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
Signs
1. Pain at medial base of thumb (ulnar aspect)
2. Test active and passive thumb abduction
3. Assess thumb metacarpophalangeal joint laxity
  1. Compare to uninjured side
  2. Test with thumb flexed to 30 degrees
  3. Test with thumb in extension
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
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
Imaging: Hand XRay
1. Evaluate for Fracture
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
Orthopedic Referral Indications
1. Associated Fracture present (esp. displaced Fracture)
2. Grade 3 sprain (see above)
3. Stener Lesion
Complications
1. Unstable MCP joint with weak pincher grasp

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This page was written by Scott Moses, MD. This page was last revised before 5/10/08, prior to consistent tracking of revision date. This page was last published on 6/1/2008. Please send comments and questions to the editor. Contact information may be found on the page About the Family Practice Notebook. These pages are best viewed with Microsoft Internet Explorer 6.0.