import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Central posterior structure**. Protection: Thin bone before Kerrison, angle Kerrison upward, microscope magnification, careful ligamentum flavum dissection. Tear rate: 1-7% primary, 15-20% revision. **Lateral recess** (L5 at L4-5 level). Protection: Identify before retraction, gentle intermittent retraction, release every 5-10 minutes. Retract at shoulder NOT at DRG. **Foramen** (L4 at L4-5 level). Protection: At risk with far-lateral disc or foraminotomy. Visualise before decompression. Lies superior to disc level. **Batson's plexus** - valveless epidural veins. Protection: Free abdomen positioning, bipolar cautery on low (8-10W), hemostatic agents (Gelfoam, FloSeal). **Absolute Indications:** - Cauda equina syndrome (emergency - surgery within 48 hours) - Progressive motor deficit (urgent - surgery within days) - Intractable pain unresponsive to maximum conservative care **Relative Indications:** - Radiculopathy with correlating imaging after 6+ weeks failed conservative treatment - Failed PT, NSAIDs, activity modification, ± epidural steroid injections - MRI showing disc herniation matching clinical dermatome/myotome **Contraindications:** - Axial back pain alone without radiculopathy - No imaging correlation with symptoms - Active infection (discitis, epidural abscess) - Significant segmental instability (consider fusion instead) **Imaging Review:** - MRI: Confirm herniation type (posterolateral, foraminal, sequestered), migration, canal/lateral recess stenosis - CT: Bone anatomy if transitional vertebrae or revision surgery - Flexion-extension X-rays: Rule out instability (>3-4mm translation, >10° angulation) **Key Decisions:** - Level confirmation with radiologist if transitional vertebrae - Microscope vs loupes (3.5-4.5x) - similar outcomes - Open vs tubular MIS approach - Concurrent foraminotomy if foraminal stenosis **Classification:** - **Posterolateral**: Most common (90%), subarticular zone - **Foraminal**: 7-10%, requires foraminotomy - **Far-lateral (extraforaminal)**: 1-3%, paramedian approach - **Central**: Risk of cauda equina, bilateral approach may be needed **Success Rate:** 85-90% good-excellent results for leg pain relief **Specific Risks:** - Dural tear/CSF leak (1-7%) - higher in revision (15-20%) - Nerve root injury (0.5-2%, usually transient) - Recurrent disc herniation (5-10% at 5 years) - Wrong-level surgery (1-4%) - Epidural hematoma (1-2%) - emergency if occurs - Infection: Superficial 1-3%, discitis 0.5-2% - Iatrogenic instability (rare if facet preserved) - Cauda equina syndrome (<1%) **Expected Recovery:** - Same-day discharge or 23-hour stay (60-70%) - Sedentary work: 2-4 weeks - Manual labour: 6-12 weeks - Full activity: 12 weeks **Positioning:** - Wilson frame or Jackson table - Prone with hips and knees flexed 90° (opens interspinous space) - Abdomen FREE - pass hand underneath (reduces epidural venous pressure 30-40%) - Arms <90° abduction on arm boards - All pressure points padded (elbows, knees, ASIS) - Head neutral on gel headrest **Instruments:** - Operating microscope (6-16x magnification) or surgical loupes (3.5-4.5x) - C-arm fluoroscopy for level confirmation - Self-retaining retractor (Taylor, McCullough, or Caspar) - High-speed burr (3-4mm) - Kerrison rongeurs (2mm, 3mm, 45° upward-angled) - Pituitary rongeurs (2mm, 3mm) - Nerve root retractors (Love, Scoville) - Nerve hooks (angled, blunt) - Penfield dissectors (#1, #4) - Cobb elevator - Bipolar cautery (8-10W setting) - Hemostatic agents (Gelfoam, Surgicel, FloSeal) **Antibiotics:** - Cefazolin 2g IV within 60 minutes of incision - Vancomycin 1g if MRSA risk or penicillin allergy ### Step 1: Positioning and Level Marking Position prone on Wilson frame with hips/knees flexed 90°. Confirm abdomen completely free (reduces epidural venous pressure 30-40%). Palpate spinous processes - iliac crest (Tuffier's line) crosses L4-5 disc or L4 spinous process. Place radiopaque skin marker. Obtain AP and lateral fluoroscopy. Count from L5/S1 (most reliable) AND from T12. **EXAM KEY**: Wrong-level surgery occurs in 1-4% of spine cases. Three-point fluoroscopic verification (before incision, after exposure with instrument on bone, before bone removal) is medicolegal standard of care. Document each verification. ### Step 2: Incision and Fascial Exposure Small 2-3cm vertical midline incision centred over target level. Incise