Distal Humerus Physeal Separation in a Neonate: A Case Report

Distal humeral physeal separation in neonates is a rare elbow injury that is often missed because of the cartilaginous nature of the distal humeral epiphysis, limited cooperation, and nonspecific signs, such as swelling, tenderness, and decreased range of motion.Maintaining the posterior elbow triangle helps distinguish this injury from elbow dislocation.At the same time, radiographic posteromedial displacement of the radio-ulnar complex strongly suggests a Salter-Harris type I distal humeral injury.Birth trauma, difficult delivery, abnormal fetal positioning, and child abuse are recognized causes.Still, this report describes a 9-day-old term neonate with distal humeral physeal separation following unintentional parental trauma.The patient exhibited elbow swelling, limited motion in the right upper limb, and normal neurovascular findings.Radiographs at 9 days demonstrated posteromedial displacement of the radio-ulnar complex.Due to delayed presentation, closed reduction was not attempted, so conservative treatment with splinting was chosen.Subsequent imaging at 16 and 60 days showed callus formation and progressive healing, with a nearly normal range of motion and mild cubitus varus.At the 4-year follow-up, the child was pain-free, had a full range of motion and normal daily function, and radiographic evidence of complete remodeling without a physeal bar or deformity, despite persistent mild but asymptomatic varus.This case suggests that in neonates with delayed diagnosis, the high remodeling potential of the distal humerus may lead to excellent long-term outcomes with conservative management alone, challenging the conventional emphasis on early reduction and pinning and underscoring the importance of long-term clinical and radiographic follow-up.