High Yield Overview

ANTERIOR CERVICAL DISCECTOMY & FUSION (ACDF)

Gold standard surgical approach for cervical degenerative disease with neural compression - Smith-Robinson technique with contemporary instrumentation | intermediate

Five Critical Anatomical Danger Zones

Recurrent Laryngeal Nerve

Location: Travels in tracheoesophageal groove - RIGHT side more vulnerable (loops under subclavian at T1-2, ascends obliquely). LEFT side loops predictably under aortic arch.

Protection: Left-sided approach preferred. Avoid retractor placement in tracheoesophageal groove. Endotracheal tube pressure monitoring - deflate/reposition q30min. Intraoperative neuromonitoring if revision/multilevel surgery.

Superior Laryngeal Nerve

Location: Exits vagus at C3 level, travels deep to carotid to pierce thyrohyoid membrane. At risk with high approaches (C3-4, C2-3) or excessive superior retraction.

Protection: Dissect only to level of surgical exposure required. Gentle superior retraction with handheld Cloward retractors. Avoid monopolar diathermy near carotid sheath above C4.

Vertebral Artery

Location: Enters transverse foramen C6 (90%) or C5 (8%). Courses 3mm lateral to uncovertebral joint. Anomalous course in 5% (medial deviation).

Protection: Limit lateral dissection to medial border of uncinate process. Preoperative CTA if revision surgery or dysplastic anatomy. Angled curettes directed medially only. Uncovertebral drilling with 3mm diamond burr at 45° trajectory.

Spinal Cord

Location: Average AP diameter cervical canal 14mm (range 10-20mm). Cord occupies 12mm - CSF 1mm anterior. Stenotic canal means minimal safety margin with instruments.

Protection: Decompress lateral-to-medial sequence. Kerrison rongeurs bite away from cord (upbiting). Trial spacer before final implant - oversizing risks cord compression. Intraoperative SSEPs/MEPs for stenotic canals or ossification of PLL.

Esophagus

Location: Immediately medial to dissection plane. Thin wall (3mm) highly vulnerable to retractor pressure, diathermy thermal injury, or sharp dissection.

Protection: Handheld retraction initially until NG tube palpated. Smooth blade retractors (not teeth). Retract esophagus gently medially - limit pressure (60-80mmHg max). Irrigate frequently. Bipolar only near midline. Methylene blue swallow test if concern.

Mnemonic

POETSACDF Approach Layers - 'POETS'

Mnemonic

DUBSACDF Decompression Sequence - 'DUBS'

Primary Indications

Absolute Indications

Progressive cervical myelopathy with cord compression (modified JOA score decline)
Cervical radiculopathy failing 6-12 weeks conservative management with MRI-confirmed nerve root compression
Cervical kyphotic deformity with anterior column deficiency requiring reconstruction
Post-traumatic cervical instability (facet disruption, ALL/disc injury) requiring stabilization
Anterior cervical tumor/infection requiring corpectomy and reconstruction

Relative Indications

Cervical radiculopathy with concordant imaging and high-demand occupation
Multilevel cervical spondylosis with predominant axial neck pain (controversial - consider arthroplasty)
Soft disc herniation with persistent radicular symptoms despite optimized non-operative care
Adjacent segment disease following prior cervical fusion

Contraindications

Absolute: Active systemic infection, severe osteoporosis (DEXA T-score less than -3.5), medical instability
Relative: Multilevel disease (greater than 3 levels - consider hybrid constructs), smoker (2.7x pseudarthrosis risk), significant dysphagia baseline, ankylosing spondylitis (avoid through fused segments)

Preoperative Planning Essentials

Imaging Analysis

MRI: T2 signal changes in cord (myelomalacia poor prognosis), disc hydration, foraminal stenosis grade
CT: Assess ossification of PLL (40% Asian population), uncovertebral hypertrophy, facet arthropathy
Flexion-extension radiographs: Document instability (greater than 3mm translation or greater than 11° angulation)
CTA: If revision surgery (scar tissue distorts anatomy) or vascular anomaly suspected

Patient Optimization

Smoking cessation 8 weeks minimum (proven 3x fusion rate improvement)
Diabetic HbA1c less than 7.5% (wound healing, infection risk reduction)
BMI optimization - obesity associated with higher dysphagia, revision rates
Discontinue NSAIDs 1 week preoperatively (theoretical fusion concern)

