Lumbar Laminectomy for Spinal Stenosis

Absolute Indications

• Cauda equina syndrome: Bilateral leg weakness, saddle anesthesia, bladder/bowel dysfunction from severe central stenosis - EMERGENCY surgery within 48 hours
• Progressive neurological deficit: Worsening motor weakness despite conservative management (foot drop, quadriceps weakness)
• Severe neurogenic claudication with functional limitation: Unable to walk >100m, failed 3-6 months conservative management (physiotherapy, NSAIDs, epidural steroid injections)

Relative Indications

• Moderate-severe neurogenic claudication: Positional leg pain with walking/standing, relieved by sitting/forward flexion, confirmed multilevel stenosis on MRI, failed conservative management
• Radiculopathy from lateral recess/foraminal stenosis: Persistent radicular leg pain, dermatomal sensory loss, myotomal weakness, failed conservative management
• Bladder dysfunction without complete cauda equina: Urinary urgency/frequency from chronic stenosis (reversibility questionable)

Contraindications - Absolute

• Active spinal infection: Epidural abscess, discitis, osteomyelitis - treat infection first, may still need decompression acutely if neurological compromise
• Severe medical comorbidities: Uncontrolled coagulopathy (INR >2), severe cardiopulmonary disease unable to tolerate anesthesia
• Mechanical instability requiring fusion: Spondylolisthesis >grade 2 (25% slip), degenerative scoliosis >30°, iatrogenic instability from previous surgery

Contraindications - Relative

• Mild symptoms: Minimal claudication distance >500m, infrequent symptoms, good quality of life - conservative management preferred
• Psychological factors: Significant depression, somatization disorder, secondary gain, unrealistic expectations
• Obesity with severe stenosis: Higher complication rate, consider weight loss first if time permits
• Peripheral vascular disease: May mimic neurogenic claudication - need vascular assessment (ABI, vascular ultrasound)

Lumbar Spinal Canal Anatomy

NORMAL CANAL DIMENSIONS

• Central AP diameter: 15-20mm (stenosis <10mm)
• Lateral recess height: 5mm (stenosis <3mm)
• Foraminal height: 15-20mm (stenosis <15mm)

THREE-ZONE STENOSIS CLASSIFICATION (Lee et al.)

1. Central Canal Stenosis

   • Contributors: Ligamentum flavum hypertrophy (30-40%, thickens from 2-3mm to 5-8mm), disc bulge/herniation (20-30%), facet joint hypertrophy (20%), congenital narrow canal (<12mm), osteophytes
   • Compression: Cauda equina roots compressed centrally
   • Symptoms: Bilateral neurogenic claudication, bilateral leg symptoms

2. Lateral Recess Stenosis

   • Boundaries: Medial = thecal sac/pedicle, Lateral = pedicle, Anterior = vertebral body/disc, Posterior = hypertrophic superior articular process (SAP)
   • Contributors: Hypertrophic SAP (most common), medially bulging disc, uncinate process hypertrophy, spondylolisthesis
   • Compression: Traversing nerve root (e.g., L5 root at L4-5 level compressed in L4-5 lateral recess)
   • Symptoms: Unilateral radiculopathy in specific dermatomal distribution

3. Foraminal Stenosis

   • Boundaries: Superior = pedicle above, Inferior = pedicle below, Anterior = vertebral body/disc, Posterior = facet joint, Medial = dural sac, Lateral = psoas muscle
   • Contributors: Disc height loss (reduces foraminal height 20-30%), facet hypertrophy, spondylolisthesis, osteophytes
   • Compression: Exiting nerve root (e.g., L4 root at L4-5 foramen)
   • Symptoms: Radiculopathy in exiting root distribution

Pathophysiology of Neurogenic Claudication

VASCULAR HYPOTHESIS (Widely accepted)

• Lumbar extension → canal narrowing → venous compression → venous hypertension → arterial insufficiency → nerve root ischemia → symptoms
• Walking increases metabolic demand → worsens ischemia
• Forward flexion opens canal → improves venous drainage → symptom relief

