Most Common Nerve Injured During Pelvic Fracture
The L5 nerve root and lumbosacral plexus are the most commonly injured neurologic structures in pelvic fractures, occurring in approximately 21% of unstable pelvic ring injuries. 1
Epidemiology and Injury Patterns
Neurologic injuries occur in 9-21% of all pelvic fractures, representing a significant source of morbidity in these high-energy trauma patients. 2, 3
Among patients with unstable pelvic ring fractures specifically, the incidence reaches 21%, with the majority (63%) presenting with both motor and sensory deficits rather than isolated sensory findings. 1
The lumbosacral plexus is most vulnerable because pelvic fractures—particularly Type B and C injuries—can damage nerve roots as they emerge from the sacral foramina and form the sacral plexus. 2
Specific Nerve Injury Patterns by Fracture Type
L5 Nerve Root
- L5 function shows the poorest prognosis for complete recovery among all nerve injuries associated with pelvic fractures, making it both common and clinically significant. 1
Sciatic Nerve
The sciatic nerve is vulnerable to injury from avulsion fractures at the ischial tuberosity where hamstring muscles attach, causing traumatic edema, hematoma, or inflammation that compresses the adjacent nerve. 4, 5
High-speed blunt trauma with pelvic or hip fractures and dislocations commonly causes stretching injuries or nerve compression from adjacent hematoma. 4, 5
Obturator Nerve
- Obturator nerve injuries occur from avulsions of adductor muscles at the inferior pubic symphysis, with the nerve vulnerable in Type A, B, and C fractures during its course alongside the inferior pubic ramus. 4, 6, 2
Pudendal Nerve
- The pudendal nerve pathway may be affected in Type B and C fractures where root fibers emerge from sacral foramina, and in all fracture types (A, B, C) during the nerve's course alongside the inferior pubic ramus. 2
Superior and Inferior Gluteal Nerves
- These nerves can be injured by avulsion fractures of gluteal muscles at the greater trochanter, with subsequent compression from local soft-tissue swelling and inflammation. 4
Prognosis and Recovery
At least one grade of muscle function improvement is consistently seen in patients with pelvic fracture-associated nerve injuries, with 53% achieving complete neurologic recovery at an average 24-month follow-up. 1
Neurologic improvement can occur as late as 24 months post-injury, emphasizing the importance of prolonged observation and rehabilitation. 1
Early anatomic reduction and stabilization of unstable pelvic ring injuries appears to improve neurologic recovery outcomes compared to historical data. 1
Critical Diagnostic Considerations
MRI of the lumbosacral plexus should ideally be delayed until approximately one month after trauma to allow resolution of hemorrhage and formation of pseudomeningocele, which improves visualization of nerve injury. 4, 5
Acute evaluation can be challenging because hemorrhage obscures nerve roots and soft-tissue edema can hide the plexus on early imaging. 6
Detection of nerve discontinuity or root avulsion is critical as these findings may require surgical intervention rather than conservative management. 6