Graft and Instrumentation Selection

Autograft iliac crest: Gold standard fusion (98% single-level) but donor site pain 20%
Allograft structural: Equivalent fusion with anterior plating (95% vs 98%), no donor morbidity
PEEK cage with demineralized bone matrix: Contemporary standard - subsidence risk 5-8%
Anterior cervical plate: Reduces pseudarthrosis 3-level from 44% to 8%, angular kyphosis
Zero-profile devices: Standalone cage with integrated screws - lower dysphagia (12% vs 28% at 3 months)

Positioning and Preparation

Patient Position

Supine with shoulder roll to extend neck (improve lordosis, open disc spaces)
Head in neutral rotation (avoid rotation - distorts anatomy, stretches vertebral artery)
Slight reverse Trendelenburg (reduce venous pressure, improve exposure)
Arms tucked, secured at sides with padding (allow lateral C-arm access)
Gardner-Wells tongs or horseshoe headrest for controlled extension (optional)

Approach Side Selection

Left side preferred: Recurrent laryngeal nerve more predictable course (1-2% injury vs 5-8% right)
Right side considerations: Surgeon left-handed, prior left neck surgery/radiation, thyroid pathology
Bilateral approach: Reserved for very wide corpectomies or tumor extirpation

Imaging and Localization

C-arm positioned on patient's right (surgeon operates from right side for left approach)
Scout lateral radiograph confirms level - count from C2 (axis, prominent spinous process)
Skin marker (21G needle) at desired level - adjust incision accordingly

Step-by-Step Operative Technique

Step 1: Skin Incision and Platysma Division

Transverse skin incision along Langer lines (skin crease) 4-5cm length centered over palpated disc level. Single-level: 4cm. Two-level: 5cm. Incise through dermis with 15-blade knife. Infiltrate with 1:200,000 epinephrine in local anesthetic for hemostasis. Divide platysma in line with muscle fibers (oblique/vertical) using monopolar cautery. Subplatysmal flaps raised superiorly and inferiorly 1cm using Metzenbaum scissors to improve exposure.

Exam Pearl

Technical Pearl: Transverse incision provides superior cosmesis and extensile exposure for 2-3 levels from single incision. Place incision at mid-level for two-level surgery (i.e., C5-6 incision for C5-7 fusion). Avoid placement at exact disc level - this limits inferior extension.

Dangers at this step

External jugular vein injury (courses obliquely across SCM) - ligate if divided
Anterior jugular veins (medial to SCM) - preserve or ligate branches
Overly vertical incision risks keloid formation, poor cosmesis

Step 2: Deep Cervical Fascia Division and Blunt Dissection

Palpate SCM lateral border and carotid pulsation. Divide investing layer of deep cervical fascia along medial border of SCM using knife or scissors. Identify correct tissue plane between carotid sheath (laterally, pulsatile) and visceral column (medially, trachea palpable). Insert index finger bluntly between these structures and develop plane with gentle spreading - structures separate easily in correct plane. Finger sweeps superiorly and inferiorly opening space to vertebral bodies. Omohyoid muscle (crossing obliquely at C5-6) retracted superiorly or divided between clips if obstructing.

Exam Pearl

Technical Pearl: Blunt dissection with finger is SAFEST - respects natural tissue planes and warns of aberrant anatomy. If plane is difficult, likely too anterior (in strap muscles) or too lateral (against carotid). Correct plane is essentially bloodless. Thyroid vessels (superior thyroid artery at C4-5, middle thyroid vein at C6) may cross midline - ligate with clips or bipolar.

Dangers at this step

Recurrent laryngeal nerve injury (in tracheoesophageal groove) - NEVER retract in midline
Sympathetic chain (on prevertebral fascia lateral) - injury causes Horner syndrome
Esophageal perforation - excessive force during medial retraction

Step 3: Longus Colli Muscle Dissection and Retractor Placement

Palpate anterior surface of vertebral bodies and midline. Incise prevertebral fascia vertically in midline using monopolar cautery. Elevate longus colli muscles bilaterally off anterior vertebral bodies using monopolar or Cobb elevator - detach 1.5cm bilaterally to allow retractor blade placement. Self-retaining retractors (Caspar or Cloward) with deep blades (15mm) placed under longus colli bilaterally - sharp teeth engage vertebral bodies above and below operative level. Adjust retractors to center disc space in field. Gentle medial retraction of esophagus with smooth blade (Army-Navy or Cloward handheld retractor).

