Water on the Knee (Effusion): What to Know
Excess fluid around the joint can cause swelling, pain, and stiffness. Common causes of fluid build-up on the knee include: What Is Cartilage? Cartilage is a flexible tissue on the ends of bones that allows bones to glide smoothly over each other. An illustration by Jessica Olah for Verywell Health Injuries Injury is the most common cause of fluid on the knee in active, healthy people. Infection Infections can also cause fluid and pain....