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Lumbar Microdiscectomy

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Lumbar Microdiscectomy

Comprehensive guide to lumbar microdiscectomy for disc herniation - patient selection, surgical technique, outcomes, recurrence, and complications for orthopaedic surgery exam preparation

complete
Updated: 2024-12-19
High Yield Overview

LUMBAR MICRODISCECTOMY - SURGICAL DECOMPRESSION

Gold Standard for Lumbar Disc Herniation | 90-95% Success | Minimal Morbidity

L4-5, L5-S195% of herniations
90-95%Leg pain relief
5-10%Recurrence rate
1-2%Dural tear rate

DISC HERNIATION TYPES

Protrusion
PatternBase wider than dome, contained by annulus
TreatmentOften conservative
Extrusion
PatternDome wider than base, through annulus, continuous
TreatmentMicrodiscectomy if symptomatic
Sequestration
PatternFree fragment, no continuity with disc
TreatmentOften requires surgery

Critical Must-Knows

  • Concordant radiculopathy required - clinical picture must match imaging level
  • L4-5 herniations compress L5 nerve (traversing root), L5-S1 compress S1
  • Failed 6-12 weeks conservative treatment is standard indication
  • Cauda equina syndrome is emergency requiring surgery within 24-48 hours
  • Recurrence 5-10% at same level, 5% at different level

Examiner's Pearls

  • "
    Posterolateral herniation = traversing root (L4-5 = L5 nerve)
  • "
    Far lateral/foraminal = exiting root (L4-5 = L4 nerve)
  • "
    CES: urinary retention, saddle anesthesia, bilateral leg symptoms
  • "
    SPORT trial: Surgery faster recovery but similar 4-year outcomes

Clinical Imaging

Imaging Gallery

Eight-panel MRI series: Top row shows four axial T2 sequences at different lumbar levels, bottom row shows four sagittal T2 sequences - comprehensive multi-sequence protocol for disc herniation assess
Click to expand
Eight-panel MRI series: Top row shows four axial T2 sequences at different lumbar levels, bottom row shows four sagittal T2 sequences - comprehensive Credit: Open-i / NIH via Open-i (NIH) (Open Access (CC BY))
Two sagittal T2 MRI images with arrow pointing to disc herniation at L5/S1 level showing posterior disc material compressing thecal sac - demonstrates classic imaging appearance
Click to expand
Two sagittal T2 MRI images with arrow pointing to disc herniation at L5/S1 level showing posterior disc material compressing thecal sac - demonstratesCredit: Ogbonnaya S et al. via J Nat Sci Biol Med via Open-i (NIH) (Open Access (CC BY))
Four-panel cross-sectional diagram: Top panels show normal spinal canal anatomy, bottom panels show disc herniation (red mass) compressing neural elements - illustrates pathomechanics of nerve compres
Click to expand
Four-panel cross-sectional diagram: Top panels show normal spinal canal anatomy, bottom panels show disc herniation (red mass) compressing neural elemCredit: Weiner BK et al. via J Orthop Surg Res via Open-i (NIH) (Open Access (CC BY))
Two-panel sagittal T2 MRI comparison (A and B) in patient with L5 transitional vertebrae and disc herniation - demonstrates importance of level identification and anatomical variants
Click to expand
Two-panel sagittal T2 MRI comparison (A and B) in patient with L5 transitional vertebrae and disc herniation - demonstrates importance of level identiCredit: Kaner T et al. via SAS J via Open-i (NIH) (Open Access (CC BY))

Critical Microdiscectomy Exam Points

Nerve Root Anatomy

Posterolateral herniation compresses the TRAVERSING root (L4-5 disc = L5 nerve). Far lateral/foraminal herniation compresses the EXITING root (L4-5 disc = L4 nerve). This is an exam favorite!

Cauda Equina Syndrome

Surgical emergency - decompress within 24-48 hours. Key features: urinary retention (most sensitive), saddle anesthesia, fecal incontinence, bilateral leg weakness. Incomplete CES has better prognosis than complete.

SPORT Trial Findings

Randomized trial showed surgery provides faster pain relief but 4-year outcomes similar to conservative treatment. Surgery accelerates recovery but doesn't change long-term outcome for most patients.

Recurrence Factors

5-10% recurrence rate at same level. Risk factors: obesity, smoking, larger annular defect, disc degeneration. Limited discectomy may reduce recurrence vs aggressive nuclectomy.

At a Glance

Lumbar Microdiscectomy - Quick Reference

FeatureDetails
DefinitionMinimally invasive removal of herniated disc fragment compressing nerve root
Most common levelsL4-5 (40-50%), L5-S1 (40-50%), L3-4 (5%)
IndicationRadiculopathy with concordant imaging, failed 6-12 weeks conservative Rx
Emergency indicationCauda equina syndrome - surgery within 24-48 hours
Success rate90-95% leg pain relief, 70-80% back pain improvement
Recurrence5-10% at same level, 5% at different level
Key anatomyPosterolateral = traversing root; far lateral = exiting root
Dural tear rate1-2% primary, 5-10% revision surgery
Return to workSedentary 2-4 weeks, physical 6-12 weeks
Hospital stayDay surgery or overnight
Mnemonic

DISC - Indications for Surgery

D
Duration (failed 6-12 weeks conservative)
Time-limited conservative trial
I
Imaging correlation
MRI matches clinical level
S
Symptoms radicular
Dermatomal pattern leg pain
C
Concordance clinical-imaging
Examination matches MRI findings

