MRI for Knee Injury in Adolescents

Initial Imaging Approach

• The American College of Radiology recommends starting with plain radiographs, not MRI, for initial imaging of acute knee trauma in adolescents 1, 4, 5
• Radiographs should be obtained if there is focal tenderness, inability to bear weight, or other specific clinical findings 4, 6, 7, 8

When MRI Becomes Appropriate

• The American College of Radiology recommends MRI without contrast as the next study after negative radiographs for suspected occult fracture, internal derangement, or persistent joint effusion 1, 2
• MRI without contrast is appropriate for evaluating suspected meniscal or ligamentous injury, or mechanical symptoms suggesting meniscal injury 2

Why MRI Without Contrast

• The American College of Radiology Appropriateness Criteria recommend MRI knee without IV contrast for evaluating suspected occult fractures or internal derangement after negative radiographs 2
• MRI without contrast provides excellent visualization of meniscal tears, cruciate ligament injuries, collateral ligament injuries, bone marrow contusions, and osteochondral lesions 1

Common Pitfalls to Avoid

• The American College of Radiology recommends against skipping radiographs, even if soft tissue injury is suspected, to rule out fractures requiring immediate intervention 4, 1
• The American College of Radiology recommends against ordering MRI with contrast, as it adds no diagnostic value for traumatic knee injuries and increases cost and potential adverse effects 4, 1, 2