Methotrexate can be used for joint cavity injections. Methotrexate is mainly used for the treatment of rheumatoid arthritis and knee osteoarthritis. Methotrexate can inhibit synovial cell proliferation, reduce synovial cell secretion of inflammatory cytokines, and reduce synovial inflammatory response, thus achieving the effect of reducing the symptoms of rheumatoid arthritis and knee osteoarthritis. Adverse effects of intra-articular injection of methotrexate are mild and generally less severe than those of oral and intramuscular methotrexate, with occasional adverse effects such as joint swelling and mild nausea. Patients with localized infection in the joints, allergy to methotrexate, pregnancy and lactation are contraindicated. Pay attention to monitor liver and kidney function and blood picture during the use of the drug. It is recommended that patients who need to use methotrexate intra-articular injection treatment should go to regular hospitals in time, and complete the treatment under the guidance of doctors.