Ottawa knee rules
Age 55 years or older
Tenderness at head of fibula
Isolated tenderness of patella
Inability to flex knee to 90 degrees
Inability to walk four weight-bearing stepsimmediately after the injury and in the emergency department
Pittsburgh decision rules
Blunt trauma or a fall as mechanism of injury plus either of the following:
	Age younger than 12 years or older than 50 years
	Inability to walk four weight-bearing steps in the emergency department