Exam Pearl

Technical Pearl: Longus colli dissection defines SAFE LATERAL LIMITS - do not extend past this boundary or risk vertebral artery injury. Retractor blade teeth should engage vertebral body bone, not disc space (risks retractor migration, spinal cord injury). Test retractor stability before proceeding. Monitor retractor pressure on esophagus - deflate endotracheal cuff intermittently to reduce total compression.

Dangers at this step

Vertebral artery injury (lateral to longus colli 3mm) - torrential bleeding, stroke risk
Spinal cord injury (retractor blade slips posteriorly through disc) - catastrophic
Esophageal pressure necrosis (excessive retraction pressure greater than 120 minutes) - delayed perforation

Step 4: Localization Radiograph

Insert 21G spinal needle into center of disc space under direct vision - angle slightly caudad to stay parallel with disc. Obtain lateral C-arm radiograph confirming correct level. Count vertebrae from C2 (axis). If incorrect level identified, reposition retractors. Mark operative level with cautery scratch on vertebral body for reference. Remove needle.

Exam Pearl

Technical Pearl: Wrong-level surgery is NEVER EVENTS. Count from C2 proximally (easily identified on lateral) and C7 (first vertebra below shoulder) distally - triangulate. C3-4 and C4-5 look similar radiographically. Save image as documentation. If any doubt, obtain AP view (lateral masses numbered).

Dangers at this step

Wrong-level surgery (medicolegal catastrophe) - systematic verification mandatory
Needle penetration through disc into canal - keep insertion superficial (3-4mm)

Step 5: Anterior Discectomy

Mark rectangular window in anterior annulus with cautery - 14mm width (vertebral body width minus 2mm each side), 6mm height. Incise anterior annulus with 15-blade knife, creating 3-sided flap hinged inferiorly (or excise completely). Use pituitary rongeurs to remove nucleus pulposus sequentially - grasp and twist to extract disc fragments. Work centrally initially, then laterally and posteriorly. Remove cartilaginous endplates with angled curettes (20° and 30°) to expose bleeding subchondral bone (essential for fusion). Preserve subchondral bone plate integrity - overly aggressive curettage risks subsidence.

Exam Pearl

Technical Pearl: Complete discectomy to POSTERIOR ANNULUS is critical. Insert ball probe through disc space to confirm posterior annulus palpable circumferentially. Incomplete discectomy leads to persistent symptoms and lower fusion rates. Angled curettes should scrape parallel to endplates - perpendicular force risks breach into vertebral body or canal.

Dangers at this step

Vertebral artery injury (overaggressive lateral discectomy beyond uncinate) - direct pressure, vascular consult
Endplate violation (excessive curettage) - graft subsidence, kyphosis, pseudarthrosis
Retained disc fragments (incomplete discectomy) - radiculopathy persistence

Step 6: Posterior Osteophyte Removal and Neural Decompression

Identify posterior longitudinal ligament (PLL) - white glistening band visible posteriorly. Using 2mm Kerrison rongeurs, resect posterior osteophytes (spondylophytes) from posterior vertebral body above and below. Bite bone with upbiting technique (rongeur jaws face away from spinal cord). For uncovertebral osteophytes (lateral spurs compressing nerve root in foramen), use 3mm diamond burr at 45° angle directed medially - drill under direct vision, protect vertebral artery (3mm lateral). Copious irrigation removes bone dust. Neural foramen adequately decompressed when ball probe passes freely into foramen bilaterally.

Exam Pearl

Technical Pearl: Posterior decompression is RATE-LIMITING STEP for symptom relief. For myelopathy, resect PLL midline to visualize dural pulsations (confirms adequate decompression). For radiculopathy, foraminotomy to "see blue sky" (epidural veins visible when nerve free). Avoid pituitary rongeurs posteriorly - risks dural tear or cord injury. High-speed diamond burr safer than cutting burr (less aggressive).

