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Introduction
  • Epidemiology
    • incidence
      • rare (<1% of all fractures)
      • third most common carpal bone fracture
      • makes up 1-5% of carpal fractures
  • Pathophysiology
    • mechanism of injury (trauma)
      • based on type of fracture
        • trapezial body
          • most common
          • can result from a variety of mechanisms (see table)
          • vertical fracture pattern is the most common, resulting from axial loading
            • May be accompanied by Bennett fracture of first metacarpal
        • trapezial ridge
        • fracture-dislocations
  • Associated conditions
    • Bennett fracture of base of first metacarpal
      • Associated with high energy mechanisms and vertical fractures of the trapezial body
    • fractures of scaphoid, trapezoid, capitate, neighboring metacarpals, and the distal radius (particularly with fracture-dislocations)
Anatomy
  • Osteology
    • trapezium located at base of thumb
    • thumb carpometacarpal joint is a biconcave saddle joint
      • Consists of four articulations:
        • Trapeziometacarpal (TM)
        • Trapeziotrapezoid
        • Scaphotrapezial (ST)
        • Trapezium-index metacarpal
    • trapezium has palmar groove for flexor carpi radialis (FCR) tendon
  • Ligaments
    • anterior oblique (volar beak) ligament
      • Primary stabilizing static restraint to subluxation of CMC joint
      • Originates from the palmar tubercle of the trapezium and inserts on the articular margin of the ulnar metacarpal base
    • dorsoradial ligament
      • primary restraint to dorsal dislocation
        • injured in dorsal CMC dislocation
      • strongest and thickest ligament
        • posterior oblique ligament
        • intermetacarpal ligament
Classification
 
Trapezium Fractures
Ridge
 • Type 1: base of ridge
 • Type 2: smaller avulsion fractures
 
Body

Walker Classification:
 • Vertical intra-articular (most common, due to axial compression)
 • Horizontal (horizontal shear)
 • Dorsal radial tuberosity (vertical shear)
 • Anterior medial ridge (loading or avulsion of transverse carpal ligament)
 • Comminuted (high energy)


Fracture-Dislocation
 • High energy injuries
 • Often missed due to concomitant injuries

 
 
Presentation
  • History
    • Patients typically recall trauma to the thumb and acute onset of pain
  • Physical exam
    • Point tenderness over base of thumb
    • Ecchymosis
    • Trapezial ridge fractures may present with more subtle "achy" pain over volar base of thumb
Imaging
  • Radiographs
    • recommended views
      • Standard PA
      • Pronated AP
      • Lateral
      • Bett view
    • optional views
      • Carpal tunnel view (trapezial ridge fracture)
  • CT
    • indications
      • Normal x-rays with high index of suspicion
      • May be required to delinate size and degree of displacement of fracture fragments
      • Allows better assessment of articular involvement
  • MRI
    • Indications
      • Typically not required
      • Can identify occult fractures or ligamentous injuries
Treatment
  • Nonoperative
    • Thumb spica case for 4-6 weeks
      • Nondisplaced body fractures
      • Acute trapezial ridge fractures
    • Observation
      • Subacute trapezial ridge fractures with stable CMC joint
  • Operative
    • Open reduction and internal fixation
      • indications
        • Displaced body fractures in active patients
        • Large fracture fragments can be fixed with headless compression screws or mini-fragmentation screws
        • Good results have also been described with k-wire fixation
      • outcomes
        • Excellent results with good restoration of thumb and wrist motion and pinch function compared to uninjured side
    • Fragment excision
      • Indications
        • Symptomatic trapezial ridge fractures
        • Consider early fragment excision for type-2 (avulsion) trapezial ridge fractures as these are associated with higher risk of symptomatic nonunion
    • Trapeziectomy
      • Indications
        • Lower demand patients
        • Painful first CMC joint prior to injury
        • Degeneartive changes of first CMC joint
    • Primary arthrodesis
      • Indications
        • Highly comminuted fractures in high demand patients
    • External fixation
      • Indications
        • Comminuted fractures with adequate alignment of articular surface
Techniques
  • Open reduction and internal fixation (ORIF)
    • Approach
      • Dictated by fracture pattern
      • Dorsal approach
        • Can go between EPL and EPB tendons or retract tendons out of the way
        • longitudinal capsulotomy
      • Wagner approach
        • Incision at the glabrous border
        • Good for sagittally oriented fractures
      • Volar approach
        • Excision of trapezial ridge fracture fragments
Complications
  • Non-union
    • Incidence not well defined
    • Type 2 trapezial ridge (avulsion) fractures high risk
  • CMC instability
  • Post-traumatic arthritis
    • Can be treated with delayed trapeziectomy
 

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