Thumb fracture

Background

Thumb fracture classification

• Type I (Bennett's fracture)
  • Fracture-dislocation of the base of the metacarpal (intra-articular)
  • Base fragment is aligned with trapezium, but distal portion is subluxed by abductor pollicis longus
  • Most common type of thumb fracture; nearly always accompanied by some subluxation or dislocation of CMC
• Type II (Rolando's fracture)
  • Comminuted version of a Bennett's fracture (intra-articular)
• Type III
  • Extra-articular (transverse or oblique)
• Type IV
  • Extra-articular pediatric fracture involving the proximal physis

Clinical Features

• Important to distinguish tenderness at base of 1st MC from injury to scaphoid, trapezium, or distal radius
• If pain or ecchymosis occurs more distally at the MCP (particularly on the ulnar side) consider ulnar collateral ligament injury (Gamekeeper's Thumb)

Differential Diagnosis

Hand and Finger Fractures

• Non-thumb metacarpal fractures
  • Head
  • Neck
  • Shaft
  • Base
  • Boxer's fracture
• Thumb fracture
• Finger (Phalanx) Fracture
  • Proximal
  • Middle
  • Distal

Evaluation

Bennett's fracture

• Imaging plain films
  • AP, lateral, oblique

Management

• Splinting
  • Type I, II - Thumb Spica Splint with the IP joint free and wrist in 30 deg of extension
  • Type III - Short arm Thumb Spica Splint extending to the IP joint and wrist in 30 deg of extension
• RICE
  • Significant swelling or overly aggressive icing to radial side of thumb may result in temporary palsy to the superficial radial nerve (numbness over the dorsum of the thumb)
• Reduction
  • Indicated for angulated (more than 20-30 degrees), extraarticular fracture if clinician is comfortable with the procedure

Disposition

• Refer within 3-5 days:
  • All intraarticular fractures warrant referral (most require surgery)
  • Extraarticular fractures that cannot be adequately reduced

See Also

• Hand and finger fractures

References

Authors

Ross Donaldson, Neil Young