Low Back Pain: Causes, Diagnosis and Treatment

Low Back Pain: Causes, Diagnosis and Treatment

Low back pain is the world's leading cause of years lived with disability. It affects approximately 80% of adults at some point in their lives and is one of the most common reasons for medical consultation, work absence, and disability retirement globally.

The good news: most episodes of acute low back pain improve significantly within 4–6 weeks with conservative management. But for a significant minority, pain becomes chronic (persisting more than 12 weeks) and may reflect a structural problem requiring more targeted treatment.

Anatomy of the Lower Back

The lumbar spine consists of five vertebrae (L1–L5) stacked between the thoracic spine above and the sacrum below. Between each pair of vertebrae lies an intervertebral disc — a tough fibrous ring (annulus fibrosus) surrounding a gel-like centre (nucleus pulposus) that acts as a shock absorber.

The spinal cord ends at approximately L1–L2, and below this level, a bundle of nerve roots called the cauda equina passes through the spinal canal before exiting through gaps in the vertebrae (foramina) to supply the legs, bladder and bowel.

Structures that can cause low back pain include: vertebral bodies and joints, intervertebral discs, nerve roots, spinal canal contents, paravertebral muscles, ligaments, and referred pain from abdominal or pelvic organs.

Causes

Muscle and Ligament Strain (Mechanical Back Pain)

The most common cause of acute low back pain — typically from sudden awkward movement, heavy lifting, poor posture, or prolonged sitting. There is no structural disc or nerve damage. Pain is usually diffuse, worse with movement, and improves with gentle activity.

Disc Herniation (Slipped Disc)

The nucleus pulposus can bulge or rupture through the outer annulus fibrosus. If the herniated disc material presses on a nerve root exiting the spinal canal, it causes radiculopathy — shooting pain, numbness, tingling or weakness radiating down the leg along the nerve's distribution. This is the classic presentation of sciatica.

The L4–L5 and L5–S1 levels are herniated most commonly. Symptoms from a herniated disc often improve over several weeks with conservative care. Symptom improvement does not establish that the herniated material has fully retracted or that the disc anatomy has normalized within a fixed period. Persistent or worsening symptoms require reassessment.

Sciatica

Sciatica describes pain radiating from the lower back or buttock down the leg, following the path of the sciatic nerve (through the back of the thigh, knee, calf and sometimes foot). It is most commonly caused by disc herniation compressing a nerve root, but can also result from spinal stenosis or piriformis syndrome.

Spinal Stenosis

The spinal canal can narrow (stenosis) due to OA-related bone and ligament overgrowth, reducing space for the spinal cord and nerve roots. This produces neurogenic claudication — pain, heaviness and weakness in the legs that worsens with walking and standing, and relieves with sitting or bending forward (flexing the spine widens the canal). It is most common in people over 60.

Degenerative Disc Disease (DDD)

As discs age, they dehydrate and lose height, reducing their shock-absorbing capacity. The vertebrae above and below shift closer together, straining facet joints and ligaments. This is a near-universal process of ageing, but becomes symptomatic when it contributes to nerve compression or mechanical instability.

Spondylolisthesis

Forward slippage of one vertebra over the one below. Types include degenerative slippage, isthmic slippage associated with a defect in the pars interarticularis, congenital/dysplastic slippage, and post-traumatic slippage. Isthmic and congenital/dysplastic are distinct classifications. Slippage can cause low back pain and, if nerve roots are compressed, leg symptoms.

Facet Joint Arthritis

The facet (zygapophyseal) joints on the back of the spine are true synovial joints susceptible to osteoarthritis. Facet OA causes localised axial back pain, often worse with extension and rotation, and may refer pain to the buttock.

