Summary

Gamekeeper's thumb (chronic) and Skier's thumb (acute) refer to insufficiency of the Ulnar Collateral Ligament (UCL) of the thumb MCP joint. The injury is caused by forced abduction (valgus stress). The critical clinical distinction is between a stable partial tear (treated with a cast) and an unstable complete tear (often requiring surgery). The Stener Lesion, where the torn ligament becomes trapped superficial to the adductor aponeurosis, is a specific complication that absolutely prevents healing and mandates surgical repair. [1,2]

Key Facts

• Mechanism: Valgus force on the thumb (e.g., falling on a ski pole, catching a ball).
• Terminology:
  • Skier's Thumb: Acute injury.
  • Gamekeeper's Thumb: Chronic attentuation (classically Scottish gamekeepers breaking rabbit necks).
• Incidence: Most common upper limb ligament injury.
• Stener Lesion: Occurs in up to 80% of complete tears. The ligament stump is "locked out" of its anatomical bed.
• Exam: Laxity >30 degrees or >15 degrees asymmetry compared to normal side.

Clinical Pearls

"Check in Extension AND Flexion":

• Test in 30 degrees Flexion: Isolates the Proper UCL.
• Test in Extension: Tests Accessory UCL and Volar Plate.
• If unstable in extension, it is a massive injury involving the volar plate.

"Don't Strain a Stener": If you suspect a fracture on X-ray, do NOT perform aggressive stress testing initially. You can displace a non-displaced fracture or convert a non-displaced ligament tear into a displaced Stener lesion. Get the X-ray first.

"The Lump": A palpable lump on the ulnar side of the MCP joint is often the stump of the Stener lesion (proximal to the adductor aponeurosis).

Steps

1. Inspect: Swelling/Bruising.
2. Palpate: Point tenderness over UCL insertion. Palpate for mass.
3. Stress Testing (The Crucial Step):
   • Prerequisite: X-ray first to rule out fracture! (Or use gentle touch).
   • Technique: Stabilise the metacarpal with one hand. Flex the thumb to 30 degrees. Apply Valgus (radial) stress.
   • Then: Repeat in Full Extension.
4. Findings:
   • Grade 1: Pain, no laxity.
   • Grade 2: Laxity with firm endpoint (Partial).
   • Grade 3: Laxity with no endpoint (Complete).

Interpretation

• Laxity >35 degrees alone = Unstable.
• Laxity >15 degrees more than normal side = Unstable.

         THUMB UCL INJURY
                ↓
              X-RAY
       ┌────────┴────────┐
    FRACTURE          NO FRACTURE
       ↓                 ↓
  DISPLACED?      CLINICAL STRESS TEST
  (>2mm / >20%)   ┌──────┴──────┐
     ↓            ↓             ↓
   YES          STABLE       UNSTABLE
    ↓          (Partial)     (Complete)
   ORIF           ↓             ↓
            THUMB SPICA      STENER LESION?
            (6 Weeks)        ┌─────┴─────┐
                             NO         YES
                              ↓          ↓
                         CAST vs       SURGERY
                         SURGERY       (Repair)

Note: High demand athletes (Skiers) with complete tears often opt for immediate repair to ensure predictable return to sport, even without Stener lesion.

1. Conservative (Partial Tears)

• Indication: Stable joint on stress testing. Small non-displaced avulsion fractures.
• Protocol:
  • Thumb Spica Cast/Splint for 4-6 weeks.
  • Must immobilise the MCP joint (wrist can be free).
  • Re-assess stability at 6 weeks.
  • Start ROM exercises. No heavy pinch for 12 weeks.

2. Surgical (Complete Tears / Stener)

• Indication:
  • Stener Lesion (Absolute).
  • Complete rupture (>30 degrees laxity).
  • Displaced bony avulsion.
  • Chronic symptomatic instability.
• Technique:
  • Acute (<3 weeks): Direct Repair. Use a Suture Anchor (Mitek) drilled into the base of the phalanx to reattach the ligament.
  • Chronic (>6 weeks): The ligament is retracted and scarred. Requires Reconstruction using a tendon graft (Palmaris Longus or Hamstring). Or MCP Joint Fusion (Arthrodesis) for salvage.

• Incision: S-shaped or Chevron incision over the ulnar collateral ligament.
• Layers: Careful dissection of skin -> Protect RSN branches -> Incise Adductor Aponeurosis -> Identify Stener lesion (if present) -> Locate proximal stump -> Reattach.
• Position: Fix in 30 degrees flexion.

Key Papers

1. Stener (1962): Original description of the lesion. "Displacement of the ruptured ulnar collateral ligament".
2. Heyman (1993): MRI sensitivity/specificity.
3. Gabl et al (1999): Ultrasound diagnosis.

Guidelines

• BSSH: Recommend surgery for Stener lesions within 3 weeks for best outcome. Chronic repairs have lower success rates.

What is it?

You have torn the main ligament that holds your thumb stable. This ligament stops your thumb from bending backwards/outwards when you pinch.

What is a "Stener Lesion"?

Imagine a rubber band snapping. The end of the band has pinged back and got stuck behind a muscle sheet. It's blocked. It physically cannot snap back to where it belongs to heal. We have to go in and put it back.

What is the recovery?

• Cast: You will be in a cast for 6 weeks (surgery or no surgery).
• Physio: At 6 weeks, the ligament is "sticky" but weak. You start moving.
• Strength: No heavy lifting or tight pinching for 3 months.
• Sport: Return to contact sports/skiing at 3 months (tape it up!).

Q1: What defines a "positive" stress test? A: Laxity >30-35 degrees absolute, OR >15 degrees asymmetry compared to the healthy side. No firm endpoint (soft feeling).

Q2: What structure blocks healing in a Stener lesion? A: The Adductor Pollicis Aponeurosis.

Q3: Why test in extension? A: Testing in full extension assesses the Accessory UCL and the Volar Plate. If unstable in extension, it implies a more significant widespread injury to the volar structures, not just the proper UCL.

(End of Topic)