Skier’s Thumb

Skier’s thumb is an acute partial or complete rupture of the ulnar collateral ligament (UCL) of the thumb metacarpophalangeal joint (MCPJ) due to a hyperabduction injury. The injury typically occurs when the thumb is subjected to a strong lateral and backward traction force. The terms “skier’s thumb” and “gamekeeper’s thumb” are often used interchangeably, but skier’s thumb relates to acute trauma, whereas gamekeeper’s thumb refers to a chronic overuse injury. An untreated injury can lead to permanent instability, reduced pinch strength and pain with movement.¹,²,³,⁴,⁵

This image, titled “Skiers thumb,” shows an avulsion fracture of the thumb following a skiing fall, visible on an X-ray; created as own work by the author Fluffy89502; hosted on Wikimedia Commons (file: https://commons.wikimedia.org/wiki/File:Skiers_thumb.jpg); licensed under Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0): https://creativecommons.org/licenses/by-sa/4.0/.

In 64–87% of cases with complete UCL rupture, a Stener lesion can occur. This happens when the adductor aponeurosis becomes interposed between the torn UCL and its insertion on the proximal phalanx. This prevents healing and requires surgical treatment.⁷

Clinically Relevant Anatomy

Anatomical structures

The thumb MCP joint is a diarthrodial joint stabilised by capsule and soft tissues.⁹ Passive stability is provided by:

• Proper collateral ligament

• Accessory collateral ligament

• Volar plate

• Dorsal capsule¹⁰

The proper collateral ligament runs from the dorsal aspect of the metacarpal head to the palmar aspect of the proximal phalanx and resists valgus stress in flexion. The accessory collateral ligament courses palmarly to the volar plate and is important in extension.¹⁰

Dynamic stabilisers

The dynamic stabilisers are:

• Extensor pollicis brevis

• Extensor pollicis longus

• Flexor pollicis longus

• Adductor pollicis

• Flexor pollicis brevis

The adductor aponeurosis lies over the MCP joint and UCL and has both superficial and deep insertions.⁹,³

Key ligaments

• Ulnar collateral ligament (UCL)

• Radial collateral ligament (RCL)

These ligaments stabilise the MCPJ from the metacarpal condyles to the base of the proximal phalanx.⁹,¹¹

Aetiology

Skier’s thumb results from forced abduction and hyperextension of the MCP joint.¹² Rupture most often occurs at the distal insertion, but proximal or midsubstance ruptures and bony avulsions can also occur.¹³ The injury can be caused by ski poles, but also by other sports such as football and basketball.¹³,¹⁴

Mechanism of Injury

The injury most commonly occurs after a fall on an outstretched hand with the thumb caught in the ski pole, creating a strong valgus stress at the MCP joint.¹⁵ It may also arise during other activities such as contact sports or even a handshake.¹³ Untreated injury can cause chronic instability, pain and osteoarthritis.

Epidemiology

Occurrence

• Skier’s thumb accounts for 86% of all injuries at the base of the thumb and affects about 200,000 patients annually in the USA.⁴

• Ski-related thumb injuries are the second most common ski injury after knee injuries and occur more often in men than women.

• Prevalence ranges from 7–32% of all ski injuries.⁴,¹⁴,¹⁶

• Only 10% of all skier’s thumb injuries actually occur while skiing—cycling, motorcycling and other activities are more common.⁴

• In children, a Salter–Harris type III avulsion is most often seen.⁴

Prevention

Measures

• Good pole technique, avoiding deep planting of the pole and using correct pole length.¹⁷,¹⁸

• Ski gloves with pole release mechanisms may also reduce risk.¹⁹,²⁰

Clinical Presentation

Acute cases present with pain, swelling and haematoma at the MCPJ, with tenderness over the UCL.¹³,⁹ Chronic cases present with pain and weakness in pinch grip. With a Stener lesion, a palpable mass may be found proximal to the adductor aponeurosis.¹⁵

Symptoms

Common symptoms

• Pain at the MCPJ

• Thumb swelling

• Difficulty gripping

• Bluish discolouration

• Tenderness on the ulnar side

• Pain with movement

• Referred pain to the wrist²¹

Classification of Thumb Sprain

Hintermann classification

• Type I: Undisplaced fracture

• Type II: Displaced fracture

• Type III: No fracture, stable

• Type IV: No fracture, unstable

• Type V: Avulsion fracture of the volar plate¹⁰

Differential Diagnoses

• Stener lesion

• Bennett or Rolando fracture¹³

• Avulsion fracture (children, Salter–Harris type III)⁴

• Wrist sprain

• Wrist fracture

• 1st MCP joint dislocation²²,²³

• Chronic MCPJ instability²⁴

• Lunate dislocation²⁵

• Radial nerve neurapraxia

• Rheumatoid arthritis / osteoarthritis

Outcome Measures

Michigan Hand Outcomes Questionnaire

• Grip strength and key pinch strength

• VAS/pain scale

• MCPJ stability (stress test)²⁶

Complications

A Stener lesion occurs when the adductor aponeurosis is interposed between the UCL and its insertion, preventing healing.²⁷ Untreated injury results in weak pinch and MCP instability.

Diagnostic Procedures

Radiography

• Standard AP and lateral views are taken to exclude bony injury.

• Avulsion fractures are seen in 20–30% of UCL ruptures, and the fragment’s position may indicate UCL location.²⁸

• If the fracture fragment is displaced >5 mm, or involves >25% of the articular surface, surgical management is considered.

• Stress radiography of the MCP joint is also used diagnostically.²⁹

Ultrasound

• Ultrasound is a cost-effective method to diagnose UCL ruptures, directly visualising the ligament and surrounding structures.

