Introduction

Lower back pain refers to pain felt in the lumbosacral area of the back, between the lower margin of the ribs and the crease of the buttocks. Many people will experience it at some point in their life and it is a very common presentation to general practice. It is also the leading worldwide cause of years lost to disability.

In the vast majority of cases, the exact cause of the pain is not known and this is termed non-specific lower back pain. However, it is important to be aware of the features and red flags that may indicate a specific and more serious underlying pathology.

Non-specific lower back pain can usually be managed by advising the patient to remain active and regular use of simple analgesia, with or without physiotherapy input. Most will recover within 4-6 weeks although some will go on to experience chronic pain or recurrent episodes.

Epidemiology

  • Incidence: 3000.00 cases per 100,000 person-years
  • Peak incidence: 30-40 years
  • Sex ratio: 1:1
Condition Relative
incidence
Lower back pain (non-specific, without sciatica)1
Lower back pain: prolapsed disc0.17
Osteoporotic vertebral fracture0.02
Ankylosing spondylitis0.003
Lumbar spinal stenosis0.003
Neoplastic spinal cord compression0.003
Cauda equina syndrome0.0003
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+

Aetiology

Risk factors for developing non-specific back pain include:
  • Previous episodes of lower back pain
  • Obesity
  • Physically demanding occupations such as those that involve heavy lifting
  • Physical inactivity
  • Psychological distress
  • Having other chronic health conditions
  • Lower socio-economic status
  • Smoking

Pathophysiology

By definition, non-specific back pain refers to pain where the underlying nociceptive stimulus cannot be identified. However, the pain could result from a combination of any pathology from:
  • Vertebrae
  • Facet joints
  • Intervertebral disc
  • Muscles/ligaments

Many 'abnormal' imaging findings seen on X-ray, CT or MRI, such as disc degeneration and internal disc rupture, can be found in both asymptomatic and symptomatic individuals. The significance of such findings are therefore unclear and there is no evidence that findings influence patient outcomes.

Clinical features

The main feature is pain in the lumbosacral region that is exacerbated by movement and varies with time and posture. A diagnosis of non-specific lower back pain can be made in the absence of any features that suggest a specific cause such as an inflammatory, infective or malignant process.

Key features which are NOT consistent with non-specific lower back pain:
  • Severe localised pain that is relieved by lying down
  • Pain worse at night / wakes patient from sleep
  • Saddle anaesthesia
  • Lower limb neurology such as weakness or abnormal sensation (numbness or tingling)
  • Bladder or bowel disturbance
  • Associated with constitutional symptoms such as fever, weight loss or night sweats

However, one study investigated over 1000 patients presenting with acute lower back pain and found that over 80% had at least one red flag in the absence of underlying significant pathology. Specific red flags with very high false-negative rates included pain that improves with exercise, morning back stiffness lasting >30 minutes and age at onset (<20 years and >55 years).

Investigations

If non-specific lower back pain is suspected, then no investigations are typically required. NICE specifically advise against routine spinal X-rays unless there is suspicion of significant pathology such as a compression fracture.

If a specific cause is suspected, then some common investigations may include:
  • Blood tests
    • Inflammatory markers - if an underlying rheumatological condition such as ankylosing spondylitis is suspected
    • WCC and inflammatory markers - if an underlying infection such as discitis or vertebral osteomyelitis is suspected
  • Urine dipstick
    • If pyelonephritis is suspected
  • Lumbar spine X-ray
    • E.g. if a vertebral fracture is suspected
  • MRI spine
    • To visualise pathology involving the soft tissues or spinal nerves


Differential diagnosis

When coming to a diagnosis of non-specific back pain, it is important to first exclude specific causes.


