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 Fracture Types

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

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