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

Key Components of Physical Examination for Suspected Sacral Fractures

The physical examination for suspected sacral fractures should focus on detailed neurological assessment, palpation of specific anatomical landmarks, and specialized maneuvers to evaluate stability and pain provocation.

Initial Assessment

• Inspection:

  • Observe for visible bruising, swelling, or deformity in the sacral region
  • Note any asymmetry in the gluteal folds
  • Check for skin breakdown or wounds that might indicate open fracture 1

• Palpation:

  • Direct palpation of the sacrum for point tenderness (highly specific finding) 1
  • Palpate the sacral spinous processes, sacral ala, and sacroiliac joints
  • Assess for crepitus which may indicate fracture mobility 2

Neurological Examination

• Comprehensive neurological assessment is critical as sacral fractures frequently involve neurological compromise: 2, 3
  • Motor strength testing of lower extremities (L4-S3 nerve roots)
  • Sensory testing of perineum and posterior thighs
  • Assessment of anal sphincter tone and bulbocavernosus reflex
  • Evaluation for saddle anesthesia (indicates possible cauda equina syndrome)
  • Testing of deep tendon reflexes (patellar and Achilles) 3, 4

Pain Provocation Tests

• Specific maneuvers to elicit pain:
  • Direct compression of the iliac wings (lateral compression test)
  • Anteroposterior compression of the pelvis
  • Passive hip rotation (especially internal rotation)
  • Gentle vertical pressure on the sacrum with the patient prone 2, 1

Functional Assessment

• Mobility evaluation:
  • Assess ability to bear weight
  • Observe gait pattern if ambulatory
  • Document any antalgic gait or inability to bear weight 5
  • Test for pain with position changes (sitting to standing, rolling in bed) 1, 6

Associated Areas to Examine

• Pelvic ring assessment:

  • Evaluate for pelvic ring instability as 30% of sacral fractures occur with pelvic ring injuries 3, 4
  • Check for leg length discrepancy which may indicate vertical displacement

• Lumbar spine examination:

  • Assess range of motion of lumbar spine
  • Check for tenderness of lumbar vertebrae
  • Evaluate for referred pain patterns 2

• Hip examination:

  • Perform hip range of motion as sacral fractures can cause radiated hip/groin pain 2
  • Rule out concomitant hip pathology

Special Considerations

• For suspected insufficiency fractures in elderly patients:

  • Evaluate for osteoporosis risk factors
  • Assess for pain with minimal activity or at rest
  • Note that symptoms may be more subtle than in traumatic fractures 6

• For suspected traumatic fractures:

  • Document mechanism of injury (high-energy trauma vs. low-energy)
  • Assess for signs of hemodynamic instability
  • Evaluate for other traumatic injuries 4, 5

Documentation

• Document the precise location of tenderness on the sacrum
• Note any neurological deficits in detail
• Record the specific pain provocation tests that were positive
• Document functional limitations and weight-bearing status

Remember that sacral fractures are frequently missed on initial evaluation, with an estimated 30% identified late 3. A thorough physical examination with particular attention to neurological status is essential for timely diagnosis and appropriate management.