import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Location**: Central canal, 2-3mm anterior to ligamentum flavum, conus ends at L1-L2 level **Protection**: Identify under-surface of ligamentum flavum before cutting, use Woodson elevator, gentle retraction only, CSF leak risk 5-15% **Location**: Exiting root under pedicle at lateral recess (L4 exits at L4-L5 foramen), traversing root medial descending to next level (L5 exits at L5-S1) **Protection**: Decompress lateral recess adequately, identify both roots before instrumentation, avoid excessive retraction, limit facetectomy to <50% **Location**: Anterior to dura, valveless Batson's plexus connecting IVC to azygos system **Protection**: Abdomen FREE positioning reduces engorgement 50%, bipolar cautery only, avoid aggressive anterior dissection, gelfoam for control **Location**: Medial cortex separates pedicle from neural canal, thinnest wall at L5 (1-2mm) **Protection**: Proper entry point at Magerl junction, 10-15° medial trajectory (20° at L5), probe all 5 walls, use ball-tip probe, feel cortical breach **Location**: Anterior to vertebral body, aorta bifurcates at L4, left common iliac vein crosses L5 **Protection**: Limit pedicle screw depth to 80% vertebral body, avoid anterior cortex breach, use fluoroscopic depth confirmation, 35-40mm typical screw length ## Indications for PLDF ### Primary Indications **Degenerative Spondylolisthesis Grade I-II** - Most common indication for PLDF - Associated with spinal stenosis and neurogenic claudication - Instability demonstrated on flexion-extension radiographs (>3-4mm translation) - Failed conservative management for 3-6 months - Evidence: Weinstein SPORT trial showed superior outcomes with fusion vs decompression alone at 4 years **Spinal Stenosis with Instability** - Central or lateral recess stenosis with spondylolisthesis - Dynamic instability on flex-ex films - Iatrogenic instability anticipated from extensive decompression (>50% facetectomy) - Multi-level stenosis requiring aggressive facet removal **Recurrent Stenosis After Prior Decompression** - Failed decompression alone - Progressive instability post-laminectomy - Residual or recurrent radicular symptoms **Degenerative Scoliosis with Stenosis** - Adult degenerative scoliosis >15-20° - Symptomatic stenosis at apex or concavity - Requires decompression and realignment ### Contraindications **Absolute** - Active infection at surgical site - Severe medical comorbidities precluding safe anesthesia - Patient unable to tolerate prone positioning **Relative** - Severe osteoporosis (T-score < -3.5) - may require cement augmentation - Active smoking (increases pseudarthrosis risk 3-4 fold) - Morbid obesity (BMI >40) - increases complications - Severe vascular disease - Previous fusion at adjacent levels ## Pre-operative Planning **Imaging Assessment** - Standing AP and lateral lumbar radiographs (assess alignment, instability) - Flexion-extension views (>3-4mm translation = instability) - MRI lumbar spine (stenosis severity, disc degeneration, nerve root compression) - CT if bone detail needed (facet arthritis, spondylolysis, previous hardware) **Level Selection** - Decompress all symptomatic stenotic levels - Fuse unstable segments only - Consider stopping at L5-S1 vs extending to sacrum (stopping at L5-S1 requires intact disc) **Implant Planning** - Pedicle diameter on axial CT or MRI (typically 6-8mm in lumbar spine, smaller at L5) - Screw length: 35-45mm typical (80% vertebral body depth) - Rod diameter: 5.5mm most common - Local autograft usually sufficient for 1-2 level, consider iliac crest or allograft for >2 levels ## Lumbar Spine Surgical Anatomy ### Surface Anatomy - Spinous processes palpable in midline - Iliac crests: L4-L5 level (Tuffier's line) - PSIS: S2 level - Midline relatively avascular plane ### Neural Anatomy - CRITICAL FOR EXAM **Spinal Cord and Conus** - Spinal cord ends at L1-L2 level in adults (conus medullaris) - Injury above L1-L2 = permanent paraplegia - Below L1-L2 = cauda equina (peripheral nerves, recovery possible) **Nerve Root Nomenclature - MUST KNOW** At L4-L5 disc level, there are TWO nerve roots: 1. **EXITING L4 nerve root** - Has descended from L3-L4 level - Passes laterally UNDER the L4 pedicle - Exits through L4-L5 foramen (above L5 