Visual Diagnosis and Treatment in Pediatrics, 3 Ed.

Arm Displacement

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.

• With an anterior dislocation of the shoulder, there is a loss of shoulder contour, and the arm is held slightly abducted and externally rotated. Axillary nerve damage can be seen following this injury and should be evaluated.

• With a posterior dislocation of the shoulder, there is a loss of shoulder contour, and the arm is held slightly adducted and internally rotated, and the shoulder is unable to be rotated externally.

• With radial head subluxation, a child usually refuses to use arm and holds it in a flexed and pronated position.

• Fractures of the elbow usually present with tenderness over the radial head or proximal ulna along with pain and swelling.

• Sprengel deformity is usually associated with muscle hypoplasia and can result in disfigurement and functional limitation of the shoulder.

 

PHOTOGRAPHS OF SELECTED DIAGNOSES

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Figure 40-1 Brachial plexus injury. An infant with left arm held in adduction with internal rotation of the arm and pronation of the forearm. (Courtesy of Joseph Piatt, MD.)

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Figure 40-2 Brachial plexus injury. Patient attempting to extend and supinate arms. Compare with the normal movement of right arm. (Courtesy of Shiners Hospitals for Children, Houston, Texas.)

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Figure 40-3 Nursemaid elbow. Child holding left arm slightly flexed and pronated toward body. Note child reaching for bubbles freely with right arm, but not with affected arm. (Courtesy of Jeoffrey K. Wolens, MD.)

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Figure 40-4 Nursemaid elbow. Child holding left arm slightly flexed and pronated toward body. Note child reaching for bubbles freely with right arm overhead, but not with affected arm. (Courtesy of Jeoffrey K. Wolens, MD.)

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Figure 40-5 Elbow dislocation. This adolescent football player had his elbow hyperextended when tackling another player. Note the sharp contour due to the prominent olecranon displaced posteriorly on the injured side. (Used with permission from Fleisher GR, Ludwig S, Baskin MN. Atlas of Pediatric Emergency Medicine. Philadelphia, PA: Lippincott Williams & Wilkins; 2004.)

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Figure 40-6 Elbow dislocation. This radiograph shows the dislocation shown in Figure 40-5 without an associated fracture. (Used with permission from Fleisher GR, Ludwig S, Baskin MN. Atlas of Pediatric Emergency Medicine. Philadelphia, PA: Lippincott Williams & Wilkins; 2004.)

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Figure 40-7 Sprengel deformity. Note right-sided deformity with elevation of scapula and asymmetry of shoulders and neck when compared with normal left side. (Courtesy of Shriners Hospitals for Children, Houston, Texas.)

DIFFERENTIAL DIAGNOSIS

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Other Diagnoses to Consider

• Cerebral palsy

• Osteogenesis imperfecta

• Ehlers–Danlos syndrome

• Larsen syndrome

• Familial joint instability syndrome

• Radioulnar synostosis

• Nonaccidental trauma

When to Consider Further Evaluation or Treatment

• Recurrent dislocation is a common complication of shoulder dislocation. All patients with a diagnosis of shoulder dislocation should be evaluated by an orthopedic surgeon after reduction, because of the high incidence of shoulder instability post-reduction.

• In suspected radial head subluxation: a child without history of a traction injury, or a child with a history consistent with radial head subluxation, with focal swelling or tenderness should have radiographs done to evaluate for a potential fracture.

• Radiographs of the arm should be obtained for any patient with a suspected radial head subluxation that is not reducible, in order to rule out fracture of the radius or ulna.

• A visible posterior fat pad on a lateral radiographic image of the elbow in the setting of trauma is usually indicative of a fracture.

• If a patient has generally worsening pain in the forearm with or without paresthesia or decreased sensation, and/or increased pain in the forearm with the passive extension of the muscles, the possibility of a compartment syndrome should be considered.

• If there is suspected nerve injury in association with a fracture, and normal function has not returned after 8 to 12 weeks of symptoms, consider electromyography and further evaluation by a neurologist.

SUGGESTED READINGS

Chasm RM, Swencki SA. Pediatric orthopedic emergencies. Emerg Med Clin North Am. 2010;28(4):907–926.

Cramer KE, Scherl SA, eds. Pediatrics: Orthopedic Surgery Essentials. Philadelphia, PA: Lippincott Williams & Wilkins; 2004:104–135.

Mariscalco MW, Saluan P. Upper extremity injuries in the adolescent athlete. Sports Med Arthrosc Rev. 2011;19:17–26.

Moukoko D, Ezaki M, Wilkes D, et al. Posterior shoulder dislocations in infants with neonatal brachial plexus palsy. J Bone Joint Surg Am. 2004;86-A(4):787–793.

Pizzutillo PD, ed. Pediatric Orthopedics in Primary Practice. New York: McGraw-Hill; 1997:9–12, 29–32, 37–44, 51–54, 61–64, 325–328.

Staheli L. Fundamentals of Pediatric Orthopedics. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2008:65–73, 268–275.

Staheli L. Practice of Pediatric Orthopedics. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2006:228–240.



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