A thin, shortened forearm with an inclination to the ulnar side, dislocation of the radial head, and limited rotational function of the forearm are among the clinical symptoms of congenital ulnar deficiency disease. The disease is caused by arm trauma, and different violent factors can cause different types of fractures: 1, direct violence: mostly seen in blows or machine injuries, the fracture is transverse or comminuted type, and the fracture line is in the same plane. 2. Indirect violence: when the palm of the hand lands during a fall, the violence is transmitted upward resulting in a fracture of the middle or upper 1/3 of the radius, and the residual violence is transmitted obliquely downward through the interosseous membrane to the ulna, resulting in an ulnar fracture, so the ulnar fracture line is lower than the radial fracture line. The radius fracture is mostly transverse or serrated, and the ulna is mostly short and oblique. 3, torsional violence: when the body is tilted to one side during the fall, the forearm is subjected to both longitudinal conduction and rotational torsion, and a spiral type double fracture of the ulnar radius occurs. The fracture line is in the same direction, mostly with the ulnar bone sloping upward to the radius outward.