Serious Causes and Warning Features — Clinical Assessment

A small minority of low back pain cases have serious underlying causes. The features below need clinical assessment in context; the suspected cause and associated symptoms determine urgency. Age at onset alone is not a reason for urgent investigation or routine imaging. New bladder or bowel dysfunction, saddle sensory loss or progressive weakness requires urgent assessment:

• Age at first onset is considered alongside the history, examination and other symptoms; age alone does not establish a serious cause
• Constant, progressive, non-mechanical pain (not relieved by rest)
• Pain at rest or at night (possible tumour or infection)
• Unexplained weight loss, fever, or night sweats
• History of cancer (possible spinal metastasis)
• Bowel or bladder dysfunction — incontinence, retention, or saddle anaesthesia (numbness in the perineum, inner thighs) — cauda equina syndrome (surgical emergency)
• Significant lower limb neurological deficit (progressive weakness)
• Structural spinal deformity
• Thoracic pain

Diagnosis

Clinical Assessment

The clinician takes a detailed history (onset, character, distribution, aggravating and relieving factors, neurological symptoms, red flags) and examines the spine, hips, and neurological function (reflexes, sensation, muscle power, straight leg raise test).

The straight leg raise test — lifting the leg while the patient lies flat, reproducing the patient's radiating leg pain at less than 60° — is highly sensitive for lumbar disc herniation compressing a nerve root.

Imaging

Important: most acute low back pain does NOT require imaging. Imaging findings (disc bulges, disc degeneration) are common in pain-free adults and do not reliably predict symptoms.

Imaging is not triggered by a fixed duration of pain alone. Suspected serious pathology or severe/progressive neurological deficits require prompt assessment. In specialist care, consider imaging when its result would change management, including planning surgery.

X-ray — shows vertebral alignment, disc space height, fractures and degenerative changes. Cannot show soft tissue (discs, nerves).

MRI of the lumbar spine — the gold standard for low back pain with neurological features. Clearly shows disc herniations, nerve root compression, spinal stenosis, cord and cauda equina, bone marrow pathology (infection, tumour), and ligament integrity. No radiation.

CT scan — may assess bony detail or be considered when MRI cannot safely or practically be performed. MRI eligibility depends on the specific implant and scanning conditions: some devices are MR Conditional. Claustrophobia should be discussed with the imaging team rather than treated as an automatic contraindication. CT uses ionising radiation.

CT myelogram — injection of contrast into the spinal fluid followed by CT; used pre-operatively when MRI is unavailable or inadequate.

Treatment

Conservative Management (First-Line)

Active management — staying active is critical. Bed rest is harmful; patients who maintain gentle daily activity recover faster. Walking and gentle stretching are encouraged from day one.

Physiotherapy — structured exercise programmes (core strengthening, flexibility) are the most effective medium-term treatment. Spinal manipulation by physiotherapists or chiropractors may provide short-term relief in acute non-specific back pain.

Analgesia — select with a clinician:

• Paracetamol — NICE does not recommend it alone for low back pain; excessive doses can cause liver damage
• NSAIDs (ibuprofen, naproxen, diclofenac) — assess gastrointestinal, kidney and cardiovascular risks; use the lowest effective dose briefly
• Muscle relaxants such as cyclobenzaprine — may be considered briefly for selected acute non-radicular pain; sedation is a concern, and this is not a routine sciatica treatment
• Opioids — not routine treatment; NICE reserves weak opioids for selected acute cases when NSAIDs are unsuitable or ineffective and advises against chronic use
• Gabapentin, pregabalin and diazepam — NICE advises against their use for sciatica
• Duloxetine — ACP allows consideration for selected chronic non-radicular low back pain after non-drug treatment fails; this does not establish benefit for sciatica

Heat therapy — continuous low-level heat wraps reduce acute back pain and improve function.

Psychological support — chronic low back pain has significant psychological components. Cognitive behavioural therapy (CBT) reduces pain catastrophising and improves function in chronic LBP.

Injections

Epidural corticosteroid injection (ESI) may be considered for selected patients with acute, severe sciatica. It may provide short-term improvement in radicular pain or disability, but benefit and duration vary; it should not be presented as a guaranteed way to avoid surgery. The specialist assesses indication, procedural risks and whether any repeat injection is appropriate rather than applying a fixed annual schedule.

Facet joint injections / medial branch blocks — diagnostic medial branch blocks may help assess suspected facet-mediated pain and select patients for radiofrequency denervation. NICE recommends denervation only after a positive diagnostic block in appropriately selected people with chronic low back pain; it advises against spinal injections for managing low back pain. The multispecialty lumbar facet guideline recommends against routine therapeutic medial branch blocks or intra-articular facet injections, while allowing selected exceptions after specialist assessment. A diagnostic or prognostic role does not establish routine therapeutic effectiveness.

