Snapshot A 4-year-old boy presents to the pediatrician with elbow pain. He was forcefully pulled onto the curb by his mother after nearly getting hit by an oncoming car. Since the incident, the child has presented with right elbow pain and has refused to move his right arm. Examination reveals an irritable child cradling his right upper limb with his left hand. The affected limb is pronated with the elbow slightly flexed. Radiographs reveal subluxation of the radial head but are otherwise negative for a fracture. Introduction Clinical definition subluxation (partial dislocation) of the radial head relative to the radiocapitellar joint also known as Nursemaid elbow Epidemiology Incidence second most common serious elbow injury in children after supracondylar fractures Demographics most common in children between 2-5 years of age Etiology Traumatic injury commonly due to excess longitudinal traction on a child's arm e.g., a parent pulling vigorously on child's arm Pathoanatomy normal anatomy of the elbow 3 joints radiocapitellar joint radial head articulates with the humeral capitellum ulnohumeral joint trochlear notch of the ulna articulates with the humeral trochlea proximal radioulnar joint radial head articulates with the radial notch of the ulna 2 ligamentous stabilizers lateral collateral ligament (LCL) complex contains the annular ligament, a proximal radioulnar joint stabilizer medial collateral ligament (MCL) complex mechanism of injury longitudinal traction applied to an extended arm leads to subluxation (partial dislocation) of the radial head inferiorly interposition of the annular ligament into the radiocapitellar joint Presentation Symptoms lateral elbow pain child will hold the elbow in slight flexion and the forearm pronated Physical examination pain and tenderness localized to the lateral aspect of the elbow Imaging Radiographs indication not routinely indicated given a strong clinical history and exam unless other bony conditions (e.g., elbow fractures) need to be ruled out findings often normal radiographs Treatment Conservative closed reduction of the radial head indication nearly all cases will resolve with closed reduction techniques hyperpronation while elbow is moderately flexed supination of the forearm and then maximal elbow flexion Open reduction rarely necessary may be indicated for chronic, symptomatic subluxations that fail closed reduction Differential Supracondylar humerus fracture distinguishing factors typically caused by fall on outstretched hand instead of excess traction will demonstrate evidence of fracture on radiography Lateral condylar fracture distinguishing factors typically caused by fall on outstretched hand instead fo excess traction will demonstrate evidence of fracture on radiography Complications Recurrence occurs in 5-39% of cases but generally ceases after 5 years of age