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A 51-year-old man with left arm pain following trauma
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A 51-year-old male pedestrian presented to a level 1 trauma center after being struck on the left side by a motor vehicle. He was hemodynamically stable on presentation. Advanced trauma life support protocol was initiated and secondary survey demonstrated isolated musculoskeletal injuries. He complained of pain in his left arm and bilateral legs.
Physical examination revealed multiple abrasions over the left arm without any open wounds but noticeable swelling and ecchymoses. Examination of the left leg revealed a 5 cm x 7 cm complex wound over the anteromedial proximal tibia with exposed bone. The patient also had gross deformity and significant swelling involving the right lower leg. He was neurovascularly intact, and compartments were noted to be soft and compressible throughout all four extremities.
Images: Riff AJ
A preliminary radiograph of the left upper extremity revealed a short-oblique, mid-shaft humerus fracture with an associated butterfly fragment (Figure 1). Radiographs of the bilateral lower extremities revealed a right mid-shaft tibial fracture and left Schatzker VI tibial plateau fracture.
Initial orthopedic management in the trauma unit involved administration of cefazolin and gentamicin, provisional irrigation of the open wound on the left lower extremity and application of bilateral long leg splints. Attention was then turned to the left upper extremity and closed reduction of the left humerus was undertaken with placement of a coaptation splint. However, post-reduction radiographs revealed persistent posterior displacement, varus angulation and diastasis at the fracture site (Figure 2). On repeat physical exam, the patient was unable to extend his left wrist, thumb and fingers. He also had diminished, albeit intact, sensation over the dorsum of his left hand.
What is your diagnosis?
See answer on next page.
Radial nerve palsy secondary to fracture site interposition
The patient was diagnosed with a secondary radial nerve palsy sustained during closed reduction of the humerus secondary to interposition within the fracture site.
Background
A recent systematic review of more than 4,500 humerus fractures reported a 12% incidence of radial nerve palsy with humeral shaft fractures. The injury to the radial nerve often occurs as a result of the injury; however in 10% to 20% of cases, the injury occurs during treatment.
Discussion
Sarmiento and his colleagues reported union in more than 98% of closed fractures treated with functional bracing. Nonsurgical management of humeral shaft fractures typically consists of application of a well-molded coaptation splint to prevent varus angulation and transition to a Sarmiento functional brace at 5 days to 7 days. Indications for operative management of a humeral shaft fracture include open fracture, vascular injury, compartment syndrome, floating elbow, pathologic fracture, polytrauma, brachial plexus palsy and failure of closed management.
While radial nerve laceration is often associated with open fracture, laceration of the radial nerve in association with a closed diaphyseal fracture of the humerus is unusual. As a result, it is accepted that radial nerve palsy associated with a closed injury can be treated with observation. Injuries resulting from closed reduction (secondary radial nerve palsy), however, are more controversial. When a radial nerve palsy is identified after fracture manipulation, many surgeons have advocated radial nerve exploration, as this situation suggests the radial nerve might be interposed within the fracture. That said, Shao and colleagues reported no difference in radial nerve recovery following primary (87%) and secondary (93%) radial nerve palsies. If a reasonable reduction is achieved closed with good opposition of the proximal and distal fragments, it is more likely the neurologic injury was secondary to traction. While these injuries can be treated closed, persistent diastasis at the fracture site and angular deformity may be evidence of an entrapped radial nerve. These fractures should not be further manipulated and consideration should be given to nerve exploration and open reduction and internal fixation (ORIF).
Management of our patient
The patient elected to undergo ORIF. Due to the persistent diastasis at the fracture site, unacceptable reduction and timing of the patient’s radial nerve palsy, it was presumed the radial nerve was entrapped within the fracture site and would not permit acceptable reduction. ORIF was also favored given the polytrauma nature of his injury, as it would permit full weight-bearing through the left upper extremity on crutches while rehabilitating from his lower extremity fractures.
The patient was placed prone, though lateral positioning can also be used. For mid-shaft humerus fractures, both anterolateral and posterior approaches are commonly utilized. In the setting of radial nerve palsy, however, the posterior approach allows more reliable visualization of the nerve. When utilizing the posterior approach in this setting, we favor the paratricipital approach as described by Gerwin and colleagues for ease of visualization of the proximal humeral shaft. As anticipated, the radial nerve was interposed within the fracture site (Figure 3). It appeared contused with evidence of swelling and hyperemia, however, it was intact throughout its length. After carefully removing the nerve from the fracture site, the fracture was easily reduced. A 2.7-mm interfragmentary lag screw was initially placed between proximal fragment and the butterfly fragment to create a simpler fracture pattern. A second 2.7-mm lag screw was then placed between the proximal and distal fragments. Finally, a 3.5-mm distal humerus plate was applied in a neutralization fashion (Figure 4).
Key points
Radial nerve palsy is the most common nerve injury following long bone fracture. While 80% to 90% of radial nerve injuries occur as a result of initial trauma, the remainder occur during treatment. Persistent diastasis of the fracture site and angular malalignment associated with secondary radial nerve palsy may be evidence of an entrapped radial nerve and further closed fracture manipulation should not be performed.
Roughly 90% of radial nerve injuries recover spontaneously with no significant difference seen between primary and secondary radial nerve palsies. If return of function is not seen in 2 months to 3 months, then an EMG should be performed.
Follow-up
Postoperatively, our patient was placed in a soft dressing and a sling for comfort. He underwent occupational therapy for application of a cock-up wrist splint and range of motion exercises to prevent contracture. Weightbearing was permitted as tolerated. At 2 months follow-up, he was noted to have return of normal hand sensation and return of thumb extension, though with some persistent weakness. By the 6-month follow-up, the patient had return of full strength to wrist extension, finger extension and thumb extension. At 9 months, radiographs revealed his fracture was well-healed (Figure 5).
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- For more information:
- Andrew J. Riff, MD, can be reached at 1611 W. Harrison St., Suite 300, Chicago, IL 60612; email: ariff8@gmail.com.
- Jan P. Szatkowski, MD, can be reached at Orthopaedic Trauma & Fracture Care, Andrews Institute for Orthopaedics & Sports Medicine, 1717 North E St., Suite 208, Pensacola, FL 32501; email: szatkowski@gmail.com.
Disclosures: Riff and Szatkowski report no relevant financial disclosures.