1)      Knee pain with normal knee exam with painful passive internal rotation and extension of hip (Slipped Capital Femoral Epiphysis, CT indicated and orthopedic referral)

2)      Sudden onset knee pain and swelling without preceding trauma in immunocompromised patients with cancer, AIDS, corticosteroid therapy (Septic arthritis)

3)      Painful swelling of the knee within 2 hrs of knee trauma (haemarthrosis with ligamental ruptures)