What examination techniques should be used for a patient with no known medical history presenting with low back pain and left flank pain after a fall?

Examination Techniques for Post-Fall Low Back and Flank Pain

Perform immediate assessment for cauda equina syndrome, vertebral compression fracture, and renal injury, as these are the most critical diagnoses in a patient with low back and flank pain after trauma. 1

Immediate Red Flag Assessment

Check for cauda equina syndrome first by specifically asking about and examining for: 1

• Urinary retention (inability to void, not just difficulty)
• Fecal incontinence
• Saddle anesthesia (numbness in perineal/perianal region)
• Bilateral lower extremity motor weakness
• Motor deficits at multiple spinal levels

Assess for vertebral compression fracture by: 1, 2

• Palpating for midline tenderness over the thoracolumbar spine (positive likelihood ratio of 14.7 in high-risk patients)
• Documenting the exact location of maximal tenderness
• Checking for visible contusion or abrasion over the spine (positive likelihood ratio of 31.09 for vertebral compression fracture in trauma patients) 2

Evaluate for renal injury given the left flank pain by: 1

• Assessing costovertebral angle tenderness (percuss or palpate the area between the 12th rib and spine)
• Checking for flank ecchymosis or swelling

Neurological Examination for Radiculopathy

Perform a focused neurological exam to identify nerve root compression: 3, 1, 4

• Motor strength testing: Test hip flexion (L2), knee extension (L3-L4), ankle dorsiflexion (L4-L5), great toe extension (L5), and ankle plantarflexion (S1) bilaterally, grading on a 0-5 scale 1

• Sensory examination: Map dermatomal distribution for light touch and pinprick in L2 (anterior thigh), L3 (medial knee), L4 (medial ankle), L5 (dorsal foot), and S1 (lateral foot) 1, 4

• Deep tendon reflexes: Check patellar (L3-L4) and Achilles (S1) reflexes bilaterally, noting any asymmetry 4

• Straight leg raise test: With patient supine, passively raise the affected leg with knee extended; positive if sciatica is reproduced between 30-70 degrees of elevation 1, 4

• Crossed straight leg raise: Raise the unaffected leg; highly specific for nerve root compression if it reproduces pain in the affected leg 4

Specific Physical Examination Maneuvers

Document range of motion limitations by having the patient: 3

• Flex forward (note if pain radiates below the knee, suggesting radiculopathy)
• Extend backward
• Lateral bend to each side
• Rotate trunk

Palpate paraspinal muscles for spasm or tenderness, which may indicate muscle injury versus deeper pathology 4

Critical Clinical Decision Points

The examination must distinguish between three categories: 3

1. Nonspecific low back pain (>85% of cases)
2. Back pain with radiculopathy or spinal stenosis (~7% of cases)
3. Back pain with specific underlying pathology such as fracture (<2% of cases)

In this trauma patient, the presence of midline tenderness strongly suggests vertebral compression fracture and mandates plain radiography as the initial imaging study. 1 The American College of Radiology recommends this approach because the trauma mechanism combined with midline and flank pain makes fracture a significant concern. 1

Common Pitfalls to Avoid

Do not miss cauda equina syndrome by failing to specifically ask about urinary retention and saddle anesthesia—delayed diagnosis leads to permanent neurologic disability. 5, 1, 4

Do not assume flank pain is renal without considering thoracic disc herniation, which can present with flank pain mimicking urinary system disorders. 6 However, in the trauma setting, fracture and renal injury take priority.

Do not skip midline palpation in trauma patients, as this single finding has the highest positive likelihood ratio for identifying vertebral compression fracture. 1, 2