The arm knocked a tendon pain, mostly because of the external force caused by fascial tissue contusion, you can consider cold compresses, drugs and other ways of treatment. 1. Ice compress: When the arm is knocked and the tendon hurts, it may be injured to the soft tissue, and the typical performance is the local pain and swelling. The local ice compresses should be applied as early as possible, including ice cubes and frozen mineral water, especially within 72h, which can effectively reduce the secondary swelling and edema caused by the injury to the soft tissues. 2. Drug treatment: If the patient has increased pain or swelling, you can consider taking some oral or external use of some swelling and pain relief, class of drugs. For example, ibuprofen, safflower oil, to reduce inflammation and reduce pain. The above medications are for reference only and should be used in accordance with your doctor’s instructions. If the pain in the injured area continues to worsen or the swelling becomes more and more obvious, it is recommended to consult a doctor in time, follow the doctor’s instructions for further examination, and under the doctor’s comprehensive analysis, choose a reasonable treatment plan.