pedicle) - Compressed by: foraminal stenosis (superior articular process of L5), far lateral disc herniation - L4 radiculopathy: knee extension weakness, reduced patellar reflex, anterior thigh numbness 2. **TRAVERSING L5 nerve root** - Just exited thecal sac at L4-L5 level - Descends medially through central canal - Will exit at NEXT level (L5-S1 foramen) - Compressed by: central/paracentral disc herniation at L4-L5, lateral recess stenosis - L5 radiculopathy: foot drop, great toe extension weakness, lateral calf numbness **Key Clinical Correlation** - L4-L5 central disc herniation compresses TRAVERSING L5 root → L5 radiculopathy - L4-L5 far lateral disc herniation compresses EXITING L4 root → L4 radiculopathy - L4-L5 decompression must address BOTH lateral recess (L5 traversing) AND foramen (L4 exiting) ### Vascular Anatomy **Epidural Venous Plexus (Batson's Plexus)** - Valveless venous system - Connects pelvic veins to azygos system - Engorges with increased intra-abdominal pressure - ABDOMEN FREE positioning reduces pressure by 50% - Main source of bleeding during decompression **Arterial Supply** - Lumbar segmental arteries from aorta - Branch into anterior spinal artery and posterior branches - Radicular arteries accompany nerve roots - Artery of Adamkiewicz (T8-L2, usually left) - critical for cord perfusion **Great Vessels** - Aorta bifurcates at L4 level - IVC to the right of midline - Left common iliac vein crosses midline at L5 - Risk with anterior pedicle breach or screw too long ### Bony Anatomy **Pedicle Dimensions** - L1-L4: 8-12mm transverse diameter, 14-16mm sagittal height - L5: 14-18mm transverse diameter (largest), allows larger screws - Medial wall thinnest (1-3mm) - most dangerous breach direction **Pedicle Screw Entry Point (Magerl Point)** - Intersection of: - Lateral border of superior articular facet - Base of transverse process - Trajectory: 10-15° medial (more convergent at L5: 20-25°) - Parallel to superior endplate on lateral view **Facet Joints** - Oriented sagittally in lumbar spine (45° in thoracic) - Resection >50% = iatrogenic instability - Medial facetectomy for lateral recess decompression ## Step-by-Step Surgical Technique ### Step 1: Positioning and Level Confirmation **Patient Positioning** - Prone on Jackson table, Wilson frame, or chest rolls - **ABDOMEN MUST BE FREE** - critical for reducing epidural venous pressure by 50% - Hips extended to reduce lumbar lordosis (easier posterior access) - Padding all pressure points: knees, genitals, breasts, face, eyes - Arms on arm boards <90° abduction or tucked at sides - Head in neutral position (avoid rotation) **Level Confirmation** - AP and lateral fluoroscopy BEFORE skin incision - Count from SACRUM upward (L5-S1, L4-L5, L3-L4...) - Mark spinous processes with marking pen - Wrong-level surgery is a NEVER EVENT (0.5-1% incidence) - Document fluoroscopic images in operative record **Exam Answer**: "Prone positioning with abdomen hanging free is CRITICAL - reduces epidural venous pressure and bleeding by 50%. I confirm the correct level with AP and lateral fluoroscopy BEFORE skin incision, counting from the sacrum upward. Wrong-level surgery is a never event that is entirely preventable with proper imaging." - Wrong-level surgery (0.5-1% incidence) - MUST confirm with fluoro - Pressure injuries (especially face, eyes, genitals) - Visual loss (rare, from prolonged prone position or hypotension) - Brachial plexus injury (arm abduction >90°) - Abdominal compression increases bleeding ### Step 2: Midline Incision and Subperiosteal Exposure **Skin Incision** - Midline longitudinal incision centered over target spinous processes - 8-12cm for single level, longer for multi-level - Through skin, subcutaneous tissue, thoracolumbar fascia in midline **Subperiosteal Dissection** - Incise fascia in midline (relatively avascular) - Elevate paraspinal muscles SUBPERIOSTEALLY off spinous processes, laminae, and facets - Use monopolar cautery to release muscle attachments - Expose laterally to transverse processes bilaterally - Preserve posterior ligamentous complex (supraspinous, interspinous ligaments) at adjacent levels **Retractor Placement** - Self-retaining retractors (Taylor, McCullough, Cerebellar) - Identify anatomic landmarks: spinous processes, laminae, facets, transverse