History: The patient began to have painful swelling of the interphalangeal joints of both hands 20 years ago, and was diagnosed with rheumatoid arthritis at an external hospital and treated with long-term oral non-steroidal analgesic drugs. 10 years ago, the patient developed pain in both knee joints with no obvious cause, with intermittent soreness and swelling, which increased when squatting and going up and down stairs, and decreased when resting, with a VAS score of 8 when the pain was severe. The pain was controlled by taking “Fotarim”. Six months ago, the pain in both knees worsened, accompanied by squatting restriction, waking up at night with a VAS score of 8. The pain was relieved at times with the use of “anti-inflammatory pain suppositories” at home. Now, the pain worsens every time he stands up, and the pain does not improve with oral “Fotarine” and other analgesic drugs, and due to the long-term oral non-steroidal analgesic drugs, the symptoms of epigastric pain appear, and external gastroscopy shows gastritis with bleeding spots. He was admitted to our hospital as an outpatient with “osteoarthritis of both knees” for further treatment. At the time of admission, he had a VAS score of 8. Since the onset of the disease, the patient was mentally well, eating well, sleeping poorly, having normal bowel movements and no significant weight loss. Past history: 20 years ago, he injured his left knee joint in a car accident and underwent debridement and suturing, and had a history of “diabetes mellitus” and “hypertension” for 11 years, which are now under control. He was admitted to the hospital with mild swelling and deformity of the interphalangeal joints of both hands, no swelling in both knees, pressure pain around both knees (+), patellar grinding test (+), and limitation of squatting in both knees. Auxiliary examinations: frontal and lateral radiographs of both knees and radiographs of both hands showed rheumatoid changes in both hands and wrists and degeneration of both knees. The electrocardiogram showed sinus rhythm, prolonged Q-T interval, and blood potassium: 3.10 mmol/L. Treatment: After admission, the diagnosis was clarified by completing relevant tests and screening for suitable non-steroidal drugs combined with tramadol for oral symptom control, and the rheumatology department was consulted to assist in formulating a treatment plan for rheumatoid arthritis. At the same time, we actively improved the preoperative preparation, and performed puncture, lavage and injection of drugs in both knee cavities and injection of painful points in both knees in the treatment room. Operation method: The patient was placed in a supine position, the knee joint was fully exposed, and after routine iodine alcohol disinfection, a sterile orifice towel was laid, two points were selected as the joint cavity entry puncture points, and after local anesthesia with 2% lidocaine 1ml, the joint cavity fluid was withdrawn and aspirated, and then a syringe was used to extract the mixture (consisting of saline 100ml + lidocaine 5 + gentamicin 1) about After that, a syringe was used to draw back the fluid mixture from the suprapatellar puncture point to exhaust the joint cavity, and the above operation was repeatedly flushed through this process. Afterwards, 10 ml of a mixture of 0.25% lidocaine + tretinoin 5 mg was injected, and about 10 ml of ozone at a concentration of 30 μg/ml was withdrawn and injected into the knee joint cavity. The puncture needle was withdrawn and the puncture site was closed with a dressing. After two sessions of joint lavage, the patient was discharged with satisfactory results, and the pain in both knees was significantly reduced, with a VAS score of 1-2. Follow-up 3 months after discharge: No pain after rest and daily activities, slight soreness in both knees after prolonged standing and walking (about 1 hour), improved after rest. Difficulty analysis: The patient had chronic rheumatoid arthritis combined with osteoarthritis. Long-term oral NSAIDs can cause side effects such as gastrointestinal and liver and kidney damage, and the analgesic effect decreases with the prolongation of the medication, and the patient was afraid of joint replacement surgery. During knee lavage, a large amount of saline and gentamicin can remove or dilute inflammatory mediators such as IB and TNF-a in the joint cavity, which is conducive to the reduction of inflammation and improvement of local immune function; it can flush out debris, small free bodies and fibrin, degenerative joint fluid, etc., which is ultimately conducive to the stabilization and restoration of the joint cavity environment and interruption of the vicious cycle. Intra-articular cavity injection of tretinoin produces local slow-release anti-inflammatory effect, while ozone reacts with biochemical molecules such as proteins in the synovial fluid to produce ROS, LOPs and other reactions that cause the next series of elimination of inflammation, promoting the recovery of joint cartilage and synovial membrane and entering a virtuous cycle to avoid relapse. This method is a better treatment option for patients with severe rheumatoid arthritis combined with osteoarthritis and who are not suitable for joint replacement surgery.