If pain occurs in the medial curvature of the arm, the first thing to do is to determine if there is any trauma. Trauma can lead to local soft tissue injury, and may also lead to rupture of the medial collateral ligament, or even fracture and dislocation of the joint, in which case the pain is very pronounced and accompanied by significant swelling. If surgery is indicated, active surgery will be performed. If there is no trauma, it may be caused by local chronic strain. A long time in one position or a long time repeating a certain action may lead to repeated strain on the soft tissues attached to the inner bend of the arm, local congestion and edema, formation of sterile inflammation, inflammatory fluid exudation, which may also lead to local chronic strain and local pain over time, and the pain will be more obvious after exertion and cold. Localized occupational diseases as well as septic and infectious diseases in the medial side of the arm bend can cause local bone destruction, soft tissue destruction, and increased local pressure and stimulation of nerve endings, which can also cause pain in the medial side of the arm bend.