and index finger (Fig. 1). If this stress is greater than the ulnar collateral ligament can tolerate, the ligament stretches, then tears slightly, and eventually tears completely (Fig. 2). The stretching and tearing may occur in the middle of the ligament or where the tissue inserts into bone. Occasionally, a small piece of bone is pulled off with the ligament. When injured, the ulnar collateral ligament and other ligaments cannot support the thumb bones. The bones cannot move together normally in the joint, and the thumb is weakened. For example, you may notice that your thumb is weak when you try to pinch with the index finger and thumb.
You should immobilize, elevate, and ice your thumb immediately after it is injured to reduce swelling and to protect it, and you should have a doctor treat the injury as soon as possible. A thorough physical examination of your thumb is the most important step in correctly diagnosing skier's thumb. The doctor will evaluate your symptoms, take x-rays of your thumb, and compare the injured with the uninjured thumb.
The most common symptom is pain directly over the injured joint and ligament. Other symptoms include joint instability and swelling, tenderness, and, occasionally, bruising over the injured joint and ligament. The doctor takes x-rays to see if a small portion of bone was pulled off as the ligament was injured. Special x-rays called stress views may be taken. A stress view is an x-ray taken while a force (often similar to the force of the injury) is applied to the thumb. By comparing the injured with the uninjured thumb, the doctor can often determine if the ligament is injured and to what degree it is injured.
Treatment
Treatment depends on the type of injury to the ligament. If the ligament is strained (stretched or partially torn), your thumb may be immobilized in a cast for 4 to 6 weeks. You may also wear a splint for up to 8 weeks after the cast is removed to protect your thumb when you participate in sports.
If the ligament is completely torn or a small piece of bone has been pulled off with the ligament, you may need surgery. Surgery to treat skier's thumb is often an outpatient procedure, so you do not have to stay overnight in the hospital. A small incision is made directly over the joint and the ligament is repaired. After surgery, the thumb will be immobilized in a cast for 2 to 6 weeks. As with a sprained ligament, you will wear a splint for 8 weeks after the cast is removed to protect your thumb when you participate in sports.
If you have a skier's thumb injury that is not correctly diagnosed and treated immediately, long-term problems can develop. Symptoms include pain, swelling, and thumb instability, as well as a weak pinch. If the injury causes a significant problem, reconstructive surgery can be performed. The doctor takes tissue from another part of your body and uses it in place of your torn ulnar collateral ligament. The results of reconstructive surgery, however, are not as good as repairing the ligament early after the injury. Therefore, it is very important to have your thumb treated by your doctor as soon as possible after you injure it.
David C. Rehak, M.D.
Columbus, Georgia