Surgical technique guide for Anterior Cervical Discectomy and Fusion (ACDF) - Single Level - FRCS exam preparation
Reviewed by OrthoVellum Editorial Team
Orthopaedic clinicians and medical editors • Published by OrthoVellum Medical Education Team
Smith-Robinson approach | Left-sided transverse incision | Avascular plane medial to carotid sheath | Discectomy with decompression | Cage + anterior plate fixation
Recurrent laryngeal nerve - LEFT: predictable course, loops under aortic arch, ascends in tracheoesophageal groove. RIGHT: loops under subclavian, more variable, may be lateral. Injury causes hoarseness.
Superior laryngeal nerve (external branch) - Runs with superior thyroid artery at C3-C4 level. Injury causes voice fatigue, pitch problems (cricothyroid muscle).
Sympathetic chain - On anterolateral vertebral bodies, under lateral longus colli. Injury causes Horner syndrome (miosis, ptosis, anhidrosis).
Carotid sheath (carotid artery, IJV, vagus nerve) - Lateral to operative field. Vagus gives off RLN. Retract gently laterally.
Vertebral artery - In transverse foramen of C1-C6, 14-18mm from midline. Risk during lateral decompression/foraminotomy.
Esophagus - Posterior to trachea, medial retraction. Perforation rate 0.1-0.5%, potentially fatal. Higher risk with revision, long retraction.
Spinal cord and nerve roots - Dura immediately posterior to PLL (no epidural space anteriorly). Decompression must be controlled.
Thoracic duct - Left-sided, enters jugular-subclavian junction. Risk at C6-C7/T1 on left. Injury causes chyle leak.
Primary Indications:
Relative Indications:
ACDF vs Posterior Approach:
Expected Outcomes:
Surface Anatomy:
Smith-Robinson Interval:
Vertebral Anatomy:
Recurrent Laryngeal Nerve:
Sympathetic Chain:
Patient Position: Supine with small shoulder roll (extends neck slightly - improves anterior exposure). Head in neutral or slight right rotation if left-sided approach (opens the interval). Arms tucked at sides with padding. All pressure points padded.
Anaesthesia Considerations:
Fluoroscopy Setup:
Skin Marking:
Position supine with shoulder roll (extends neck for exposure). Head neutral or slight right rotation for left-sided approach. Arms tucked, pressure points padded. Tape shoulders caudally for lower cervical levels (C6-T1). Establish neuromonitoring baseline (MEPs, SSEPs) after induction.
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Positioning Principles:
Fluoroscopy to identify target disc level using surface landmarks (C4-C5 at thyroid cartilage, C6 at cricoid). Place spinal needle into disc space under fluoroscopy to confirm correct level - MUST obtain lateral image to confirm. Mark transverse skin incision in skin crease at target level. This is the most important step to prevent wrong-level surgery.
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Level Confirmation Protocol:
Transverse skin incision 4-5cm along skin crease. Divide subcutaneous tissue and expose platysma. Divide platysma transversely (fibers run vertically, transverse division reduces tension on closure). Identify deep cervical fascia beneath platysma.
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Platysma Division:
Palpate medial border of SCM. Incise deep cervical fascia along medial border of SCM. Develop avascular plane BETWEEN SCM/carotid sheath laterally (retract laterally) and strap muscles/trachea/esophagus medially (retract medially). This plane is bloodless if developed correctly with blunt finger dissection.
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Smith-Robinson Interval Pearls:
Continue blunt dissection medially until prevertebral fascia identified (shiny white layer over vertebral bodies). Palpate midline (feel anterior longitudinal ligament and vertebral bodies). Identify disc space (soft) between hard vertebral bodies. Place self-retaining retractor.
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Prevertebral Fascia Exposure:
Insert Caspar distraction pins into vertebral bodies above and below target disc. Confirm level AGAIN with lateral fluoroscopy (second confirmation with retractors in place). Place self-retaining retractor blades UNDER elevated longus colli muscles bilaterally. Apply distraction to open disc space.
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Retractor Placement Critical Points:
Incise anterior longitudinal ligament (ALL) over disc with scalpel. Remove disc material with pituitary rongeurs and curettes. Use high-speed burr to remove osteophytes from vertebral body margins if present. Proceed posteriorly systematically, removing all disc material to posterior longitudinal ligament (PLL).
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Discectomy Technique:
Remove posterior longitudinal ligament (PLL) to visualize dura - there is NO epidural space anteriorly in the cervical spine. Use Kerrison rongeurs to remove PLL and visualize dural pulsations. Perform bilateral foraminotomy by removing medial uncinate processes with Kerrison rongeurs - ensure nerve roots are decompressed.
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Decompression Goals:
Prepare superior and inferior vertebral endplates by removing cartilage with curettes. Expose bleeding cancellous bone (enhances fusion). Avoid violating endplate integrity (subchondral bone should remain intact - prevents subsidence). Create parallel surfaces for cage seating.
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Endplate Preparation Principles:
Select appropriate interbody cage (PEEK most common, titanium, or allograft). Size cage with trials - should be slight press-fit, restore disc height but avoid overdistraction. Pack cage with bone graft material (local autograft, allograft, synthetic). Insert cage and position flush with anterior vertebral body margin. Confirm position with fluoroscopy.
