Chronic radial head dislocation can be secondary to a congenital anomaly or trauma. Controversy remains regarding the treatment of the skeletally immature patient. Reconstruction and relocation of the radial head has not been uniformly successful. This study reports the various pathologic changes around the radiocapitellar joint that prevents a stable reduction in untreated radial head dislocations. The cohort consisted of fifteen elbows in fourteen children. Two had bilateral congenital dislocations and 12 had unilateral posttraumatic dislocations. Separate analysis of each type was performed because of the different pathoanatomy. Persistent pain, limitation of motion, and deformity, unacceptable to either the patients or parents, were indications for intervention. In the traumatic group, six were isolated radial head dislocations and six were Monteggia-type injuries. Various radiographic measures were used to identify the abnormalities.
The congenital cases exhibited findings that have been reported previously. The capitella were irregular, and the radial heads were dome-shaped. The dislocations were either anterior or anterolateral. The post-traumatic dislocations demonstrated dysplastic changes in nine out of the twelve patients. There were a variety of abnormalities affecting the distal humerus, proximal radius, proximal ulna, and wrist. The ulna was bowed in the proximal shaft in nine out of the twelve patients. The bow was in the same direction as the radial head dislocation. More severe dysplastic changes were observed in patients who had a dislocated radial head for a longer period of time.
The study concurs with previous assessments of posttraumatic radial head dislocation, resulting in dysplastic changes about the elbow. The dysplastic changes are attributed to defects in growth plate maturation that occur after radial head dislocation. In contrast, congenital radial head dislocation has pathoanatomy unrelated to trauma. The authors attempt to equate the secondary changes after trauma to developmental dislocation of the hip. Although this concept has certain flaws, the changes appear to be secondary and related to the persistent dislocation. Early reduction of a chronic radial head dislocation may fair better than delayed cases. However, neither open reduction nor radial head resection are uniformly successful in alleviating pain, restoring stability, and promoting optimum outcome.