Fractures of the distal humeral physis in children under the age of years, and especially infants under the age of year, should raise concern for possible abuse Radiographic diagnosis of humerus physeal fractures is difficult as the distal humerus and proximal radius and ulna have not yet ossified To distinguish distal humeral physeal separation from elbow dislocation, one should note that displacement of the proximal radius and ulna is usually posterior and medial in the former With dislocation, the proximal radius and ulna are typically displaced posterolaterally, and the relationship between proximal radius and lateral condyle epiphysis is disrupted Separation of the distal humerus physis is an infrequently seen elbow injury in the pediatric ED and the diagnosis is frequently missed leading to delays in diagnosis Most injuries involving the entire distal humeral physis occur before age Recognition is both difficult and important, especially in infants, in whom this particular injury is often the result of physical abuse The proposed mechanism in abused children is forceful twisting of the arm that shears off the distal epiphysis Elbow swelling, pain, and disuse of the extremity, but without significant deformity, in the setting of a FOOSH are the usual history and examination With significant displacement, the appearance may mimic that of an elbow dislocation Dislocations more commonly occur in early adolescence than in children less than years old Radiographic diagnosis requires recognition of subtle displacement and may necessitate comparison views In the normal relationship, the shaft of the ulna should align with the shaft of the humerus on the anteroposterior view, whereas the ulna will be medial on the AP view compared with this injury With clinical concern, ultrasound may be a useful adjunct Given the frequent need for reduction and pinning, all suspected epiphyseal separations of the distal humerus merit immediate orthopedic referral MRI or ultrasound studies may be necessary to define the extent of damage to the cartilaginous structures The risk of avascular necrosis and growth disturbance increases with delay in diagnosis Olecranon Fractures CLINICAL PEARLS AND PITFALLS