Key Facts

Low back pain is an extremely common condition that is the leading cause of years lived with disability globally. The vast majority of cases are non-specific and self-limiting. Management focuses on reassurance, activity, and avoiding over-investigation.

Epidemiology

• Lifetime prevalence: 80%; point prevalence: 20-30%
• Most common cause of sickness absence in the UK
• Peak prevalence: 35-55 years
• Annual cost to NHS: >£1 billion; total UK economic cost: >£12 billion/year
• 90% improve within 6 weeks; 7-10% develop chronic pain (>12 weeks)

Aetiology

• Non-specific (>90%): no identifiable pathological cause; likely multifactorial (muscle, ligament, disc, facet joint)
• Radiculopathy/sciatica (5-10%): nerve root compression (disc prolapse most common, L4/5 and L5/S1)
• Serious pathology (<1%): cauda equina syndrome, spinal fracture, malignancy, infection, inflammatory spondyloarthropathy
• Risk factors for chronicity: psychosocial ('yellow flags') — fear-avoidance, catastrophising, depression, job dissatisfaction, compensation claims

Pathophysiology

• Degenerative changes in discs, facet joints, and ligaments (universal with ageing, poorly correlated with symptoms)
• Muscle deconditioning and spasm
• Central sensitisation in chronic pain
• Disc herniation: nucleus pulposus protrusion irritating/compressing nerve root
• Cauda equina syndrome: large central disc prolapse or other mass compressing cauda equina (below L2)

Non-Specific Low Back Pain

• Pain between costal margin and gluteal folds
• May radiate to thighs (not below knee)
• Mechanical: worse with movement, better with rest (or worse with sustained postures)
• No neurological deficit

Sciatica (Radiculopathy)

• Leg pain worse than back pain
• Pain radiating below the knee in a dermatomal distribution
• Positive straight leg raise (SLR) <45°
• Neurological signs: reduced reflexes, weakness, sensory loss in nerve root distribution
• L5 root: foot drop, weakness of great toe dorsiflexion, sensory loss dorsum of foot
• S1 root: reduced ankle jerk, weakness of plantarflexion, sensory loss lateral foot

Red Flags (Exclude Serious Pathology)

• Cauda equina: bilateral sciatica, saddle anaesthesia, urinary retention/incontinence, loss of anal tone, bilateral neurological deficit — EMERGENCY
• Cancer: age >55, history of cancer, unexplained weight loss, pain at rest, night pain, thoracic pain
• Fracture: osteoporosis, steroid use, significant trauma, structural deformity
• Infection: fever, IV drug use, immunocompromised, recent surgery, tuberculosis risk
• Inflammatory: age <40, morning stiffness >30 min, improves with exercise, family history of spondyloarthropathy

Bedside

• Comprehensive clinical examination: range of motion, SLR, neurological assessment (power, sensation, reflexes)
• STarT Back tool: risk stratification (low, medium, high)
• PR examination: if cauda equina suspected (anal tone)

Bloods

• Not routinely indicated for non-specific LBP
• ESR, CRP: if inflammatory/infectious cause suspected
• PSA, calcium, ALP: if malignancy suspected
• HLA-B27: if ankylosing spondylitis suspected

Imaging

• Do NOT routinely image non-specific low back pain (NICE NG59)
• MRI: gold standard when imaging indicated
  • Cauda equina syndrome: EMERGENCY MRI within hours
  • Red flags suggesting serious pathology
  • Sciatica not improving after 6 weeks (if surgery being considered)
• X-ray: limited utility; consider for suspected fracture
• MRI SIJ: if inflammatory spondyloarthropathy suspected

Special Tests

• Nerve conduction studies: rarely needed; if diagnostic uncertainty regarding radiculopathy vs peripheral neuropathy

Non-pharmacological (NICE NG59)

• Reassurance and education: back pain is common, not dangerous, self-limiting in most cases
• Encourage staying active: bed rest is harmful; return to normal activities as soon as possible
• Group exercise programme: biomechanical, aerobic, mind-body (yoga, Pilates) — any form of exercise beneficial
• Manual therapy (spinal manipulation, mobilisation, massage): as part of a treatment package including exercise
• CBT/psychological therapy: for medium-high risk on STarT Back
• Self-management support

Pharmacological (NICE NG59)

• First-line: NSAID (ibuprofen 400mg TDS or naproxen 250-500mg BD) — shortest effective course; PPI cover if risk factors
• If NSAID contraindicated: weak opioid (codeine 30mg QDS) with or without paracetamol — SHORT TERM ONLY
• Paracetamol alone: NOT recommended for LBP (insufficient evidence — Cochrane)
• Do NOT offer opioids for chronic LBP (NICE NG59)
• Do NOT offer gabapentinoids for non-specific LBP
• Neuropathic agents (amitriptyline, gabapentin, pregabalin): for sciatica with neuropathic pain component

Surgical

• Spinal decompression (discectomy/laminectomy): for sciatica with confirmed nerve root compression not improving with conservative management after 6-12 weeks
• Spinal fusion: rarely; for specific indications after comprehensive MDT assessment
• Do NOT offer facet joint injections, disc replacement for non-specific LBP (NICE NG59)

Referral Criteria

• Emergency: cauda equina syndrome (same-day MRI and neurosurgical assessment)
• Urgent: progressive neurological deficit, suspected malignancy or infection
• Routine: physiotherapy, pain management programme, orthopaedic/spinal surgeon if surgery candidate
• Occupational health: advice on work modifications and return to work

• 90% of acute LBP improves within 6 weeks
• 7-10% develop chronic pain (>12 weeks)
• Psychosocial factors ('yellow flags') are the strongest predictors of chronicity, NOT imaging findings
• Disc degeneration on MRI is universal with ageing and does NOT correlate with symptoms (up to 80% of asymptomatic individuals have disc changes)
• Sciatica: >50% improve within 6 weeks; >90% within 12 months
• Surgery for sciatica: faster recovery but similar outcomes at 1-2 years vs conservative management
• Cauda equina syndrome: outcome depends on timing of decompression; delay >48 hours associated with worse outcome

STarT Back Risk Stratification

Sciatica — Key Nerve Roots

Yellow Flags (Psychosocial Risk Factors for Chronicity)