The accuracy of sonography in evaluating various conditions of the musculoskeletal system has been demonstrated and its utility as a primary diagnostic imaging modality in the musculoskeletal system in the United States has been increasing in frequency. Sonography is universally tolerated across a broad patient population, including pediatric and pregnant patients and those in whom traditional magnetic resonance (MR) imaging is not an option, due either to absolute or relative contraindications. Sonographic examinations are relatively quick compared with an MR or computed tomographic study, and delays in scheduling are therefore minimal, an advantage for those patients who have traveled a long distance or who are in a considerable amount of discomfort at the time of their visit to the orthopedic surgeon. With portable ultrasound units, examinations can be performed on the playing field, immediately at the time of the acute injury, for rapid diagnosis. Lastly, ultrasound can be used to guide for therapeutic procedures at the same time the diagnostic exam is performed.