CHAPTER 38 ■ IMMOBILE ARM GALINA LIPTON, SARA SCHUTZMAN An infant or child brought for the evaluation of an “immobile arm” is not moving the limb because of pain or weakness The evaluation is often a challenge because most of these children are preverbal; therefore, the history is second or third hand if available at all, patients are unable to report symptoms or pain location, and the physical examination is often difficult because of children’s fear of strangers These children can be considered as having an upper extremity equivalent of “limp.” Children with this complaint can be diagnosed and managed using historical information, physical findings, selective radiologic studies, and laboratory tests DIFFERENTIAL DIAGNOSIS Table 38.1 lists causes of decreased arm movement Trauma is by far the most common cause of diminished arm use in children ( Table 38.2 ) Although lifeand limb-threatening causes ( Table 38.3 ) are less common, clinicians should have a high index of suspicion for these conditions in certain clinical scenarios Any injury from the clavicle to the fingertips can cause arm pain in children and can lead to decreased use of the limb These injuries range from a simple contusion or sprain, to a fracture or dislocation with neurovascular compromise Most young children with diminished arm use have radial head subluxation (“nursemaid’s elbow”), fracture, or soft tissue injury Radial head subluxation is by far the most common cause of arm disuse and is a common elbow injury that is unique to young children, typically those younger than years (peak incidence age to years) The classic mechanism involves a sudden pull of the arm However, injuries may be caused by other mechanisms including falling and twisting Many patients have no known history of trauma The child with radial head subluxation typically holds the affected arm slightly flexed with the forearm pronated and without spontaneous arm movement The child is usually not distressed unless the affected arm is moved Classically, there is no reproducible tenderness, warmth, or swelling (best evaluated while distracting the child) With musculoskeletal injuries, the child may have an obvious abnormality, such as a deformity or ecchymosis, or more subtle findings of localized tenderness or decreased arm movement Radiographs are useful for demonstrating most fractures or dislocations but may appear normal with Salter–Harris type I