MECHANICAL HYPOTHESIS

• Direct nerve root compression causes symptoms
• Inflammation from chronic compression (prostaglandin E2, IL-6, TNF-α)

DISTINGUISHING FEATURES vs Vascular Claudication

• Neurogenic: Positional (worse with extension/walking, better with flexion/sitting), bilateral/asymmetric, numbness/weakness, pulses normal, bicycle test positive (can cycle further than walk)
• Vascular: Exercise-related (distance-specific, not positional), calf pain predominant, pulses diminished, ABI <0.9, bicycle test negative

Clinical Assessment

HISTORY TAKING - KEY ELEMENTS

• Symptom characterization: Neurogenic claudication (bilateral leg pain/numbness with walking, relieved by sitting/flexion), radiculopathy (dermatomal pain/numbness/weakness), claudication distance (quantify disability)
• Positional factors: Worse with extension (walking, standing), better with flexion (sitting, leaning forward, cycling)
• Red flags: Cauda equina symptoms (saddle anesthesia, bladder/bowel dysfunction, bilateral leg weakness) - EMERGENCY
• Conservative management failed: Physiotherapy >3 months, medications (NSAIDs, neuropathic agents), epidural steroid injections, activity modification
• Functional impact: Unable to perform ADLs, work limitations, recreational restrictions, quality of life

PHYSICAL EXAMINATION

• Neurological: Full motor exam (L2-S1 myotomes), sensory exam (dermatomes), reflexes (knee L4, ankle S1), straight leg raise (usually negative in stenosis, positive in disc herniation)
• Gait assessment: Antalgic gait, foot drop, Trendelenburg (L5 weakness affecting gluteus medius)
• Provocative tests: Extension worsens symptoms (standing, walking), flexion relieves symptoms (sitting, toe touches)
• Vascular: Pulses (rule out peripheral vascular disease), ABI if vascular claudication suspected

Imaging Studies

PLAIN RADIOGRAPHS

• AP and Lateral lumbar spine: Assess alignment, disc space narrowing, facet hypertrophy, pars defects
• Flexion-Extension laterals: Assess for dynamic instability (>3mm translation or >10° angulation = spondylolisthesis/instability)
• Standing films: Load-bearing assessment of spondylolisthesis/scoliosis

MRI LUMBAR SPINE (Gold standard)

• T1-weighted: Anatomical detail, identify central stenosis, lateral recess stenosis, foraminal stenosis
• T2-weighted: Ligamentum flavum hypertrophy (dark signal), disc pathology, nerve root compression, assess for myelomalacia (signal change)
• Quantitative assessment: AP canal diameter <10mm = absolute stenosis, 10-12mm = relative stenosis
• Identify levels: Document all stenotic levels (L3-4, L4-5, L5-S1 commonly affected)

CT LUMBAR SPINE

• Indications: MRI contraindicated (pacemaker, claustrophobia), assess bony detail for surgical planning, evaluate ossified ligamentum flavum
• CT Myelography: If MRI contraindicated and need neural compression detail

OTHER INVESTIGATIONS

• Bone density scan (DEXA): If >50 years, assess osteoporosis risk (affects fusion/instrumentation decisions)
• Vascular studies: ABI, arterial duplex if vascular claudication suspected
• EMG/NCS: If diagnosis uncertain, differentiate stenosis from peripheral neuropathy, identify specific nerve root compression

Surgical Planning Checklist

• Confirm diagnosis: Neurogenic claudication/radiculopathy, failed conservative management 3-6 months
• MRI correlation: Symptoms correlate with imaging findings (level of stenosis matches clinical pattern)
• Identify all stenotic levels: Decompress all symptomatic levels (common mistake: decompress one level, leave adjacent stenotic levels)
• Assess for instability: Spondylolisthesis on flexion-extension XR, scoliosis, previous surgery → may need fusion
• Medical optimization: Control diabetes (HbA1c <7%), stop smoking 4 weeks pre-op, optimize nutrition (albumin >3.5), stop anticoagulation/antiplatelet appropriately
• Consent discussion: Realistic expectations (70% good outcomes, 30% fair/poor), risks (dural tear 3-7%, infection 1-3%, hematoma 0.5-1%, need for fusion 5-10%, revision surgery 5-10% at 5 years)
• Anesthesia assessment: General anesthesia, prone positioning, anticipated blood loss <200mL single level

