Isolated anterior dislocation of the elbow in an adolescent

Introduction

The elbow joint consists of three articulations; the ulnohumeral, the radiocapitellar, and the radioulnar articulations. The movements around the elbow include flexion and extension of the elbow joint, and pronation and supination of the forearm. The dislocation of the elbow can be anterior, posterior, lateral, or medial-based on the mechanism of injury.^[1],[2] A fall on an outstretched hand is the most common mechanism of elbow dislocation.^[3] The most common elbow dislocation is the posterior, whereas the rarest one is the anterior.^[4],[5] The dislocations are usually associated with fractures of the medial epicondyle followed by the lateral condyle of the humerus.^[1],[5] Most of the reported cases of anterior dislocation were associated with fracture of the olecranon process or distal end of the humerus.^[1] It is even more rare to have an isolated anterior elbow dislocation without fracture in adolescents.^[6]

The elbow is the most common joint to become dislocated in children.^[5] The rate of elbow dislocations, among other elbow injuries in children, is 3%–6% annually.^[7] Hyvönen et al. reported the rate of elbow dislocations in children between 1996 and 2014; the rate was 6.4 per 100,000 annually. Anterior dislocation reported in only 1.9% of the cases. The common injury mechanism of anterior elbow dislocation is a fall with a direct blow to the back of the elbow (olecranon). Falls off trampolines and snowboards are examples of such injuries.^[8]

Case Report

A 14-year-old girl was admitted to the hospital with a history of trauma to her right elbow 2 h before presentation. Her right arm was caught and twisted vigorously in the roller of the washing machine while holding a wet blanket. The patient presented with severe pain, swelling, and deformity. She was holding her elbow in about 45° of flexion. The injury was closed with an intact neurovascular evaluation.

There was simple anterior elbow dislocation with no associated fractures, which is seen as anteromedial rather than anterior dislocation on anteroposterior and lateral radiographs, because positioning for proper radiograph was difficult due to pain [Figure - 1].

Figure 1: Radiographs of the right elbow showing isolated anterior elbow dislocation (no radio-ulna divergence indicating an intact annular ligament)

Surgical technique

Under general anesthesia, a trial of gentle closed reduction of the elbow joint was not successful. Open reduction through the posterolateral (Kocher) approach was performed. Neurological preoperative examination as well as plain radiographs showing no radio-ulna divergence indicating an intact annular ligament, and the anterior interosseous nerve. There was complete peeling of the soft tissues from the distal part of the humerus with buttonholing through the triceps muscle and the anconeus facia [Figure - 2]. The elbow joint was reduced after the removal of the interposed triceps and anconeus muscles. It was clinically stable throughout the range of motion after reduction with no fractures or growth plate injuries [Figure - 3]. Repair of the lateral collateral ligament and the anconeus facia was carried out. Above elbow, The back slab in 90° of flexion and mid pronation position was applied and kept for 3 weeks to allow for soft-tissue healing. The patient was started on a self-assisted range of motion immediately after slab removal. She regained a functional range of motion the elbow within 3 months of rehabilitation.

Figure 2: A posterolateral approach used for the open reduction

Figure 3: Postoperative radiographs (2 weeks) with congruent stable reduction of the elbow joint

Discussion

In 1787, the first case of anterior elbow dislocation was reported by Evers.^[9] Since then only few sporadic cases were reported in the literature. A direct blow to the back of the elbow (olecranon).^[6] While in flexion is the most common mechanism of anterior elbow dislocation. In our case, the patient presented with an unusual mechanism of injury (vigorous twisting injury of the elbow). Among the rare cases with anterior dislocation, the case that was reported by Tees and McKim, in Montreal in 1923; they reported a patient with almost the same mechanism of injury with the arm caught between the rollers of a washing machine, although in that case the dislocation was associated with an olecranon fracture.^[10]

The stability of the elbow depends on the primary stabilizers and secondary stabilizers. The primary stabilizers consist of bony articulation (ulno-humeral joint), the anterior band of the medial collateral ligament, and the lateral collateral ligament complex. The secondary stabilizers consist of the radiocapitellar articulation, the joint capsule, the common flexors and extensors origin, and the dynamic stabilizers. Disruption of the posterior column by fracturing the olecranon process is required to produce anterior dislocation.^[11] This would explain the rarity of isolated anterior elbow dislocation.

By reviewing the literature, none of the cases reported as isolated anterior dislocation without a fracture. Carlioz and Abols reported that 64% of children with elbow dislocation had fractures in addition to the dislocation.^[12] The elbow dislocation is usually anterior when there is an avulsion fracture of the olecranon process, as reported by Rasool.^[1] The mechanism of an anterior elbow dislocation in association with an avulsion fracture of the olecranon process is usually caused by a direct blow to the posterior aspect of the elbow. The incidence of such injury is 1.9% of all elbow injuries in children and adolescents.^[1],[8]

Most of the dislocations of the elbow in children are treated with closed reduction and splinting. Few cases may need to be operated on when closed reduction fails, associated with displaced fractures, unstable after reduction or neglected, and late presenting cases.^[1],[8]

The outcome of closed reduction found to be better regarding regaining the elbow range of motion.^[1] The closed reduction should be done gently to avoid growth plate injury, nerve entrapment, or fractures. In this case, open reduction was necessary and was successful.

To avoid stiffness of the elbow joint, it is recommended to start a range of motion and functional treatment as soon as possible.^[13] This report is limited by the radiological short follow-up documentation, but the patient had full clinical recovery without complication.

Conclusion

Isolated anterior elbow dislocation can occur with a vigorous twisting injury of the arm. Early diagnosis and gentle, closed or open, concentric reduction of the joint and soft-tissue repair with early physiotherapy is required to regain the normal function of the elbow on the short-term follow-up.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient's parents have given their consent for her images and other clinical information to be reported in the journal. The parents understand that the patient's name and initials will not be published and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors..

Conflicts of interest

There are no conflicts of interest.

Authors' contributions

MLSA in charged of conceived, designed, conducted the research; analyzed and interpreted results of the work. FFA in charged for literature review. All authors have critically reviewed and approved the final draft and are responsible for the content and similarity index of the manuscript.