ConditionClinical features
Radicular pain (sciatica)Caused by nerve-root involvement which results in a dermatomal leg pain that radiates down one leg to below the knee. May be described as a shooting, tingling, or burning sensation. It is associated with a positive straight leg raise on examination due to stretching of the nerve. Back pain, if present, is less severe than the leg pain.
RadiculopathyWhere impingement of a particular nerve root results in weakness, loss of sensation, loss of reflexes or, a combination of these. May be associated with radicular pain.
Cauda equina syndromeCauda equina syndrome: Associated with saddle anaesthesia, lower limb neurology, reduced anal tone and sensation, bowel incontinence and urinary retention/overflow incontinence.
Spinal fractureMay occur as a result of significant trauma (e.g. a road traffic collision or fall from height) or minor trauma in a patient at risk of bone fractures (e.g. osteoporosis or long-term steroid use). The pain is typically severe with localised tenderness and may be relieved by lying down.
MetastasesIn older patients with known malignancy (particularly adenocarcinomas - prostate, breast, lung, thyroid and GI) or as a first presentation of previously undiagnosed malignancy. The pain is typically worse at night and may wake the patient from sleep. There may be associated constitutional symptoms such as weight loss or night sweats.
Spinal infectionsE.g. discitis, vertebral osteomyelitis. Typically associated with systemic upset such as fever. Risk factors include IV drug use and immunosuppression.
Ankylosing spondylitisPresents with morning stiffness and pain that eases with movement throughout the day. It is most common in males under the age of 40.
Spinal stenosisThe cardinal symptom is neurogenic claudication - unilateral or bilateral leg pain, numbness and weakness that worsens on walking and is relieved by sitting or forward flexion. Around half of patients will also have back pain that is usually bilateral and diffuse. The most common cause is degenerative arthritis of the spine.

Other causes due to intra-abdominal pathology:
  • Genitourinary
    • Pyelonephritis
    • Kidney stones
    • Prostatitis
    • Pelvic inflammatory disease
  • Gastrointestinal
    • Pancreatitis
    • Peptic ulcer

Management

NICE recommend using the STarT Back tool to stratify the risk of back pain disability.
  • Low risk patients: can be managed with reassurance and encouragement to remain active, early managed return to work and simple analgesia
  • Medium risk patients: should be managed as per low risk in addition to offering a referral to physiotherapy
  • High risk patients: should be referred to psychologically informed physiotherapy.

BackCare has produced a good patient information leaflet for back exercises that patients can do at home.

Analgesia
NICE recommends NSAIDs such as ibuprofen or naproxen as the first line analgesia. The lowest effective dose should be used for the shortest possible duration.

It is important to take into account the risk of adverse effects associated with NSAID use. A PPI such as omeprazole or lansoprazole should be offered in conjunction with the NSAID.

Paracetamol alone is not recommended as the evidence shows this is not effective.

If NSAIDs are contraindicated, or ineffective, a weak opioid such as codeine, dihydrocodeine, or tramadol, may be considered.

If muscle spasms are thought to be the primary issue, then a short course (2-5 days) of diazepam may be used. Initially this should be 2mg diazepam to be taken as required up to three times a day. The dose can be titrated up to 5mg tds if required.

Other management strategies
For patients at higher risk of poor outcome, NICE recommends considering the following:
  • Referral to a group exercise programme
  • Referral to physiotherapy for manual therapy
  • Referral for CBT as part of a treatment package including exercise +/- manual therapy

Radiofrequency denervation
NICE advises consider referral for radiofrequency denervation in patients with chronic back pain where:
  • The patient has failed to respond to non-surgical treatment
  • The main source of pain is thought to be related to structures supplied by the medial branch nerve
  • The pain is rated as 5 or more on a visual analogue scale or equivalent

Prognosis

In the majority of patients, lower back pain will resolve with conservative management by 4-6 weeks.

Those at risk of long-term pain and disability include:
  • Initial high pain intensity
  • Pain lasting longer than 12 weeks
  • Psychosocial distress
  • Maladaptive coping strategies
  • Negative thought patterns about the future 'catastrophising'
  • Accompanying pain at multiple body sites