History

• Initial history should focus on the patient’s age and pain characteristics (onset, duration, severity, quality, radiation, aggravating factors, alleviating factors).
• Question patient about mechanism of injury and occupation.
• Determine if serious underlying conditions (red flags) are responsible for the back pain: fracture (steroid use, trauma, menopausal status); infection (fever, intravenous [IV] drug use, adenopathy, immunosuppression); cancer (weight loss, adenopathy, previous cancer); cauda equina syndrome (bowel or bladder incontinence, saddle anesthesia, major limb motor weakness).
• Assess psychological and socioeconomic problems.
• The patient should be assessed for the following red flags:
  • Is patient <20 or >55 yr with no prior history of back pain?
  • Known or previous cancer? Assume bone metastasis until otherwise proven.
  • IV drug abuse? Assume spinal abscess if tender.
  • Is pain increased or unrelieved by rest? Is low back pain relieved by bed rest?
  • Is pain associated with fever, chills, or weight loss? Look for infection or tumor.
  • Loss of bowel or bladder control and/or caudal anesthesia? Look for cauda equina syndrome.

Physical Exam

• Pain located below the costal margin but above the inferior gluteal folds
• Possible radiation of pain to buttocks and lower extremity
• Pain aggravated by movement and alleviated by rest
• Limited range of motion of the lumbar spine
• Paraspinal muscular spasm is common.
• Assess severity of pain by observing the patient’s gait, posture, and demeanor.
• Prior to examining the back, check the temperature, weight, skin, abdomen, pelvis, groin, peripheral pulses, and lymph nodes for pathology that may mimic spinal disease. A rectal exam should be performed to assess sphincter tone.
• With the patient standing, assess stance, spinal curvature, range of motion, heel-walk, toe-walk, and squat. Locate area of maximal pain.
• With patient sitting, assess patellar and Achilles deep tendon reflexes.
• With the patient supine, assess the straight-leg raise and contralateral straight-leg raise, ankle and great toe dorsiflexion, hip range of motion, sacroiliac joint stability, muscle strength testing, and sensory testing.
• With the patient in the prone position, assess buttock symmetry and perform femoral stretch test.
• Pain in low back is exacerbated by movement and is often accompanied by focal muscle spasm in the lumbar extensors.
• Patients prefer to stand in a semiflexed position and move slowly rather than sit motionless on the exam table.
• Walk on heels (L4–L5) and then toes (S1–S2).
• Assess back muscles for uncoordination or guarding (signs for spasm).
• Straight-leg raising and crossed straight-leg raising (can suggest radicular etiology such as acute disc herniation)

Differential Diagnosis

• Herniated disc
• Musculoskeletal sprains and strains
• Degenerative joint disease
• Posterior facet syndrome
• Spondylolisthesis
• Spinal stenosis
• Osteoporosis
• Ankylosing spondylitis
• Referred pain
• Tumor
• Infection
• Fracture
• Genitourinary
• Gynecologic
• Psychogenic
• 85% mechanical back pain (MBP)
• 5% symptomatic herniated disc
• 4% compression fracture
• 4% spondylolysis/spondylolisthesis
• 2% tumor, infection, rheumatologic disease, or referred pain

Diagnostic Tests & Interpretation

• In the absence of red flag symptoms, imaging can usually be delayed until 30 days after the initial assessment. This approach allows 90% of patients to recover spontaneously and avoids unneeded testing and procedures.
• If symptoms persist >30 days, consider plain radiographs, computed tomography (CT) scan, magnetic resonance imaging (MRI), and bone scan.
• If no red flags are identified in the history, then no imaging tests or laboratory tests are indicated.
• If a red flag is identified, then proceed with diagnostic testing as indicated.