Lower back pain


  • Pain lasting >6wks is risk factor for more serious disease
  • Night pain and unrelenting pain are worrisome symptoms
  • Back pain in IV drug user is spinal infection until proven otherwise
  • 95% of herniated discs occur at L4-L5 or L5-S1 (for both pain extends below the knee)
  • Lumbago: acute, nonspecific back pain

Back Pain Risk factors and probability of Fracture or Malignancy[1]

Factor Post Test Probability (95%CI)
Older Age (>65yo)9% (3-25%)
Prolonged corticosteroid33% (10-67%)
Severe trauma11% (8-16%)
Presence of contusion or abrasion62% (49-74%)
Multiple red flags90% (34-99%)
History of malignancy33% (22-46%)

Clinical Features

Symptoms by Causes of Low back pain

Musculoskeletal pain Spinal stenosis Sciatica Cauda equina syndrome Rheumatologic
Radiation?NoPossible (can be bilateral)Yes (in the distribution of a lumbar or sacral nerve root)Possible?
Worsened by:Movement (e.g. twisting of torso)Walking (pseudo-claudication) and prolonged standingCoughing, Valsalva, sittingMorning stiffness >30minutes
Improved by:RestForward flexion, especially sittingLying in supine positionMovement throughout the day
Other symptoms:Urinary/bowel disturbances, perineal anaesthesiaOther rheum symptoms (e.g. ankylosing spondylitis, psoriatic arthropathy, IBD arthropathy, Reiter's disease)

Waddell's Signs of Non-Organic Low back pain[2]

3 or more positives suggest non-organic or alternative organic source:

  • Over-reaction to the examination
  • Widespread superficial tenderness not corresponding to any anatomical distribution
  • Pain on axial loading of the skull or pain on rotation of the shoulders and pelvis together
  • Severely limited straight leg raising on formal testing in a patient who can sit forwards with the legs extended
  • Lower limb weakness or sensory loss not corresponding to a nerve root distribution

Differential Diagnosis

Lower Back Pain



  • Straight leg raise testing
    • Screening exam for a herniated disk (Sn 68-80%)
    • Lifting leg causes radicular pain of affected leg radiating to BELOW the knee
    • Pain is worsened by ankle dorsiflexion
    • Pain may be relieved by pressing across biceps femoris and pes anserinus tendons behind knee ('bowstringing')
  • Crossed Straight leg raise testing (high Sp, low Sn)
    • Lifting the asymptomatic leg causes radicular pain down the affected leg
  • Nerve root compromise
  • Rectal exam, perineal sensation, palpable bladder?


  • Pregnancy test
  • Only necessary if concerned for infection, tumor, or rheumatologic cause
    • CBC, UA, ESR (90-98% Sn for infectious etiology)
  • Consider post void residual



Acute, Non-traumatic, Non-Radicular Back Pain

  • Instruct to continue daily activities using pain as limiting factor
  • Medications
    • Acetaminophen and/or NSAIDs
      • 1st line therapy
      • Consider gel/patch like diclofenac or ketoprofen (shown to be more effective than PO form and placebo in one study[3])
    • Lidocaine patch
    • Capsaicin or Cayenne
      • Skin desensitization upon repeated exposure
    • Muscle relaxants (limited evidence)
      • cyclobenzaprine 10 mg PO OR
      • methocarbamol 1500 mg PO
    • Opioids
      • Appropriate for moderate-severe pain but only for limited duration (<1 week)

Not Indicated

Acute, Radicular Back Pain (Sciatica)

80% of patients will ultimately improve without surgery

  • Treatment is mostly the same as for acute non-radicular back pain
  • Consider also gabapentin (titrate slowly) or TCAs (nortriptyline, amytriptyline)
    • Gabapentin Oral: Immediate release: 400mg-1200mg PO TID

Spinal stenosis

  • Treatment is the same as for musculoskeletal back pain

Cauda equina syndrome

  • Immediate spine surgery consultation for spinal decompression to avoid permanent bowel/bladder/neurologic injury


  • Normally outpatient, as long as no signs of emergent pathology and able to ambulate

See Also




  1. Downie A, et al. Red flags to screen for malignancy and fracture in patients with low back pain: systematic review. BMJ. 2013; 347:f7095.
  2. Waddell G, et al. Non-organic physical signs in low-back pain. Spine. 1980; 5:117-125.
  3. Mazières B, Rouanet S, Velicy J, et al. Topical ketoprofen patch (100 mg) for the treatment of ankle sprain: a randomized, double-blind, placebo-controlled study. Am J Sports Med. 2005;33:515-523
  4. Friedman BW, et al. "Diazepam is no better than placebo when added to Naproxen for acute low back pain." Annals of EM. August 2017. 70(2):169-176
  5. Holve, RL, et al. Oral steroids in initial treatment of acute sciatica. J Am Board Fam Med. 2008; 21(5):469-474.
  6. Goldberg H, et al. Oral steroids for acute radiculopathy due to a herniated lumbar disk: a randomized clinical trial. JAMA. 2015 May 19;313(19):1915-23. PMID 25988461.
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