Memory Hook:DISC surgery needs DISC criteria - duration, imaging, symptoms, concordance

Mnemonic

CAUDA - Cauda Equina Syndrome Features

C
Continence lost
Urinary retention most sensitive
A
Anal tone decreased
Fecal incontinence
U
Unilateral to bilateral
Progressive bilateral leg symptoms
D
Dead saddle
Saddle anesthesia (S2-S5)
A
Acute emergency
Decompress within 24-48 hours

Memory Hook:CAUDA equina has CAUDA features - all require emergent decompression

Mnemonic

LEVEL - Nerve Root Localization

L
L3-4 = L4 root
Weak knee extension, diminished patellar reflex
E
Exit at foramen above
Exiting root = one level up
V
Verify traversing vs exiting
Posterolateral vs far lateral
E
EHL for L5
L5 = great toe extension (EHL), no reflex
L
Last is S1
S1 = ankle plantar flexion, Achilles reflex

Memory Hook:Know your LEVELs - the most common exam topic in disc surgery

Mnemonic

SPORT - Key Trial Findings

S
Spine Patient Outcomes Research Trial
Landmark RCT for disc herniation
P
Prospective randomized
501 surgical vs conservative patients
O
Outcomes similar at 4 years
Both groups improved substantially
R
Recovery faster with surgery
3-month advantage for surgery
T
Treatment effect diminishes
Difference narrows over time

Memory Hook:SPORT showed surgery is faster but not necessarily better long-term

Overview

Lumbar microdiscectomy is the most commonly performed spinal surgery worldwide, involving removal of herniated disc material compressing a nerve root through a minimally invasive approach. It remains the gold standard surgical treatment for symptomatic lumbar disc herniation unresponsive to conservative management.

Historical Development

Open discectomy was first described by Mixter and Barr in 1934. Caspar and Yasargil introduced the operating microscope for spine surgery in the 1970s. Modern microdiscectomy achieves decompression through incisions of 2-3 cm with minimal tissue disruption.

Epidemiology

Lumbar disc herniation affects 1-3% of the population. Peak incidence occurs in the 30-50 age group. L4-5 and L5-S1 account for 95% of herniations. Approximately 10% of symptomatic patients ultimately require surgery.

Exam Pearl

The natural history of lumbar disc herniation is generally favorable - 90% of patients improve with conservative treatment alone. Surgery accelerates recovery but does not change long-term outcomes for most patients (SPORT trial).

Pathophysiology and Mechanisms

Spinal Canal Anatomy

Key Structures:

  • Dural sac containing cauda equina
  • Traversing nerve root (descending to exit one level below)
  • Exiting nerve root (leaving at current foramen)
  • Epidural fat and veins
  • Ligamentum flavum posteriorly

Nerve Root Anatomy - Critical for Exams

Disc Level vs Nerve Root Compressed

Disc LevelPosterolateral HerniationFar Lateral HerniationClinical Distinction
L3-4L4 traversing rootL3 exiting rootPosterolateral is more common
L4-5L5 traversing rootL4 exiting rootMost common level overall
L5-S1S1 traversing rootL5 exiting rootSecond most common

Pathophysiology of Radiculopathy

Mechanical Compression:

  • Direct pressure on nerve root
  • Venous congestion
  • Ischemia

Chemical Irritation:

  • Nucleus pulposus is inflammatory
  • Phospholipase A2, TNF-alpha release
  • May cause symptoms without mechanical compression

Disc Herniation Classification

By Location:

  • Central: May cause bilateral symptoms or CES
  • Posterolateral: Most common, affects traversing root
  • Foraminal: Affects exiting root
  • Far lateral/extraforaminal: Also affects exiting root

By Morphology:

  • Protrusion: Base wider than dome, contained
  • Extrusion: Dome wider than base, through annulus
  • Sequestration: Free fragment separated from disc

Cauda Equina Syndrome

Large central disc herniation can cause cauda equina syndrome - a surgical emergency. Features: urinary retention (most sensitive), saddle anesthesia, fecal incontinence, bilateral leg weakness. Requires decompression within 24-48 hours for best outcomes.

Classification Systems

MSU Classification (Michigan State University)

MSU Disc Herniation Classification

TypeDescriptionPLL IntegrityFragment Containment
ProtrusionFocal bulge, base wider than domeIntactContained by annulus
ExtrusionDome wider than base, continuous with discTornThrough annulus but attached
SequestrationFree fragment, no disc continuityTornCompletely separated

The MSU classification guides surgical approach based on disc morphology.

Anatomical Location Classification

Disc Herniation by Location

LocationDefinitionRoot AffectedSurgical Approach
CentralMidline, compresses caudaBilateral/multipleStandard midline or bilateral
ParacentralLateral to midline in canalTraversing rootStandard unilateral approach
ForaminalWithin neural foramenExiting rootLateral or far-lateral approach
ExtraforaminalLateral to foramenExiting rootWiltse paraspinal approach

Anatomical location determines both which root is affected and optimal surgical approach.

Modic Changes (Endplate Changes)

Modic Classification of Endplate Changes

TypeT1 SignalT2 SignalSignificance
Type ILow (dark)High (bright)Inflammatory/edema, may predict back pain
Type IIHigh (bright)High (bright)Fatty replacement, stable
Type IIILow (dark)Low (dark)Sclerotic, end-stage

Modic changes may influence prognosis and treatment decisions in disc herniation management.