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Cage Selection and Insertion:
Select plate to span from mid-superior vertebral body to mid-inferior body. Plate provides load-sharing and increases fusion rate (reduces non-union from 10% to 5%). Position plate midline on vertebral bodies. Insert screws with 12-15 degrees convergent trajectory. Confirm plate and screw position with fluoroscopy (AP and lateral).
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Plate Fixation Principles:
Remove distractor pins. Confirm neuromonitoring unchanged from baseline. Fluoroscopy to confirm final cage and plate position. Release retractors and allow soft tissues to return to anatomic position. Meticulous hemostasis with bipolar cautery (careful near RLN). Irrigate thoroughly. Drain placement optional (controversial). Close platysma (3-0 Vicryl), subcutaneous (3-0 Vicryl), skin (subcuticular 4-0 Monocryl).
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Closure and Post-operative Considerations:
| Complication | Recognition | Prevention | Management |
|---|---|---|---|
| Dysphagia (50% early, 5% persistent) | Difficulty swallowing, choking, aspiration, odynophagia | Minimize retractor time, release retractors periodically, careful medial retraction, avoid excessive cage height | Usually self-limiting (6-12 weeks), speech pathology assessment, soft diet, severe cases may need gastrostomy |
| Recurrent laryngeal nerve injury (2-11%) | Hoarseness immediately post-op, weak cough, voice changes, aspiration | Left-sided approach (predictable RLN course), minimize retraction force, release retractors periodically, careful cautery | Most temporary (neuropraxia) - recover 6-12 weeks; permanent <1% - ENT referral, voice therapy, medialization procedures if persistent |
| Retropharyngeal hematoma (0.5-1%) | Progressive dyspnea, stridor, neck swelling, anxiety - can progress rapidly to complete obstruction | Meticulous hemostasis, consider drain (controversial), monitor closely 24 hours post-op | EMERGENCY - call for help, prepare for intubation/cricothyroidotomy, return to OR for evacuation, may need bedside evacuation if impending arrest |
| Esophageal perforation (0.1-0.5%) | May be immediate (recognized intraoperatively) or delayed (fever, neck swelling, mediastinitis) | Careful medial retraction, avoid sharp instruments near esophagus, recognize anatomy, gentle tissue handling | If recognized early: primary repair, NPO, antibiotics. Delayed: often requires drainage, antibiotics, may need flap coverage, high mortality if missed |
| Vertebral artery injury (0.3-0.5%) | Massive arterial bleeding during foraminotomy or lateral decompression | Stay within 14mm of midline during foraminotomy, know anomalous artery patterns, careful burring | Direct pressure, pack with hemostatic agent, may need interventional radiology for embolization, accept some stenosis rather than repair |
| Spinal cord injury (<0.5%) | Immediate motor/sensory loss, worsened myelopathy post-operatively | Controlled decompression, neuromonitoring, avoid instruments posterior to PLL, careful technique | If intraoperative neuromonitoring change: stop, check position, consider steroids. Post-op: MRI urgently, may need revision if compression |
| Dural tear/CSF leak (0.5-1%) | Clear fluid in wound, headache with upright position, meningitis signs if infected | Careful PLL removal, recognize dura (blue-grey, pulsating), controlled technique | Primary repair if possible (patch with muscle/fat, fibrin glue), watertight closure, may need lumbar drain, bedrest if persistent |
| Horner syndrome (0.1-1%) | Ptosis, miosis, anhidrosis on operative side immediately post-op | Elevate longus colli subperiosteally, place retractor blades UNDER longus colli, avoid lateral dissection | Usually temporary (resolves weeks-months), rarely permanent, patient education and reassurance |
| Cage subsidence/failure (5-10%) | Loss of disc height on follow-up X-rays, recurrent symptoms, kyphosis | Preserve endplate integrity, appropriate cage sizing, plate fixation, smoking cessation | If asymptomatic: observe with imaging. If symptomatic or kyphotic: revision surgery with larger cage or corpectomy |
| Adjacent segment disease (2-3%/year) | New radiculopathy or myelopathy at level above or below fusion, years after index surgery | Controversial if preventable - may use disc arthroplasty in selected patients, maintain lordosis, avoid long fusions | Conservative management first, if fails: extend fusion or decompression, consider arthroplasty at new level |
Practice these scenarios to excel in your viva examination
"You are performing a single-level ACDF at C5-C6 on a 45-year-old with radiculopathy. During closure, the anaesthetist mentions the patient is 'a bit stridorous' after extubation. What is your immediate management?"
"A patient wakes up from ACDF with a hoarse voice. How do you assess and counsel this patient?"
"Why do many surgeons prefer a left-sided approach for ACDF, and in what situations would you consider a right-sided approach?"
High-Yield Exam Summary
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Kaiser MG, Haid RW Jr, Subach BR, et al. Anterior cervical plating enhances arthrodesis after discectomy and fusion with cortical allograft. Neurosurgery. 2002;50(2):229-238.
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Apfelbaum RI, Kriskovich MD, Haller JR. On the incidence, cause, and prevention of recurrent laryngeal nerve palsies during anterior cervical spine surgery. Spine. 2000;25(22):2906-2912.
Fraser JF, Härtl R. Anterior approaches to fusion of the cervical spine: a metaanalysis of fusion rates. J Neurosurg Spine. 2007;6(4):298-303.
Epstein NE. Airway complications of multilevel anterior cervical surgery. J Spinal Disord. 2001;14(2):135-140.