Magnetic resonance imaging (MRI) and x-ray have traditionally been used to identify musculoskeletal pathology. Diagnostic musculoskeletal ultrasound, however, is becoming increasingly popular among physiatrists.

A 35-year-old male runner with no significant past medical history presented with a complaint of right medial knee pain for the past 6 to 8 weeks. He reports that he had recently increased his running mileage significantly while running in shoes that were due to be replaced. He had stopped running but noted that the pain persisted. He described the pain as located in one specific spot on the medial aspect of the right knee, rated 4/10 most of the time, but was exacerbated by putting more force through his leg with activities including jogging, going up and down stairs, or carrying heavy objects.

X-rays of the right knee were obtained and were normal, which prompted further imaging with an MRI one week later, which was also normal. Laboratory testing was remarkable for vitamin D deficiency of 13ng/mL. Musculoskeletal ultrasound revealed a small fracture of the medial epicondyle of the femur measuring 3mm×3mm that was tender to sonopalpation. The patient was instructed to avoid running until pain free for at least 2 weeks before starting on a graduated return to running protocol.

Musculoskeletal ultrasound may be a useful imaging modality for identifying stress fractures even in some cases where traditional imaging with x-ray and MRI are negative. This may have important implications for use in resource-limited settings where ultrasound is portable and relatively inexpensive in comparison to MRI.