processes - Adequate exposure for instrumentation and decompression **Exam Answer**: "Midline approach is relatively avascular. I perform strict SUBPERIOSTEAL dissection to preserve the segmental nerve supply to paraspinal muscles and reduce denervation-related postoperative pain. I preserve the posterior ligamentous complex at adjacent levels to prevent iatrogenic instability." - Excessive muscle stripping = denervation, chronic postop pain - Violation of adjacent level facets or ligaments = iatrogenic instability - Bleeding from muscle if not subperiosteal - Loss of anatomic landmarks ### Step 3: Pedicle Screw Insertion **Entry Point Identification (Magerl Point)** - Junction of: - Lateral border of superior articular facet - Base (junction) of transverse process - Decorticate entry point with burr or curette **Trajectory** - 10-15° medial angulation (more convergent: 20° at L5) - Parallel to superior endplate on lateral fluoroscopy - "Gear-shift" trajectory - rotate, not just push **Pedicle Preparation** - Use awl or starting pedicle probe to penetrate posterior cortex - Advance with gentle rotation ("gear-shift" technique) - Feel for breakthrough - should be smooth resistance - Depth: to anterior 1/3 of vertebral body (35-45mm typical) **5-Wall Probing Technique - CRITICAL** - Use ball-tip pedicle probe - Palpate ALL 5 walls: 1. Medial wall (MOST DANGEROUS - neural canal) 2. Lateral wall (psoas, less critical) 3. Superior wall (superior disc space) 4. Inferior wall (inferior disc space) 5. Anterior floor (vertebral body, great vessels) - All walls must be INTACT (solid cortical bone) - If breach detected - redirect or use shorter screw **Screw Insertion** - Tap pedicle if dense bone (optional in osteoporotic bone) - Insert appropriately sized screw (6-8mm diameter, 35-50mm length) - 80% vertebral body depth is safe - Confirm with AP and lateral fluoroscopy - Screw head should be positioned for rod placement **Exam Answer**: "Entry point is the Magerl point - junction of transverse process base and lateral superior facet. I use a 10-15° medial trajectory, parallel to the endplate. CRITICAL STEP: I probe and palpate ALL FIVE WALLS before screw insertion - medial, lateral, superior, inferior, and anterior floor. All must be intact. Medial breach is most dangerous as it violates the neural canal." - Medial breach (5-10%): neural injury, dural tear - MOST DANGEROUS - Lateral breach: into psoas, less critical but weakens fixation - Superior/inferior breach: disc space violation - Anterior breach: great vessels (aorta at L4, IVC, iliac vessels) - Screw too long: anterior cortex perforation, vascular injury ### Step 4: Laminectomy **Spinous Process Removal** - Remove spinous process at operative levels with rongeur - Save bone for local autograft **Bilateral Laminectomy** - Use Kerrison rongeurs (various angles) or high-speed burr - Remove lamina bilaterally from medial pedicle to medial pedicle - Create adequate exposure of dural sac - Thinning technique: thin lamina with burr, then remove with rongeur (safer) **Ligamentum Flavum Removal - CRITICAL TECHNIQUE** - **ALWAYS identify UNDER surface first** (safer approach) - Use Woodson elevator to define plane between ligamentum flavum and dura - Dura is 2-3mm anterior to ligamentum flavum - Incise ligamentum flavum laterally, then peel off medially - Work lateral to medial to progressively visualize dura - Bilateral removal for central stenosis **Decompression Assessment** - Adequate central canal decompression - Should see CSF pulsations transmitted to dura - Dural sac should be decompressed and mobile **Exam Answer**: "The SAFEST technique for ligamentum flavum removal is to identify the UNDER surface first with a Woodson elevator before cutting. This defines the plane anterior to the ligamentum and protects the dura. I then work lateral to medial, progressively exposing the dural sac. Cutting from superficial to deep is dangerous and risks dural tear." - Dural tear (5-15% incidence, higher in revision surgery) - Nerve root injury in lateral recess - Epidural venous bleeding (Batson's plexus) - Inadequate decompression - Excessive bone removal = instability ### Step 5: Foraminotomy and Nerve Root Decompression **Lateral Recess Decompression** - Remove medial portion of superior articular