The causes of arm joint swelling and pain, bending or straightening pain include trauma, joint strain, osteoarthritis, etc. It is necessary to clarify the cause of the disease and take general treatment, medication or surgical treatment to improve the symptoms. 1. Trauma: trauma caused by muscle strain or fracture of the arm joints will appear after swelling and pain and bending and straightening pain, you can restore the normal function of the joints through local immobilization, manipulation, or surgical incision and reset, and when the pain is severe, you can take ibuprofen to relieve the pain. 2. Joint strain: Repeated heavy lifting, long-term use of arms, joint degeneration will cause local joint strain and thus cause pain in the joints, can be relieved through adequate rest, local hot packs, avoid overwork and other discomforts. 3. Osteoarthritis: Pain caused by osteoarthritis can be alleviated by taking acetaminophen and other drugs to reduce pain, injection of sodium vitrate into the joint cavity to improve the function of the joints, and in severe cases, you can choose to replace the joints artificially. When there is swelling and pain in the joints of the arm, it is recommended to go to the hospital in time to clarify the cause of the disease, and actively cooperate with the doctor to receive standardized treatment, and drugs should be used under the guidance of the doctor.