Step 1: Patient Positioning and Level Localization

POSITIONING - Critical for success

• Prone on radiolucent frame: Wilson frame or Jackson table (allows fluoroscopy)
• Abdomen free: Use chest rolls OR frame with indentation - ensures NO abdominal compression (reduces epidural venous pressure by 50%, decreases bleeding significantly)
• Hip flexion 30-45°: Opens interlaminar spaces maximally (facilitates laminectomy, easier ligamentum flavum removal)
• Pressure point padding: Eyes (avoid corneal abrasion), elbows, knees, genitals (males), breasts (females)
• Arm position: At sides OR on arm boards with shoulder abduction <90° (prevents brachial plexus injury)

LEVEL LOCALIZATION - Never event prevention

• Fluoroscopy MANDATORY: AP and lateral views
• Count from sacrum upward: L5-S1, L4-5, L3-4 (most common stenotic levels)
• Mark skin: Use radiopaque marker at correct levels, document fluoroscopic images
• Confirm in both planes: AP view shows midline, lateral view shows correct level

Step 2: Incision and Subperiosteal Exposure

INCISION

• Midline posterior: Centered over stenotic levels identified with fluoroscopy
• Length: 4-6cm single level, 8-12cm multilevel (must expose adequately for bilateral decompression)
• Local infiltration: 0.25% bupivacaine with 1:200,000 adrenaline (hemostasis, post-op analgesia)

EXPOSURE

• Incise in layers: Skin → subcutaneous fat → lumbodorsal fascia (thick midline raphe - avascular plane)
• Subperiosteal dissection: Cobb elevator, stay ON BONE at all times (preserves muscle innervation from dorsal rami 1.5cm lateral to facet)
• Dissect bilaterally: Off spinous processes, laminae, medial facet joints (expose facet joints bilaterally for adequate decompression)
• Self-retaining retractor: Taylor, McCulloch, or Caspar retractor (maintains exposure throughout)
• Meticulous hemostasis: Bipolar coagulation of muscle insertions on spinous processes (critical for visualization)

Step 3: Laminectomy - Bone Removal

SPINOUS PROCESS REMOVAL

• Leksell rongeur: Remove spinous processes at base (preserves interspinous ligament between adjacent levels if not decompressing)
• Bone conservation: Save bone for graft if fusion planned

LAMINA REMOVAL - Burr-Thin Technique

• High-speed burr: Thin lamina to eggshell thickness bilaterally
• Superior edge: Burr undersurface of lamina above (creates working space)
• Inferior edge: Burr superior surface of lamina below
• Lateral extent: To medial aspect of facet joints bilaterally
• Kerrison removal: Once thinned to eggshell, use Kerrison rongeurs to remove bone piecemeal (minimizes dural trauma vs en bloc removal)

FACET PRESERVATION - Critical Rule

• Preserve >50% facet joint: Measure from lateral extent (total facet width), remove only medial 50% maximum
• If need >50% removal: Consider adding fusion (excessive facetectomy causes iatrogenic instability 2-5%)
• Document facet preservation: Note in operative report percentage estimated

Step 4: Ligamentum Flavum Removal

IDENTIFICATION

• Yellow color: Confirms ligamentum flavum (vs white dura deep to it)
• Thickness: Normal 2-3mm, stenotic 5-8mm (hypertrophy contributes 30-40% canal narrowing)
• Calcification/ossification: Common in elderly, Asian populations (ossified yellow ligament)

REMOVAL TECHNIQUE - LATERAL TO MEDIAL (Safer for dura)