Clinical Assessment

Patient Selection

Good Surgical Candidate

  • Dominant leg pain (radiculopathy) more than back pain
  • Dermatomal distribution matching disc level
  • Positive tension signs (SLR, femoral stretch)
  • MRI correlation with clinical findings
  • Failed 6-12 weeks conservative treatment
  • Motivated patient with realistic expectations

Poor Surgical Candidate

  • Dominant axial back pain without radiculopathy
  • Non-dermatomal pain pattern
  • Imaging does not correlate with symptoms
  • Significant psychosocial factors
  • Pending litigation/workers compensation
  • Secondary gain issues
  • Minimal conservative treatment trial

Physical Examination

Neurological Assessment:

Root Level Examination

RootMotorSensoryReflex
L3Hip flexion, knee extensionAnterior thighNone reliable
L4Knee extension, ankle dorsiflexionMedial leg/footPatellar (knee jerk)
L5Great toe extension (EHL), hip abductionLateral leg, dorsum footNone reliable
S1Ankle plantar flexion, hip extensionLateral foot, posterior calfAchilles (ankle jerk)

Tension Signs:

  • Straight leg raise (SLR): Positive 30-70°, worse with dorsiflexion
  • Crossed SLR: Raising unaffected leg causes affected side pain (highly specific)
  • Femoral stretch test: For L2-L4 radiculopathy
  • Bowstring sign: Popliteal pressure during SLR reproduces pain

Red Flags - Require Urgent Evaluation

Cauda Equina Syndrome:

  • Urinary retention or incontinence
  • Fecal incontinence
  • Saddle anesthesia
  • Bilateral progressive weakness

Other Red Flags:

  • Progressive motor deficit
  • Fever, infection signs
  • History of malignancy
  • Unexplained weight loss

Exam Pearl

The most sensitive feature of CES is urinary retention - specifically inability to void with a distended bladder. Always perform post-void residual if CES suspected. More than 100-200ml is concerning.

Investigations

Gold Standard Imaging

Standard Protocol:

  • Sagittal T1, T2 sequences
  • Axial T2 at each level
  • Consider gadolinium for recurrent disc vs scar tissue

Key Findings:

  • Disc herniation location and size
  • Nerve root compression and displacement
  • Foraminal stenosis
  • Disc degeneration (Pfirrmann grading)
  • Modic changes in endplates

Correlation with Symptoms:

  • Critical to match imaging findings with clinical level
  • Incidental disc abnormalities common (30-40% of asymptomatic individuals)
  • Clinical correlation mandatory before surgery

MRI provides essential anatomic detail and helps distinguish between different herniation types.

CT Scan:

  • Useful for bony anatomy assessment
  • Less sensitive for soft disc herniation
  • May be used if MRI contraindicated

CT Myelography:

  • Intrathecal contrast injection
  • Better for bony stenosis evaluation
  • Used when MRI contraindicated or equivocal
  • Shows dynamic compression

CT is particularly useful for patients with pacemakers or other MRI contraindications.

EMG/NCS:

  • Confirms radiculopathy
  • Distinguishes from peripheral neuropathy
  • Localizes level when imaging equivocal
  • Assesses chronicity and severity

Indications:

  • Atypical presentation
  • Multi-level disease on imaging
  • Peripheral neuropathy suspected
  • Medicolegal documentation

Timing:

  • Changes take 3-4 weeks to develop
  • Acute disc herniation may have normal EMG
  • False negatives possible in early stages

Electrodiagnostics are most useful when clinical and imaging findings are discordant.

Additional Investigations

Plain Radiographs:

  • Limited role for disc herniation
  • Assess alignment, instability, degenerative changes
  • Flexion-extension views for instability

Diagnostic Injections:

  • Selective nerve root block (SNRB)
  • Helpful when imaging shows multi-level disease
  • Confirms symptomatic level before surgery
  • Therapeutic and diagnostic