facet (medial facetectomy) - Use Kerrison rongeur or burr - LIMIT to <50% facet resection (>50% = iatrogenic instability) - Decompress both EXITING and TRAVERSING nerve roots **Nerve Root Identification** - At L4-L5 level: - **EXITING L4 root**: passes laterally under L4 pedicle in foramen - **TRAVERSING L5 root**: descends medially, will exit at L5-S1 - Both roots must be identified and decompressed **Foraminotomy** - Undercut superior articular process of caudal vertebra (L5 at L4-L5) - Remove ligamentum flavum from foramen - Decompress exiting nerve root in foramen - Root should be mobile, free, and pulsating with CSF **Adequacy Check** - Pass instrument (e.g., Penfield or ball-tip probe) around nerve root - Root should be completely free circumferentially - CSF pulsations visible - No residual compression **Exam Answer**: "At L4-L5, I must decompress TWO nerve roots: the EXITING L4 root passing laterally under the L4 pedicle, and the TRAVERSING L5 root descending medially. I perform medial facetectomy to decompress the lateral recess, limiting resection to <50% to avoid iatrogenic instability. The root should be completely mobile and pulsating with CSF when adequately decompressed." - Nerve root injury from traction or direct trauma - Excessive facetectomy (>50%) = iatrogenic instability - Pars interarticularis fracture - Inadequate decompression = persistent symptoms - Dural tear at root sleeve ### Step 6: Fusion Bed Preparation **Decortication** - Remove soft tissue from transverse processes - Decorticate transverse processes with osteotome or high-speed burr - Remove cortical surface to expose bleeding cancellous bone - Decorticate remaining facet surfaces - Creates posterolateral fusion bed (transverse process to transverse process) **Fusion Surface** - Bilateral intertransverse fusion gutters - Adequate bleeding bone surface - Remove all soft tissue that could block fusion **Exam Answer**: "Posterolateral fusion is the classic lumbar fusion technique - transverse process to transverse process bilaterally. I decorticate with a burr until I see bleeding cancellous bone. The quality of the fusion bed is critical for achieving solid arthrodesis. Local autograft from removed lamina is ideal because it's osteogenic, osteoinductive, osteoconductive, and has no donor site morbidity." - Inadequate decortication = pseudarthrosis - Excessive lateral dissection = segmental vessel injury - Violation of disc space ### Step 7: Bone Graft Application **Local Autograft** - Use removed lamina, spinous processes, and facets - Morselized into 3-5mm pieces - Excellent graft material: osteogenic, osteoinductive, osteoconductive - No donor site morbidity **Graft Placement** - Pack generously into bilateral intertransverse gutters - Place on decorticated transverse processes and facets - Should fill fusion bed completely - Typically 10-20cc per level **Supplemental Graft (if needed)** - Allograft (cancellous chips or DBM) - Iliac crest autograft (if local insufficient, e.g., >2 levels) - BMP (rhBMP-2) - expensive, risk of ectopic bone formation, radiculopathy, use with caution **Fusion Rate Expectations** - Posterolateral-only fusion: 80-85% at 1 year - Instrumented posterolateral fusion: 85-95% at 1 year - Adding interbody cage: 95%+ at 1 year **Exam Answer**: "Local autograft from the removed lamina and spinous processes is the IDEAL graft material - it's osteogenic (contains cells), osteoinductive (contains growth factors), osteoconductive (provides scaffold), and has no donor site morbidity. I pack it generously into the intertransverse gutters. Fusion rates with instrumented posterolateral fusion are 85-95% at one year." - Inadequate graft volume = pseudarthrosis (10-15% posterolateral-only) - BMP overuse = ectopic bone formation, radiculopathy, seroma - Graft displacing into canal = nerve compression - Iliac crest harvest = donor site pain, hematoma, infection ### Step 8: Rod Placement and Final Construct **Rod Contouring** - Contour rods to restore physiological lumbar lordosis (typically 40-60°) - Match patient's sagittal alignment - Avoid flat-back deformity **Rod Insertion** - Insert pre-contoured rods into pedicle screw heads - May require slight screw head adjustment - Ensure rod fully seated in screw heads **Compression/Distraction** - Compression