UCL Injury (Skier’s Thumb)

Ulnar collateral ligament (UCL) injury, or skier’s thumb, is a tear of the ligament that stabilizes the base of the thumb, commonly caused by a forceful sideways bend of the thumb.

Pain and swelling at the base of the thumb, weakness or instability with pinching and gripping following an injury such as a fall or forceful thumb bend.

A fall onto an outstretched hand while gripping an object (classically a ski pole), or any forceful sideways stress to the thumb, can tear the UCL.

Seek assessment promptly after a thumb injury with pain, swelling, or a feeling of instability at the base of the thumb.

Clinical examination assessing thumb joint stability with stress testing, compared to the uninjured side.

X-rays rule out an associated fracture; MRI or ultrasound can assess the degree of ligament injury and identify a Stener lesion.

Partial tears without instability can be treated with thumb splinting or casting for four to six weeks.

Surgery is considered for complete tears, joint instability, or when a Stener lesion (displaced ligament) is present, as these do not heal with splinting alone.

Surgical repair reattaches the torn ligament to restore thumb stability, typically performed within a few weeks of injury for best results.

Splinting or casting continues for four to six weeks after repair, followed by hand therapy to regain strength and motion.

Most patients regain stable, functional pinch and grip strength with appropriate treatment.

Infection, stiffness, residual instability, and reduced pinch strength in some cases.