Hand & Wrist

Skier's Thumb (UCL Injury of the Thumb)

Skier's thumb is an injury to the ulnar collateral ligament (UCL) of the thumb's metacarpophalangeal (MCP) joint. This is the structure that stabilizes the thumb when it is pushed away from the hand. Named for its frequency among skiers who fall with a pole in hand, the injury also occurs in any sport or activity that forcibly abducts the thumb. An accurate diagnosis is critical: partial UCL tears heal with splinting, but a completely torn UCL (particularly one with a Stener lesion) requires surgery.

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What is skier's thumb (ucl injury of the thumb)?

The ulnar collateral ligament (UCL) of the thumb MCP joint runs along the ulnar (index-finger side) of the joint and provides stability during lateral pinch, gripping, and forceful thumb opposition. It is injured when the thumb is forcibly pushed radially (away from the palm), a valgus stress, overstretching or tearing the ligament.

The ulnar collateral ligament (UCL) of the thumb MCP joint runs along the ulnar (index-finger side) of the joint and provides stability during lateral pinch, gripping, and forceful thumb opposition. It is injured when the thumb is forcibly pushed radially (away from the palm), a valgus stress that overstretches or tears the ligament.

Gamekeeper's thumb is the chronic, attritional version of the same injury, historically described in gamekeepers who repeatedly stressed the UCL by breaking rabbit necks.

The Stener Lesion — Why It Matters

When the UCL tears completely at its distal (phalangeal) attachment, the adductor pollicis aponeurosis (a flat sheet of fibrous tissue) can interpose between the torn ligament and its bony attachment site. This is called a Stener lesion, present in approximately 80% of complete UCL tears. In a Stener lesion, the ligament is displaced above (superficial to) the aponeurosis and cannot heal spontaneously even with prolonged immobilization, because the interposed tissue prevents the torn ends from ever re-contacting the bone. Surgical repair is mandatory for Stener lesions.

Symptoms — do you recognize these?

Sudden pain at the ulnar base of the thumb following a valgus (outward) injury
Swelling and bruising over the thumb MCP joint, ulnar side
Weakness and pain with pinching (turning a key, writing, zipping)
A palpable lump at the ulnar MCP joint (may represent the displaced ligament in a Stener lesion)
Instability of the thumb MCP joint with lateral stress

Call us at (301) 515-0900. Same-day appointments available at our Bethesda and Germantown locations.

How we diagnose it

Physical Examination: Stress testing of the UCL:

Apply valgus stress to the thumb MCP joint in both full extension and 30° of flexion (which isolates the UCL from the accessory UCL and volar plate)
>35° of opening compared to the uninjured side, or absolute laxity >35°, indicates complete rupture
Absence of a firm endpoint with stress testing also suggests complete tear
A palpable mass at the ulnar MCP joint strongly suggests a Stener lesion

X-rays: Obtained before stress testing to rule out:

Avulsion fracture at the proximal phalanx (the UCL can avulse a bony fragment rather than tear through ligament substance)
An avulsion fragment that is minimally displaced and not articular may still be treated non-operatively; a large or displaced fracture fragment may require surgical fixation

Stress X-rays (optional): Fluoroscopic stress views provide objective documentation of instability if clinical examination is equivocal.

Ultrasound / MRI: Ultrasound by an experienced musculoskeletal radiologist or MRI can directly visualize the ligament, confirm complete tear, and identify a Stener lesion. MRI is particularly useful in cases where clinical examination is indeterminate.

Treatment options

Non-Operative

Partial tears heal well when the thumb is protected in a spica cast or splint for four to six weeks. Most patients return to sport with a protective splint shortly after completing immobilization, and the ligament heals without any procedure.

Surgical Procedure

Wrist Arthroscopy

Diagnostic and operative arthroscopic evaluation of the wrist joint to assess and treat TFCC tears, scapholunate ligament injuries, synovitis, and loose bodies with minimal disruption to surrounding structures.

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Recovery & rehabilitation

Splinting (non-operative): Thumb spica 4–6 weeks; hand therapy; return to light grip at 6 weeks; sport with orthosis at 8 weeks.
Surgical repair: Thumb spica cast 4–6 weeks post-op; gentle motion at 6 weeks; return to unrestricted sport at 3–4 months.

Pinch strength typically returns to near-normal values by 3 months after repair.

Frequently Asked Questions

Can I wait and see if my thumb gets better before deciding on surgery?

Early consultation is recommended. If a Stener lesion is present, delay beyond 3–4 weeks reduces the likelihood of a successful direct repair and may require reconstruction. Early imaging and clinical assessment avoid this problem.

Will I have arthritis in my thumb if I don't treat this?

Chronic UCL insufficiency alters MCP joint mechanics and increases the risk of post-traumatic arthritis. It also produces chronic pinch weakness that limits many daily activities.

How common is Skier's Thumb?

UCL injuries of the thumb MCP joint represent approximately 1 in 4 of all ski injuries. The injury is not limited to skiing. It also occurs in football, basketball, rugby, and falls.

How long does recovery take after surgery for Skier's Thumb?

After surgical repair of a complete UCL tear of the thumb, the thumb is immobilized in a thumb spica cast or splint for approximately 4–6 weeks to allow the repaired ligament to heal. Physical therapy then begins to restore motion and strength. Most patients can return to light daily activities at 6–8 weeks and to sports or manual work at 3–4 months. Return to skiing or other high-demand gripping activities typically takes 4–6 months. Your MOS hand surgeon will tailor the return-to-activity timeline based on the quality of the repair and your healing progress.

What is a Stener lesion, and why does it matter?

A Stener lesion occurs when the torn end of the ulnar collateral ligament flips over the adductor pollicis aponeurosis (a layer of tissue in the thumb) and becomes lodged in a position where it cannot heal back to bone on its own. Stener lesions are present in approximately 80% of complete UCL tears of the thumb and are the main reason surgery is recommended for complete tears. If a Stener lesion is present and the ligament is not surgically repositioned and repaired, the thumb will remain chronically unstable and lead to pain, weakness of grip, and eventual arthritis. Your MOS surgeon will assess for a Stener lesion clinically and on MRI to guide the treatment decision.

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Peter G. Fitzgibbons, MD

Hand Surgery · Orthopedic Surgery

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Medically reviewed by Peter G. Fitzgibbons, MD

Last reviewed May 1, 2026