Dangers at this step

Spinal cord injury (Kerrison bites cord) - upbiting technique mandatory, never downbite
Dural tear (overly aggressive PLL resection) - repair primarily, CSF leak risk
Vertebral artery injury (lateral foraminotomy) - limit drilling to medial half of foramen
Nerve root injury (foraminotomy) - instrument away from nerve, copious irrigation

Step 7: Distraction and Disc Space Preparation

Insert vertebral body spreader (Caspar distractor pins) into vertebral bodies 2cm lateral to midline (in safe zone medial to uncinate). Gradually distract disc space 1-2mm to restore disc height and tension ligaments. This improves visualization posteriorly and foraminal height. Measure disc space height (anterior, middle, posterior) with calibrated trial spacers. Prepare endplates with curettage ensuring parallel surfaces - remove all cartilage to bleeding bone. Morselized local bone from osteophytes placed in disc space as graft.

Exam Pearl

Technical Pearl: Distraction should restore normal disc height (5-6mm at C5-6), not exceed physiologic height (risks facet distraction, ASD). Measure at anterior and posterior disc space - select graft 1mm larger than posterior measurement to restore lordosis (2-4° per level). Parallel endplates prevent subsidence and kyphosis. Over-distraction risks C5 palsy (nerve root tethering) - limit to 2mm.

Dangers at this step

C5 nerve palsy (excessive distraction tethers root) - rare but devastating complication 5%
Facet violation (over-distraction fractures facets) - instability, pain
Vertebral body fracture (distractor pin placement too lateral) - osteoporotic bone at risk

Step 8: Interbody Graft or Cage Placement

Select appropriately sized graft: structural allograft, autograft (iliac crest), or interbody cage (PEEK, titanium). For structural graft, fashion cortical-cancellous block 1mm larger than measured height, width to fill disc space (14mm typically). Contour lordotic angle 4-6° with rongeur or burr. For cage, pack with morselized autograft (local bone) or DBM. Insert graft under direct vision with impactor - central position in disc space verified. Graft should sit flush with anterior vertebral cortex or recessed 2mm. Remove distractor pins - graft should be stable with ligamentotaxis compression.

Exam Pearl

Technical Pearl: Graft sizing is CRITICAL - undersized graft migrates (extrusion, pseudarthrosis), oversized graft causes cord compression or endplate fracture. Final implant should restore disc height and lordosis without excessive distraction. Stand-alone cages require 6° lordotic angle to prevent subsidence. Anterior position (flush to cortex) increases extrusion risk but improves lordosis; recessed position (2mm) reduces swelling but risks kyphosis.

Dangers at this step

Graft extrusion (undersized or anterior positioned) - dysphagia, esophageal erosion
Spinal cord compression (oversized graft) - immediate quadriparesis, emergency removal
Graft subsidence (endplate violation, osteoporosis) - kyphosis, pseudarthrosis
Vertebral artery injury (graft migrates laterally) - rare catastrophic complication

Step 9: Anterior Cervical Plate Fixation (if used)

Select appropriate plate length - spans one vertebral body above to one below (single-level). Position plate in midline over graft, touching superior endplate (within 5mm of disc space). Mark screw trajectories with AWL - 4 screws (2 per vertebra) positioned 3-4mm from endplate, 2mm from lateral edge. Drill pilot holes with 14mm drill guide - trajectory 12-15° caudad (away from adjacent disc). Measure depth with depth gauge. Insert self-tapping fixed-angle or variable-angle screws (typically 14mm length). Tighten screws sequentially to desired torque (8-10 Nm). Confirm bicortical purchase but not excessive length (greater than 18mm risks canal penetration). Locking screws prevent backout.

Exam Pearl

Technical Pearl: Plate positioning is TECHNICAL KEY - too close to disc (less than 5mm) causes dysphagia from soft tissue impingement, too far (greater than 5mm) reduces stability. Screw trajectory must angle AWAY from adjacent disc (cranial screws angle cranially, caudal screws angle caudally) to prevent violation. Variable-angle screws accommodate kyphotic deformity. Zero-profile devices (cage with integrated screws) have 50% lower dysphagia rates at 3 months - consider for C5-6, C6-7.

Dangers at this step

Screw malposition (anterior blow-out) - esophageal injury, catastrophic bleeding if vertebral artery
Screw penetration into disc (wrong trajectory) - adjacent segment degeneration
Spinal canal penetration (excessive screw length) - cord injury, CSF leak
Plate prominence (greater than 3mm from bone) - dysphagia, esophageal erosion

Step 10: Intraoperative Imaging Confirmation

Obtain lateral C-arm fluoroscopy confirming: (1) Correct level, (2) Graft position within disc space, (3) Restoration of disc height and lordosis, (4) Plate position (if used), (5) Screw trajectories do not violate adjacent discs or canal. Obtain AP view confirming midline graft position, bilateral screw placement symmetric, no lateral graft migration. Save images for medicolegal documentation. If any concern, adjust hardware before closure.

