Antero-posterior divergent dislocation of elbow with ipsilateral fractures of ulnar and radial shafts in adult: A case report

1 Introduction

The proximal ends of the ulna and radius migrate together as a single unit with intact proximal radioulnar joint (PRUJ) in a conventional elbow dislocation. In divergent dislocation, PRUJ is disrupted in addition to elbow dislocation. PRUJ separations might be minor or large in divergent dislocations. While substantial separations are more common in adults with high velocity trauma, subtle separations are more common in youngsters. The two types of divergent dislocation of elbow with substantial separation of PRUJ are the antero-posterior (AP) type and the transverse or mediolateral (ML) type. When the proximal ulna dislocates on the medial side in relation to the distal end of the humerus and the radial head dislocates on the lateral side, it is termed as mediolateral or transverse divergent dislocation. The radial head dislocates anteriorly and the proximal ulna dislocates posteriorly in the anteroposterior form.

Traumatic divergent dislocation is an uncommon injury that primarily affects youngsters, with even fewer cases reported in adults. In 1981, De Lee reported the first-ever incidence of divergent dislocation of the elbow in a 6-year-old kid.¹ This injury was reported by Moritomo in 2003 as a consequence of the Sauve Kapandji operation in a patient suffering from rheumatoid arthritis.²

Only a small number of studies have been done on adult cases of divergent elbow dislocations.³ To the best of our knowledge, no adult case of divergent dislocation of the elbow with ipsilateral fractures of the ulna and radius shafts has been reported. We want to draw attention to this uncommon injury, its surgical treatment, and the clinical result in this case report.

2 Case report

A 29 year old man, right hand dominant, presented to casualty with trauma around his elbow following road traffic accident. Initial examination revealed significant swelling and deformity around the elbow. Deformity was also noticed in the mid forearm. There were no external injuries. Radial pulse was felt well and there was no sensory deficit in the hand. Standard radiographs of the elbow, anteroposterior and lateral views were taken. There was divergent dislocation of elbow with anterior dislocation of radial head and posterior dislocation of proximal ulna. There were displaced fractures in the middle third of the shafts of radius and ulna [Fig. 1]. There was no fracture in the distal humerus, proximal end of radius and proximal end of ulna. The distal radioulnar joint was intact.

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Fig. 1 Anteroposterior and lateral radiographs of the left elbow with forearm showing a divergent antero-posterior dislocation with fracture of radial and ulna shaft.

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Surgical procedure: The surgery was performed under brachial block anesthesia without tourniquet. Through dorsal approach, ulna shaft fracture was reduced and fixed with 3.5mm compression plate and screws. The ulnar surgical wound was closed. Through conventional volar approach, radius shaft fracture was reduced and fixed with 3.5mm compression plate and screws. Because of extensive soft tissue swelling, the radial surgical wound could not be closed. Secondary closure was done 2 weeks after the primary surgery.

After reduction and fixation of shaft fractures, elbow was viewed by image intensifier. The divergent dislocation was lying unreduced. With gentle traction and manipulation, reduction was done under image intensifier. The humero-ulnar joint could be reduced with traction and flexion, but it was unstable in extension ie, got dislocated with less 40 degrees of flexion. With elbow at 90 degrees of flexion, radial head was lying dislocated anteriorly. The humero-radial joint could be reduced with traction in extension and manipulation. With more than 30 degrees of flexion, the reduction was unstable ie., got dislocated anteriorly. In full extension and less than 40 degrees of flexion, the proximal ulna was lying dislocated posteriorly.

The humero-ulnar joint was held reduced in more than 90 degrees of flexion. The anteriorly dislocated radial head was manipulated posteriorly and reduced. Holding radial head reduction, the humeroradial joint was fixed with 2 trans-articular 1.8mm K wires. After reduction of both humero-radial and humero-ulnar joints, the proximal radioulnar joint got reduced [Fig. 2]. An above elbow posterior POP slab was applied for 4 weeks. At the end of 4 weeks, check X-rays were taken, trans-articular K wires were removed. An elbow ROM splint was applied and elbow mobilization started. Patient underwent supervised physiotherapy for 6 weeks after POP removal. At the end of 12 weeks, x-ray revealed union of fracture both bones forearm, well aligned elbow joint and PRUJ [Fig. 3]. Clinically, patient had full flexion and full extension at elbow; supination was full and terminal pronation was restricted [Fig. 4]. There was no varus or valgus instability at elbow.

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Fig. 2 Anteroposterior and lateral radiographs of the left elbow with forearm showing fixation of radius and ulna with 3.5mm compression plates and trans-articular K wire fixation of radio-humeral joint. Note that the elbow is flexed at 100°.

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Fig. 3 Anteroposterior and lateral radiographs of left elbow at the end of 4 months shows consolidated forearm bone fractures and well aligned elbow joint.

