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Difficulty: HardOrthopedic Surgery

A 34-year-old right-handed male presents to the emergency department one hour after an altercation in which he was struck on the right upper arm with a heavy steel pipe. He complains of intense pain and an inability to use his right hand. His vital signs are within normal limits. On physical examination, the right arm reveals significant soft tissue swelling, ecchymosis, and a visible deformity over the mid-humerus. The skin is completely intact. Neurological examination of the right upper extremity reveals an inability to extend the wrist or fingers. Sensation to pinprick is diminished over the dorsal aspect of the first web space. The radial and ulnar pulses are 2+2+ and symmetric. Capillary refill is less than 22 seconds in all digits. Anteroposterior and lateral radiographs of the right humerus demonstrate a displaced transverse fracture of the middle third of the humeral shaft. Which of the following is the most appropriate next step in management?

  1. A
    Intravenous antibiotics and urgent surgical debridement
  2. B
    Immediate surgical exploration of the radial nerve
  3. Application of a coaptation splint and clinical observationAnswer
  4. D
    Open reduction and internal fixation of the humerus
  5. E
    Electromyography and nerve conduction studies of the right arm

Answer

Application of a coaptation splint and clinical observation
The clinical presentation is consistent with a closed midshaft humeral fracture complicated by a primary radial nerve palsy. The radial nerve courses through the spiral groove on the posterior aspect of the humerus, making it uniquely vulnerable to midshaft fractures. This injury results in weakness of wrist and finger extension (wrist drop) and sensory loss over the dorsal first web space. In the setting of a closed fracture, this is almost always a neurapraxia (stretch injury) rather than nerve transection. Because >90%>90\% of these palsies recover spontaneously within 3 to 4 months, the standard of care is conservative management. This involves immobilizing the fracture with a coaptation splint (or functional brace) and scheduling close outpatient follow-up to monitor for clinical signs of nerve recovery. Surgical exploration is generally reserved for open fractures, associated vascular injuries requiring repair, or a secondary nerve palsy (a deficit that appears only after a closed reduction attempt, suggesting the nerve has become entrapped in the fracture site).

Step-by-Step Solution

1
Identify the primary injury from the physical exam and radiographic findings.
The patient has a closed, displaced transverse fracture of the midshaft humerus.
Establishing the correct anatomical fracture pattern is necessary to anticipate common complications.
2
Analyze the neurological deficits to identify the specific nerve involved.
Inability to extend the wrist/fingers and numbness in the first dorsal web space indicate a radial nerve palsy.
The radial nerve runs along the spiral groove of the mid-humerus, making it highly susceptible to injury in midshaft fractures.
3
Determine the appropriate management for a primary radial nerve palsy in a closed humeral shaft fracture.
Conservative management with a splint is chosen.
Primary radial nerve palsies in closed fractures are almost always neurapraxias that resolve spontaneously in >90%>90\% of cases. Immediate surgery is contraindicated unless specific criteria are met.

Key Concept

Primary radial nerve palsy in the setting of a closed humeral shaft fracture does not require immediate surgical exploration. Initial management is conservative with immobilization (e.g., coaptation splint) and clinical observation.
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Orthopedic Surgery

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