OSCE Orthopedics: Back Pain - Focus on Herniated Nucleus Pulposus (HNP)

1. Patient Introduction & Communication

• Introduction: Greet the patient warmly. Verify their identity by name and age, and explain each step of the physical exam to ensure understanding and cooperation.
• Consent: Obtain consent, stating the purpose of assessing their back pain and explaining that some maneuvers may provoke pain.
• Explanation: Before each maneuver, explain what will be done and why it’s essential, especially if discomfort is expected.

2. History Taking

• Location and Radiation of Pain:
  • HNP: Sharp, shooting pain radiating down the leg, often below the knee and following a specific dermatome. Commonly unilateral (e.g., right leg pain).
• Onset, Duration, and Progression:
  • HNP: Sudden onset, often following activities involving heavy lifting or a twisting motion.
  • Key History Point: For example, "30-year-old male, leg pain following lifting heavy objects" suggests HNP.
• Character of Pain:
  • HNP: Electric-shock-like or sharp pain exacerbated by activities that increase intraspinal pressure, such as coughing, sneezing, or bending.
• Associated Symptoms:
  • Neurological Deficits: Numbness, tingling, or weakness following the path of the compressed nerve (usually L4, L5, or S1 roots).
• Red Flags:
  • Important to assess for signs like bowel/bladder dysfunction, night pain, significant weight loss, and unexplained fever, which may indicate serious pathology (e.g., cauda equina syndrome).

3. Physical Examination

• Inspection:
  • Observe posture and alignment. Check for spinal curvatures (kyphosis, lordosis) and assess gait for asymmetries.
  • Pelvic Symmetry: Ensure the iliac crests are level and observe gait for limping or guarded movement.
• Palpation:
  • Palpate spinous processes and paraspinal muscles for tenderness or spasm, especially in the lower lumbar area.
  • Check Step-Off Deformities: Feel along the spine for any vertebral misalignment, which may indicate spondylolisthesis.
• Range of Motion (ROM):
  • Flexion and Extension: HNP patients typically experience increased pain with flexion, whereas extension may be limited but less painful.
  • Rotation and Lateral Bending: Evaluate for pain provocation, particularly during flexion.
• Special Tests:
  • Straight Leg Raise Test (SLRT):
    • Essential for HNP. Positive if pain radiates down the leg at 30-60 degrees of hip flexion.
    • A classic sign for lumbar disc herniation, especially involving L5 or S1 roots.
  • Crossed Straight Leg Raise (Contralateral SLR):
    • Pain induced in the symptomatic leg when the opposite leg is raised suggests severe HNP.
  • Lasegue Maneuver (foot dorsiflexion test):
    • Exacerbates pain if there is nerve root compression, specifically when dorsiflexing the foot during SLR.
  • Bowstring Test:
    • Confirms sciatic involvement by reproducing pain when applying pressure on the sciatic nerve in a flexed knee position.
• Neurological Examination:
  • Motor Testing:
    • L2: Hip flexion
    • L3: Knee extension
    • L4: Ankle dorsiflexion
    • L5: Great toe extension
    • S1: Plantar flexion
  • Sensory Testing:
    • Test for numbness or reduced sensation in relevant dermatomes:
      • L3: Medial knee
      • L4: Medial leg
      • L5: Dorsum of the foot
      • S1: Lateral foot
  • Reflexes:
    • Diminished Patellar reflex (L4) or Achilles reflex (S1) may indicate root compression.

4. Differential Diagnosis

• Primary Diagnosis:
  • Herniated Nucleus Pulposus (HNP): Unilateral, dermatomal pain extending below the knee, positive SLR, and neurological deficits.
• Secondary Differential:
  • Spinal Stenosis: Pain worsens with extension and prolonged standing; relieved by sitting or bending forward (pseudoclaudication).
  • Mechanical Back Pain: Pain localized to the back, improved with rest, without radicular symptoms.
  • Others:
    • Cauda Equina Syndrome: Incontinence, saddle anesthesia, bilateral leg weakness—requires urgent referral.
    • Infectious Causes: Fever, recent infection, IV drug use, or immunocompromised status (e.g., osteomyelitis, discitis).
    • Neoplastic: Persistent night pain, unexplained weight loss, history of cancer.

5. Diagnostic Investigations

• MRI of the Lumbar Spine:
  • HNP: Visualizes disc herniation impinging on nerve roots, confirms diagnosis and level of compression.
• X-ray of the Lumbar Spine:
  • Useful to rule out vertebral fractures or degenerative changes.
• Electromyography (EMG):
  • May assist in assessing nerve root involvement if symptoms are unclear or inconclusive.
• CT Myelogram:
  • Considered if MRI is contraindicated or if additional details about spinal canal anatomy are needed.

6. Management Plan

• Conservative Management:
  • Pain Management: NSAIDs, muscle relaxants, or short-term use of opioids in severe cases.
  • Physical Therapy: Emphasis on core strengthening, lumbar stabilization, and gentle stretching.
  • Activity Modification: Advise against heavy lifting or activities that exacerbate pain.
• Interventional Management:
  • Epidural Steroid Injections: For patients unresponsive to initial conservative treatment, targeting inflammation at the affected nerve root.
• Surgical Intervention:
  • Microdiscectomy: Indicated for severe or persistent pain beyond 6 weeks or progressive neurological deficits.

7. Patient Education and Follow-Up

• Education:
  • Explain the nature of HNP and emphasize the importance of adherence to therapy and activity modifications.
  • Advise on proper lifting techniques and ergonomic adjustments to minimize future strain.
• Follow-Up:
  • Schedule regular follow-up appointments to monitor symptoms and recovery.
  • Educate the patient to report any worsening symptoms, particularly those suggestive of cauda equina syndrome (e.g., bowel/bladder dysfunction).