A 7-year-old boy is brought to the emergency department after falling during recess. His teacher saw him jump off a swing and fall onto his outstretched left arm. The patient developed immediate pain in the arm and now refuses to move it at the elbow. On examination, the left arm is grossly deformed, swollen, and slightly pale. The radial pulse is intact. The patient's x-ray is shown below.
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Two hours later, while the patient is awaiting surgery, pain and swelling continue to increase despite administration of nonsteroidal anti-inflammatory drugs and opioid analgesics. Which of the following complications is most likely present in this patient?
Supracondylar fracture | |
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Supracondylar humerus fractures are the most common type of pediatric elbow fracture, particularly in children age 2-7. The typical history involves a high-impact fall onto an outstretched arm with the elbow hyperextended. Radiographs may show a fracture line and displacement of the humerus (as seen in this patient). In the case of an occult fracture, inflammation surrounding the fracture displaces the synovial fat. On x-ray, this appears as a wide anterior fat pad (normally narrow or absent) and a posterior fat pad (normally absent).
Compartment syndrome is a rare but serious complication of supracondylar humerus fractures that results from increased pressure (ie, swelling) within an anatomic space. It can occur before or after orthopedic intervention, and those with a displaced fracture or concomitant forearm fracture are at increased risk. Compartment syndrome should be suspected in a patient with increasing swelling and pain that is unresponsive to escalating analgesics. Additional red flags include the "4 Ps": pallor, paresthesia, pulselessness, and paralysis. Initial management includes removal of any bandages, measurement of compartment pressures, and emergency fasciotomy.
(Choice A) Avascular necrosis of the humeral physis is a rare complication that presents with insidious pain and decreased range of motion months to years after a supracondylar fracture with vessel injury. Compartment syndrome is more likely in this patient with acute pain and swelling shortly after an injury.
(Choices C and D) Neurovascular injury involving the brachial artery or median nerve is a major concern in patients with displaced supracondylar humerus fractures because these structures pass anterior to the humerus. Brachial artery injury presents with diminished distal pulses. Median nerve neurapraxia is characterized by transient motor or sensory loss due to stretching of the nerve. In this patient, the pulses are intact, and the increasing pain is more consistent with compartment syndrome than neurovascular injury.
(Choice E) Venous thrombosis can occur as a complication of surgery or prolonged immobilization. It is an unlikely complication immediately after an injury.
Educational objective:
Compartment syndrome is a rare complication of supracondylar humerus fractures, particularly those that are displaced or occur in conjunction with forearm fractures. Initial symptoms may include increasing swelling and pain that is unresponsive to escalating analgesics.