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Thumb fracture
Other Resources UpToDate PubMed

Thumb fracture

Contributors: Anusha Patil BA, Aabra Ahmed MD, Danielle Wilbur MD
Other Resources UpToDate PubMed


Causes / typical injury mechanism: Thumb fractures are caused by a downward / axial force occurring while the thumb is in a hyperflexed or hyperextended position. This is usually caused by direct trauma such as falling on an outstretched hand or facing a direct blow to the hand. Indirect causes include excessive twisting motions and strong muscle contractions.

Classic history and presentation: Injury due to twisting or flexing the thumb during –
  • Carpentry
  • Skiing
  • Contact sports
  • Martial arts
  • Basketball
  • Wrestling
  • Thumb fractures are common because the thumb is highly mobile. Thumb fractures account for 25% of all metacarpal fractures, with 80% involving the base of the thumb.
  • This is most common in children younger than 16 years (often from crush mechanisms) and adults older than 65 years.
  • Thumb metacarpal fractures usually occur in younger males between ages 10 and 30 years.
Risk factors: Grade / classification system: Green and O'Brien classification –
  • Type I (Bennett fracture)
    • Most common thumb fracture.
    • Intra-articular fracture involving the carpometacarpal (CMC) joint with a clean break, resulting in a palmar ulnar fragment.
  • Type II (Rolando fracture)
    • Intra-articular fracture involving the CMC joint with a Y-shaped or T-shaped break, resulting in 2 or more fragments.
  • Type III
    • Extra-articular oblique or transverse fracture.
    • Extra-articular epibasal thumb fracture (pseudo-Bennett).
  • Type IV
    • Extra-articular pediatric fracture involving the proximal physis.
  • Intra-articular comminuted
    • Severely shattered intra-articular fracture.


S62.509A – Fracture of unspecified phalanx of unspecified thumb, initial encounter for closed fracture

274160002 – Fracture of phalanx of thumb

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Last Reviewed:12/20/2022
Last Updated:01/04/2023
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Thumb fracture
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