Smith-Robinson Approach (Anterior Cervical Spine)

What it exposes. The Smith-Robinson approach gives direct anterior access to the cervical vertebral bodies and disc spaces from C3 to T1 through the visceral-vascular interval — the avascular plane between the carotid sheath laterally and the trachea and oesophagus medially. It is the workhorse exposure for anterior cervical discectomy and fusion (ACDF), cervical corpectomy, cervical disc arthroplasty and, via a proximal extension, anterior odontoid screw fixation. Why anterior (and why left). An anterior route gives direct decompression of disc, osteophyte and vertebral-body pathology compressing the cord and roots from the front, and it places the interbody graft under compression — ideal for fusion. The approach is conventionally left-sided: the left RLN branches from the vagus in the mediastinum, loops under the aortic arch, and ascends in the tracheo-oesophageal groove to enter the larynx at the cricoid (C6) — a long, consistent course present in about 99.5 percent of patients. On the right the RLN loops under the subclavian artery and can be non-recurrent in 0.3 to 0.8 percent (associated with an aberrant right subclavian artery, arteria lusoria), crossing the surgical field at disc level. Note that the highest-quality evidence (Apfelbaum 2000) shows the dominant mechanism of RLN palsy is endotracheal-tube compression, not the side chosen — so technique and ET-cuff management matter at least as much as the side. Indications — the Big 5. 1. Cervical radiculopathy (about 60 percent). Dermatomal arm pain from disc herniation or foraminal (uncovertebral) stenosis, after 6 to 12 weeks of failed conservative care or with a progressive deficit. 2. Cervical myelopathy (about 20 percent). Cord compression with hand clumsiness, gait instability, hyperreflexia, Hoffman or Babinski signs. Progressive in about 75 percent; surgery is the only treatment that reliably halts progression. 3. Trauma (about 10 percent). Facet dislocation (disc removal before reduction prevents disc herniation into the canal), burst/teardrop vertebral-body fractures, and selected Type II odontoid fractures via an extended approach. 4. Tumour (about 5 percent). Vertebral-body metastasis with pathological fracture or cord compression — corpectomy and reconstruction for palliation and neurological preservation. 5. Infection (less than 5 percent). Discitis/osteomyelitis unresponsive to antibiotics or with neurological compromise — anterior debridement with autograft, instrumentation deferred until infection is controlled. Contraindications. Absolute: active infection at the surgical site; severe medical comorbidity precluding anaesthesia; pure posterior pathology (ligamentum flavum hypertrophy) needing a posterior approach. Relative: prior anterior neck surgery or neck radiation (scarred/poor-quality tissue, higher RLN and oesophageal risk), ankylosing spondylitis with a fused spine, severe COPD, morbid obesity, and multilevel (4 or more levels) disease where a posterior or combined approach may be safer.

Position & landmarks. Supine on a radiolucent table with a small shoulder roll between the scapulae to extend the neck, a head ring or horseshoe headrest, arms tucked and padded, and tape across the forehead and pulling the shoulders caudally to clear the lower levels on fluoroscopy. Palpate the cricoid cartilage at C6 (the single most important landmark), the hyoid at C3, the thyroid cartilage at C4-5, and the carotid tubercle of Chassaignac (C6 transverse process). The C-arm stands on the opposite side; confirm a true lateral before starting. Global practice & counselling. NASS- and NICE-aligned pathways reserve ACDF for radiculopathy or myelopathy with imaging that correlates with the clinical level — radiculopathy after a documented trial of non-operative care, myelopathy treated more urgently. Return to work is roughly 2 to 6 weeks for sedentary work and 3 to 6 months for heavy manual labour. Smoking is the strongest modifiable predictor of pseudarthrosis after multilevel interbody fusion (Hilibrand 2001) — counsel cessation, signpost national quit services, and consider corpectomy strut-grafting (which fused in 93 percent of smokers and non-smokers alike) when multilevel fusion is unavoidable.

Work down through the neck in the visceral-vascular interval: skin and platysma, then open the plane medial to SCM, retract the carotid sheath laterally and the trachea/oesophagus medially, and finally incise the prevertebral fascia and elevate the longus colli to seat the self-retaining retractors. The dissection is entirely extracapsular and avascular until the disc is deliberately opened.

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Extensile options. The approach is extensile along the medial border of SCM from C3 to T1. Extend proximally (longitudinal along the medial SCM) to reach C2-3 for anterior odontoid screw fixation or high-cervical pathology — the superior thyroid artery crosses C3-4 and may require ligation, and the external branch of the superior laryngeal nerve is at risk at this level. For very low levels (C7-T1), pull the shoulders caudally or use a more transverse low incision. Left versus right is guided by the RLN course (left by convention), but also by the side of pathology and any previous anterior neck surgery. Closure. Remove the retractors and Caspar pins, irrigate copiously (500 to 1000 mL), and achieve meticulous haemostasis with bipolar and bone wax for vertebral-body bleeding. Inspect the oesophagus before closing — any concern mandates immediate general-surgery/ENT review and oesophagoscopy. Close in layers: prevertebral fascia over the hardware (3-0 Vicryl), platysma (3-0 Vicryl), subcutaneous tissue (3-0 Vicryl), and skin (subcuticular 4-0 Monocryl with or without glue). Place a closed-suction drain superficial to the prevertebral fascia for multilevel, revision or actively bleeding cases (never deep to the fascia, where it could compress the oesophagus or trachea).

• ACDF — single-level and cervical spinal fusion (ACDF) — the principal operations. Score and remove the annulus and nucleus, decorticate the endplates down to bleeding bone, and remove posterior osteophytes; excise the posterior longitudinal ligament to expose the dura centrally and the nerve roots laterally. Perform a foraminotomy (Kerrison on the uncovertebral joint) for foraminal stenosis. Trial and insert an interbody cage to restore native disc height without over-distraction (flush or 1 to 2 mm proud), packed with autograft, allograft or graft substitute. Apply an anterior plate with unicortical screws aimed toward the midline and cephalad (typically 14 to 15 mm), or a zero-profile device to reduce dysphagia.
• Corpectomy — vertebral-body tumour, burst or teardrop fracture, and multilevel spondylotic myelopathy; reconstruct with an expandable cage or strut graft. In smokers, autogenous strut-grafting after corpectomy fuses in 93 percent (equivalent to non-smokers, Hilibrand 2001) and is preferred when multilevel interbody fusion is unavoidable.
• Cervical disc arthroplasty — a motion-preserving alternative for selected one- or two-level soft-disc disease with preserved facets and alignment (durable relief at 10 years, Lombardi 2020).
• Anterior odontoid screw fixation — selected Type II odontoid fractures in young patients with favourable anatomy, via an extended approach to C2-3.
• Infection — discitis/osteomyelitis with neurological compromise: anterior debridement with autograft (rib or iliac crest), instrumentation deferred until infection is controlled.