ORIGINAL ARTICLE Posterior Divergent Dislocation of the Elbow in Children and Adolescents A Report of Three Cases and Review of the Literature Altay O. Altuntas, MB, BS,*† Jitendra Balakumar, MB, BS,* Robert J. Howells, MB, BS, FRACS,* and H. Kerr Graham, MD, FRCS(Ed), FRACS† Abstract: Divergent dislocation of the elbow is defined as a specific elbow dislocation in which the distal humerus is forced between the proximal radius and ulna, resulting in separation or divergence of the proximal forearm bones. This is an uncommon injury in children, with 14 cases reported in the last 23 years. The authors report three additional cases and the findings from cadaver elbow dissections in which the injury was reproduced. The authors propose that there is only one type of divergent dislocation, resulting from indirect forces transmitted to the elbow from a fall on the outstretched hand. The injury predominantly occurs in younger children because joint laxity is a predisposing cause. Early recognition, followed by a closed reduction and a 3- to 4-week period of cast immobilization, should result in a full recovery for most children. Key Words: elbow, dislocation, divergent, trauma (J Pediatr Orthop 2005;25:317–321) D islocations of the elbow are uncommon in children, representing just 3% of elbow injuries in a large series reported from Gothenburg, Sweden. 1 The peak incidence is in the second decade, usually between ages of 13 and 14, as the physes close. 2 Posterior dislocations are by far the most common type, with anterior dislocations particularly rare. 2 Divergent dislocation is a rare subgroup of the posterior dislocation group, first described clinically by Warmont in 1854 3 and by Wright in 1893. 4 The first report in the modern era supported by radiology was by DeLee in 1981. 5 Since then, there have been a total of 14 cases reported, with varying views as to etiology, classification, management, and outcome. 6,7 We report three additional clinical cases and review the literature on this uncommon injury. In an effort to understand the patho- anatomy and its relationship to radiologic findings, we re- produced the injury in two cadaver elbows. PATIENTS AND METHODS Patient 1 A 6-year-old boy presented to the emergency department with a painful and deformed left elbow following an un- witnessed fall while playing. The elbow was held in about 40 degrees of flexion, with marked swelling and widening. The radial and ulnar pulses were both present at the wrist and the limb was neurologically intact. A radiograph showed posterior divergent dislocation of the elbow (Fig. 1). The ossification center of the radial head was not visualized on the initial x-ray but was confirmed to be present on ultrasound, similar to the uninjured side. Closed reduction of the dislocation was performed in the emergency department using intravenous sedation with midazolam and ketamine. Closed reduction was achieved by longitudinal traction while simultaneously squeezing the proximal radius and ulna together to reduce the proximal radioulnar joint, the technique described by Thompson. 2 The neurovascular status of the limb was intact following reduction and the elbow was immobilized at 90 degrees of flexion in a plaster back slab for 4 weeks. Follow-up at 4 weeks showed good range of movement, from 15 degrees of fixed flexion to nearly full flexion. He remained out of the slab and was encouraged to exercise the elbow with caution. A radiograph at this point showed maintenance of the reduction and a small periosteal callus reaction around the proximal radius. The child had a normal elbow at 4 months. Patient 2 A 6-year-old boy was transferred from another hospital with an injury to the right elbow, described as a posterior dislocation of the elbow with disruption of the proximal radioulnar joint. The injury was caused by a fall on the out- stretched hand while running. On examination, several hours after injury, the elbow was painful and swollen. Radiographs showed a posterior divergent dislocation (Fig. 2). There were no neurovascular complications, despite an interval of 15 hours from injury to presentation for management. Closed reduction, under general anesthesia, was achieved with longi- tudinal traction and compression of the proximal radius and ulna as described above (Fig. 3). The elbow was immobilized in a plaster back slab in 90 degrees of elbow flexion and neutral forearm rotation for 3 weeks and a further 2 weeks in a collar and cuff. Following mobilization, the child achieved full range of movement of the elbow at 3 months after the injury, at which time four of the five Wynne-Davies criteria for From *Box Hill Hospital, Melbourne, Australia; and †Royal Children’s Hospital, Melbourne, Australia. Study conducted at Box Hill Hospital and Royal Children’s Hospital, Melbourne, Australia. None of the authors received financial support for this study. Reprints: Prof. H. Kerr Graham, Professor and Director of Orthopaedic Surgery, University of Melbourne Department of Orthopaedics, Royal Children’s Hospital, Flemington Road, Parkville, Victoria 3052, Australia (e-mail: kerr.graham@rch.org.au). Copyright Ó 2005 by Lippincott Williams & Wilkins J Pediatr Orthop  Volume 25, Number 3, May/June 2005 317