• Lateral edge: Identify free lateral edge of flavum (not adherent to dura laterally)
• Elevate laterally: Use Penfield #4 or Woodson elevator to lift lateral edge
• Work medially: Progressively separate flavum from underlying dura using gentle Penfield dissection
• Kerrison removal: Once separated, remove with Kerrison rongeur working lateral to medial
• Extend to lateral recesses: Remove flavum completely to expose lateral recesses bilaterally

ADHERENT FLAVUM MANAGEMENT

• Revision surgery: Flavum often densely adherent to dura from scarring
• Elderly patients: Age-related adhesions common
• Technique: Extremely gentle Penfield dissection, sharp dissection with micro-scissors if needed, accept leaving thin layer of flavum adherent rather than risk durotomy

Step 5: Lateral Recess and Foraminal Decompression

LATERAL RECESS ANATOMY

• Boundaries: Medial = thecal sac, Lateral = pedicle (2-4mm medial to pedicle), Posterior = hypertrophic SAP, Anterior = posterior vertebral body/disc
• Normal height: 5mm (stenosis <3mm)
• Contents: Traversing nerve root (courses to exit at next level down - e.g., L5 root traverses L4-5 lateral recess, exits L5-S1 foramen)

LATERAL RECESS DECOMPRESSION

• Identify pedicle: Lateral boundary (use fluoroscopy if uncertain)
• Remove hypertrophic SAP: High-speed burr to thin, then Kerrison to remove (opens lateral recess)
• UNDERCUT technique: Burr UNDER remaining facet joint laterally (decompresses hidden lateral recess while preserving facet integrity)
• Confirm nerve root mobility: Use nerve hook - root should be freely mobile

FORAMINOTOMY - If Foraminal Stenosis Present

• Indications: MRI shows foraminal stenosis, radiculopathy in exiting root distribution (not responsive to lateral recess decompression alone)
• Technique: Remove medial portion of superior facet (superior articular process), thin inferior articular process if needed, use angled curettes to remove osteophytes from foramen
• Limits: Preserve >50% facet joint (if need more extensive foraminotomy, add fusion)
• Fluoroscopy: Confirm extent of foraminotomy (can see increased foraminal height on lateral view)

Step 6: Assessment of Decompression Adequacy

VISUAL ASSESSMENT

• Dura expansile: Pulsates with respirations (not tethered or compressed)
• Nerve roots visible: Bilateral nerve roots visible throughout course in lateral recesses
• No residual compression: No bone, ligament, disc compressing canal or recesses

FUNCTIONAL TESTS

• Valsalva maneuver: Anesthetist sustains 30-40cmH₂O airway pressure → dura should balloon out if adequately decompressed (most sensitive test)
• Nerve hook test: Can pass nerve hook 360° around each nerve root freely (confirms mobility)
• Instrument passage: Can pass small nerve hook or Penfield up and down lateral recesses without obstruction

FLUOROSCOPIC CONFIRMATION

• Verify levels decompressed: AP and lateral fluoroscopy shows extent of bone removal
• Check for residual stenosis: Ensure all symptomatic levels addressed

Step 7: Hemostasis and Preparation for Closure

METICULOUS HEMOSTASIS - Critical to prevent epidural hematoma

• Bipolar coagulation: Low setting (15-20W) near neural elements, all visible bleeding points
• Valsalva test: Sustain 30-40cmH₂O pressure to identify occult venous bleeding (IVC pressure elevation reveals hidden epidural venous bleeders)
• Hemostatic agents: Gelfoam, Surgicel (oxidized cellulose), Floseal (gelatin-thrombin matrix), thrombin-soaked Gelfoam for persistent oozing
• Packing technique: Pack with hemostatic agent during sustained Valsalva, remove before closure

IRRIGATION

• Copious saline: 3-4 liters warm normal saline (0.9% NaCl)
• Antibiotic irrigation: Controversial (some use gentamicin 80mg/L or vancomycin 1g/L, evidence mixed for benefit)
• Remove all debris: Bone fragments, soft tissue, hemostatic agents (except intentionally placed)

