What is skier's thumb?

The thumb has a strong ligament on its inner (ulnar) side that holds the base of the thumb (the metacarpophalangeal joint) stable when you pinch. This ligament, the ulnar collateral ligament, can be sprained or torn when the thumb is forced outwards away from the hand, for example in a fall while holding a ski pole. Without this ligament the thumb becomes weak and painful on any pinching or gripping task.

The injury was historically described in Scottish gamekeepers, who developed chronic instability of the thumb from repeatedly killing rabbits with their hands. In modern times the most common cause is a fall while skiing (the pole catches the thumb and bends it outwards), but it is also seen in racket and ball sports and in falls onto the outstretched hand.

A particular concern is the "Stener lesion", in around a third of complete tears, the torn end of the ligament flips back over the adductor muscle of the thumb and cannot heal by itself. This requires surgical repair. Distinguishing partial from complete tears, and identifying Stener lesions, are the key tasks of assessment.

Common causes

Fall while holding a ski pole, classic mechanism
Fall onto the outstretched hand with the thumb extended
Racket sport injury, thumb caught against racket
Ball sport injury, thumb forced backwards by a ball
Direct blow to the inside of the thumb

Who is at risk? Skiing, particularly using ski poles with traditional straps, is the dominant risk. Modern strapless poles have reduced injury rates but the injury still occurs. Racket sports and football are other common sources.

Symptoms

Symptoms vary depending on the severity and duration of the condition. Common symptoms include:

Pain and swelling at the base of the thumb, especially on the inner side
Bruising around the thumb base
Difficulty and pain on pinching, gripping, or holding a pen
A sense of instability or weakness of the thumb
Tenderness directly over the ulnar collateral ligament
In chronic untreated cases: a feeling that the thumb "gives way" on pinch

When to seek help: Any significant thumb injury with persistent pain or instability should be assessed within the first 1-2 weeks. Early diagnosis and treatment of complete tears gives the best outcome, chronic injuries are harder to repair.

How is it diagnosed?

Your hand surgeon will take a detailed history and examine the hand and wrist. The following investigations may be arranged to confirm the diagnosis:

Clinical examination, tenderness over the UCL, swelling
Valgus stress testing, assesses ligament stability in extension and 30 degrees of flexion
Comparison with the other thumb
Ultrasound, assesses ligament integrity and identifies Stener lesions
MRI, gold standard if there is doubt; identifies Stener lesions reliably

A Stener lesion (the displaced torn ligament caught above the adductor aponeurosis) is the key finding that determines surgical treatment. Any clinically complete tear should have either ultrasound or MRI to assess for a Stener lesion before deciding on conservative versus operative treatment.

Treatment pathway

Treatment is tailored to the severity of the condition, your age, activity level, and overall health. Most conditions are treated in a stepwise fashion, starting with the least invasive options.

Partial tears

Thumb spica cast or splint

For partial tears with end-feel on stress testing, a thumb spica cast or splint is worn for 4-6 weeks. The base joint of the thumb is immobilised while the IP joint is left free. Most partial tears heal well with this approach.

Complete tears without Stener lesion

Cast immobilisation

Selected complete tears without a Stener lesion can be treated in cast for 6 weeks with reasonable outcomes, particularly in older or low-demand patients. Surgical opinion is still usually sought.

Complete tears or Stener lesion

Surgical repair

Open repair of the torn ligament to bone (often with a small bone anchor) gives reliable restoration of stability. Performed within the first few weeks of injury for best results. Chronic injuries (more than 6 weeks old) may need reconstruction with a tendon graft.

Recovery

After surgical repair the thumb is held in a splint for around six weeks, followed by hand therapy to restore pinch and grip. Return to contact sports is delayed until ligament healing is complete (around 3-4 months). Outcomes are generally excellent if the diagnosis is made and treated early.

Cast or splint: 4-6 weeks
After surgery, splint: 6 weeks
Hand therapy and return to light pinch: 6-10 weeks
Return to contact sport: 3-4 months

What results can I expect?

Excellent for acutely repaired or appropriately immobilised tears. Outcomes are less reliable for late presentations: chronic UCL instability requires reconstruction with a tendon graft, and although results are good, they are not quite as reliable as acute repair. Delayed treatment also predisposes to early arthritis of the joint.

In numbers

Stener

lesion needs surgery[1]

when the torn end of the ligament is trapped outside the adductor aponeurosis, healing cannot occur without operation

Partial

tears heal with splinting[1]

undisplaced partial tears typically heal in a thumb spica

4-6

weeks immobilised[1]

typical thumb spica splint or cast time for non-operative treatment

Pinch

grip preserved with treatment[1]

good restoration of pinch grip is the usual outcome with appropriate management

What the evidence shows

The ulnar collateral ligament (UCL) of the thumb metacarpophalangeal joint stabilises pinch grip, tearing it makes the thumb feel weak when gripping or pinching[1]

A complete tear with displacement of the torn end above the adductor aponeurosis is called a Stener lesion, this needs surgical repair because the interposed tendon prevents the ligament healing back[1]

Examination under local anaesthetic or imaging (ultrasound or MRI) helps distinguish complete from partial tears and identify Stener lesions[1]

Untreated complete tears can lead to chronic instability and secondary osteoarthritis of the thumb MCP joint years later[1]

Although named after skiing, the same injury occurs with any forceful thumb abduction, including ball sports, falls onto the hand, and motor vehicle accidents[1]

When can I…?

Typical activity timelines for this condition. These are approximate and vary considerably between patients. Always follow the specific guidance given by your surgeon and hand therapist.

Activity	Typical timeline	Notes
Wear thumb spica	4-6 weeks	Continuous thumb-spica splinting or casting is the mainstay for non-operative treatment.[1]
Drive	When grip is safe	Most patients can drive with the splint in place once they can hold the wheel safely. Discuss with insurer.[2]
Shower	Splint covered	A waterproof cover keeps the splint dry.
Desk work	Within days	Light typing and writing in the splint, finger movement of the index, middle, ring, and little fingers should be free.
Light pinch grip	After splinting period	Gentle pinch and key-grip exercises start under hand therapy guidance after splint removal.[3]
Manual work	8-12 weeks (non-op) or 12 weeks (post-op)	Heavy gripping waits until ligament healing is consolidated.[1]
Sport	3-4 months	Contact and ball sports return as pinch strength rebuilds and the joint feels stable. A protective taping or splint may help.[1]

Is this normal?

Common concerns from patients with this condition or recovering from treatment, and whether they are expected or worth mentioning to your team.

Yes, early on. Pinch strength rebuilds gradually after splint removal. Most patients regain near-normal pinch with hand therapy over 2-3 months.[3]

It is worth assessing. A palpable lump on the ulnar side of the thumb MCP joint can be a Stener lesion (a torn ligament trapped above the adductor aponeurosis), which usually needs surgical repair.[1]

No, persistent looseness merits assessment. Chronic instability of the thumb MCP joint affects pinch grip and can cause long-term arthritis if untreated. Surgery may still be an option even some time after the original injury.[1]

Yes, early in recovery. Tasks that load the ulnar collateral ligament (resisted thumb abduction, twisting jar lids) are typically painful while the ligament heals. They settle as healing progresses.[1]

References & further reading

References are to UK clinical guidance and patient information from recognised organisations. This page is for general information and does not replace personalised advice from your own clinical team.

Skier's thumb (UCL injury)