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Condition

Thumb UCL Injury (Skier's Thumb)

A tear of the ligament at the base of the thumb, usually from a fall. Prompt evaluation matters because some tears will not heal without surgery.

What is a thumb UCL injury?

The ulnar collateral ligament (UCL) is a small but critical ligament on the inner side of the thumb, at the big knuckle where the thumb meets the hand (the MCP joint). The UCL is what allows the thumb to pinch against the index finger with strength. When the thumb is forced sideways — most often by a ski-pole fall, a tackle in football, or any fall onto an outstretched hand with the thumb extended — the UCL can stretch or tear.

An acute tear is commonly called skier's thumb. A chronic, long-standing tear is sometimes called gamekeeper's thumb, a historical term from people who killed rabbits by twisting their necks against the base of the thumb.

Common symptoms

  • Pain and swelling at the base of the thumb on the side closest to the index finger
  • Bruising around the thumb MCP joint
  • Weakness of pinch — trouble holding a key, turning a doorknob, or gripping a pen
  • A feeling that the thumb is loose or gives way when pinching
  • In chronic untreated tears, a bump on the inner side of the thumb joint and ongoing weakness

Why it matters — the Stener lesion

When the UCL tears completely, the torn end sometimes flips up and out of position, trapped on top of a broad tendon called the adductor aponeurosis. This is called a Stener lesion. A Stener lesion cannot heal on its own because the ligament is no longer touching the bone it needs to reattach to — a piece of tendon is in the way. This is the single most important reason to have any significant thumb UCL injury evaluated early, because a missed Stener lesion leads to long-term weakness and instability.

How it is diagnosed

  • Exam. Dr. Barrera will press along the ligament, check for tenderness, and gently stress the thumb sideways to see whether the ligament is intact or loose. In some cases the thumb is first numbed with a small injection so the stress test can be done without guarding.
  • X-rays. Used to look for a small piece of bone that may have pulled off with the ligament (an avulsion fracture), which changes treatment.
  • Ultrasound or MRI. Sometimes used to confirm a complete tear and specifically to look for a Stener lesion before surgery is planned.

Treatment options

Non-surgical treatment

  • Thumb spica cast or splint. For partial tears and for complete tears that are not displaced, 4 to 6 weeks of immobilization in a thumb spica gives the ligament time to heal. Hand therapy follows to restore motion and pinch strength.
  • Small bony avulsions. If only a tiny piece of bone has pulled off and it is still in good position, this can also be treated non-operatively with a cast.

Surgical treatment

  • Acute ligament repair. For complete tears, especially with a Stener lesion, the ligament is reattached to the bone using a small suture anchor. This is an outpatient procedure through a small incision on the side of the thumb. It is followed by a thumb spica splint or cast for several weeks, then therapy.
  • Fixation of a displaced bony avulsion. When a larger piece of bone has pulled off and is out of position, the fragment is repaired back to the base of the thumb with a small screw or suture anchor.
  • UCL reconstruction. For chronic tears that were not caught in time, or for tears where the ligament is too poor in quality to repair, a small tendon graft (usually the palmaris longus from the forearm) is used to rebuild a new ligament.

What to expect at your visit

Dr. Barrera will examine your thumb, obtain x-rays, and often perform a gentle stress test to judge how much the ligament is torn. If the exam or imaging suggests a complete tear with a Stener lesion, an MRI or ultrasound may be ordered to confirm. Together you will decide between a period in a thumb spica or a repair. Recovery from either path typically takes about 3 months until full pinch strength returns, with therapy along the way.

Dr. Barrera's approach

The most important decision in thumb UCL injuries is whether the ligament has fully torn and flipped out of place (a Stener lesion), because that changes the treatment entirely. Dr. Barrera evaluates these injuries promptly and uses imaging selectively when the exam is not definitive. When surgery is indicated, early repair gives much better long-term pinch strength than a delayed reconstruction.

When to call the office sooner

Call us if the thumb feels grossly unstable, if you cannot pinch at all, if the skin over the thumb is broken or deeply bruised, if there is numbness in the thumb, or if pain and swelling are worsening rather than improving.

Questions?

Call your office location for non-urgent questions:

See our office contact information for addresses and fax numbers.