Knee pain is a common condition that can affect people of all ages. It may develop gradually over time or suddenly after an injury. The knee is a complex joint made up of bones, cartilage, ligaments, tendons, and muscles—when any of these structures become irritated or damaged, pain and discomfort can occur.
Common causes of knee pain include overuse, arthritis, ligament injuries, meniscus tears, and inflammation from conditions such as tendonitis or bursitis. Symptoms may include swelling, stiffness, weakness, reduced mobility, or a popping sensation in the joint.