Early stress fracture of fibula on ultrasound

The two ultrasound images above were taken at the initial office visit of a young athlete complaining of pain at the distal fibula. Plain radiographs were normal, but the ultrasound images clearly show cortical disruption and callus formation consistent with a stress fracture. The disruption of the fibular cortex (which appears as a dense white line) is apparent below the arrow and callus in the top image. Callus formation can also be seen within the box in the lower image.