Patients suffering from acute synovitis may have the following symptoms: 1. severe localized pain in the joint, which may cause the patient to be afraid to move. 2. severe swelling of the joint, such as diffuse swelling around the joint in the early stage, followed by a rapid increase in the fluid inside the joint, which is characterized by a very full joint space, protruding outward, and a fluctuating sensation of pressing a hot water bag when pressed. 3. There may be changes in the joint surface, such as redness, swelling, and heat when touching the joint surface. 4. There may be obvious restriction of movement, which is caused by pain in the early stage, and as the disease progresses, there is too much fluid inside the joint, resulting in swelling and pain inside the joint, which makes the patient reluctant to move. 5. sweating, weight loss, etc.