across spondylolisthesis (reduces slip, compresses graft) - Distraction for foraminal height restoration (carefully - can overdistract) - Typically 1-2mm compression per level **Final Tightening** - Tighten all set screws with appropriate torque - Avoid over-torque (can strip threads) - Check construct stability - Cross-links optional (I use for long constructs >3 levels) **Fluoroscopic Confirmation** - AP view: screws within pedicle shadows, rod position - Lateral view: lordosis restored, screw depth, construct alignment **Exam Answer**: "I contour rods to restore physiological lordosis. Compression across the spondylolisthesis helps reduce the slip and compresses the graft for fusion. I ensure all set screws are adequately tightened - loose screws cause construct failure. Final fluoroscopy confirms screw position, lordosis restoration, and overall alignment." - Loss of lordosis = sagittal imbalance, flat-back syndrome - Over-compression = nerve root impingement - Under-tightening = construct failure, screw loosening - Rod too short/long = junctional problems - Screw head prominence = soft tissue irritation ### Step 9: Final Decompression Assessment **Central Canal** - Pass instrument behind dura easily - No residual compression - CSF pulsations visible **Nerve Roots** - All roots free and mobile - Pulsating with CSF - Can pass instrument around roots (360° free) **No Construct Compression** - Ensure graft not compressing neural elements - Screw heads not impinging on roots **Fluoroscopic Assessment** - Lateral view confirms adequate decompression - No residual stenosis on imaging **Exam Answer**: "Before closure, I perform a final systematic check: central canal adequately decompressed, all nerve roots completely free and pulsating, no compression from graft or hardware. Inadequate decompression is the main reason for failed surgery. The roots should be mobile with visible CSF pulsations." - Inadequate decompression = persistent symptoms - Graft in canal = nerve compression - Hardware impingement on roots - Unrecognized dural tear ### Step 10: Hemostasis and Dural Tear Management **Hemostasis** - METICULOUS bipolar cautery for epidural veins - Gelfoam for persistent oozing - Avoid aggressive cautery near nerve roots - Patient should be normotensive - Achieve complete hemostasis before closure **Dural Tear Recognition** - Look for CSF egress - Visible defect in dura - STOP if identified **Dural Tear Repair - Critical Skill** **Small Tear (<5mm, accessible)** - PRIMARY REPAIR with 4-0 or 5-0 non-absorbable suture (Prolene, Nurolon) - Running or interrupted technique - Watertight closure - Test with Valsalva maneuver - Cover with DuraSeal or fibrin glue **Large Tear (>5mm) or Accessible** - PATCH REPAIR with dural graft: - Cadaveric dura - Synthetic (DuraGen, Durepair) - Autologous fascia (rare) - Suture if possible, seal edges with fibrin glue - Test integrity with Valsalva **Inaccessible Tear (Anterior Dura)** - Cannot primarily repair - Apply fibrin glue only - Tight fascial closure - Bed rest 24-48 hours postop - No lumbar drain (controversial, I avoid due to infection risk) **Post-Repair Management** - DOCUMENT in operative report - Counsel patient about CSF leak risk - Drain controversial (may increase leak, I avoid if good repair) - Bed rest 24-48hrs if large tear - Monitor for postop headache, CSF leak signs **Exam Answer**: "If I identify a dural tear intraoperatively, I assess size and accessibility. Small accessible tears are repaired primarily with 4-0 or 5-0 non-absorbable suture and tested with Valsalva. Large or inaccessible tears get fibrin glue and tight fascial closure. I document the tear, counsel the patient, and typically avoid drains as they may increase CSF leak risk. Bed rest for 24-48 hours postoperatively." - Unrecognized dural tear = CSF leak, pseudomeningocele, meningitis - Inadequate hemostasis = epidural hematoma, cauda equina syndrome - Drain with dural tear = persistent CSF leak - Excessive cautery near roots = nerve injury ### Step 11: Wound Closure **Irrigation** - Copious irrigation with normal saline or antibiotic solution - 3-6 liters typical - Remove all debris and bone dust **Fascial Closure - CRITICAL LAYER** - Close thoracolumbar fascia with 0 or 1 Vicryl - Strong absorbable sutures - Interrupted