Approach to the Problem
Arm displacement in children frequently occurs as a result of trauma. Dislocation of the upper extremity can also be the result of an underlying congenital musculoskeletal abnormality that causes joint laxity. Consideration should be given to the mechanism of injury when dealing with traumatic dislocations. It is important to identify fractures that could cause a problem with future arm growth and function.
Key Points in the History
• Brachial plexus injuries may lead to shoulder dislocation as early as 3 months of age.
• Risk factors for neonatal brachial plexus injuries include shoulder dystocia, fetal macrosomia, large for gestational age infants, and history of traumatic birth.
• In infants and younger children, pain from a dislocation usually presents as a pseudoparesis, where the child refuses to move the affected extremity.
• Congenital dislocations are frequently seen without a history of trauma and often associated with other defects. When evaluating a patient, it is important to determine whether there is a prior history of dislocation.
• An anterior shoulder dislocation is usually caused by trauma to the abducted, externally rotated and extended arm, and is usually associated with sports-related injuries.
• A posterior shoulder dislocation is less common. This injury is usually from trauma to the anterior shoulder.
• A traction injury of the upper extremity frequently leads to acute radial head subluxation, also known as “nursemaid elbow.” Radial head subluxation develops from displacement of the annular ligament, which is unlikely to be displaced after 5 years of age. The peak incidence of nursemaid elbow is between 2 and 3 years of age.
• An elbow dislocation is commonly seen in contact sports, such as wrestling or football, and in noncontact activities, such as gymnastics. This dislocation is most commonly posterior and secondary to falling on an outstretched arm, or a twisting injury to the elbow.
• Fractures of the distal radius are more common in adolescents than in younger children, and the usual history includes a fall on a hyperextended wrist.
• Habitual dislocations can be seen in children who have ligamentous laxity who are also able to voluntarily dislocate their joints.
• Sprengel deformity is a congenital elevation of the scapula, which may have multidirectional joint instability. Patients with a diagnosis of Sprengel deformity should undergo evaluation for other abnormalities of the vertebrae and ribs.
Key Points in the Physical Examination
• Physical examination should always include inspection, palpation, range of motion evaluation, neurologic evaluation, and vascular evaluation.
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