If a small piece of bone is knocked out of the arm, it has no effect on the joint and the fracture is small, no surgery is needed. If the bone is knocked out and affects the flatness of the joint, surgery is needed if the symptoms are severe. Whether or not surgery is needed for a small piece of bone knocked out of the arm depends on the size of the bone knocked out, its effect on the joint, and the separation of the fracture. If the bone does not affect the stability of the joint, and does not affect the flatness of the joint surface, surgery may not be needed for the time being, and anti-inflammatory and analgesic treatment and external fixation will be taken. If the above two aspects are affected, and the knocked-out fracture block is relatively large, then surgical treatment should be considered. The most common type of arm fracture is ulnar humerus fracture, which is mainly characterized by displacement and dislocation of the fracture, obvious swelling, and elbow dysfunction, and must be treated surgically at this time. If the arm knocked off a small piece of bone, it is recommended to go to the hospital in time, early formal treatment.