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Emergency And Acute Medicine – Sacral Fracture
Sacral fractures are a significant component of pelvic trauma, occurring in approximately 45% of all pelvic fractures and rarely presenting in isolation. These injuries are typically classified based on the orientation of the fracture line—either transverse or vertical—and their location relative to the sacral foramina and canal. Common mechanisms include axial compression (such as falls from height), direct posterior trauma, and high-energy crush injuries. In elderly or osteoporotic patients, sacral insufficiency fractures may occur even with minimal trauma and should be considered in those presenting with unexplained severe lower back or sacral pain.
Transverse fractures above the S4 level are associated with a high risk of neurologic injury, including potential development of cauda equina syndrome. Those occurring below S4 are less likely to cause neurologic deficits but may be associated with rectal injuries. Vertical fractures are further categorized into zones: lateral (zone 1), foraminal (zone 2), and central canal (zone 3). Zone 1 fractures may affect the L5 nerve root and cause sciatica but usually have minimal neurologic deficits. Zone 2 fractures frequently involve nerve roots (L5–S2) and may result in bowel or bladder dysfunction. Zone 3 fractures, involving the central canal, carry the highest risk, with more than 50% of patients experiencing significant neurologic impairment, including bowel, bladder, and sexual dysfunction.
Clinically, patients often present with pain localized to the buttocks, perirectal area, or posterior thigh. Physical findings may include swelling, ecchymosis over the sacrum, and tenderness. Neurologic deficits are critical to assess and may include decreased or absent anal sphincter tone, perineal sensory loss, and bowel or bladder incontinence. A rectal examination is essential, as it may reveal sacral tenderness or blood, suggesting an open fracture or associated rectal injury.
Evaluation begins with a thorough history and physical examination, with special attention to neurologic status, including sphincter tone and perianal sensation. Because sacral fractures are rarely isolated, clinicians must actively search for associated pelvic, spinal, and intra-abdominal injuries. Imaging is crucial for diagnosis. Plain radiographs detect only about 30% of sacral fractures, making CT scan the imaging modality of choice for accurate identification. MRI is indicated when neurologic deficits are present to assess nerve involvement and soft tissue injury.
Management follows standard trauma principles. In the prehospital setting, patients should be immobilized with spinal precautions due to the high likelihood of associated injuries. Initial stabilization focuses on airway, breathing, and circulation, along with adequate pain control using NSAIDs or opioid analgesics. Unstable vertical fractures or those associated with significant trauma require urgent evaluation for life-threatening injuries and prompt orthopedic consultation. Surgical intervention is often necessary when fractures are displaced or associated with neurologic compromise.
Isolated, nondisplaced transverse sacral fractures without neurologic deficits may be managed conservatively with limited weight-bearing and close outpatient orthopedic follow-up. However, any evidence of neurologic impairment warrants admission and specialist involvement. Elderly patients may require admission or assisted care due to reduced mobility and higher complication risk.
A key clinical pearl is that sacral fractures are seldom isolated injuries; clinicians must maintain a high index of suspicion for concurrent pelvic and spinal trauma. A detailed neurologic examination—including assessment of anal sphincter tone and perianal sensation—is essential. Additionally, placement of a Foley catheter in trauma patients may mask underlying neurogenic bladder dysfunction, so careful monitoring is required.
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