Review Question - QID 219366

A 4-year-old female presents to your pediatric emergency department with an elbow injury after falling off of a set of playground equipment. There is diffuse tenderness to palpation and swelling about the elbow but no ecchymosis or skin compromise. There are no paresthesias and cardinal hand movements are intact. Initial radiographs demonstrate a posterolateral elbow dislocation with no obvious fracture. The chief resident calls you because both she and the junior resident have been unable to achieve a concentric reduction under sedation in the emergency department. What is the most likely reason they have been unsuccessful in achieving a concentric reduction?