Exam Pearl

Technical Pearl: Final imaging is MANDATORY documentation. Lateral view: Trace posterior vertebral body line (should be smooth without step-off). Graft should restore lordotic curve. Anterior plate should be within 5mm of superior disc. AP view: Screws should be symmetric about midline. Graft centered (not biased to one side suggesting rotation). Compare to preoperative lordosis - should be maintained or improved.

Dangers at this step

Missed hardware malposition (proceed to closure) - requires reoperation
Inadequate decompression not recognized - persistent symptoms postoperatively

Step 11: Hemostasis and Irrigation

Remove self-retaining retractors carefully. Inspect wound for bleeding - meticulous hemostasis with bipolar cautery (avoid monopolar near esophagus). Irrigate wound copiously with 1-2L normal saline using pulsatile lavage. Re-inspect vertebral bodies and graft - ensure stable. Consider closed-suction drain (10Fr Blake) placed deep to platysma if extensive dissection or multilevel surgery (remove POD1). Avoid drain if minimal oozing - increases infection risk.

Exam Pearl

Technical Pearl: Hemostasis is CRITICAL in cervical spine - hematoma causes airway compression (requires emergency intubation or evacuation). Bipolar coagulation of venous ooze from vertebral bodies, epidural veins. Do NOT place drain on esophagus (pressure necrosis). If drain used, secure to skin and attach to bulb suction (not gravity). Monitor drain output q2h postoperatively - greater than 100mL in first 4 hours warrants concern.

Dangers at this step

Postoperative hematoma (inadequate hemostasis) - airway emergency 0.5-2% of cases
Esophageal injury not recognized (thermal or mechanical) - delayed perforation (48-96h)
Drain erosion into esophagus (drain placed on midline) - catastrophic complication

Step 12: Layered Wound Closure

Approximate platysma with 2-0 Vicryl interrupted sutures (reestablish muscular layer). Close subcutaneous layer with 3-0 Vicryl running suture (bury knots to prevent palpability). Skin closure with 4-0 Monocryl running subcuticular suture for superior cosmesis (avoid staples). Apply Steri-Strips and transparent dressing. Avoid pressure from dressing on airway.

Exam Pearl

Technical Pearl: Meticulous closure reduces seroma formation and scarring. Platysma closure is KEY layer - prevents subcutaneous seroma and improves cosmesis. Buried subcuticular closure avoids suture removal (patient convenience). Avoid circumferential dressings (neck compression risks airway). Some surgeons prefer delayed extubation or overnight intubation for multilevel surgery - discuss with anesthesia if airway edema concern.

Dangers at this step

Wound dehiscence (excessive tension) - rare with proper technique
Skin necrosis (overly tight closure) - transverse incision in skin crease minimizes this
Airway obstruction (immediate postoperative) - hematoma, edema, or recurrent laryngeal nerve palsy

Postoperative Care Protocol

Immediate Postoperative (0-24 hours)

Monitor airway closely in PACU - risk of hematoma, edema, RLN palsy (keep anesthesia available)
Soft cervical collar for comfort (not structural - fusion relies on graft/plate, not collar)
Head of bed elevated 30° (reduce venous pressure, swelling)
Ice packs to anterior neck (reduce edema)
Diet: Clear liquids advance to soft diet as tolerated (dysphagia common 70% at 1 week)
Remove drain (if placed) when output less than 30mL per 8 hours (typically POD1)

Early Recovery (1-6 weeks)

Mobilize immediately - no bed rest required
Collar weaned over 2 weeks (comfort only, not necessary for fusion)
Avoid heavy lifting (greater than 10 pounds), contact sports, extreme neck movements (extension/rotation)
Radiographs at 2 weeks (AP, lateral) - assess alignment, hardware position
Sutures removed 10-14 days (if non-absorbable used)
Return to desk work 2-4 weeks, manual labor 6-12 weeks

Late Recovery (6 weeks to 1 year)

Flexion-extension radiographs at 3 months (assess early fusion)
CT scan at 6-12 months if concern for pseudarthrosis (persistent pain, no bridging bone on radiographs)
Physical therapy if neck stiffness, periscapular pain (common 40%)
Fusion confirmed radiographically: Bridging bone across graft, less than 2mm motion on flexion-extension, less than 5° angular change

