"Unhappy triad" of the trauma elbow in children: Diagnosis, classification, and mid-term outcomes.

Background: The aim of this study was to describe the epidemiology, physiopathology, and outcomes of elbow "unhappy triad" trauma in children, combining a posterior dislocation, a proximal radius fracture, and a third lesion (i.e. bony or capsuloligamentous injury). Methods: A retrospective bicentric study was conducted between 1999 and 2020. All skeletally immature children who presented to the emergency department and underwent surgery for a proximal radius injury were selected. Among this selection, only patients with two associated ipsilateral elbow injuries (i.e. posterior elbow dislocation and a bony and/or capsuloligamentous injury) were included. Active elbow ranges of motion, Mayo Elbow Performance Score and Quick-Disabilities Of The Arm, Shoulder And Hand scores and standard radiographs were recorded at last follow-up. Results: Twenty-one patients met the inclusion criteria (mean age at surgery = 11.4 years) among 737 selected. The "unhappy triad" diagnosis was made preoperatively in nine cases (bone lesion only), intraoperatively in nine cases, and postoperatively in one case. The third lesions were surgically treated when the lesion was a bony fracture or if the elbow remains unstable between 60° and 90° of flexion (i.e. capsuloligamentous injury). Twenty patients were reviewed (mean follow-up = 5.8 years). The complications and re-operations rates were of 10%. Conclusion: The "unhappy" triad of the child's elbow is a rare injury, where the preoperative diagnosis is frequently missed and lead to 10% of complications and re-operations. Level of evidence: level III.