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….

[DDET What about the lateral ??]

[/DDET]

[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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Chris Partyka

Dr Chris Partyka MBBS, BMedSci, MD. Staff Specialist in Emergency Medicine, Royal North Shore Hospital. Prehospital and Retrieval Specialist, NSW Ambulance. Clinical Lecturer, University of Sydney