ACR Appropriateness Criteria® Acute Trauma to the Knee.

Acute trauma to the knee is a common presentation seen in the emergency department. After a routine clinical examination, imaging is frequently performed to facilitate the diagnosis and almost always starts with radiographs. If clinically indicated, advanced cross-sectional imaging may then be performed for further evaluation. CT is often performed for preoperative planning of the complex tibial plateau and distal femur fractures. Currently, MRI is the study of choice for evaluation of bone marrow, internal derangements, and other soft-tissue injuries about the knee joint. In patients with knee dislocations, MR angiography may be performed simultaneously with MRI for evaluation of internal derangements and vascular injuries with less morbidity compared to conventional angiography. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.