Ottawa knee rule

A knee x-ray is only required for knee injury patients with any of these findings:

• age 55 or over
• isolated tenderness of the patella (no bone tenderness of the knee other than the patella)
• tenderness at the head of the fibula
• inability to flex to 90 degrees
• inability to weight bear both immediately and in the casualty department (4 steps - unable to transfer weight twice onto each lower limb regardless of limping)