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Difficulty: MediumOrthopedic Surgery

A 7-year-old boy is brought to the emergency department by his parents 30 minutes after falling from a playground structure. He fell onto his outstretched left arm and immediately complained of severe elbow pain. Vital signs include a temperature of 37.0°C (98.6°F), blood pressure of 105/65 mm Hg, heart rate of 112/min, and respiratory rate of 20/min. Physical examination reveals a distressed child holding his left arm. There is marked swelling and an "S-shaped" deformity at the left elbow. There are no open wounds or visible ecchymoses.

Neurovascular assessment demonstrates a palpable radial pulse and a capillary refill time of 1 second in the fingers. When asked to make an "OK" sign with his left hand, the patient is unable to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. Sensation to light touch is intact over the median, ulnar, and radial nerve distributions. Anteroposterior and lateral radiographs of the left elbow show a displaced extension-type supracondylar humerus fracture with posterior displacement of the distal fragment.

Which of the following is the most appropriate next step in the management of this patient?

  1. Closed reduction and percutaneous pinningAnswer
  2. B
    Application of a long-arm cast and discharge home with orthopedic follow-up
  3. C
    Immediate computed tomography angiography of the left upper extremity
  4. D
    Open reduction and internal fixation with dual anatomic plates
  5. E
    Hospital admission for arm elevation and delayed operative reduction

Answer

Closed reduction and percutaneous pinning
The patient has a displaced extension-type supracondylar humerus fracture complicated by an anterior interosseous nerve (AIN) neurapraxia. The AIN is a motor branch of the median nerve; its function is assessed by the ability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger (the 'OK' sign). AIN injuries are the most common neurological complication of this fracture pattern. Because the limb remains well-perfused (palpable pulse, brisk capillary refill), vascular compromise is absent. The gold standard management for displaced pediatric supracondylar fractures is urgent closed reduction and percutaneous pinning (CRPP). This stabilizes the fracture, relieves tension on the anterior neurovascular structures, and minimizes the risk of compartment syndrome. The AIN neurapraxia typically resolves spontaneously over several months following anatomic reduction of the fracture.

Step-by-Step Solution

1
Analyze the mechanism of injury, clinical findings, and radiograph results.
The fall onto an outstretched hand, S-shaped elbow deformity, and radiograph confirm a displaced extension-type supracondylar humerus fracture.
Identifying the specific fracture pattern is essential for determining surgical urgency and potential associated injuries.
2
Interpret the specific neurovascular deficits presented in the physical examination.
The inability to form a proper 'OK' sign indicates an anterior interosseous nerve (AIN) palsy. The palpable radial pulse and normal capillary refill confirm that the limb remains well-perfused.
AIN injuries are the most common neurological complication of extension-type supracondylar fractures. A well-perfused limb rules out an immediate vascular emergency (such as brachial artery entrapment) that would dictate open exploration.
3
Select the optimal management strategy for a displaced pediatric supracondylar fracture with a nerve neurapraxia.
Urgent closed reduction and percutaneous pinning (CRPP) is indicated.
CRPP provides definitive fracture stabilization, relieves tension on the neurovascular bundle, and prevents compartment syndrome. The associated nerve palsy is almost always a neurapraxia that resolves on its own without requiring open nerve exploration.

Key Concept

Management of displaced pediatric supracondylar humerus fractures and associated anterior interosseous nerve (AIN) palsy
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Topics

Orthopedic Surgery

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