DRAIN PLACEMENT - Controversial

• Arguments FOR: Large dead space, multilevel surgery, revision case, significant bleeding, may reduce hematoma
• Arguments AGAINST: No proven benefit in RCTs, may increase infection risk, drain failure common (clots)
• Current evidence: Cochrane review 2018 - no benefit for routine drain use, consider selectively
• If placed: 10Fr suction drain, secure with suture, remove at 24-48h or when output <30mL/8h

Step 8: Wound Closure

LAYERED CLOSURE

1. FASCIA (Most important layer)

   • Suture: 1-0 Vicryl or PDS (strong absorbable)
   • Technique: Interrupted or running, ensure watertight closure (especially if dural tear repaired)
   • Tension: Approximate under slight tension (prevents dehiscence)

2. SUBCUTANEOUS

   • Suture: 2-0 or 3-0 Vicryl
   • Technique: Interrupted or running, obliterate dead space (reduces seroma/hematoma)

3. SKIN

   • Subcuticular: 3-0 Monocryl (absorbable, excellent cosmesis, no removal needed)
   • OR Staples: Faster placement, easier removal, equivalent outcomes, remove at 10-14 days
   • Tissue adhesive: Dermabond over subcuticular (reinforcement, waterproof)

DRESSING

• Waterproof dressing: Allows showering at 48h (reduces infection vs non-waterproof)
• If drain: Secure drain to skin with 2-0 nylon suture, mark exit site

Step 9: Post-operative Neurological Assessment

IMMEDIATE RECOVERY ROOM ASSESSMENT

• Motor function: Test all myotomes (L2 hip flexion, L3 knee extension, L4 ankle dorsiflexion, L5 great toe extension, S1 ankle plantarflexion)
• Sensory: Light touch/pinprick all dermatomes (L1-S1)
• Radicular pain: Assess leg pain compared to pre-op (neurogenic claudication should improve immediately)
• Back pain: Expect increased back pain initially (surgical trauma, muscle dissection) - normal finding
• Bladder function: Ensure can void (trial of void within 6-8h, catheterize if retention)

EXPECTED POST-OP FINDINGS

• Improved: Neurogenic claudication (positional leg pain with walking), radiculopathy (if was present)
• Unchanged: Pre-existing numbness (nerve recovery takes weeks-months), weakness (if chronic >6 months, may be permanent)
• Worse: Back pain (surgical trauma), paraspinal muscle spasm (normal, improves over days)

NEW DEFICIT RECOGNITION - URGENT INVESTIGATION

• Causes: Epidural hematoma (most common, 6-24h presentation), incomplete decompression, nerve root injury, positioning injury
• Workup: Urgent MRI lumbar spine (or CT if MRI unavailable), assess for compressive hematoma
• Management: If hematoma causing cauda equina syndrome or severe radiculopathy → emergency re-exploration and evacuation

Immediate Post-operative Care (0-24 hours)

MONITORING

• Neurovascular observations: 2-hourly for first 12h, then 4-hourly (assess for hematoma - new weakness, sensory loss, severe pain)
• Pain management: Multimodal analgesia (paracetamol 1g QID, NSAIDs if not contraindicated, opioids PRN - minimize opioid use)
• Bladder function: Trial of void within 6-8h, catheterize if urinary retention (common from opioids, anesthesia)
• Drain management: If placed, monitor output (should be <100mL/24h), remove at 24-48h or when <30mL/8h

MOBILIZATION

• Day 0 (same day): Sit up in chair within 4-6h (prevents DVT, improves respiratory function)
• Day 1: Walk with physiotherapy assistance (gradual ambulation program)
• No brace required: Laminectomy alone without fusion does NOT require post-op bracing

Inpatient Phase (1-3 days)

PHYSIOTHERAPY

• Gait re-education: Normal gait pattern (patients often have antalgic gait from pre-op stenosis)
• Stairs practice: Safe stair climbing technique
• Home exercise program: Gentle range of motion, avoid bending/lifting/twisting initially

DISCHARGE CRITERIA

• Mobilizing independently or with usual aids
• Pain controlled on oral medications
• No complications (infection, hematoma, CSF leak)
• Bladder function normal (can void without catheter)
• Drain removed (if used)
• Wound check satisfactory (no excessive drainage, erythema)

