Association of radial head dislocation with fracture and acute plastic deformation of the ulna: unreported subtype of Monteggia fracture-dislocation in children.

Abstract

Treatment of a Monteggia fracture-dislocation primarily includes anatomical reduction and fixation of the ulna. However, in rare cases, reduction of the radial head remains impossible even after performing this standard procedure. We have encountered patients with Monteggia fracture-dislocation whose radial head could be reduced by 'overcorrecting' the ulna. In this retrospective study, we aimed to propose an unreported subtype of Monteggia fracture-dislocation. Data of three patients (age 6, 14, and 16 years) with Monteggia fracture-dislocations whose radial head could not be reduced by anatomical fixation of the ulna were retrospectively reviewed. In all three patients, the radial head could not be reduced by anatomical reduction and internal fixation of the ulna even after confirmation of the absence of interposed tissue such as annular ligament in the radiocapitellar joint. However, the radial head could be reduced by fixation of the ulna in a posterior convex shape at the fracture site. At the final follow-up, stable reduction of the radial head was maintained in all patients. We hypothesized that these patients had simultaneous existence of a fracture and acute plastic deformity of the ulna. To the best of our knowledge, this pathological state has not been reported previously but it may not be extremely rare and may only be unrecognized. We believe that a new subtype, that is, type A + C, should be established based on Letts' classification.