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Skier's thumb is the tearing of a ligament in the thumb, and the injury is usually isolated to a single thumb ligament (the ulnar collateral ligament) which is the primary stabilizing ligament for such activities as turning keys in locks, opening jars and turning doorknobs.
Skier's Thumb is caused by a significant traumatic event to the hand due to a wide variety of mechanisms. While Skier's Thumb is frequently the result of a fall while skiing in which the thumb is driven directly into the snow and bent excessively back or to the side, it can occur with any fall or direct blow, or even while lifting a young child. Ice skating and basketball are other common sports in which Skier's Thumb occurs.
Pain and swelling about the thumb after a significant traumatic event to the hand may indicate Skier's Thumb. The patient may or may not have heard or felt a "pop," and the amount of initial pain and swelling is proportional to the magnitude of the initial trauma. The initial pain and swelling is often mild (especially if the hands are cold from skiing) and rapidly abates, thus providing a false sense of security after several days. As routine activities are resumed, however, the functional deficits--including difficulty turning door knobs, opening jars and turning keys--manifest and treatment may only then be sought.
Diagnosis of Skier's Thumb is fairly straightforward. After taking a history of the injury, the physician examines the degree of side to side motion of the metacarpophalangeal joint (the second joint from the thumb tip) when stressed. Usually, the normal thumb will not deviate more than 10 to 20 degrees under stress, whereas a joint in which a collateral ligament is completely torn will allow deviation of more than 40 degrees and have no clear endpoint. There may or may not be a sense of grinding or crackling (crepitus) with joint motion.
In general, the history and physical examination is accurate in diagnosing a complete ulnar collateral ligament tear in over 90 percent of cases. Some hand surgeons (the subspecialists who treat the majority of these hand injuries) prefer to take an x-ray with the thumb under stress to document the degree of abnormal angulation. Still, most hand surgeons find this additional information unnecessary in counseling the patient regarding the treatment options. Standard x-ray views of the thumb are quite helpful in looking for an abnormal relationship between the two bones that comprise the joint in question. The basic x-rays will also identify any bone fracture associated with the injury. Though unnecessary in the majority of cases, MRI scans or ultrasonic evaluation can readily identify the torn ligament.
Partial tears of the ulnar collateral ligament do not render the joint unstable and are characterized by well less than 40 degrees of stress deviation, a clear endpoint to manual stress testing and no radiographic abnormalities.
Complete tears are best treated with primary surgical repair in most patients. If performed by a qualified surgeon, the surgery is performed as an outpatient procedure under regional (numbing the arm) or local (numbing the hand) anesthesia with minimal risk. When indicated, the surgically repaired ligament heals more predictably due to restoration of the ligament to its anatomic (pre-injury) position.
