II. Pathophysiology

  1. Ulnar collateral ligament rupture from forced abduction
  2. Occurs at first metacarpophalangeal joint (thumb base)
    1. Skier falls with pole strap wrapped at wrist
    2. Pole strap levers thumb into abduction and extension
  3. Radial collateral ligament tear may also occur instead
    1. Not common

III. Anatomy: Ulnar collateral ligament

  1. Proper ulnar collateral ligament (UCL)
    1. Attaches dorsal First Metacarpal head to ulnar base of proximal phalanx
  2. Accessory ulnar collateral ligament (UCL)
    1. Attaches volar First Metacarpal head to ulnar base of proximal phalanx

IV. Signs

  1. Pain at medial base of thumb (ulnar aspect)
  2. Test active and passive thumb abduction
  3. Assess thumb metacarpophalangeal joint (MCP) laxity
    1. Compare with uninjured side
    2. Apply valgus stress at MCP joint (radially deviating the thumb) in each of 2 positions
      1. Test proper UCL with thumb flexed to 30 degrees at MCP joint
      2. Test accessory UCL with thumb in extension at MCP joint
  4. Assess for Stener Lesion
    1. Proximal UCL trapped outside adductor aponeurosis
    2. Presents as tender mass at UCL, and joint instability
    3. Requires surgery

V. Grading: Compare to uninjured side

  1. Grade 1 sprain: No laxity
  2. Grade 2 sprain: Increased laxity, but firm endpoint
  3. Grade 3 sprain
    1. Increased laxity with no firm endpoint
    2. Joint opening usually >35 degrees

VI. Imaging: Hand XRay

  1. Evaluate for Fracture

VII. Management

  1. Indications for Surgical Repair: Unstable thumb
    1. No endpoint in abduction of thumb
  2. Initial: Splinting for 6 weeks
    1. Molded plastic thumb lock immobilizer or
    2. Thumb Spica Cast or splint
  3. Later: Dynamic Splinting for additional 6 weeks
    1. Indicated for athletes - splint during sports only
    2. Use one of splints above or taping
    3. Dorsal Taping (0.5 inch tape)
      1. Apply anchor strips at wrist and over distal thumb
      2. Start tape at anchor strip at wrist
        1. Apply over web space between thumb and index
        2. Attach at distal anchor strip on thumb
      3. Build upwards with consecutive tapes
  4. Return to sports
    1. May participate if splinted and no pain or reinjury

VIII. Orthopedic Referral Indications

  1. Associated Fracture present (esp. displaced Fracture)
  2. Grade 3 sprain (see above)
  3. Stener Lesion

IX. Complications

  1. Unstable MCP joint with weak pincher grasp

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