Imaging Gallery

MRI Assessment and Pathophysiology

Sagittal MRI demonstrating lumbar disc herniation at L5-S1 with arrow annotation
Click to expand
Two sagittal T2-weighted MRI images demonstrating the classic appearance of lumbar disc herniation at the L5-S1 level (most common site, accounting for ~45% of herniations). The arrow indicates posterior disc material extending from the disc space into the spinal canal, compressing the anterior aspect of the thecal sac. This posterolateral herniation pattern typically compresses the traversing S1 nerve root, causing S1 radiculopathy with posterior thigh/calf pain, plantar flexion weakness, and diminished ankle reflex. The annotation helps identify the pathology clearly for surgical planning and demonstrates the critical concept of imaging-clinical correlation - the imaging findings must match the patient's dermatomal pain pattern and examination findings before proceeding with surgery.Credit: Ogbonnaya S et al. via J Nat Sci Biol Med via Open-i (NIH) (Open Access (CC BY))
Four-panel cross-sectional diagram showing normal spinal anatomy and disc herniation compressing neural elements
Click to expand
Four-panel anatomical diagram illustrating the pathomechanics of lumbar disc herniation and neural compression. Top two panels: Normal cross-sectional anatomy showing the thecal sac (purple/blue) containing the spinal cord and nerve roots within a properly sized spinal canal, surrounded by vertebral bone and posterior elements. Bottom two panels: Pathological anatomy demonstrating disc herniation (red/orange mass) protruding posteriorly into the spinal canal, compressing and displacing the neural elements. Key concepts: (1) Disc material (nucleus pulposus) extrudes through a tear in the annulus fibrosus; (2) Herniated material occupies space in the canal, mechanically compressing nerve roots; (3) Compression causes both mechanical irritation and chemical inflammation (disc material contains inflammatory proteins); (4) Microdiscectomy removes the offending disc fragment to decompress neural elements and relieve symptoms. This simplified diagram is ideal for patient education and understanding the surgical rationale.Credit: Weiner BK et al. via J Orthop Surg Res via Open-i (NIH) (Open Access (CC BY))
Eight-panel MRI series showing comprehensive multi-sequence assessment of lumbar disc herniation
Click to expand
Eight-panel MRI series demonstrating the comprehensive imaging protocol required for pre-operative assessment of lumbar disc herniation. Top row: Four axial T2-weighted MRI sequences at different lumbar levels showing cross-sectional anatomy of the spinal canal, disc spaces, and neural foramina - essential for assessing canal dimensions, lateral recess stenosis, foraminal narrowing, and the relationship of disc herniation to nerve roots. Bottom row: Four sagittal T2-weighted MRI sequences showing the lumbar spine in lateral view with vertebral bodies, disc spaces, and spinal canal - demonstrate vertebral alignment, disc height, disc signal intensity (degeneration), and direction of herniation. Multi-level assessment is critical because disc pathology often affects multiple levels. This case illustrates recurrent L5-S1 disc herniation in a 43-year-old male, demonstrating the importance of comprehensive imaging for surgical planning including identification of the correct level, understanding extent of pathology, and planning the surgical approach.Credit: Open-i / NIH via Open-i (NIH) (Open Access (CC BY))
Two-panel sagittal MRI comparison showing disc herniation with L5 transitional vertebrae
Click to expand
Two-panel sagittal T2-weighted MRI comparison (Panels A and B) in a 38-year-old female patient with disc herniation and L5 transitional vertebrae (sacralization or lumbarization). This case highlights critical surgical safety concepts: (1) **Transitional anatomy** - common anatomical variant where L5 may appear partially fused to sacrum or have characteristics of both lumbar and sacral vertebrae; (2) **Level counting importance** - transitional anatomy mandates careful radiographic-MRI correlation to avoid wrong-level surgery (sentinel event); (3) **Pre-operative planning** - requires counting from easily identifiable landmarks (often C2 or T12) and correlating with multiple imaging sequences; (4) **Intra-operative confirmation** - must confirm correct level with fluoroscopy or X-ray before incision. Wrong-level surgery is a never event - careful pre-operative imaging review and intra-operative level confirmation are mandatory to prevent this catastrophic error.Credit: Kaner T et al. via SAS J via Open-i (NIH) (Open Access (CC BY))

Management Algorithm

📊 Management Algorithm
lumbar microdiscectomy management algorithm
Click to expand
Management algorithm for lumbar microdiscectomyCredit: OrthoVellum

Conservative Management

First-Line Treatment (90% effective):

  • Activity modification (avoid aggravating positions)
  • NSAIDs, muscle relaxants
  • Physical therapy
  • Time (natural history favorable)

Additional Options:

  • Epidural steroid injections
  • Oral corticosteroid taper
  • Nerve root blocks

Duration of Conservative Trial:

  • Standard: 6-12 weeks
  • May be shortened with progressive deficit
  • Cauda equina: No conservative trial - emergency surgery

Conservative management is successful in 90% of disc herniation patients.

Surgical Indications

Surgical Indications

IndicationUrgencyRationale
Cauda equina syndromeEmergency (24-48 hours)Prevent permanent neurological deficit
Progressive motor weaknessUrgent (days)Preserve motor function
Intractable pain despite conservative RxElectiveQuality of life improvement
Failed 6-12 weeks conservativeElectiveNatural history trials completed
Recurrent radiculopathyElectivePrevious successful surgery, new symptoms

Surgery is indicated when conservative management fails or urgent neurological indications exist.

Surgical Options

Standard Microdiscectomy:

  • Most common approach
  • 2-3 cm incision
  • Operating microscope
  • Laminotomy with medial facet preservation

Endoscopic Discectomy:

  • Fully endoscopic technique
  • Smaller incision (8mm)
  • Learning curve considerations
  • Similar outcomes to open

Tubular Microdiscectomy:

  • Uses tubular retractor system
  • Minimizes muscle damage
  • May reduce postoperative pain

Choice of surgical technique depends on surgeon experience and patient factors.

Surgical Technique

Preoperative Planning

Positioning: Prone on Wilson frame or Jackson table

  • Hip flexed to flatten lumbar lordosis
  • Abdomen free to reduce venous pressure
  • Eyes protected, arms positioned

Level Confirmation:

  • Fluoroscopy mandatory
  • Mark incision preoperatively
  • Verify with intraoperative imaging

Surgical Steps

Incision and Exposure:

  1. Midline incision (2-3 cm) centered over disc level
  2. Dissect through subcutaneous tissue
  3. Incise fascia paramedian on symptomatic side
  4. Subperiosteal muscle elevation off spinous process and lamina
  5. Identify interlaminar window
  6. Confirm level with fluoroscopy

Key Landmarks:

  • Spinous process of upper vertebra
  • Interlaminar space
  • Medial facet joint

The approach should preserve the majority of the facet joint to prevent instability.

Laminotomy and Discectomy:

  1. Remove ligamentum flavum with Kerrison rongeurs
  2. Identify and protect dural sac and nerve root
  3. Retract traversing nerve root medially (gently)
  4. Identify disc herniation
  5. Incise posterior annulus
  6. Remove disc fragment with pituitary rongeurs
  7. Probe foramen to ensure complete decompression

Technical Pearls:

  • Stay lateral to dural sac
  • Protect nerve root with angled retractor
  • Identify epidural veins, control with bipolar
  • Avoid aggressive curettage (recurrence risk)
  • Remove only loose fragments

Adequate decompression of the nerve root is the goal while preserving as much normal anatomy as possible.

