Timing of Humeral Shaft Fracture Repair Does Not Affect Risk of Iatrogenic Radial Nerve Injury

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Iatrogenic injury of the radial nerve is common during surgical management of diaphyseal humerus fractures and nonunions. In the acute setting, when hematoma and unstable fracture fragments are present, surgical manipulation might exacerbate a subclinical radial nerve injury. On the other hand, delaying surgery allows scar tissue and callus to form, increasing the difficulty of exposing and mobilizing the nerve. Despite these possibilities, no research has ever investigated the optimal timing of surgery.

Orthopedic Trauma Surgeon Marilyn Heng, MD, MPH, FRCSC, Chief of the Department of Orthopaedics Mitchel B. Harris, MD, and colleagues at Harvard Medical School recently conducted a retrospective study to evaluate that issue. According to their report in the Journal of Orthopaedic Trauma, time elapsed since injury did not influence the risk of iatrogenic radial nerve palsy after surgical fixation of diaphyseal humerus fractures or nonunions.

The researchers identified 325 patients who underwent open reduction internal fixation of either an acute fracture or nonunion of the diaphyseal humerus between December 2001 and February 2015. These patients had intact radial nerve function documented before surgery.

Twenty-five patients (7.7%) developed iatrogenic radial nerve palsy after surgery, observed in the post-anesthesia care unit or at the first postoperative clinic visit. The complication was defined as weakness of the extensor pollicus longus and wrist extensors, or sensory deficits in the radial nerve distribution.

The research team found that time to surgery was not significantly associated with the risk of radial nerve palsy. This was true whether time was treated as a continuous variable or divided into categories of acute surgery (0-4 weeks after injury), subacute surgery (4-12 weeks) or delayed surgery (>12 weeks). However, there was a trend toward lower risk of radial nerve palsy in patients treated more than 12 weeks from their injuries.

The only significant risk factors for radial nerve palsy were distal fracture location and previous fixation. Both factors nearly quadrupled the risk. The authors point out that distal third fractures are often treated through a posterior approach with more extensive exploration and manipulation of the radial nerve, which may increase the risk of injury. The presence of previous hardware is often associated with significant scar tissue that requires more surgical dissection and more mobilization of the nerve.

The researchers also studied recovery of radial nerve function in the 25 patients who sustained iatrogenic injury. Their prognosis was generally good, as 22 of them, about 90%, fully recovered with expectant management. The median time to recovery was between eight and nine weeks postoperatively, and 80% of patients recovered within the first six months. Two patients had persistent palsies that required either a nerve graft or tendon transfers (in one case due to nerve entrapment under a plate; in the other case the cause was unknown).

The researchers report that in their experience, delayed surgical treatment is more complicated than an acute procedure. However, given the trend depicted in the figure, they find it unlikely that delayed surgery actually presents a higher risk. They emphasize that they compensate for the presence of scar tissue and callus by using more extensive exposures and more meticulous dissection techniques.

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