DISCHARGE MEDICATIONS

• Analgesia: Paracetamol 1g QID regular, NSAIDs (celecoxib 200mg BD or ibuprofen 400mg TDS) if not contraindicated, opioids PRN (minimize duration, wean off within 2 weeks)
• Laxatives: If on opioids (senna + macrogol to prevent constipation)
• VTE prophylaxis: Aspirin 100mg daily for 4 weeks (low-risk surgery) OR enoxaparin 40mg SC daily for 10-14 days if high risk (BMI >35, previous VTE, prolonged immobility)

Early Outpatient Phase (2-6 weeks)

WOUND CARE

• Dressing removal: 48-72h post-op if waterproof dressing
• Showering: Allowed after 48h (waterproof dressing), pat dry, avoid soaking/bathing for 2 weeks
• Staple/suture removal: 10-14 days post-op (subcuticular Monocryl absorbable - no removal needed)

ACTIVITY RESTRICTIONS

• Avoid: Heavy lifting (>5kg), repetitive bending, prolonged sitting (>30min initially), twisting
• Walking program: Gradual increase in distance (start 5-10min TDS, increase by 5min every few days as tolerated)
• Return to driving: 2-3 weeks (when can perform emergency stop without pain, not on opioids)

FIRST CLINIC REVIEW (2-3 weeks)

• Wound check: Assess healing, rule out infection
• Neurological exam: Compare to pre-op (expect improved neurogenic claudication, radiculopathy)
• Plain radiographs: Not routinely required unless concern for instability

Intermediate Outpatient Phase (6-12 weeks)

PHYSIOTHERAPY REFERRAL

• Core strengthening: Multifidus, transversus abdominis, core stability exercises
• Flexibility: Hamstring stretching, hip flexor stretching
• Functional restoration: Progress activities gradually

RETURN TO WORK

• Sedentary work: 4-6 weeks (office work, desk job)
• Light manual work: 8-10 weeks (light lifting, walking-based jobs)
• Heavy manual labor: 12 weeks (heavy lifting, construction, farming)

SECOND CLINIC REVIEW (6 weeks)

• Clinical assessment: Neurogenic claudication resolution, walking distance improved
• Standing AP and Lateral lumbar XR: Assess for instability (if any concern)
• Flexion-Extension XR: If clinical suspicion of instability (new mechanical back pain, spondylolisthesis progression) - >3mm translation or >10° angulation = instability requiring fusion

Long-term Follow-up (3-12 months)

3-MONTH REVIEW

• Outcome assessment: SF-36, ODI (Oswestry Disability Index) - compare to baseline
• Neurological status: Expect 70-80% maximal improvement by 3 months (further recovery up to 12 months)
• Imaging: Only if concerns (persistent symptoms, clinical instability, new deficit)

6-MONTH REVIEW

• Standing lumbar radiographs: Assess for spondylolisthesis progression, adjacent segment degeneration
• Decision on further intervention: If persistent symptoms - investigate cause (incomplete decompression, instability, adjacent level stenosis, wrong diagnosis)

12-MONTH REVIEW

• Final outcome assessment: 70% good/excellent outcomes expected (SPORT trial)
• Long-term plan: Discharge if doing well, annual review if concerns

Surveillance for Late Complications

ADJACENT SEGMENT STENOSIS

• Incidence: 10-15% at 10 years (natural disease progression, not surgical complication)
• Presentation: Recurrent neurogenic claudication, new level symptoms
• Investigation: MRI shows new stenosis at adjacent level(s)
• Management: Conservative initially, revision surgery if failed conservative management

INSTABILITY DEVELOPMENT

• Risk factors: >50% facetectomy, pre-existing spondylolisthesis, multilevel laminectomy
• Presentation: Mechanical back pain (worse with activity, relieved by rest), spondylolisthesis progression
• Investigation: Flexion-extension radiographs show >3mm translation or >10° angulation
• Management: Fusion if symptomatic instability