Which of the following is part of the Ottawa knee rules?

• A. Inability to bear weight both immediately and in the ED
• B. Tenderness at the head of the fibula
• C. Isolated tenderness of the patella
• D. Age 55 or older

Answer: (A)

Ottawa knee rules use a few simple clinical clues to decide when knee X-rays are needed after an acute injury. If any one of these is present, imaging is indicated: age 55 or older; tenderness at the patella (kneecap); tenderness at the head of the fibula; inability to flex the knee to 90 degrees; and inability to bear weight both immediately after the injury and in the emergency department (four steps). The inability to bear weight in both settings is a key criterion, but it sits alongside the other findings. In practice, any one of these findings justifies radiographs to look for a fracture.