or running technique - MUST be watertight, especially if dural tear - This layer bears most tension **Subcutaneous Layer** - 2-0 or 3-0 Vicryl - Eliminate dead space - Reduce seroma risk **Skin Closure** - Staples (most common, easy removal) - Running subcuticular (better cosmesis) - Interrupted sutures **Drain Placement (Optional)** - Subfascial drain for multilevel or significant bleeding - I use Blake or Jackson-Pratt drain - Remove when <30ml over 8 hours (typically 24-48hrs) - Controversial if dural tear (may increase CSF leak) **Exam Answer**: "Fascial closure is the CRITICAL layer - it must be watertight, especially if there was a dural tear. I use strong absorbable sutures (0 or 1 Vicryl). Drain placement is controversial - it may reduce hematoma but slightly increases infection risk. I use drains for multilevel cases or significant bleeding, and remove at 24-48 hours when output <30ml/8hrs." - Inadequate fascial closure = wound dehiscence - Wound hematoma = infection risk, dehiscence - Drain with dural tear = CSF leak - Surgical site infection (1-5% in spine surgery) ## Complications of PLDF ### Additional Complications **Wrong-Level Surgery (0.5-1%)** - Prevent with preop and intraop fluoroscopy, count from sacrum, mark skin, TIME-OUT - Management: immediate reoperation at correct level, document fully, disclose to patient **Hardware Failure** - Screw breakage (stress fracture from pseudarthrosis or under-sized screw) - Rod breakage (usually at connector or contour point) - Management: revision if symptomatic or progressive deformity **Junctional Problems** - Proximal junctional kyphosis (PJK): kyphosis at upper end of construct - Prevent: avoid over-correction, include UIV+1 if osteoporotic - Management: extension of fusion if symptomatic ## Postoperative Management ### Immediate Postoperative (0-24 hours) **Recovery Room** - Neuro checks every 2 hours (motor, sensory, reflexes) - Monitor drain output - Pain control: IV opioids initially, transition to oral - Log-roll only for 24-48hrs **Red Flags - Immediate Action** - New motor deficit (foot drop, paralysis) → MRI urgently (hematoma vs screw malposition) - Saddle anesthesia, urinary retention → cauda equina → OR immediately - Excessive drain output (>200ml/hr) → bleeding - Clear wound drainage → CSF leak ### Early Postoperative (1-7 days) **Mobilization** - Mobilize day 0-1 with physiotherapy (unless dural tear - bed rest 24-48hrs) - Log-roll technique for getting in/out of bed initially - Gradual increase in ambulation - NO bending, lifting >5kg, twisting (BLT restriction) **Drain Management** - Remove when output <30ml over 8 hours - Typically 24-48 hours - Monitor for CSF if dural tear repaired **Discharge Planning** - Typically discharge day 2-4 for uncomplicated single-level - Multilevel may stay 4-7 days - Discharge criteria: ambulating independently, pain controlled on oral meds, no complications **Discharge Instructions** - NO BLT (bending, lifting >5kg, twisting) for 3 months - Wound care: keep dry for 2 weeks, no submersion - Activity: walk regularly, increase distance gradually - Red flags: new weakness, numbness, bowel/bladder dysfunction, fever, wound drainage ### Rehabilitation (Weeks 2-12) **Bracing** - Controversial for instrumented fusion - I do NOT routinely brace for instrumented single or 2-level PLDF - May consider for osteoporotic bone, obesity, or non-compliance risk - If used: rigid TLSO, wear for 6-12 weeks **Physical Therapy** - Start gentle ROM exercises week 2-4 - Core strengthening at 6-8 weeks - Avoid flexion exercises (increase load on anterior column) - Focus on neutral spine postures **Activity Progression** - Weeks 0-6: walking only, no BLT - Weeks 6-12: gradual increase activities, start PT - 3 months: may resume light activities, driving - 6 months: return to full activity if fusion progressing **Return to Work** - Desk work: 6-12 weeks - Light physical work: 3-4 months - Heavy labor: 6-12 months (when fusion solid) ### Long-term Follow-up and Fusion Assessment **Clinic Visits** - 2 weeks: wound check, remove staples - 6 weeks: X-rays (AP, lateral, flexion-extension) - 3 months: X-rays, assess progress - 6 months: X-rays - 12 months: CT scan to assess fusion **Radiographic Assessment** - X-rays: maintenance of alignment, hardware