Modified Approach for Foraminal/Extraforaminal Disc:

Wiltse Paraspinal Approach:

  1. Incision 3-4 cm lateral to midline
  2. Split between multifidus and longissimus
  3. Expose transverse processes and facet
  4. Identify exiting nerve root
  5. Remove disc fragment lateral to foramen

Key Differences:

  • Does not enter spinal canal
  • Targets exiting (not traversing) root
  • Preserves facet joint completely
  • Lower dural tear risk

Far lateral herniations require a different mindset and approach than standard posterolateral herniations.

Intraoperative Considerations

Dural Tear Management:

  • Primary repair with 4-0 or 5-0 suture if possible
  • Dural sealant (fibrin glue, DuraSeal)
  • Fat graft or muscle patch
  • Bed rest 24-48 hours postoperatively
  • May need lumbar drain for persistent leak

Hemostasis:

  • Bipolar cautery for epidural veins
  • Avoid monopolar near neural structures
  • Hemostatic agents (Gelfoam, Surgicel)
  • Ensure dry field before closure

Complications

Intraoperative Complications

Intraoperative Complications

ComplicationIncidencePreventionManagement
Dural tear1-2% primary, 5-10% revisionCareful technique, identify dura earlyPrimary repair, sealant, bed rest
Nerve root injuryLess than 1%Gentle retraction, visualizationObservation, steroids if needed
Wrong level surgeryRare but seriousFluoroscopic confirmationIntraoperative correction, documentation
Vascular injuryVery rare (0.01-0.05%)Anterior awareness, depth controlImmediate vascular surgery consult
Epidural hematomaRareMeticulous hemostasisUrgent decompression if symptomatic

Postoperative Complications

Early Complications:

  • Wound infection (1-2%)
  • CSF leak (if dural tear)
  • Recurrent herniation (5-10%)
  • Persistent radiculopathy

Late Complications:

  • Recurrent disc herniation
  • Adjacent segment disease
  • Chronic pain
  • Instability (rare with limited laminotomy)

Recurrent Disc Herniation

Incidence: 5-10% at same level, 5% at different level

Risk Factors:

  • Obesity (BMI above 25)
  • Smoking
  • Larger annular defect
  • Occupational factors
  • Diabetes

Management:

  • Conservative treatment trial again
  • Repeat imaging (MRI with gadolinium)
  • Revision microdiscectomy vs fusion
  • Consider fusion if significant instability

Exam Pearl

MRI with gadolinium helps distinguish recurrent disc (no enhancement) from postoperative scar tissue (enhances). This distinction is important for surgical planning - scar tissue does not require reoperation.

Postoperative Care

Immediate Postoperative

Day of Surgery:

  • Mobilize same day (most patients)
  • Neurological assessment
  • Pain management (multimodal)
  • Encourage ambulation

Day 1:

  • Discharge if stable (day surgery or overnight stay)
  • Wound care instructions
  • Activity guidelines

Activity Guidelines

Postoperative Activity Progression

ActivityTimelineRestrictions
WalkingImmediateEncouraged, gradually increase
SittingImmediateLimit prolonged sitting initially
Lifting2-4 weeksLess than 5 kg initially, gradually increase
Driving1-2 weeksOff narcotics, comfortable sitting
Sedentary work2-4 weeksGradual return
Physical work6-12 weeksDepends on demands
Contact sports3-6 monthsSurgeon clearance required

Rehabilitation

Physical Therapy:

  • Core strengthening (delayed 2-4 weeks)
  • Flexibility exercises
  • Posture education
  • Ergonomic training

Lifestyle Modifications:

  • Weight optimization
  • Smoking cessation
  • Proper lifting technique
  • Activity modification

Follow-up Schedule

  • 2 weeks: Wound check, early progress
  • 6 weeks: Clinical assessment, activity progression
  • 3 months: Outcome assessment
  • 12 months: Final follow-up (if needed)

Exam Pearl

Recovery after microdiscectomy is typically rapid - most patients notice immediate leg pain relief upon waking from surgery. Back pain and residual numbness may take longer to improve.

Outcomes and Prognosis

Success Rates

Leg Pain Relief: 90-95% of patients Back Pain Improvement: 70-80% Return to Work: 80-90% Patient Satisfaction: 80-85%

SPORT Trial Findings

Key Results:

  • Surgery provides faster improvement in first 3 months
  • By 4 years, outcomes similar between surgical and conservative
  • Both groups showed substantial improvement
  • Cross-over rates were high (affects interpretation)

Clinical Implications:

  • Surgery accelerates recovery but doesn't change ultimate outcome
  • Patient preference important in decision-making
  • Conservative treatment remains reasonable option

Prognostic Factors

Favorable:

  • Leg pain more than back pain
  • Short duration of symptoms
  • Clear imaging correlation
  • No previous surgery
  • Extruded/sequestered disc
  • Good psychosocial status

Unfavorable:

  • Predominant back pain
  • Long symptom duration
  • Previous failed surgery
  • Workers compensation
  • Depression/anxiety
  • Obesity, smoking

Evidence-Based Practice

SPORT Trial (Weinstein et al., 2006)

