Fluid buildup in the knee joint simply means that there is an increase in the amount of joint fluid in the joint, and there are both physiologic and pathologic causes of fluid buildup in the knee joint.
Normally, joint fluid is secreted by the synovial membrane, which serves to maintain the normal lubrication of the joint and nourish the articular cartilage. The secretion and absorption of normal joint fluid are in a balanced state. If the synovial membrane secretes more joint fluid and absorbs the same or less due to various reasons, it will cause an imbalance between the secretion and absorption of joint fluid, resulting in the appearance of joint effusion.
Knee joint effusion may be physiological, such as long-term running, mountain climbing and other sports people, due to the knee joint in a state of long-term activity, will cause the synovial membrane secretion of joint fluid compensatory increase, increase joint lubrication; may also be pathologic, such as knee trauma, surgical trauma, autoimmune diseases, degenerative diseases of the knee joint, and so on.
If knee joint effusion is diagnosed, early and standardized treatment is recommended to reduce the adverse effects of the disease.