Case report: triplane fracture of distal humeral epiphysis diagnosed using ultrasonography

Introduction: We encountered a rare case of distal humeral triplane fracture. Ultrasonography was useful for the diagnosis. Case Report: A boy, aged 5 years 11 months, fell from a height of 1.5 m and injured with his left arm. X-ray (XR) and computed tomography (CT) studies were conducted and showed a fracture at the metaphysis of the lateral humerus. The forearm axis was dislocated posteromedially to the humeral axis, but the ossification center of the capitellum was correctly located on the radial axis. By using ultrasonography, we diagnosed a triplane fracture of distal humeral epiphysis. Surgery was performed and the patient was observed via ultrasonography. Conclusion: Distal humeral epiphysiolysis is often overlooked or is misdiagnosed. Ultrasonography was useful for a detailed observation of the fracture. When diagnosing a distal humeral epiphysiolysis or lateral humeral condyle fracture, clinicians should suspect the possibility of a triplane fracture, evaluate the epiphysis, and confirm the presence of the fracture by using ultrasonography. Keywords: distal humeral epiphysiolysis, Salter Harris type II, lateral humeral condyle fracture, triplane fracture