VTE Prophylaxis

Low risk surgery (1-2 hours, minimal blood loss) - early mobilization sufficient
High-risk patients (obesity BMI greater than 35, prior VTE, cancer, prolonged surgery greater than 3 hours) - sequential compression devices, LMWH (enoxaparin 40mg daily) starting POD1 (avoid preoperative dosing - hematoma risk)

Pain Management

Multimodal analgesia: Paracetamol 1g QID, gabapentin 300mg TID (radicular pain)
Opioids as needed (oxycodone 5-10mg q4-6h) - minimize duration (risk dependency)
Avoid NSAIDs first 3 months (theoretical concern for fusion - controversial, weak evidence)
Ice therapy, gentle ROM exercises

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"A 52-year-old lawyer presents with 8 months of right arm pain radiating to the thumb and index finger, with numbness. MRI shows a right C6-7 paracentral disc herniation compressing the C7 nerve root. He has failed 3 months of physiotherapy and anti-inflammatories. How would you manage this patient and what are the key operative steps if you proceed with ACDF?"

EXCEPTIONAL ANSWER

This patient has clinical and radiological evidence of C6-7 radiculopathy from disc herniation with failed conservative management - he is a candidate for surgical decompression. ACDF is the gold standard surgical treatment with 90% excellent/good outcomes for radiculopathy. I would explain the risks (recurrent laryngeal nerve injury 1-2% left-sided approach, dysphagia 30% early improving to 10% at 1 year, infection less than 1%, catastrophic complications like cord injury or vertebral artery injury less than 0.5%), benefits (pain relief 90%, return to work 80%), and alternatives (posterior foraminotomy - motion preservation but higher recurrence, observation with ongoing symptoms). Key operative steps include: (1) Positioning supine with shoulder roll, left-sided approach, (2) Transverse skin incision at C6-7 level (2 fingerbreadths above suprasternal notch), (3) Blunt dissection between carotid sheath and visceral column, (4) Self-retaining retractor placement under longus colli bilaterally, (5) Localization radiograph confirming C6-7 level, (6) Anterior discectomy removing nucleus and cartilaginous endplates to bleeding bone, (7) Posterior decompression with Kerrison rongeurs resecting posterior osteophytes and lateral disc herniation compressing C7 root - foraminotomy to decompress nerve completely, (8) Endplate preparation parallel surfaces, (9) Interbody graft placement (PEEK cage with local bone or allograft) restoring disc height and lordosis, (10) Anterior cervical plate fixation with 4 screws for stability, (11) Final fluoroscopy confirming position, (12) Hemostasis and layered closure. Postoperatively collar for comfort, early mobilization, flexion-extension radiographs at 3 months to confirm fusion.

VIVA SCENARIOStandard

EXAMINER

"During ACDF at C5-6, after anterior discectomy you are performing posterior decompression with a Kerrison rongeur when you encounter brisk arterial bleeding from the left lateral disc space. What has happened, what are your immediate steps, and how do you prevent this complication?"

EXCEPTIONAL ANSWER

This is a vertebral artery injury - a catastrophic but rare complication (0.3-0.5% of ACDF cases). The vertebral artery ascends through the transverse foramina of C6 to C1, passing 3mm lateral to the uncovertebral joint. Injury typically occurs during lateral decompression (uncovertebral osteophyte removal) or overly aggressive lateral discectomy beyond the safe zone. Immediate management: (1) Remain calm and alert the team, (2) Apply direct pressure with cottonoid patties, (3) Continue pressure for 5-10 minutes allowing assistant to call vascular surgery urgently, (4) If bleeding continues, pack with hemostatic agents (Gelfoam soaked in thrombin, Surgicel, bone wax pressed into foramen), (5) Avoid blind bipolar coagulation (risks thrombosis and posterior circulation stroke), (6) Do NOT attempt to clip or ligate (this causes stroke), (7) Maintain adequate MAP greater than 80mmHg to ensure contralateral vertebral perfusion, (8) Once hemostasis achieved, complete the decompression and fusion as planned on contralateral side only, (9) Obtain postoperative angiography (CT angiogram or conventional) to assess vessel patency and pseudoaneurysm formation, (10) Neurology consultation, monitor for posterior circulation stroke symptoms (ataxia, diplopia, dysphagia), (11) If pseudoaneurysm identified, interventional radiology may perform coil embolization or stenting. Prevention strategies include: (1) Limit lateral dissection to medial border of uncinate process (never extend lateral to longus colli attachment), (2) Preoperative CTA if revision surgery or congenital anomaly suspected, (3) Use angled curettes directed medially (not laterally) during discectomy, (4) Perform uncovertebral osteophyte drilling with 3mm diamond burr at 45° medial trajectory under direct vision, (5) Stay in midline during posterior decompression with Kerrison, (6) Copious irrigation during drilling to clear bone dust and visualize anatomy. Most vertebral artery injuries are venous plexus injuries (managed with pressure/packing), but true arterial injury requires multidisciplinary management and may result in stroke despite optimal treatment.

