Synovitis does not cause swelling of the feet in the early stages, but may cause swelling of the feet in more severe cases. Synovitis is a joint disease in which the synovial membrane is irritated and produces inflammation, resulting in the formation of fluid accumulation due to the imbalance of secretion, and the knee joint is the joint with the most synovial membrane in the joints of the whole body, and synovitis is more common in the knee joint. The main manifestation of synovitis is swelling and pain in the knee joint. If synovitis persists for a long time, causing extensive damage to the knee joint and serious dysfunction of the knee joint, secondary changes in the distal part of the limb may occur, resulting in swelling of the feet. If foot swelling occurs in synovitis, it is recommended to go to the hospital in time, under the guidance of the doctor for standardized treatment, in order to reduce the adverse effects of the disease.