Lateral epicondyle fracture presenting severe elbow instability in adolescence: a case report

Elbow joint dislocation is uncommon in children, accounting for 3% of elbow joint injuries.²² Pure dislocations are rare, and > 60% of these cases are dislocated fractures with associated fractures.¹⁸ The most predominant pattern of injury was an elbow dislocation with a medial epicondyle fracture or a radial neck fracture plus one other associated injury such as a lateral condyle fracture, olecranon fracture, or coronoid fracture.⁵ Lateral epicondyle fracture complications are very rare. Here, we report an adolescent diagnosed with a posterior fracture dislocation with associated fractures of the lateral epicondyle of the humerus and the coronoid process of the ulna.

Case presentation

A 13-year-old female patient fell from a vaulting box onto her outstretched arm and was admitted to the emergency department with right elbow pain, swelling, and deformity. The patient presented no neurovascular disorders but with restricted range of motion in the right elbow due to pain. Plain X-ray and computed tomography scans detected a posterior dislocation with lateral epicondyle and coronoid fractures (Fig. 1). Computed tomography revealed a 2-mm–sized coronoid fracture at the tip, classified as tip, subtype 1, following the classifications of O'Driscoll (Fig. 2).¹⁴ The patient underwent closed reduction under regional anesthesia on the day of the injury, but posterior lateral rotational instability (PLRI) remained, particularly, a positive pivot shift test.¹⁹ Therefore, the patient underwent surgery. A lateral incision was created centered over the lateral epicondyle. The lateral epicondyle was fractured off the humerus with the lateral collateral ligament securely attached to it. After reducing the lateral epicondyle fracture, we performed tension band wiring fixation with a 1.5-mm Kirschner wire and 0.9-mm soft wire. Afterward, the pivot shift test was negative, and the varus and valgus stress demonstrated no instability (Figure 3, Figure 4 and Figure 3, Figure 4). Therefore, we did not perform internal fixation of the coronoid process fracture and additional ligament repair.

Figure 1.

Plain radiographs demonstrating posterior elbow dislocation and lateral epicondyle fracture. (A) Frontal view. (B) Lateral view.

Figure 2.

Three-dimensional computed tomography image demonstrating a posterior dislocation of the elbow and fractures of the lateral epicondyle of the humerus and coronoid process of the ulna. (A) Frontal view. (B) Lateral view.

Figure 3.

Intraoperative images of the elbow. Elbow instability disappeared after repositioning the lateral epicondyle dislocation and fixation. (A) Lateral epicondyle before fixation. (B) Lateral epicondyle after fixation. (C) Frontal view with valgus stress. (D) Frontal view with varus stress.

Figure 4.

Postoperative radiographs demonstrating the repositioned dislocation and the fixed lateral epicondyle.

Immediately postoperatively, the elbow joint was immobilized in a posterior splint at 90° of flexion in neutral rotation for 2 weeks. The patient was then allowed to perform active elbow range of motion exercises. Radiographic union was achieved 4 months postoperatively. At the same time, the patient had a restricted range of motion, with −25° of extension and 130° of flexion, and a Mayo Elbow Performance Score of 100 points. Wires were removed under general anesthesia 9 months postoperatively (Fig. 5). After the removal, the range of motion improved to 0° in extension and 135° in flexion. The patient demonstrated no laxity in valgus and varus stress and PLRI and was able to return to previous activity levels. The Mayo Elbow Performance Score remained at 100 points.

Figure 5.

Radiographs after removal of the wires revealed lateral epicondyle bone union. (A) Frontal view. (B) Lateral view.

Discussion

The lateral epicondylar apophysis begins to ossify around 10-11 years of age and consolidates with the shaft in the 14th year. The present case, a 13-year-old female, was in the process of the fusion. In fractures of the lateral side of the humerus, the lateral epicondyle and capitellum are often involved together due to virtue of the contiguity of their respective metaphyses.²⁰ Therefore, the lateral epicondyle fractures are an uncommon type of fracture which can occur in a limited period between the appearance of the apophysis and its fusion. Elbow joint stabilizers include the humeroulnar joint, the lateral support consisting of the proximal radius and lateral collateral ligament complex, the medial collateral ligament, the coronoid process, and the anterior capsule.^13,15 The lateral epicondyle fracture caused elbow instability because the lateral collateral ligament complex is attached to the lateral epicondyle. Studies reported posterior dislocation and PLRI due to lateral epicondyle fractures and their nonunion.^1,6,23 Posterior elbow dislocation with associated proximal radius and coronoid fractures is called a terrible triad injury (TTI).³ In TTIs, lateral collateral ligament tears are thought to be universally present, while the medial collateral ligament is the last structure to fail.⁸ Ligaments in the immature skeleton, such as children, are less likely to tear under traumatic circumstances, and bony structures, especially the epiphyseal plates, are damaged under stress.¹¹ Therefore, in adolescents, lateral epicondyle fractures are more likely to occur instead of ligamentous injuries. A lateral epicondylar fracture, in this case, occurred in addition to a posterior elbow dislocation and a coronoid fracture. There is no similar injury in a systematic review of TTI variations and case series of pediatric complex elbow injury,^8,10 but the exact same fracture pattern for 12-year-old and 14-year-old boys has been reported in 2 cases in Japan.^4,25 Additionally, a similar case has been reported in a 14-year-old male, involving a lateral epicondylar fracture, coronoid fracture, posterior dislocation, and proximal radial epiphyseal injury.¹² While our case is comparable in age, the patient's epiphyseal plate was already closed due to being a female adolescent. These fracture patterns are considered variations of TTI and may be described as “adolescent TTI.”

Current guidelines recommend a step-by-step surgical approach to TTIs in adults.¹⁷ Bony injuries are first approached, from the radial head fracture to the coronoid fracture. A stable elbow at this point concludes the operation. A surgical repair of the lateral collateral ligament and the medial collateral ligament may be necessary for a more severe injury.^7,8,24 Not many studies have been reported on coronoid fractures in adolescents and the treatment strategy remains unknown. The coronoid fracture, in our case, was classified as a tip, subtype 1 fracture, which is a transverse coronoid tip fracture. Since no instability was observed following lateral epicondyle fixation, coronoid tip fracture fixation was not performed. This case suggests that internal fixation of the lateral epicondyle fracture alone can be an effective treatment for this injury pattern.

TTI was named due to its historically poor outcomes and high complication rates, which include heterotopic ossification, stiffness, nerve injury, instability, pain, post-traumatic arthritis, and recurrent subluxation or dislocation of the elbow.^2,9 Since the surgical protocol for TTI was introduced 20 years ago,¹⁷ favorable functional outcomes have been increasingly reported.²¹ One study even refers to TTI as “the treatable triad.”¹⁶ Similarly, in the pediatric population, most reported cases have shown satisfactory clinical outcomes with a low complication rate.⁸

Conclusion

We report an adolescent diagnosed with a posterior fracture dislocation with associated fractures of the lateral epicondyle of the humerus and the coronoid process of the ulna. The patient was successfully treated using tension band wiring fixation for lateral epicondyle fracture. In adolescents, the mechanism by which TTI occurs may predispose to lateral epicondyle fractures of the humerus instead of ligament injuries and fractures of the radial head.

Acknowledgments

The authors would like to thank Enago (www.enago.jp) for the English language review.

Disclaimers

Funding: No funding was disclosed by the authors.

Conflicts of interest: The authors, their immediate families, and any research foundations with which they are affiliated have received no financial payments or other benefits from any commercial entity related to the subject of this article.

Patient consent: Obtained.