I
Key Findings:
  • Randomized trial of surgery vs conservative for lumbar disc herniation
  • 501 patients randomized, high crossover rate
  • Both groups improved substantially
  • Surgery faster initial improvement
  • 4-year outcomes similar between groups
Clinical Implication: This evidence guides current practice.
Limitation: High crossover rate limits intention-to-treat analysis
Source: JAMA

SPORT 8-Year Follow-up (Lurie et al., 2014)

I
Key Findings:
  • Long-term follow-up of SPORT cohort
  • Both groups maintained improvement
  • Surgical advantage persisted at 8 years
  • Reoperation rate 10% at 8 years
  • Treatment effects durable
Clinical Implication: This evidence guides current practice.
Limitation: Selection bias in as-treated analysis
Source: Spine

Sequestrectomy vs Subtotal Discectomy (Barth et al., 2008)

I
Key Findings:
  • Randomized trial comparing techniques
  • Sequestrectomy: remove only free fragment
  • Similar clinical outcomes at 2 years
  • Sequestrectomy may reduce recurrence
  • Less aggressive approach preferred
Clinical Implication: This evidence guides current practice.
Limitation: Small sample size, short follow-up
Source: J Neurosurg Spine

Recurrence After Lumbar Discectomy Meta-Analysis (McGirt et al., 2009)

I
Key Findings:
  • Pooled analysis of recurrence rates
  • Overall recurrence: 5-10%
  • Risk factors: obesity, diabetes, smoking
  • Limited discectomy may reduce recurrence
  • Annular repair techniques under investigation
Clinical Implication: This evidence guides current practice.
Limitation: Heterogeneous study populations
Source: J Neurosurg Spine

Cauda Equina Syndrome Timing Meta-Analysis (Ahn et al., 2000)

II
Key Findings:
  • Analysis of timing of decompression
  • Better outcomes with surgery under 48 hours
  • Incomplete CES better prognosis than complete
  • Urinary function most sensitive indicator
  • Urgent decompression recommended
Clinical Implication: This evidence guides current practice.
Limitation: Retrospective studies included, heterogeneous definitions
Source: Spine

Special Considerations

Revision Microdiscectomy

Indications:

  • Recurrent disc herniation (not scar tissue)
  • New symptoms at same level
  • Failed to improve or worsening after initial surgery

Technical Considerations:

  • MRI with gadolinium to distinguish recurrence from scar
  • Epidural fibrosis increases dural tear risk (5-10%)
  • Consider fusion if significant instability or multiple recurrences

Microdiscectomy vs Fusion

When to Consider Fusion:

  • Significant instability
  • Multiple recurrent herniations
  • Concomitant spondylolisthesis
  • Large annular defect with disc space collapse
  • Significant back pain component

Endoscopic vs Open Microdiscectomy

Endoscopic Advantages:

  • Smaller incision
  • Less muscle damage
  • Faster recovery
  • Day surgery

Open Advantages:

  • Better visualization
  • Shorter learning curve
  • Lower complication rate early in experience
  • More versatile

Workers Compensation Cases

Considerations:

  • Outcomes generally inferior
  • Higher recurrence rates reported
  • Multidisciplinary approach recommended
  • Clear documentation essential
  • Manage expectations carefully

Clinical Algorithm

Management Pathway

Step 1: Clinical Assessment

  • Confirm radiculopathy (dermatomal, tension signs)
  • Rule out red flags (CES, progressive weakness, infection, malignancy)
  • Assess symptom duration and severity

Step 2: Imaging

  • MRI lumbar spine
  • Confirm imaging-clinical correlation
  • Assess herniation type and location

Step 3: Conservative Trial (6-12 weeks)

  • Activity modification, NSAIDs
  • Physical therapy
  • Consider ESI if symptoms severe

Step 4: Surgical Decision

  • If failed conservative: Offer surgery
  • If CES: Emergency surgery
  • If progressive weakness: Urgent surgery

Step 5: Surgical Planning

  • Standard approach for posterolateral herniation
  • Wiltse approach for far lateral
  • Consider tubular or endoscopic based on expertise

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

L5 Radiculopathy Surgical Candidate

EXAMINER

"A 35-year-old man presents with 3 months of right leg pain radiating to the dorsum of the foot and great toe. He has weakness of great toe extension. MRI shows L4-5 right posterolateral disc herniation. He has failed 8 weeks of physiotherapy and two epidural injections. How would you manage this patient?"

EXCEPTIONAL ANSWER
This is classic L5 radiculopathy based on dermatomal pain and EHL weakness. The L4-5 posterolateral herniation compresses the L5 traversing root, which is concordant with clinical findings. Having failed adequate conservative trial of 8 weeks plus two epidural steroid injections, he meets criteria for surgical intervention. I would counsel him on expected 90-95% leg pain relief with 5-10% recurrence rate at same level. Motor recovery is variable. I would perform a right L4-5 microdiscectomy with prone positioning, fluoroscopic level confirmation, limited laminotomy preserving the facet, and removal of loose disc fragments only with limited discectomy technique. Return to sedentary work in 2-4 weeks and physical work in 6-12 weeks.
KEY POINTS TO SCORE
L4-5 posterolateral herniation compresses L5 traversing root (not L4 exiting root)
Clinical concordance essential: dermatomal pain and EHL weakness match imaging
Adequate conservative trial before surgery: 6-12 weeks including physiotherapy and ESI
90-95% leg pain relief expected, 5-10% recurrence rate
Limited discectomy technique - remove only loose fragments
COMMON TRAPS
✗Confusing traversing vs exiting root - L4-5 posterolateral affects L5 (traversing)
✗Operating without adequate conservative trial
✗Not confirming level intraoperatively with fluoroscopy
✗Aggressive discectomy increasing instability risk
LIKELY FOLLOW-UPS
"What if this was a far lateral herniation at L4-5 - which root would be affected?"
"What is the SPORT trial evidence for disc herniation surgery?"
"How would you counsel about recurrence risk factors?"
VIVA SCENARIOCritical

Cauda Equina Syndrome Emergency

EXAMINER

"A 50-year-old woman presents with sudden onset bilateral leg weakness, urinary retention requiring catheterization, and saddle anesthesia. MRI shows large central L4-5 disc herniation. How do you manage her?"

