Chronic Back Pain — Causes, Biopsychosocial Model & Management Guide — Symptoms, Causes & Treatment | MyMedicPlus

Chronic back pain is defined as pain in the lumbar, thoracic, or cervical spine persisting for 12 weeks or more. It is the world's leading cause of disability, affecting 619 million people globally and causing more years lived with disability than any other condition. Chronic back pain is distinguished from acute back pain (lasting under 6 weeks) and subacute back pain (6-12 weeks). Unlike acute back pain, which usually has a clear mechanical trigger and resolves spontaneously, chronic back pain is strongly influenced by psychosocial factors — the biopsychosocial model recognises that biological, psychological (fear, anxiety, catastrophising), and social (work, relationships) factors all contribute to pain persistence. The modern biopsychosocial understanding of chronic back pain — recognising that psychological factors such as fear-avoidance, catastrophising, and depression are as important as structural pathology in determining pain experience and disability — has fundamentally changed management approaches away from passive physical treatments toward active, function-focused rehabilitation programmes.

Structural causes: lumbar disc herniation ('slipped disc') compressing nerve roots; lumbar spinal stenosis (narrowing of the spinal canal — causing neurogenic claudication in older adults); degenerative disc disease (loss of disc height, osteophyte formation); spondylolisthesis (vertebral slippage); facet joint osteoarthritis; sacroiliac joint dysfunction; and, rarely, serious pathology (spinal fracture, infection, tumour — 'red flags' requiring urgent investigation). Psychosocial risk factors (major contributors to chronicity): anxiety and depression; fear-avoidance behaviour (avoiding activity due to fear of pain worsening); pain catastrophising; low job satisfaction; poor social support; previous chronic pain; and obesity. These factors are stronger predictors of pain chronicity than structural imaging findings.

Chronic low back pain: persistent dull, aching, or burning lumbar pain lasting over 12 weeks, often worsened by prolonged sitting, bending, or lifting, and eased by movement or lying down. Radiation to buttock or leg (sciatica — dermatomal pattern) when nerve root is compressed. Neurogenic claudication: bilateral buttock/leg pain and weakness provoked by walking/standing and relieved by sitting or forward flexion (spinal stenosis). Red flag symptoms requiring urgent investigation: new onset back pain over 50 years (tumour risk); unexplained weight loss; night pain disrupting sleep; morning stiffness over 45 minutes (ankylosing spondylitis); fever; trauma; bladder/bowel dysfunction or saddle anaesthesia (cauda equina syndrome — surgical emergency).

History and examination exclude red flags and identify specific causes. MRI lumbosacral spine is the imaging of choice — reveals disc herniation, stenosis, nerve compression, and sinister pathology. However, MRI findings often don't correlate with pain severity — degenerative changes are found in 50% of asymptomatic 40-year-olds. Routine MRI for non-specific chronic back pain without red flags is not recommended by most guidelines (it increases surgery rates without improving outcomes). Straight leg raise (Lasegue's test) for nerve root tension (sciatica). Screening for psychosocial risk factors (yellow flags): STarT Back Tool identifies prognostic risk. Exclude systemic disease with ESR, CRP, FBC, and myeloma screening in older patients.

Active self-management is fundamental — staying active, not resting in bed (bed rest worsens outcomes). Physiotherapy: supervised exercise programmes (strengthening, stretching, aerobic exercise — all reduce pain and disability); manual therapy (manipulation, mobilisation — short-term benefit for acute/subacute pain). Psychological therapies: cognitive behavioural therapy (CBT) addressing fear-avoidance, catastrophising, and pain beliefs is the most evidence-based psychological intervention; acceptance and commitment therapy (ACT); pain education ('explain pain' reduces fear). Pharmacological: paracetamol, NSAIDs (short courses for flares); tricyclic antidepressants (amitriptyline) or duloxetine for neuropathic component; avoid long-term opioids (limited efficacy, significant harms). Interventional: facet joint injections, epidural steroid injections (for sciatica — short-term benefit); radiofrequency ablation of facet joint nerves. Surgery: microdiscectomy for sciatica from proven disc herniation not responding to 6 weeks of conservative treatment; spinal decompression for severe symptomatic spinal stenosis; spinal fusion for spondylolisthesis with instability.

Inadequately managed chronic back pain leads to progressive functional decline, work disability, and catastrophic impact on quality of life. Long-term opioid use for back pain causes dependence, tolerance, opioid-induced hyperalgesia (paradoxical pain worsening), endocrine dysfunction, and falls risk in older patients. Fear-avoidance behaviour leads to deconditioning (muscle weakness and cardiovascular unfitness) — creating a vicious cycle that amplifies pain. Depression and anxiety comorbidities develop in up to 40% of patients with chronic back pain. Cauda equina syndrome (from central disc herniation compressing the cauda equina) — causing paralysis, bladder/bowel dysfunction, and saddle anaesthesia — is an orthopaedic emergency requiring immediate surgical decompression.

Stay active — regular exercise (walking, swimming, cycling, yoga, pilates) strengthens spinal muscles and reduces chronic pain risk and recurrence. Maintain a healthy weight — each additional kilogram of body weight increases lumbar disc loading. Improve posture and ergonomics: position computer monitor at eye level; use ergonomic chair with lumbar support; adjust car seat height; use a standing desk periodically. Lift correctly — bend at the knees, not the waist, and keep loads close to the body. Quit smoking — smokers have higher rates of disc degeneration and poor surgical outcomes. Address psychosocial factors early: treat depression and anxiety, manage work stress, and seek CBT at the first signs of chronic pain to prevent it becoming established. Good sleep hygiene reduces pain amplification.

Call emergency services or go to A&E immediately for: new bladder or bowel dysfunction (unable to pass urine, or faecal incontinence) with back pain — possible cauda equina syndrome requiring emergency MRI and surgery within hours to prevent permanent paralysis; saddle anaesthesia (numbness around the perineum); or bilateral leg weakness. See your GP the same day for: back pain after a fall or road traffic accident (fracture risk); new back pain in a patient with a known cancer history (metastatic disease); back pain with fever, night sweats, and weight loss (possible spinal infection or malignancy). See your GP within 2 weeks for: persistent back pain lasting more than 12 weeks that is not responding to rest, simple analgesia, and self-management — chronic pain rehabilitation and physiotherapy referral is indicated. Refer to a pain management programme if active physiotherapy alone has not achieved functional improvement after 3 months.