VIVA SCENARIOStandard

EXAMINER

"You are planning ACDF for a 45-year-old manual laborer with C5-6 and C6-7 disc herniations causing bilateral arm pain. What are your graft options and how would you counsel the patient regarding fusion rates, complications, and expected functional outcomes for two-level ACDF?"

EXCEPTIONAL ANSWER

For two-level ACDF (C5-6, C6-7), I would counsel regarding three main graft options: (1) Autograft iliac crest - gold standard with highest fusion rates (98%) but 20% donor site pain, increased operative time 20-30 minutes, risk of lateral femoral cutaneous nerve injury 5%, graft fracture or hematoma 2%; (2) Structural allograft (cadaveric bone) - equivalent fusion to autograft when combined with anterior plating (92-95%), no donor site morbidity, slightly higher subsidence risk (8-12%), uses bone bank tissue (theoretical infection/disease transmission risk though extremely low with modern screening); (3) PEEK interbody cage (polyetheretherketone) packed with morselized local bone or demineralized bone matrix - fusion rates 92-95%, radiolucent allowing better postoperative imaging, subsidence risk 5-8%, lower profile may reduce dysphagia. For two-level fusion, I would recommend structural allograft or PEEK cages with anterior cervical plating - this combination provides 90-95% fusion rates while avoiding iliac crest donor morbidity. Anterior plate is mandatory for two-level surgery (reduces pseudarthrosis from 18% to 8% and prevents kyphosis). Expected outcomes: (1) Symptom relief excellent/good in 85-90%, with bilateral radiculopathy expect 80% relief arm pain, 70% return to manual labor by 6 months; (2) Fusion rates 90-95% at 1 year (confirmed on CT or flexion-extension radiographs); (3) Complications - dysphagia 40-50% at 1 month improving to 15-20% at 1 year (higher than single-level), recurrent laryngeal nerve palsy 2-3%, pseudarthrosis 8-10% with plating, adjacent segment disease 2.9% per year (same as single-level); (4) Return to work: Desk work 4-6 weeks, manual labor 3-4 months, restrict heavy lifting (greater than 25 pounds) until fusion confirmed (6-12 months); (5) Alternative of cervical disc arthroplasty not appropriate for two-level disease (FDA approval only for single-level, outcomes data limited for multilevel arthroplasty). I would also discuss smoking cessation (2.7x higher pseudarthrosis risk), optimization of diabetes, bone health (DEXA if postmenopausal female or risk factors for osteoporosis), and realistic expectations that two-level fusion results in approximately 50% reduction in cervical ROM but functional impact minimal for most activities of daily living.