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Fig. 4 Clinical photograph of the patient showing elbow range of movement at the end of 4 months follow up.

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3 Discussion

Casstevens et al.⁴ reported a case of ML divergent dislocation associated with humeral shaft fracture and open perilunate dislocation wherein closed reduction of the elbow was performed and open reduction of the humeral shaft was done. For the residual radiocarpal instability, the radio carpal joint was fixed with 2 K-wires. Elbow joint was found to be stable and no ligament repair was required. Antero-posterior divergent dislocation with radial shaft fracture, ulnar deformation, and distal radio-ulnar joint instability was described by Laratta et al..⁵ They diagnosed the injury as an unclassifiable Monteggia variety and used plate fixation of the proximal ulna, suture anchors for collateral medial and lateral ligament repair, K wire stabilization of the DRUJ, and a hinged external fixator spanning the elbow joint. A case of transverse divergent dislocation of the elbow with ipsilateral fractures of the ulnar shaft and radial styloid process was reported by Hassini L. et al..⁶ The ulnar fracture was fixed with plate, and the radial styloid fracture was fixed using K wires. Two trans-articular K wires were used to support the elbow in the humero-radial joint, and the medial collateral ligament was repaired.

Several authors have performed open collateral ligament repair after closed reduction of the elbow joint in conventional elbow dislocation. Josefsson et al.⁷ compared conservative treatment with surgical repair of the injured ligaments in a group of thirty patients, in which he found no statisticaly significant differences between the two groups in terms of instability, recurrence of dislocation, weakness, and range of motion; nevertheless, a small number of patients in the surgery group experienced loss of terminal extension. Our patient's diffuse swelling around the elbow and throughout the forearm was so severe that it was impossible to close the surgical site on the radial side. Given the condition of the soft tissues, we deferred open repair of the elbow collateral ligaments. Like Hassini et al. case, we stabilized the humeroradial joint with 2 trans-articular K wires. The lack of instability in the long-term follow-up suggested adequate collateral ligament healing.

The mechanism of injury that produces dislocation of the posterior part of the elbow joint starts by disrupting the integral stability of the elbow that occurs with extreme supination of the forearm when the body is driven into internal direction as compared to the fixed position of the upper limb.⁸ Altuntas et al.⁹ discussed the mechanism of injury in divergent dislocation as “surplus amount of soft tissue injury” around the elbow joint. These injuries include torn or damaged anterior capsule, the collateral ligaments, the annular ligaments and the proximal third of the interosseous membrane of the radius and ulna. After a fall onto an outstretched hand and valgus loading of the elbow joint, the distal portion of the humerus separates the radius and ulna, disrupting the proximal radioulnar joint. This ultimately results in tearing of the ligaments and anterior capsule of the elbow joint, bringing about divergence of the elbow joint.

In our case, we believe that the injury was caused by two different sets of forces. The first is a substantial indirect force that caused AP divergent dislocation, as suggested by Altuntus et al. The second force was most likely a direct impact to the forearm which resulted in the fracture of the shaft of the forearm bones.

4 Conclusion

Traumatic divergent antero-posterior dislocation of the elbow in adults is a complex injury. The superadded fracture of the radial and ulnar shafts has rendered this injury discrete and challenging. The anatomical reduction of the shaft fractures, radiohumeral, humeroulnar and proximal radioulnar joints along with supervised physiotherapy has resulted in good radiological and clinical outcome.

This case emphasizes the fact that every case of elbow dislocation should be thoroughly evaluated by standard radiographs using true antero-posterior and lateral views to rule out PRUJ dislocation.To rule out forearm bone fractures and distal radio-ulnar joint (DRUJ) dislocations, radiographs of the ipsilateral whole forearm and wrist are required in all cases of elbow dislocations. The surgeon should be aware of this rare type of injury which can help to select appropriate treatment with confidence.

Author statement

1st author- Dr Satishkumar BRJ MS(ortho), DNB- Senior Orthopaedic consultant; BRJ Ortho Centre and MAK hospital, Coimbatore. Perfomed the given technique, Wrote the paper, Data support. 2nd author- Dr Vivek Ponnusamy MS (ortho): Orthopaedic consultant; BRJ Ortho Centre and MAK hospital, Coimbatore, Data support. 3rd author- Dr Lester Frank MS (ortho)(corresponding author): Senior Registrar in orthopaedics; BRJ Ortho Centre and MAK hospital, Coimbatore, Wrote the paper, Collected material regarding the related subject.

Ethical statement

Ethical approval for the case report has been obtained.

Funding statement

No financial funding was done for the above case report.

Guardian/patient's consent

The above case report has been studied and prepared after obtaining consent from the patient for the use of radiological and clinical pictures.