Metacarpophalangeal ulnar ligament rupture
- Also known as "Gamekeeper's thumb" or "Skier's thumb"
- Ulnar collateral ligament ruptures at insertion into proximal phalanx (due to radial deviation of MCP)
- If left untreated, it will causes decreased thumb adduction and inability to perform opposition.
- The mechanism of injury is usually a rapid deceleration while holding onto an object (such as a ski pole)
- Swelling and localized tenderness over ulnar border of the thumb MCP joint
- Weakness of pinch
- Distal finger
- Other finger/thumb
- X-ray (perform before joint stressing)
- There is a high association with avulsion fractures from insertion of UCL into proximal phalanx
- Proximal phalanx volar subluxation and radial deviation suggests complete UCL rupture
- Apply radial stress to the thumb with MCP in partial flexion
- Compare relative laxity to other thumb.
- >35 degrees of joint laxity or 15 degrees of releative laxity compared to other thumb is diagnostic of a complete UCL rupture
- This phenomenon occurs when there is a UCL tear that results in entrapment of the adductor pollicis aponeurosis within the UCL. Clinically characterized by extensive laxity on stress testing of the thumb MCP. Patients will require surgical repair
- All patients with suspected UCL injury should be referred to a hand surgeon within 1 week. Reevaluation will dictate operative management.
- Partial rupture → Immobilization in thumb spica for 4 weeks with thumb in neutral position
- Full rupture or Stener lesion → Operative repair
- Ritting A et al. Ulnar collateral ligament injury of the thumb metacarpophalangeal joint. Clin J Sport Med. 20110;20(2):106-112
- Bowers WH, Hurst LC. Gamekeeper's thumb. Evaluation by arthrography and stress roentgenography. J Bone Joint Surg Am. 1977;59(4):519-524