What are the key components of a physical examination for a patient with a suspected sacral fracture?

Physical Examination for Suspected Sacral Fracture

A thorough physical examination for suspected sacral fracture must include detailed neurologic assessment of the lumbosacral nerve roots, inspection for perineal/scrotal hematoma and blood at the urethral meatus, rectal examination for sphincter tone and prostate position, and palpation of the sacrum for tenderness and step-off deformities. 1, 2

Critical Initial Assessment Components

Hemodynamic Status Evaluation

• Assess for hemodynamic instability defined as systolic blood pressure <90 mmHg, requirement for bolus infusions/transfusions or vasopressors, base deficit >6 mmol/L, shock index >1, or transfusion requirement of 4-6 units of packed red blood cells within 24 hours 1
• Sacral fractures are among the principal injuries associated with hemodynamic instability in pelvic trauma, particularly open-book injuries, vertical-shear injuries, and sacral fractures themselves 1

Detailed Neurologic Examination

• Perform comprehensive lumbosacral nerve root assessment as neurologic deficits occur in 15.1% of all sacral fractures, but this rate increases dramatically with fracture pattern and pelvic instability 3
• The rate of neurological deficits correlates more strongly with the degree of pelvic instability than with specific sacral fracture patterns: stable injuries (TILE A) rarely have deficits, type B injuries show 10% deficit rate, while unstable fractures (TILE C) demonstrate 32.6-63.6% neurological impairment depending on fracture zone 3
• Test motor function, sensory distribution, and reflexes in all lower extremity nerve distributions, with particular attention to S2-S4 nerve roots 2
• Assess bowel and bladder function as sacral nerve root involvement can cause autonomic dysfunction 2

Perineal and Genitourinary Examination

• Inspect the perineum and scrotum for hematoma, which suggests urethral injury that occurs in 7-25% of pelvic ring fractures 1
• Check for blood at the urethral meatus, a key clinical sign of urethral injury 1
• Do not insert a transurethral catheter without prior investigation if any signs of urethral injury are present, as this can worsen the injury 1

Rectal Examination

• Perform digital rectal examination to assess for high-riding or non-palpable prostate, which indicates urethral injury 1
• Evaluate sphincter tone as decreased tone suggests sacral nerve root injury 2
• Palpate for bony fragments or step-off deformities that may be palpable through the rectal wall 2

Direct Sacral Palpation

• Palpate the sacrum directly for tenderness, crepitus, and step-off deformities 2
• Assess for visible deformity or ecchymosis over the sacral region 2

Associated Injury Assessment

Pelvic Stability Testing

• Assess pelvic ring stability through gentle compression and distraction maneuvers, as sacral fractures commonly occur with pelvic ring injuries 1, 2
• Avoid aggressive manipulation in unstable fractures to prevent further displacement and neurologic injury 2

Hip Examination

• Evaluate for hip dislocation, which requires prompt reduction and is important to identify on initial pelvic radiographs 1

Critical Pitfalls to Avoid

• Do not miss the diagnosis due to distracting injuries: Sacral fractures are frequently overlooked because they occur in polytrauma patients with multiple severe injuries—89.4% of patients with sacral fractures have at least one additional body region injured 3
• Do not rely solely on clinical examination: Clinical assessment for thoracolumbar spine fractures has only 81% sensitivity and 68% specificity in children, and similar limitations exist in adults 1
• Do not assume absence of neurologic deficit excludes significant injury: An estimated 30% of sacral fractures are identified late, and delayed diagnosis can lead to progressive deformity and chronic pain 2
• Do not overlook additional risk indicators: Avulsion fractures of the sacrum, comminuted fracture patterns, and bilateral fracture lines significantly increase the risk of neurological impairment 3

Documentation Requirements

• Document all neurologic findings in detail including specific nerve root distributions, as neurologic improvement with timely intervention has been demonstrated 2
• Record hemodynamic parameters to guide subsequent imaging and management decisions 1
• Note all associated injuries as these influence treatment algorithms 2, 3