Fifth metatarsal fracture

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Background

  • Os peroneum is an accessory bone (ossicle) located at the lateral side of the tarsal cuboid, proximal to the base of 5th metatarsal, commonly mistaken for fx

3 types of 5th metatarsal fx:

  1. Tuberosity (styloid) avulsion fracture:
    • Most common fx at base of 5th metatarsal
    • Sx often mild, pts usually present with sprained ankle complaint
    • Occurs due to forced inversion foot/ankle while in plantar flexion
  2. Jones or metaphyseal-diaphyseal junction fracture:
    • Second most common fx at base of 5th metatarsal
    • Abrupt onset of lateral foot pain, with no prior h/o pain at that site, suggests acute injury and helps distinguish from stress injury
    • Occurs due to sudden change in direction w/ heel off the ground
    • Edema & ecchymosis usually present, may not be able to bear weight
  3. Diaphyseal stress fracture:
    • Occurs through repetitive microtrauma, usually in younger athletes
    • Important to identify given propensity for delayed union and nonunion
    • Usually present with h/o months of pain, which is more intense during exercise or weight-bearing
      • always ask about persistent pain prior to acute event to help distinguish worsening stress fx from acute fx

Diagnosis

5th Metatarsal fx types

Plain radiographs are usually adequate

  • Must distinguish Jones fx from diaphyseal stress freacture:
    • Acute fx will have narrow fx line that appears sharp, normal thin cortex adjacent to fx, and normal intramedullary canal
    • Stress fx will demonstrate cortical thickening near fx line, older stress fx will demonstrate widened fx line and intramedullary sclerosis

Differential Diagnosis

Foot and Toe Fractures

Hindfoot

Midfoot

Forefoot

Management

  • Tuberosity (Styloid) Avulsion Fracture
    • Refer to ortho if > 3mm displacement
    • Nondisplaced fx usually require only symptomatic tx, RICE
    • Walking boot (casting rarely necessary) and weight-bearing as tolerated, f/u in 1 week
  • Jones Fracture (non-displaced)
    • Posterior Ankle Splint, strict NWB, RICE, ortho f/u in 3-5 days
    • 50% of Jones fx treated conservatively may result in nonunion or refracture
    • Conservative tx failure usually due to poor vascular supply of bone and premature return to weight-bearing
  • Diaphyseal Stress Fracture
    • Strict NWB short-leg cast, RICE
    • Ortho referral for all stress fxs

See Also

References

Video