EXCEPTIONAL ANSWER
This is cauda equina syndrome, a surgical emergency. Key features confirming CES include urinary retention (most sensitive sign), saddle anesthesia (S2-S5), and bilateral leg symptoms. I would immediately insert a urinary catheter, obtain surgical consent, and book emergency theatre. Emergency decompression should occur within 24-48 hours, ideally sooner. The surgical approach requires wider exposure than standard microdiscectomy - possibly bilateral laminotomy or laminectomy - to achieve thorough decompression of the entire cauda equina. I would counsel on prognosis: incomplete CES (urinary retention with overflow) has better outcomes than complete CES. Bladder function may take months to recover and may be permanent. Careful documentation of symptom onset timing and surgery timing is essential for medicolegal purposes.
KEY POINTS TO SCORE
Cauda equina syndrome is a surgical emergency - decompress within 24-48 hours
Urinary retention is the most sensitive clinical sign
Saddle anesthesia (S2-S5) and bilateral symptoms are hallmark features
Incomplete CES has better prognosis than complete CES
Document timing of symptom onset and surgery carefully for medicolegal reasons
COMMON TRAPS
✗Delaying surgery beyond 48 hours significantly worsens outcomes
✗Missing urinary retention by not checking post-void residual
✗Under-decompressing - may need bilateral approach or laminectomy
✗Not documenting timing of symptom onset for medicolegal purposes
LIKELY FOLLOW-UPS
"What is the difference between complete and incomplete CES?"
"What is the evidence for timing of surgery in CES?"
"How do you distinguish incomplete from complete CES clinically?"
VIVA SCENARIOChallenging

Intraoperative Dural Tear Management

EXAMINER

"You perform an L5-S1 microdiscectomy and encounter a dural tear during removal of the ligamentum flavum. Describe your management."

EXCEPTIONAL ANSWER
I would stay calm as this is a recognized complication occurring in 1-2% of primary cases. Immediately I would reduce Trendelenburg position to lower CSF pressure and improve visualization. I would identify the extent and location of the tear, extending the laminotomy if needed for adequate exposure. For repair, I would attempt primary closure with 4-0 or 5-0 non-absorbable suture in running or interrupted fashion, then test with Valsalva maneuver. If primary repair is not possible, I would use dural sealant, fat graft, or muscle patch. I would complete the primary discectomy procedure if possible, then verify watertight closure. Postoperatively, I would prescribe bed rest for 24-48 hours, avoid straining with stool softeners, and monitor for headache and wound drainage. If CSF leak persists, I would consider a lumbar drain. Documentation and disclosure to the patient is essential.
KEY POINTS TO SCORE
Dural tear occurs in 1-2% of primary cases, 5-10% in revisions
Primary repair with 4-0 or 5-0 non-absorbable suture is preferred
Test repair with Valsalva maneuver before closure
Alternative closure: dural sealant, fat graft, or muscle patch
Postoperative bed rest 24-48 hours with stool softeners to avoid straining
COMMON TRAPS
✗Panicking rather than systematically addressing the complication
✗Not reducing Trendelenburg to lower CSF pressure
✗Abandoning the primary procedure without completing discectomy
✗Failing to document and disclose the complication to the patient
LIKELY FOLLOW-UPS
"What if the leak persists postoperatively despite bed rest?"
"How do you prevent dural tears in revision surgery?"
"What is a pseudomeningocele and how do you manage it?"
VIVA SCENARIOChallenging

Recurrent Disc vs Epidural Fibrosis

EXAMINER

"A 45-year-old man is 18 months post L4-5 microdiscectomy with excellent initial result. He now has recurrent right leg pain identical to his original presentation. MRI shows enhancement around the previous surgical site. How do you proceed?"

EXCEPTIONAL ANSWER
The differential includes recurrent disc herniation, epidural fibrosis (scar tissue), new disc at different level, missed fragment, or instability. The key investigation is MRI with gadolinium: scar tissue ENHANCES (vascular) while recurrent disc does NOT enhance (avascular). Given the described enhancement, this likely represents epidural fibrosis. If scar tissue, surgery is NOT indicated as scar recurs after excision. Management is conservative with medications, physiotherapy, epidural injections, and spinal cord stimulation if refractory. If MRI shows non-enhancing recurrent disc, I would trial conservative management first, then consider revision microdiscectomy if it fails. I would warn about higher dural tear risk of 5-10% in revisions. Consider fusion if there is instability, multiple recurrences, or significant back pain.
KEY POINTS TO SCORE
MRI with gadolinium distinguishes scar (enhances) from recurrent disc (does not enhance)
Epidural fibrosis does NOT respond to surgery - scar recurs after excision
Recurrent disc can be treated with revision microdiscectomy if conservative Rx fails
Revision surgery has higher dural tear risk (5-10%)
Consider fusion for instability, multiple recurrences, or significant back pain
COMMON TRAPS
✗Operating on epidural fibrosis - scar recurs and outcomes are poor
✗Not obtaining MRI with gadolinium to distinguish disc from scar
✗Not warning patient about higher complication rates in revision surgery
✗Missing instability that would require fusion
LIKELY FOLLOW-UPS
"Why does scar tissue enhance and disc not on gadolinium MRI?"
"What are non-operative options for epidural fibrosis?"
"When would you add fusion to a revision discectomy?"

