Quick Case #01

A 24 year old male rugby player presents to your ED with a severely painful, swollen left hand which occurred during a tackle and subsequent ruck.

These are his x-rays….

CMCD AP  CMCD AP2

[DDET What about the lateral ??]

CMCD lat

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[DDET What’s going on here ??]

Carpometacarpal Dislocation

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[DDET The Anatomy…]

  • The carpometacarpal (CMC) joints form the base of the metacarpal arch of the hand.
  • The metacarpal bases articulate with each other & with the distal carpal row.
      • This is a complex structural configuration.
      • Supported by volar, dorsal and interosseous ligaments.
      • Reinforced by broad insertions of wrist flexors and extensors as well as the deep transverse metacarpal ligament.
  • The ring & little finger MCs articulate with the hamate.
      • These are more mobile and hence more susceptible to dislocation (5th >> 4th digit).

[/DDET]

[DDET The Injury…]

  • Dislocations of the carpometacarpal (CMC) joints are rare.
      • Often the diagnosis is missed.
      • Most commonly a dorsal dislocation.
      • Commonly associated with fractures.
  • Clinically;
      • Occurs as a result of MVAs, falls, crush injuries and closed-fist trauma.
      • Marked swelling and deformity with pain over the dorsum of the hand.
      • Thorough neurovascular examination is mandatory.
      • Assess deep motor branch of ulnar nerve
          • Passes adjacent to hook of hamate & can be directly injured.
      • Beware of compartment syndrome.
  • Radiologically;
      • Fractures may be subtle on x-ray.
      • Superimposed carpal & metacarpal bones.
      • Extra-oblique films may be helpful.
  • Management;
      • Analgesia & limb elevation initially.
      • Closed reduction can be attempted (following adequate sedation +/- regional anaesthesia)
          • Traction & flexion with simultaneous longitudinal pressure on the MC base.
          • Followed by extension of the MC head.
      • Requires Hand-Surgeon referral & will likely need surgical fixation (K-wire).
      • Volar dislocations are very rare and require Hand-Surgery involvement.
  • Complications;
      • Arthritis
      • Weakness.

[/DDET]

[DDET References.]

  1. Rosenʼs Emergency Medicine. Concepts and Clinical Approach. 7th Edition
  2. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 7th Edition.
  3. Wheeless’ Textbook of Orthopaedics

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