Population: Subjects will be recruited from the Sports Medicine clinic at the University of Virginia Health System in the Department of Physical Medicine and Rehabilitation. Subjects will have suspected acute stress fracture of the lower extremity and will be age 14 years and older. Anatomic locations included in this study are as follows: all bones of the foot and ankle, tibia, fibula, and femoral shaft. Patients with suspected stress fracture of the femoral neck will be excluded due to the difficulty of appropriate ultrasound evaluation secondary to depth as well as the potential for significant morbidity if not diagnosed properly. We estimate that the Sports Medicine clinic diagnoses approximately 12 acute stress fractures per month per physician amongst the three physician's clinics involved in this study. Therefore, our anticipated number of subjects over a 6 month period will be at least 216 patients.