position, no loosening (halo sign) - Flexion-extension at 12 months: <3mm motion = fused - CT at 12 months: GOLD STANDARD for fusion assessment - Bridging bone across fusion bed - Solid bony bridge = successful fusion **Fusion Criteria (CT at 12 months)** - Bilateral posterolateral fusion: bone bridge from TP to TP - Grade A: solid bilateral fusion - Grade B: unilateral solid fusion - Grade C: questionable fusion - Grade D: non-union (no bridging bone) **Management of Pseudarthrosis** - Asymptomatic: observe - Symptomatic (mechanical back pain): revision fusion with interbody support (TLIF) ### Medications **Pain Management** - Acute (weeks 0-6): opioids short-term, NSAIDs controversial (may impair fusion), paracetamol - Neuropathic pain: gabapentin or pregabalin for radicular symptoms - Transition to non-opioids by 6 weeks **Bone Health** - Vitamin D supplementation (target >75 nmol/L) - Calcium 1200mg daily - Smoking cessation (CRITICAL) - Bisphosphonates controversial (may impair fusion, stop 3-6 months) **Thromboprophylaxis** - Risk-based approach - Low risk: early mobilization, compression stockings - High risk (age >60, obesity, previous VTE): enoxaparin or rivaroxaban for 10-14 days ## References 1. Weinstein JN, Lurie JD, Tosteson TD, et al. Surgical compared with nonoperative treatment for lumbar degenerative spondylolisthesis. Four-year results in the Spine Patient Outcomes Research Trial (SPORT) randomized and observational cohorts. J Bone Joint Surg Am. 2009;91(6):1295-1304. PMID: 19487505. *Landmark RCT showing fusion + decompression superior to decompression alone for degenerative spondylolisthesis at 4-year follow-up* 2. Ghogawala Z, Dziura J, Butler WE, et al. Laminectomy plus fusion versus laminectomy alone for lumbar spondylolisthesis. N Engl J Med. 2016;374(15):1424-1434. PMID: 27074067. *RCT demonstrating superiority of fusion + decompression vs decompression alone for Grade I degenerative spondylolisthesis* 3. Forsth P, Ólafsson G, Carlsson T, et al. A randomized, controlled trial of fusion surgery for lumbar spinal stenosis. N Engl J Med. 2016;374(15):1413-1423. PMID: 27074066. *Showed no significant difference between decompression alone vs decompression + fusion for spinal stenosis WITHOUT spondylolisthesis at 2 years* 4. Abdu WA, Lurie JD, Spratt KF, et al. Degenerative spondylolisthesis: does fusion method influence outcome? Four-year results of the spine patient outcomes research trial. Spine. 2009;34(21):2351-2360. PMID: 19934809. *SPORT substudy comparing posterolateral vs interbody fusion techniques* 5. Chou R, Baisden J, Carragee EJ, et al. Surgery for low back pain: a review of the evidence for an American Pain Society Clinical Practice Guideline. Spine. 2009;34(10):1094-1109. PMID: 19363455. *Evidence-based guidelines for surgical management of degenerative lumbar spine conditions* 6. Gertzbein SD, Robbins SE. Accuracy of pedicular screw placement in vivo. Spine. 1990;15(1):11-14. PMID: 2326693. *Classic study defining pedicle screw breach rates and classification system* 7. Kim YJ, Bridwell KH, Lenke LG, et al. Pseudarthrosis in long adult spinal deformity instrumentation and fusion to the sacrum: prevalence and risk factor analysis of 144 cases. Spine. 2006;31(20):2329-2336. PMID: 16985461. *Analysis of pseudarthrosis risk factors including smoking, fusion technique, and construct rigidity* 8. Wang JC, Bohlman HH, Riew KD. Dural tears secondary to operations on the lumbar spine. Management and results after a two-year-minimum follow-up of eighty-eight patients. J Bone Joint Surg Am. 1998;80(12):1728-1732. PMID: 9875930. *Long-term outcomes of incidental durotomy management strategies* 9. Magerl FP. Stabilization of the lower thoracic and lumbar spine with external skeletal fixation. Clin Orthop Relat Res. 1984;189:125-141. PMID: 6478690. *Describes the Magerl point for pedicle screw entry and technique* 10. Martin BI, Mirza SK, Spina N, et al. Trends in lumbar fusion procedure rates and associated hospital costs for degenerative spinal diseases in the United States, 2004 to 2015. Spine. 2019;44(5):369-376. PMID: 30074971. *Epidemiology and trends in lumbar fusion surgery, cost analysis, and utilization patterns*

Posterior Lumbar Decompression and Fusion (PLDF)

Posterior Lumbar Decompression and Fusion (PLDF)