skin and subcutaneous tissue with monopolar cautery to lumbodorsal fascia. Identify white glistening fascia. Make vertical fascial incision 0.5-1cm paramedian on side of herniation - avoids interspinous ligament. ### Step 3: Subperiosteal Muscle Dissection Using Cobb elevator, perform subperiosteal dissection of paraspinal muscles UNILATERALLY from spinous process and lamina. Sweep laterally to expose lamina and medial facet. Place self-retaining retractor to hold muscles. Expose: inferior edge of superior lamina, superior edge of inferior lamina, interlaminar window, medial 1/3 of facet. **Technical Point**: Unilateral dissection reduces muscle trauma vs bilateral approach - less postoperative pain and faster recovery. Use smallest effective retractor - over-retraction causes muscle ischemia. ### Step 4: Final Level Confirmation Place metallic marker (Penfield, K-wire) on spinous process or lamina. Obtain lateral fluoroscopy. Count vertebral levels from L5/S1 AND T12. Document image in operative record. This is the final checkpoint before bone removal - last chance to prevent wrong-level surgery. NEVER remove bone without fluoroscopic confirmation. ### Step 5: Microscope Positioning Bring in operating microscope. Focus on interlaminar window. Adjust for 6-16x magnification with coaxial illumination. Surgical loupes (3.5-4.5x) are acceptable alternative with similar outcomes. ### Step 6: Laminotomy - Thinning Bone Using 3-4mm high-speed burr, thin inferior edge of superior lamina from midline to lateral edge of interlaminar space. Create eggshell-thin bone - should see blue-grey dura through translucent bone. **EXAM KEY**: Thinning bone before Kerrison removal prevents sudden dural penetration - this is the key safety step. Always thin to translucency first before removing with rongeurs. ### Step 7: Laminotomy - Kerrison Removal Using 2-3mm 45° upward-angled Kerrison rongeurs, remove thinned inferior edge of superior lamina. Start medially and work laterally. Create window 10-15mm wide exposing ligamentum flavum and lateral dural edge. NEVER plunge Kerrison downward - ALWAYS angle upward away from dura. Downward plunge = dural tear. Grasp bone, pull toward you and upward. ### Step 8: Ligamentum Flavum Removal Identify thickened yellow ligamentum flavum (normal 2-3mm, hypertrophied up to 6mm in stenosis). Using Penfield #4 or right-angled curette, dissect ligamentum off underlying dura. Work from cephalad to caudad, staying on deep surface of ligamentum. Grasp with pituitary forceps and peel away. **EXAM KEY**: Ligamentum flavum often densely adherent to dura in elderly and revision cases. Sharp dissection with micro-scissors may be needed. Never avulse ligamentum - peel carefully to prevent dural tear. ### Step 9: Anatomical Identification After ligamentum removal, systematically identify under microscope: 1. **Dural sac** - lateral edge, pulsatile, blue-white 2. **Traversing nerve root** - lateral recess (L5 at L4-5) 3. **Exiting nerve root** - foramen (L4 at L4-5) 4. **Disc space** - ventral to neural structures 5. **Medial facet** - dorsal/lateral Never retract until you know what you're retracting. Clear anatomical identification prevents nerve injury. ### Step 10: Nerve Root Retraction Using small blunt nerve root retractor (Love, Scoville), gently retract traversing nerve root medially to expose disc space. Use minimal force. Intermittent retraction - release every 5-10 minutes. Retract at root shoulder, NOT at dorsal root ganglion. **EXAM KEY**: Excessive or prolonged retraction causes permanent nerve injury. Retraction neurapraxia is most common cause of new postoperative deficit - usually recovers over weeks to months if recognised early. ### Step 11: Annulotomy and Discectomy Create small vertical incision (5-8mm) in posterior annulus with micro #15 blade (box cut or cruciate incision). Using 2mm pituitary rongeurs, grasp and remove extruded disc fragment. Remove herniated and LOOSE fragments only. **Evidence**: Limited discectomy (herniated + loose fragments only) preferred over aggressive discectomy (curet nucleus, endplate). SPORT trial, LAPIDUS trial, Cochrane review: Similar recurrence rates (5-10% at 5 years), fewer complications (discitis, subsidence, pain) with limited technique. Limited discectomy is evidence-based standard of care. ### Step 12: Foramen Exploration - Critical Step Using angled nerve hook or Penfield, probe foramen CEPHALAD (superiorly) and CAUDAD (inferiorly) along nerve root course to identify sequestered/migrated disc fragments. Up to 30% of herniations have fragments that migrate away from main herniation. Remove identified fragments with pituitary rongeur. Retained sequestered fragments are the leading cause of failed back surgery (persistent radiculopathy despite technically good discectomy). Thorough foramen exploration is MANDATORY, not optional. ### Step 13: Lateral Recess and Foraminal Decompression (If Needed) If imaging shows lateral recess stenosis or root still compressed after discectomy: - **Lateral recess**: Undercut medial facet with burr or Kerrison, remove medial 1/3 only - **Foraminal stenosis**: Remove lateral aspect of superior facet to unroof foramen - Preserve >50% of facet to prevent instability ### Step 14: Confirm Adequate Decompression Use 2mm nerve hook to probe around nerve root: - Root should be completely mobile - lifts away from disc and pedicle - Probe passes freely circumferentially - No residual compression from disc or bone - Root is pulsatile, pink, round (vs compressed = flat, white, immobile) ### Step 15: Hemostasis and Closure Remove retractor. Irrigate with warm saline (500-1000ml). Control epidural bleeding with bipolar cautery (8-10W, brief pulses), Gelfoam/Surgicel, or FloSeal. Perform Valsalva maneuver (20-30 cmH2O for 10 seconds) to identify occult venous bleeding. Close fascia with interrupted or running 0-Vicryl (watertight). Subcutaneous tissue with 2-0 Vicryl. Skin with staples or subcuticular 3-0/4-0 Monocryl. Drain rarely needed for single-level microdiscectomy. **EXAM KEY**: Watertight fascial closure is critical - if incidental durotomy occurred, this is the last line of defense against CSF leak. Valsalva test before closure is mandatory to detect epidural bleeding (hematoma risk 1-2%). **Day 0:** - Neurological examination immediately post-extubation (compare to preop) - Mobilise out of bed within 2-6 hours if stable - Ambulate with physiotherapy - Oral analgesia: NSAIDs (ibuprofen 600mg TID) ± short-term opioids - Neuropathic agents if radicular pain persists (gabapentin 300mg TID) - Same-day discharge common (60-70%) or 23-hour observation **Activity Restrictions (6 weeks):** - No BLT: Bending, Lifting, Twisting - No lifting >5kg - Avoid prolonged sitting >30 minutes (2 weeks) - Walking encouraged **Follow-up:** - Week 2: Wound check, suture removal - Week 6: Clinical review, commence physiotherapy (core strengthening, McKenzie extensions) - Return to work: Sedentary 2-4 weeks, manual labour 6-12 weeks, heavy lifting 12 weeks **Expected Outcomes:** - 85-90% good-excellent results - Immediate leg pain relief: 80-90% - Back pain improvement: 50-60% - Patient satisfaction: 85-90% - Return to baseline activity: 3-6 months 1. Weinstein JN, et al. Surgical vs Nonoperative Treatment for Lumbar Disk Herniation: The Spine Patient Outcomes Research Trial (SPORT): A Randomized Trial. JAMA. 2006;296(20):2441-2450. 2. Kreiner DS, et al. An evidence-based clinical guideline for the diagnosis and treatment of lumbar disc herniation with radiculopathy. Spine J. 2014;14(1):180-191. 3. Jacobs WC, et al. Surgical techniques for sciatica due to herniated disc: A systematic review. Eur Spine J. 2012;21:2232-2251. 4. Watters WC 3rd, et al. An evidence-based clinical guideline for the diagnosis and treatment of degenerative lumbar spondylolisthesis. Spine J. 2009;9(7):609-614. 5. Mayer HM, Brock M. Percutaneous endoscopic discectomy: surgical technique and preliminary results compared to microsurgical discectomy. J Neurosurg. 1993;78(2):216-225. 6. Rasouli MR, et al. Minimally invasive discectomy versus microdiscectomy/open discectomy for symptomatic lumbar disc herniation. Cochrane Database Syst Rev. 2014;(9):CD010328. 7. McMorland G, et al. Manipulation or microdiskectomy for sciatica? A prospective randomized clinical study. J Manipulative Physiol Ther. 2010;33(8):576-584. 8. Carragee EJ, et al. A prospective controlled study of limited versus subtotal posterior discectomy. Spine. 2006;31(6):653-657. 9. Thome C, et al. Outcome after lumbar sequestrectomy compared with microdiscectomy: A prospective randomized study. J Neurosurg Spine. 2005;2(3):271-278. 10. Desai A, et al. Lumbar microdiscectomy: A historical perspective and current technical considerations. Cureus. 2019;11(3):e4204.

Microscopic Lumbar Discectomy

Microscopic Lumbar Discectomy