Metacarpophalangeal ulnar ligament rupture

Background

• Also known as gamekeeper's thumb or skier's thumb
• Ulnar ligament ruptures at insertion into proximal phalanx (due to radial deviation of MCP)

Clinical Features

• Swelling and localized tenderness over ulnar border of joint
• Weakness of pinch

Differential Diagnosis

Hand and finger injuries

• Distal finger
  • Finger amputation
  • Fingertip laceration
  • Nail avulsion
  • Nailbed laceration
  • Subungual hematoma
• Other finger/thumb
  • Boutonniere deformity
  • Mallet finger
    • Swan neck deformity
  • Jammed finger
  • Jersey finger
  • Trigger finger
  • Ring avulsion injury
  • De Quervain tenosynovitis
  • Infiltrative tenosynovitis
  • Metacarpophalangeal ulnar ligament rupture (Gamekeeper's thumb)
• Hand
  • Dupuytren contracture
• Wrist
  • Drummer's wrist
  • Ganglion cyst
  • Lunotriquetral ligament instability
  • Scaphoid fracture
  • Extensor digitorum tenosynovitis
  • Compressive neuropathy ("bracelet syndrome")
  • Intersection syndrome
  • Snapping Extensor Carpi Ulnaris
  • Vaughn Jackson syndrome
• General
  • Hand and finger dislocations
  • Hand and finger fractures
  • Hand and finger infections
  • Gout and pseudogout
  • Hand and finger tendon injuries
  • High-pressure injection injury
  • Osteoarthritis
  • Rheumatoid arthritis
  • Ring removal

Diagnosis

• X-ray (perform before joint stressing)
  • Bony avulsion from insertion of UCL into proximal phalanx
  • Associated condylar fracture
  • Proximal phalanx volar subluxation and radial deviation suggests complete UCL rupture

Partial versus complete rupture

• Valgus stress testing with joint in full extension and in 30 deg of flexion
  • >35 deg of joint laxity or 15 deg of laxity beyond that present in uninjured thumb is consistent w/ complete UCL rupture

Management

• Partial rupture
  • Immobilize in thumb spica for 4wk
• Full rupture
  • Referral within 1wk