A Monteggia fracture, also known as a Monsignor fracture, is a type of fracture in which the upper third of the ulna is fractured and there is a combined dislocation of the flexor tuberosity. This type of fracture has a radial tuberosity dislocation and cannot be treated by simply resetting the ulnar fracture without managing the radial tuberosity dislocation. If the radial tuberosity is not reset in a timely manner during treatment, the prognosis can seriously affect the rotational function of the forearm; therefore, surgical treatment is required for most of the treatment of Men’s fractures. Intraoperative dissection is required to reset the ulnar fracture and also to reset the dislocated radial tuberosity. A small percentage of Monsignor fractures can be treated conservatively with plaster brace fixation because the dislocated radial tuberosity has reset itself. During the course of plaster brace fixation, the radiographs need to be reviewed periodically to see if the radial tuberosity is dislocated again. If the dislocation of the radial tuberosity is not treated promptly, it can cause serious sequelae.