Inability to bend the knee joint and swelling are usually due to damage to the structures inside the knee joint, such as the meniscus, cruciate ligament and synovium, which can cause small blood vessels to rupture and form swelling. In addition, the inflammatory exudate of synovitis in the knee increases gradually, resulting in fluid accumulation in the joint, which also results in pain and impaired movement, as well as swelling. In this case, the following measures are usually taken: First, an MRI should be performed in the hospital to see to what extent the structures in the knee joint are damaged and whether there is more fluid in the joint. If the damage is severe, surgical treatment is usually indicated. If the injury is mild, external fixation in a cast and brace can be performed for about 4 weeks, after which the cast and brace can be removed and functional exercises for knee flexion and extension can be performed. Secondly, if there is a joint injury or synovitis that results in a large amount of fluid in the joint, an empty needle puncture is usually performed to aspirate the fluid from the knee joint after the puncture, which can significantly reduce the pressure on the joint capsule and help to alleviate the symptoms. Again, mannitol and dexamethasone injections should be given intravenously to relieve local inflammatory edema and reduce pain. Finally, non-steroidal anti-inflammatory painkillers such as Nimesulide and Loxoprofen sodium can be taken orally, which can effectively reduce inflammatory edema, alleviate pain and promote the metabolism of inflammatory metabolites. After the above treatment, the symptoms will be significantly improved in 7-10 days.