II. Epidemiology

  1. Boys are affected at a younger age than girls

III. Pathophysiology

  1. Traction injury of peroneus brevis insertion at base of fifth Metatarsal
    1. Repeat microtrauma to peroneus brevis insertion

IV. Signs

  1. Fifth Metatarsal base pain, swelling, tenderness
  2. Provocative maneuvers
    1. Resisted Eversion
    2. Passive Inversion
    3. Plantar Flexion

V. Imaging

  1. Bedside Ultrasound or XRay
    1. Fragmentation and widening of the apophysis (or normal)
  2. MRI
    1. Indicated to evaluate for alternative diagnosis (e.g. Stress Fracture suspected)

VI. Differential Diagnosis

  1. Fifth Metatarsal Fracture
    1. Acute inversion injury with avulsion Fracture
  2. Os Vesalianum (normal accessory bone)
    1. Smooth rounded bone edges (contrast with irregular edges of Apophysitis)

VII. Management

  1. Relative rest
  2. Hard-soled shoe (indicated if pain is severe)

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