Radiofrequency ablation (RFA) of medial branch nerves — longer-lasting facet pain relief (6–18 months) by heat-destroying the nerves carrying pain from facet joints.

Surgery

Surgery is indicated for:

• Cauda equina syndrome — emergency surgery within hours
• Progressive neurological deficit — worsening leg weakness
• Severe radiculopathy not responding to 6–12 weeks of optimal conservative treatment
• Spinal stenosis causing significant disability

Microdiscectomy (lumbar disc herniation) — minimally invasive removal of the herniated disc fragment through a small incision; the most common elective spinal surgery. Success rate for relief of leg pain (sciatica) exceeds 90%. Most patients are mobilised the same day and discharged within 1–2 days.

Decompressive laminectomy (spinal stenosis) — removal of the lamina and overgrown ligamentum flavum to decompress the spinal canal; relieves neurogenic claudication in 70–85% of patients.

Spinal fusion — joining two or more vertebrae permanently with bone graft and instrumentation (screws, rods, cages). Used for spondylolisthesis, segmental instability, or following extensive decompression. Longer recovery (3–6 months) and mixed evidence for non-specific chronic back pain; generally reserved for cases with clear structural pathology.

Minimally invasive spinal surgery (MISS) — increasingly available; uses tubular retractors and endoscopic techniques to achieve decompression through smaller incisions, with less muscle damage and faster recovery.

Vertebroplasty / kyphoplasty may be considered for selected painful osteoporotic vertebral compression fractures, particularly severe ongoing pain from a recent unhealed fracture despite optimal pain management, with the pain confirmed at that fracture level. Vertebroplasty injects cement for stabilization; balloon kyphoplasty may restore some vertebral height, but anatomical restoration is not guaranteed.

Spinal Care in China

For spinal care in China, ask the proposed hospital to confirm the services appropriate to your assessment:

• Comprehensive lumbar spine work-up: clinical assessment, standing X-rays, MRI and electrophysiology (EMG/nerve conduction)
• Discectomy and decompression: confirm the proposed surgeon’s experience, available endoscopic or minimally invasive techniques, and the individually planned admission and discharge arrangements
• Complex spinal reconstruction: ask about experience and suitability for instrumented fusion, deformity correction (scoliosis, spondylolisthesis), or revision surgery
• Interventional pain management: CT/fluoroscopy-guided ESI, medial branch blocks, and radiofrequency ablation
• Cost: obtain the receiving hospital’s written, itemised quote and clarify separately charged coordination services before committing; this guide does not establish comparative savings.
• Full English care navigation throughout assessment, treatment and recovery

Contact a PriumCare care navigator to arrange a spinal assessment or surgical consultation.

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Medical content based on MSD Manuals and international spine surgery guidelines. Evidence reviewed 2025.

Targeted editorial source check

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Editorial source check: 25 October 2026. This update addresses the specific classification, investigation, medication or outcome claims listed in the correction record and qualifies unverified service claims. It is not a clinical review of the whole article and does not add a medical reviewer. Original publication date and existing external-source attribution are retained.

Additional targeted source clarification

Editorial source check: 25 October 2026. These changes address specific diagnostic, procedural and emergency-care statements; this is not a whole-article medical review.

• Source 1
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Targeted facet-intervention source clarification

Editorial source check: 25 October 2026. This checks only the diagnostic/prognostic and therapeutic roles of facet interventions clarified above; it is not a whole-article medical review and adds no named clinical reviewer. The original publication date is retained.

• NICE NG59: spinal injections and radiofrequency denervation selection
• Multispecialty lumbar facet guideline: diagnostic blocks and therapeutic evidence

Targeted age-at-onset and assessment clarification

Editorial source check: 26 October 2026. This checks only the age-at-onset warning and adjacent assessment explanation clarified above; it is not a whole-article medical review and adds no named clinical reviewer. The original publication date is retained.

• NICE NG59: assessment and selective imaging in people over 16
• NHS: back-pain assessment, urgent symptoms and emergencies