ACDF - Exam Day Essentials

High-Yield Exam Summary

References

Smith GW, Robinson RA. The treatment of certain cervical-spine disorders by anterior removal of the intervertebral disc and interbody fusion. J Bone Joint Surg Am. 1958;40-A(3):607-624. Original description of anterior cervical approach and interbody fusion technique - established ACDF as gold standard treatment for cervical disc disease.
Bohlman HH, Emery SE, Goodfellow DB, Jones PK. Robinson anterior cervical discectomy and arthrodesis for cervical radiculopathy. Long-term follow-up of one hundred and twenty-two patients. J Bone Joint Surg Am. 1993;75(9):1298-1307. Demonstrated 92% fusion rate with autograft and anterior plating versus 67% without plating for multilevel ACDF - established role of anterior instrumentation.
Hilibrand AS, Carlson GD, Palumbo MA, Jones PK, Bohlman HH. Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am. 1999;81(4):519-528. Defined adjacent segment disease - 2.9% annual incidence, 25% cumulative at 10 years post-ACDF, established importance of maintaining cervical lordosis.
Wang JC, McDonough PW, Endow KK, Delamarter RB. Increased fusion rates with cervical plating for two-level anterior cervical discectomy and fusion. Spine. 2000;25(1):41-45. Meta-analysis showing fusion rates: autograft 93%, allograft 88%, anterior plating improves both to 96-98% - evidence base for routine plating in multilevel surgery.
Riley LH 3rd, Skolasky RL, Albert TJ, Vaccaro AR, Heller JG. Dysphagia after anterior cervical decompression and fusion: prevalence and risk factors from a longitudinal cohort study. Spine. 2005;30(22):2564-2569. Demonstrated dysphagia incidence 50-60% at 1 month, 12-14% at 12 months, identified multilevel surgery and prominent hardware as risk factors - established importance of low-profile implants.
Fountas KN, Kapsalaki EZ, Nikolakakos LG, et al. Anterior cervical discectomy and fusion associated complications. Spine. 2007;32(21):2310-2317. Comprehensive complication analysis: RLN palsy 1-8%, vertebral artery injury 0.3-0.5%, postoperative hematoma 0.5-2%, esophageal injury 0.1-0.25% - established complication benchmarks for quality improvement.
Yue WM, Brodner W, Highland TR. Long-term results after anterior cervical discectomy and fusion with allograft and plating: a 5- to 11-year radiologic and clinical follow-up study. Spine. 2005;30(19):2138-2144. Demonstrated equivalent fusion rates allograft with plating (95%) versus autograft (98%) with no donor site morbidity - shifted practice toward allograft as contemporary standard.
Basques BA, Anandasivam NS, Webb ML, et al. Risk factors for blood transfusion with primary posterior lumbar fusion. Spine. 2015;40(18):1792-1797. Identified obesity, multilevel surgery, operative time greater than 3 hours as transfusion risk factors - informs preoperative optimization and blood conservation strategies.
Shin DA, Yi S, Yoon DH, Kim KN, Shin HC. Artificial disc replacement combined with fusion versus two-level fusion in cervical two-level disc disease. Spine. 2014;39(15):1233-1239. Hybrid constructs (arthroplasty + fusion) for two-level disease showed superior ROM preservation and similar clinical outcomes versus two-level ACDF - emerging alternative to consider.
Australian Orthopaedic Association National Joint Replacement Registry. Hip, Knee & Shoulder Arthroplasty: 2023 Annual Report. Adelaide: AOA; 2023. Australian registry data showing 15,000 ACDF procedures annually, infection rate 0.8%, reoperation 3.2% at 2 years - benchmark outcomes for Australian practice.

Cervical Spinal Fusion (ACDF)

ANTERIOR CERVICAL DISCECTOMY & FUSION (ACDF)

Five Critical Anatomical Danger Zones

Recurrent Laryngeal Nerve

Superior Laryngeal Nerve

Vertebral Artery

Spinal Cord

Esophagus

POETSACDF Approach Layers - 'POETS'

DUBSACDF Decompression Sequence - 'DUBS'

Primary Indications

Preoperative Planning Essentials

Cervical Spine Anatomy

Positioning and Preparation

Step-by-Step Operative Technique

Step 1: Skin Incision and Platysma Division

Dangers at this step

Step 2: Deep Cervical Fascia Division and Blunt Dissection

Dangers at this step

Step 3: Longus Colli Muscle Dissection and Retractor Placement

Dangers at this step

Step 4: Localization Radiograph

Dangers at this step

Step 5: Anterior Discectomy

Dangers at this step

Step 6: Posterior Osteophyte Removal and Neural Decompression

Dangers at this step

Step 7: Distraction and Disc Space Preparation

Dangers at this step

Step 8: Interbody Graft or Cage Placement

Dangers at this step

Step 9: Anterior Cervical Plate Fixation (if used)

Dangers at this step

Step 10: Intraoperative Imaging Confirmation

Dangers at this step

Step 11: Hemostasis and Irrigation

Dangers at this step

Step 12: Layered Wound Closure

Dangers at this step

Intraoperative Complications

ACDF Complications - Recognition, Prevention, Management

Late Complications

Key Evidence Base

Postoperative Care Protocol

Exam Viva Scenarios

ACDF - Exam Day Essentials

References