Which sign indicates knee effusion when performing a physical examination?

• A. Knee effusion
• B. ACL injury
• C. Meniscal tear
• D. Patellar tracking disorder

Answer: (A)

Detecting knee effusion is all about recognizing fluid within the joint. The hallmark is the swelling that comes from excess intraarticular fluid, which you can confirm with signs like a bulge or a ballot (fluid waves) in the suprapatellar region. Those signs directly indicate the presence of joint fluid, meaning knee effusion itself is the sign you’re identifying.

Other conditions listed describe injuries or disorders that can accompany swelling or cause different symptoms (instability with ACL tear, mechanical symptoms with a meniscal tear, or maltracking with patellar tracking disorder), but they do not specifically indicate the presence of joint fluid.