MCQ Practice Points

High-Yield MCQ Topics

Nerve Root Anatomy - Most Tested

Q: L4-5 posterolateral disc herniation typically affects which nerve root?

A: The L5 nerve root (traversing root). Posterolateral herniations affect the traversing root, which exits one level below. Far lateral herniations at L4-5 would affect L4 (the exiting root).

Cauda Equina Syndrome Recognition

Q: What is the most sensitive clinical feature of cauda equina syndrome?

A: Urinary retention (specifically inability to void with a distended bladder). Post-void residual more than 100-200ml is concerning. Other features include saddle anesthesia (S2-S5) and bilateral leg symptoms.

Distinguishing Recurrence from Scar

Q: What MRI finding distinguishes recurrent disc herniation from epidural fibrosis (scar tissue)?

A: Gadolinium enhancement pattern. Scar tissue ENHANCES (it is vascular). Recurrent disc does NOT enhance (it is avascular). This distinction is critical as scar tissue does not benefit from surgery.

SPORT Trial Key Finding

Q: What did the SPORT trial show about lumbar microdiscectomy for disc herniation?

A: Surgery provides faster initial recovery (advantage at 3 months) but 4-year outcomes are similar between surgical and conservative treatment. Both groups improved substantially. The natural history of disc herniation is generally favorable.

Far Lateral Herniation

Q: A far lateral L4-5 disc herniation affects which nerve root?

A: The L4 nerve root (exiting root). Unlike posterolateral herniations that affect the traversing root one level below, far lateral/foraminal herniations affect the exiting root at the same level.

Australian Context

Current Practice in Australia

Lumbar microdiscectomy is one of the most commonly performed spinal surgeries in Australia. It is performed in both public and private hospitals by neurosurgeons and orthopaedic spine surgeons.

Standard practices follow international guidelines with emphasis on appropriate patient selection and adequate conservative treatment trial before surgery. Day surgery is increasingly common for uncomplicated cases.

Medicolegal Considerations

Key documentation points for medicolegal protection include recording of red flag assessment, documentation of concordance between symptoms and imaging, consent discussion including recurrence risk and dural tear possibility, and level confirmation process (pre-operative marking, fluoroscopy).

Cauda equina syndrome cases require careful documentation of timing, specifically when symptoms began, when patient presented, when imaging obtained, and when surgery performed.

Lumbar Microdiscectomy Key Points

High-Yield Exam Summary

Nerve Root Anatomy

  • •Posterolateral herniation = traversing root (L4-5 = L5)
  • •Far lateral/foraminal = exiting root (L4-5 = L4)
  • •L4: knee extension, patellar reflex
  • •L5: EHL (great toe extension), no reflex
  • •S1: plantar flexion, Achilles reflex

Cauda Equina Syndrome

  • •Emergency - surgery within 24-48 hours
  • •Most sensitive: urinary retention
  • •Saddle anesthesia (S2-S5)
  • •Bilateral leg weakness
  • •Incomplete better prognosis than complete

SPORT Trial

  • •Surgery faster initial improvement
  • •4-year outcomes similar
  • •Both groups improved substantially
  • •Natural history favorable for most

Surgical Technique

  • •Prone on Wilson frame, fluoroscopy for level
  • •Laminotomy, preserve facet
  • •Protect dura and traversing root
  • •Remove loose fragments only (limited discectomy)
  • •Dural tear 1-2% primary, 5-10% revision

Recurrence

  • •5-10% at same level
  • •Risk factors: obesity, smoking, large defect
  • •MRI + gadolinium: scar enhances, disc does not
  • •Revision vs fusion decision based on instability

Outcomes

  • •90-95% leg pain relief
  • •70-80% back pain improvement
  • •Day surgery or overnight stay
  • •Return to work: sedentary 2-4 weeks, physical 6-12 weeks

Summary

Key Takeaways

  1. Nerve Root Anatomy is Essential: Posterolateral herniations affect the traversing root (L4-5 = L5), while far lateral herniations affect the exiting root (L4-5 = L4). This is the most commonly tested topic.

  2. Cauda Equina Syndrome is a Surgical Emergency: Recognize the triad of urinary retention, saddle anesthesia, and bilateral leg symptoms. Decompress within 24-48 hours for best outcomes.

  3. SPORT Trial Shapes Practice: Surgery accelerates recovery but 4-year outcomes are similar to conservative treatment. Patient preference matters in surgical decision-making.

  4. Patient Selection is Critical: Best outcomes when leg pain predominates over back pain, imaging correlates with symptoms, and adequate conservative trial has failed.

  5. Limited Discectomy Preferred: Remove only loose fragments rather than aggressive curettage. This may reduce recurrence while achieving adequate decompression.

  6. Dural Tear is a Recognized Complication: 1-2% in primary surgery, higher in revisions. Know repair techniques and postoperative management.

  7. Recurrence Requires MRI with Gadolinium: Distinguishes recurrent disc (no enhancement) from scar tissue (enhances). Scar tissue does not benefit from surgery.

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