What is the initial approach to managing a patient presenting with low back pain?

Differential Diagnosis for Low Back Pain

Red Flag Conditions Requiring Urgent Evaluation

The most critical first step is identifying red flags that indicate serious underlying pathology requiring immediate imaging and specialist consultation. 1

Emergency Conditions

• Cauda equina syndrome presents with urinary retention (90% sensitivity), fecal incontinence, bilateral leg weakness, and saddle anesthesia—this requires immediate MRI and neurosurgical consultation 1, 2
• Severe or progressive neurologic deficits warrant urgent MRI or CT imaging 1
• Spinal infection should be suspected with fever, recent infection, and midline tenderness 1

Serious Underlying Pathology

• Malignancy is suggested by history of cancer, unexplained weight loss, age over 70, and failure to improve with conservative therapy 1, 3
• Vertebral compression fracture presents with midline tenderness in patients with osteoporosis, steroid use, or significant trauma 1
• Spinal fracture requires consideration with history of significant trauma 1

Common Mechanical and Structural Causes

Nonspecific Low Back Pain (>85% of cases)

• Myofascial pain is the most common etiology in patients without red flags 4
• Mechanical low back pain improves with activity modification and typically resolves within 6 weeks in 90% of cases 5

Radicular Pain and Nerve Compression

• Radiculopathy is identified by positive straight leg raise test, dermatomal sensory changes, motor weakness in specific distributions, and reflex abnormalities 1, 2
• Spinal stenosis presents with neurogenic claudication worsening with walking and improving with forward flexion 6
• Herniated disk causes radicular symptoms following dermatomal patterns 6

Facet and Joint-Related Pain

• Facet joint pain is characterized by axial pain worsened by extension and rotation 4
• Sacroiliac joint pain presents with unilateral buttock pain and positive provocative maneuvers 4
• Discogenic pain is axial pain without radicular features 4

Age-Specific Considerations

Pediatric Patients

• Spondylolysis is common in young athletes with repetitive hyperextension activities 2
• Scheuermann's disease causes thoracolumbar kyphosis and pain in adolescents 2
• Apophyseal injuries occur at growth plates in skeletally immature patients 2

Older Adults

• Compression fractures are more likely with age over 70, osteoporosis, or chronic steroid use 3
• Spinal stenosis increases in prevalence with degenerative changes 6
• Metastatic disease must be considered with prior cancer history 3

Inflammatory and Systemic Causes

• Ankylosing spondylitis presents with morning stiffness improving with activity, typically in younger males 7
• Inflammatory arthropathies cause persistent pain with systemic symptoms 7
• Renal pathology may present as referred back pain with associated urinary symptoms 3

Psychosocial Risk Factors (Yellow Flags)

• High-risk patients identified by STarT Back tool at 2 weeks show anxiety, depression, catastrophizing, fear-avoidance beliefs, and job dissatisfaction—these predict progression to chronic disabling pain 8, 1, 6
• Medium-risk patients have some psychosocial factors but lower overall risk 1
• Low-risk patients have minimal psychosocial barriers to recovery 8

Common Pitfalls to Avoid

• Do not order routine imaging for nonspecific low back pain without red flags, as findings correlate poorly with symptoms and expose patients to unnecessary radiation 1, 9
• Do not attribute pediatric back pain to "growing pains" without proper evaluation, as this may miss spondylolysis or other serious pathology 2
• Do not miss cauda equina syndrome by failing to assess for urinary retention, fecal incontinence, and saddle anesthesia in every patient 1, 2
• Do not overlook psychosocial factors that predict chronicity—use the STarT Back tool at 2 weeks to stratify risk 8, 1