• Ultrasound detects the injury in ~90% of cases.¹⁶

• Diagnosis should be established with ultrasound before considering conservative casting.

• Limitations: ultrasound is best within one week of injury; after this, ligament retraction and scarring complicate diagnosis, especially in chronic injuries.²,³⁰

• Sensitivity for Stener lesion 95.4%, specificity 80%. Dynamic ultrasound is reliable and reproducible for detecting Stener lesions.

MRI

• MRI is often considered the gold standard, with sensitivity 96–100% and specificity 95–100%.²

• Particularly useful in chronic injuries.²,³¹

Arthrography

• Arthrography can demonstrate focal defects in the UCL or contrast extravasation suggestive of ligament avulsion.

• Indirect signs include visualising the adductor pollicis head.¹³,³²

Clinical Examination

Observation and palpation

• Inspect the hand at rest and in flexion.

• Assess sensation, active and passive ROM, and strength to check tendon integrity.⁹

• There is often tenderness and possible haematoma on the ulnar side of the MCPJ.⁴

• If fracture of the metacarpal or proximal phalanx is suspected, obtain radiographs before stress testing.

Objective examination and stress test

• Radiography and objective examination are sensitive for detecting UCL injuries.³³

MCP joint stability is tested by:

• Stabilise the MCP with one hand• Flex MCP 30° and apply radial stress; then repeat in extension

• Side-to-side difference >15° in flexion or >35° in extension suggests complete rupture

• Lack of a firm end-point indicates complete rupture.³,⁴

• A ligamentous “lump” may be palpable in Stener lesions.

• Stress testing can be painful; local anaesthesia may be used. One study showed Oberst anaesthesia (1–2 ml lidocaine) increases diagnostic accuracy from 28% to 98%.

• An unstable MCPJ also indicates chronic UCL injury.¹³

General Principles

A UCL injury may be treated conservatively or surgically depending on several factors:

• Time of presentation (acute vs chronic)

• Injury severity

• Presence of a Stener lesion (displaced injury)

• Rupture location (midsubstance vs peripheral)

• Associated injuries (bone, volar plate)

• Patient factors (occupational demands, etc.)¹³

According to the Hintermann classification, recommendations are:

• Type I: Casting for 4 weeks

• Type III and V: Casting for 3 weeks

• Type II and IV: Surgical treatment

Surgical Management

• Operative care depends on rapid diagnosis. Chronic injuries are harder to repair due to tissue attenuation over time.³⁵

Indications for surgery

• Acutely unstable joint

• Stener lesion

• Displaced avulsion fracture

• Volar subluxation on radiographs³⁶,³⁷

Surgical techniques

Dynamic procedures:

• Extensor indicis proprius transfer

• Extensor pollicis brevis transfer

• Adductor pollicis brevis transfer

• These provide good mobility but may loosen over time.³⁸

Static procedures:

• Figure-of-eight graft

• Parallel or triangular configurations

• Double suture anchoring

• Hybrid techniques

• Free tendon graft³⁸,³⁹

Most techniques yield good results, but there is no universal consensus on the best approach.³⁸,³⁹ Good outcomes are usually achieved if surgery is performed within 3–4 weeks. Immobilisation for 6 weeks is standard, followed by radiographic review and physiotherapy. Full function often returns by ~3 months.³⁹

Conservative Management

Indications

• Partial tears, lower functional demands or degenerative MCP joints may be treated non-operatively.³⁵

• Bony skier’s thumb without displacement can also be treated conservatively if the MCPJ is stable on testing.¹⁵

Immobilisation

• 4–6 weeks, up to 12 weeks for larger injuries³³

Orthoses:

• Short-arm thumb spica cast• Thermoplastic splint

• Removable orthosis that immobilises the MCPJ while keeping the IPJ free¹⁵,⁴¹

• Position the thumb in slight flexion and ulnar deviation to facilitate healing. The IPJ should not be immobilised.⁴⁰

Physiotherapy

After conservative care

• ROM training begins after immobilisation (~4 weeks).

• Strengthening begins after 8 weeks. Full loading is not allowed until 12 weeks.¹⁵,³⁵

• Pinch and grip training is introduced cautiously after 10–12 weeks.³⁵

After surgery

• Immobilisation: 6 weeks²⁶,⁴¹

• Post-immobilisation radiographic check.

• Early motion yields better outcomes.

• A functional splint is recommended.

• Athletes usually return to sport after 3–4 months.³⁹,⁴¹

Exercises

Thumb exercises

• Stretch: move the thumb away from the palm, hold 5 s, return; 15 reps × 2 sets.

• Opposition to little finger: hold 5 s, return; 15 reps × 2 sets.⁴³

Wrist exercises

• Flexion: bend wrist forwards, hold 5 s, 15 reps × 2 sets.

• Extension: bend wrist backwards, hold 5 s, 15 reps × 2 sets.

• Side-to-side (radial/ulnar deviation): handshake motion, hold 5 s, 15 reps × 2 sets.⁴³

Strength exercises

• Squeeze a rubber ball, hold 5 s, 15 reps × 2 sets.

• Resistance band for fingers, 15 reps × 2 sets.• Dumbbell/wrist loading:

• Flexion (palm up): 15 reps × 2 sets, progress gradually.

• Extension (palm down): 15 reps × 2 sets, progress gradually.⁴³

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Follow-Up

The patient is followed by an orthopaedic surgeon after surgery or casting. Thumb mobility is assessed before further planning. Full function is expected after ~3 months.³⁹,⁴¹

Refrences:

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