Diagnosis and Treatment of Varus Posteromedial Rotational Instability of the Elbow Joint in Children: Re-Understanding of the Injury Mechanism Associated With Coronoid Process Fractures

Purpose: To investigate the injury mechanism, diagnosis, and treatment of varus-posteromedial rotational instability of the elbow joint in children. Methods: According to the diagnostic criteria of varus posteromedial rotational instability of elbow joint, 16 children with coronoid process fractures treated in our department from July 2013 to July 2017 were re-evaluated. There were 14 males and 2 females, aged 7 to 14 years, with an average age of 11.6 years. Eight cases on left and 8 cases on right side. An associated elbow dislocation occurred in 8 of 16 cases. Nine patients were treated with a lateral soft tissue repair only. In 7 other patients in addition to the lateral soft tissue repair, the coronoid process fractures were treated with open reduction and fixation. At the last clinical follow-up, each elbow joint range of motion was recorded, radiographs were obtained, and functional performance was evaluated by the Mayo elbow performance score (MEPS). Results: The average follow-up time was 81.9 months for the 9 patients treated with lateral elbow soft tissue repair. At the last follow-up, 2 of the patients had MEPS scores as excellent, 1 was good, and 6 were rated as moderate or poor. Four patients had a cubitus varus deformity. The average follow-up time was 30.3 months for the 7 patients treated with both soft tissue repair and coronoid fracture stabilization. The elbow joint MEPS scores for each of these 7 patients was excellent at the last follow-up, and no complications such as cubitus varus occurred. Conclusion: The results of the study suggest that children could also develop elbow varus-posterior medial rotational instability injuries under the same mechanism. Although the morbidity rate is low, due to insufficient understanding of the injury mechanism, it is prone to missed diagnosis, misdiagnosis, and delayed treatment, resulting in severe complications such as elbow instability, dislocation, traumatic arthritis, and elbow stiffness. On the contrary, according to the treatment principle of the posterior medial rotational instability of the elbow joint in adult, while the lateral repair is carried out, strong and effective reduction and fixation of the coronoid process fractures are adopted, it is expected that such children with rare elbow injuries can obtain excellent treatment outcomes.