What is the initial evaluation and treatment for patients presenting with low back ache?

Low Back Pain: Causes and Evaluation

Initial Classification and Risk Stratification

Conduct a focused history and physical examination to classify patients into one of three categories: nonspecific mechanical low back pain (>85% of cases), back pain with radiculopathy or spinal stenosis (~7%), or back pain with specific underlying pathology (<2%). 1, 2, 3

Red Flags Requiring Immediate Action

Identify these critical conditions that demand urgent imaging and specialist consultation:

• Cauda equina syndrome (0.04% prevalence): urinary retention, fecal incontinence, saddle anesthesia, and motor deficits at multiple levels—requires immediate MRI and neurosurgical consultation 2, 3
• Vertebral malignancy (0.7% prevalence): history of cancer (positive likelihood ratio 14.7), unexplained weight loss, age >50, failure to improve with conservative therapy 3
• Vertebral compression fracture (4% prevalence): history of osteoporosis or steroid use, midline tenderness, significant trauma—obtain plain radiography initially 2, 3
• Spinal infection (0.01% prevalence): fever, recent infection, IV drug use, immunocompromised status—check CBC, ESR/CRP, urinalysis 1, 3
• Ankylosing spondylitis (0.3-5% prevalence): age <45 years, morning stiffness >30 minutes improving with movement, worsening with rest 3, 4

Neurologic Examination Components

Perform these specific assessments to identify radiculopathy or spinal stenosis:

• Straight leg raise test for radiculopathy—positive if reproduces radicular pain below the knee 2, 3
• Dermatomal sensory testing to identify specific nerve root involvement 3
• Motor strength testing in specific nerve root distributions (L4: ankle dorsiflexion, L5: great toe extension, S1: ankle plantarflexion) 3
• Reflexes: knee (L4), ankle (S1) 1

Psychosocial Risk Factors (Yellow Flags)

Use the STarT Back tool at 2 weeks to identify patients at high risk for chronic disability. 2, 3 High-risk features include:

• Depression, anxiety, catastrophizing 2, 3
• Fear-avoidance beliefs 2
• Job dissatisfaction 1, 3
• Passive coping strategies 3
• Higher baseline disability levels 3

Diagnostic Imaging Strategy

Do not obtain routine imaging for nonspecific low back pain without red flags—it does not improve outcomes and may lead to unnecessary interventions. 1, 2, 3

When to Image

• Immediate MRI or CT: red flags present (cauda equina, severe/progressive neurologic deficits, suspected malignancy or infection) 2, 3
• Plain radiography at 4-6 weeks: persistent symptoms despite conservative management, suspected compression fracture in high-risk patients 2, 5
• MRI preferred over CT: better soft tissue visualization, avoids radiation exposure (single lumbar x-ray equals >1 year of daily chest x-rays in gonadal radiation) 2, 3

Initial Management Approach

Nonpharmacologic Treatment (First-Line)

Advise patients to stay active and avoid bed rest—maintaining activity reduces disability and improves outcomes. 2, 5, 6

For acute/subacute low back pain (<12 weeks):

• Superficial heat (heating pads)—moderate-quality evidence 1, 2
• Massage—low-quality evidence 1, 2
• Acupuncture—low-quality evidence 1, 2
• Spinal manipulation—low-quality evidence 1, 2

For chronic low back pain (>12 weeks):

• Exercise therapy—moderate-quality evidence 2
• Multidisciplinary rehabilitation—moderate-quality evidence 2
• Cognitive behavioral therapy—low-quality evidence 2
• Mindfulness-based stress reduction—moderate-quality evidence 2
• Tai chi or yoga—low-quality evidence 2

Pharmacologic Treatment (Second-Line)

If nonpharmacologic treatment is insufficient, use NSAIDs or skeletal muscle relaxants for acute pain. 1, 2

Medication hierarchy:

• First-line: NSAIDs (moderate-quality evidence) or acetaminophen (up to 4g daily) 1, 2, 5, 6
• Adjunct for acute pain: Skeletal muscle relaxants (moderate-quality evidence)—note increased drowsiness when combined with NSAIDs 1, 7
• Second-line for chronic pain: Tramadol or duloxetine if inadequate response to NSAIDs 2, 8
• Last resort: Opioids only with careful monitoring—lack superior efficacy and carry abuse potential 2, 8

Avoid systemic corticosteroids for long-term management. 2

Follow-Up and Referral Criteria

Reassessment Timeline

• At 2 weeks: Apply STarT Back tool for risk stratification 2
• At 1 month: Reevaluate patients with persistent, unimproved symptoms 2
• Earlier reassessment: Older patients, signs of radiculopathy/spinal stenosis, worsening symptoms 2

Referral Indications

• Physical therapy: Medium-risk patients at 2 weeks, or any patient not improving at 4-6 weeks 2
• Comprehensive biopsychosocial assessment: High-risk patients (by STarT Back tool) at 2 weeks, review by 12 weeks 2
• Specialist consultation: No response to standard noninvasive therapies after 3 months minimum, progressive neurologic deficits, persistent functional disabilities despite comprehensive conservative therapy 2

Critical Pitfalls to Avoid

• Routine imaging for uncomplicated acute low back pain exposes patients to unnecessary radiation without clinical benefit 2, 3
• Overlooking inflammatory causes in younger patients (<45 years) with chronic symptoms and morning stiffness delays access to TNF-blocking agents 3
• Failing to recognize cauda equina syndrome leads to permanent neurologic disability from delayed surgical decompression 3
• Missing cancer in patients with prior malignancy—posttest probability jumps from 0.7% to 9% in this population 3
• Prescribing prolonged bed rest worsens outcomes and increases disability 2, 5
• Overreliance on opioids for pain management without exhausting nonpharmacologic and non-opioid pharmacologic options 2, 8