Subject Recruitment: Subjects presenting to the Sports Medicine clinic with suspected acute stress fracture of the lower extremity on initial presentation will be offered participation. Participation includes an additional clinic visit with a separate physician to perform a diagnostic ultrasound of the area of concern in addition to the standard work up they would receive for their presenting complaint. Informed consent was obtained at the time of study enrollment. Subjective will be offered ultrasound evaluation as well as follow up confirmatory MRI. The cost of follow up MRI is included in the study to prevent selection bias based on insurance coverage for MRI. The costs associated with the additional clinic visit for diagnostic ultrasound is also included in the study budget.