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Base of thumb fracture in Adult
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Base of thumb fracture in Adult

Contributors: Michael Catanzaro MD, Danielle Wilbur MD
Other Resources UpToDate PubMed

Synopsis

Causes / typical injury mechanism: A 1st metacarpal base fracture typically occurs when an axial load is applied to a partially flexed thumb. Additionally, a hyperabduction or hyperflexion injury may lead to a 1st metacarpophalangeal (MCP) base fracture.

Classic history and presentation: Often related to acute traumatic injuries (eg, sports injuries, falls, or physical altercations). Patients will typically present immediately following the traumatic injury with pain, dorsal swelling, and limited motion at the MCP and carpometacarpal (CMC) joints.

Prevalence: First metacarpal base fractures comprise 5% of all hand fractures. Eighty percent of 1st metacarpal fractures involve the metacarpal base.

Risk factors: Acute traumatic events that result in an axial load on the thumb while the thumb is in slight flexion.

Pathophysiology:
  • Bennett fracture – Internal thenar muscles pull the distal end of the distal fracture segment ulnarly and volarly. The proximal end of this segment is pulled dorsally and radially by the abductor pollicis longus. The proximal fracture segment is anchored by the anterior oblique ligament.
  • Rolando fracture – Fractures have a T or Y pattern, without the displacement described above, as the fragments are held in place by a stable volar plate.
Grade / classification system: These fractures can be classified as intra-articular or extra-articular.

Intra-articular:
  • Bennett – Partial intra-articular fracture of the thumb metacarpal base. The fracture fragment is unicondylar and involves the volar ulnar corner of the proximal aspect of the metacarpal.
  • Rolando – Complete intra-articular fracture of the entire thumb metacarpal base with multiple articular fragments. No portion of the metacarpal shaft remains in continuity with the CMC joint.
  • Severely comminuted – Complete intra-articular fracture.
Extra-articular:
  • Oblique – Oblique fracture of the metacarpal without articular involvement.
  • Transverse – Transverse fracture of the metacarpal without articular involvement.
  • Pediatric – Extra-articular fractures involving the proximal physis (Salter-Harris type II is most common).

Codes

ICD10CM:
S62.513A – Displaced fracture of proximal phalanx of unspecified thumb, initial encounter for closed fracture
S62.516A – Nondisplaced fracture of proximal phalanx of unspecified thumb, initial encounter for closed fracture

SNOMEDCT:
69916004 – Fracture of base of thumb

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Last Reviewed:10/06/2021
Last Updated:10/06/2021
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Base of thumb fracture in Adult
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