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Introduction
  • Base of the thumb metacarpal fractures include
    • Bennett fracture (intra-articular)  
    • Rolando fracture (intra-articular) 
    • extra-articular fractures 
  • Epidemiology
    • incidence
      • 80% of thumb fractures involve the metacarpal base
      • most common variant is the Bennet fracture
  • Pathophysiology
    • mechanism of injury
      • most fractures caused by axial force applied to the thumb
    • pathoanatomy
      • three muscles provide deforming forces at base of thumb 
        • abductor pollicis longus (PIN) 
        • extensor pollicis longus (PIN) 
        • adductor pollicis (Ulnar n.) 
      • the thumb has extensive CMC motion in sagittal plane
        • allows for angulation up to 30 degrees in this plane
Bennett Fracture
  • Intra-articular fracture/dislocation of base of 1st metacarpal characterized by  
    • volar lip of metacarpal based attached to volar oblique ligament
      • ligament holds this fragment in place
      • small fragment of 1st metacarpal continues to articulate with trapezium 
  • Pathoanatomy
    • lateral retraction of distal 1st metacarpal shaft by APL and adductor pollicis 
      • shaft pulled into adduction
      • metacarpal base supinated
  • Prognosis
    • better than Rolando fx 
  • Imaging
    • radiographs
      • recommended views
        • fracture best seen with hyper-pronated thumb view
      • findings
        • minimal joint step-off considered best
  • Treatment
    • nonoperative
      • closed reduction & cast immobilization
        • indications
          • nondisplaced fractures
        • technique
          • reduction maneuver with traction, extension, pronation, and abduction
    • operative
      • closed reduction and percutaneous pinning
        • indications
          • volar fragment is too small to hold a screw
          • anatomic reduction unstable
        • technique
          • can attempt reduction of shaft to trapezium to hold reduction
      • ORIF
        • indications
          • large fragment
          • 2mm+ joint displacement
  • Complications
    • post-traumatic arthritis
      • there is no agreement regarding the relationship of post-fixation joint incongruity and post-traumatic arthritis
Rolando Fracture
  • Intra-articular fracture of base of 1st metacarpal characterized by 
    • intra-articular comminution
  • Epidemiology
    • less common than Bennett's fracture
  • Pathoanatomy
    • deforming forces are the same as Bennett's fracture 
      • volar fragment should have volar oblique ligament attached
      • shaft pulled dorsally
    • typically the base is split into a volar and dorsal fragment
      • commonly called a 'Y' fracture
    • often have more than two proximal fragments
  • Prognosis
    • worse than Bennett fx
  • Treatment
    • nonoperative
      • immobilization
        • indications
          • for severe comminution, stable
          • start early range of motion
    • operative
      • external fixation, CRPP
        • indications
          • for severe comminution, unstable
        • technique
          • can approximate large fragments with k-wires
      • ORIF
        • indications
          • most common fixation method
        • technique
          • use t-plate or blade plate
          • can use k-wires of fragments are too small for screw purchase
  • Complications
    • commonly results in post-traumatic osteoarthritis
Extra-articular fracture
  • Extra-articular fracture of base of 1st metacarpal
    • can be transverse or oblique in nature 
  • Treatment
    • nonoperative 
      • spica casting
        • indications
          • if joint is reduced and there is less than 30 degrees of angulation
    • operative
      • CRPP
        • indications
          • if reduction cannot be held to result in less than 30 degrees of angulation
        • outcome
          • these fractures typically have the best outcome
 

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Questions (1)

(OBQ08.91) Which of the following muscles provide the primary deforming forces to Bennett and Rolando fractures (base of the 1st metacarpal fractures)? Review Topic

QID: 477
1

Pronator quadratus

0%

(18/3663)

2

Flexor pollicis longus

2%

(55/3663)

3

Extensor pollicis longus

3%

(95/3663)

4

Adductor pollicis longus and abductor pollicis

9%

(346/3663)

5

Abductor pollicis longus and adductor pollicis

86%

(3132/3663)

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