Occipitocervical Fusion

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Occipitocervical fusion is indicated when the occipito-atlantal joint is unstable, destroyed, or must be crossed to obtain fixation.

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Position: prone, Mayfield pins, reverse Trendelenburg (reduces venous bleeding), head in neutral or the planned reduced position; confirm alignment on lateral fluoroscopy before draping. Eyes free, abdomen free.

Imaging/equipment: fluoroscopy (biplanar ideal) or navigation; neuromonitoring running; occipital plate system with polyaxial cervical screws; high-speed burr; cell salvage available.

Preparation: midline mark inion to lower cervical spine; antibiotics; tranexamic acid per protocol.

Approach: midline posterior incision from the EOP to below the caudal instrumented level; strictly midline avascular raphe (ligamentum nuchae) dissection; subperiosteal exposure of the occiput below the superior nuchal line, C1 posterior arch (no more than 12 to 15 mm lateral to midline on the cranial surface — VA groove), and C2 lamina/pars.

Dissection at-risk zones: VA in the C1 sulcus arteriosus and lateral to C2 pars; C2 venous plexus around the C1-C2 joint; greater occipital nerve.

Reduction: for reducible basilar invagination — preoperative or intraoperative skull traction, or Goel-type C1-C2 joint distraction with intra-articular spacers/cages, translating the odontoid caudally and ventrally away from the brainstem; hold the reduction with the rods.

Alignment — the critical step: before final tightening, obtain a true lateral and confirm the O-C2 angle and posterior occipitocervical angle match the preoperative neutral standing film; confirm no fixed rotation or coronal tilt (check that the mandible, EOP, and spinous processes align).

The number to hold in your head while you do it. Miyata measured the change in O-C2 angle (postoperative minus preoperative) against the cross-sectional area of the oropharynx in 29 fusions. The relationship is linear, and the ends of it are unambiguous: every patient whose angle fell more than 10 degrees lost more than 40 per cent of oropharyngeal area and developed dyspnoea, dysphagia or both — and no patient whose angle increased developed either. So the target is a non-negative change from that patient's own preoperative film, not any particular absolute angle. Note also that all five affected patients in that series had short constructs: a short fusion is no protection, because the angle is set at the occiput regardless of how far down the construct runs.

Fixation: occipital plate with bicortical midline keel screws; C1 lateral mass and C2 pedicle (or bailout) screws; contour and seat rods; compression/distraction as needed; final tighten.

Grafting: decorticate occiput and C1/C2 laminae with a burr; structural corticocancellous iliac crest or rib strut onlay from occiput to laminae, supplemented with local autograft/cancellous chips; secure graft under the construct or with cables.

Closure: meticulous layered closure over prominent hardware — approximate deep muscle to the nuchal fascia, avoid dead space; drain per preference; skin without tension (fragile rheumatoid skin — consider nylon sutures).

Aftercare: rigid collar 6 to 12 weeks per construct security; upright lateral radiograph before discharge; formal swallowing assessment before oral intake if any dysphagia; CT at 6 to 12 months if fusion in doubt.

• Global epidemiology of indications varies markedly: rheumatoid craniocervical disease has declined in high-resource settings with biologic therapy but remains a major indication where access to disease-modifying treatment is limited; congenital craniovertebral junction anomalies (atlas assimilation, os odontoideum, basilar invagination) form a large proportion of practice in South Asian centres, where the Goel joint-distraction philosophy was developed; trauma (atlanto-occipital dislocation) dominates in high-energy road trauma populations.
• Society guidance: AO Spine craniovertebral junction knowledge forum publications and AANS/CNS cervical spine guidelines address atlanto-occipital dislocation (early rigid internal fixation, avoid traction) and odontoid pathology; there is no single dedicated O-C fusion guideline — practice is technique- and evidence-driven.
• Registry evidence: craniocervical procedures are low-volume and not captured by arthroplasty registries; evidence rests on institutional series and multicentre spine study groups, which consistently report fusion rates above 95 percent with modern screw-rod constructs.
• Resource-setting variation: where navigation and CT angiography are unavailable, surgeons rely more on translaminar C2 fixation and generous fluoroscopy; halo immobilisation with wiring constructs remains a legitimate option where modern implants are unaffordable, accepting longer immobilisation and lower union rates.

• Occipital plate versus condyle screws: condyle screws lower profile and preserve squamous occiput but carry hypoglossal canal and VA risk; keel plates remain standard.
• Posterior-only reduction versus anterior decompression for basilar invagination: the Goel distraction school treats most cases posteriorly; some centres still favour endonasal/transoral odontoidectomy for truly irreducible ventral compression — the threshold for "irreducible" is contested.
• Caudal extent of fusion: stop at C2 versus routine extension to C3/C4 in poor bone — longer constructs are stiffer but increase adjacent segment load and dysphagia.
• Allograft, BMP, and graft strategy: structural autograft remains gold standard; off-label BMP use at the craniocervical junction is debated because of swelling risk near the airway.
• Prophylactic O-C fusion in asymptomatic Down syndrome instability: most advocate observation with activity modification unless neurological signs or marked instability — thresholds vary between guidelines.

Related pages. The shorter operation, and when it is enough: Atlantoaxial C1-C2 Fusion — including C1-C2 costs you about half of cervical rotation, so do not cross the occiput without a reason. The indications: Basilar Invagination, Atlanto-occipital Dislocation, Atlantoaxial Instability, Atlantoaxial Arthritis, Atlantoaxial Rotatory Subluxation, Odontoid Fractures and the syndromic instabilities in Down Syndrome and Klippel-Feil Syndrome. What is being decompressed: Cervical Myelopathy and Chiari Malformation. The complication that governs screw choice: Vertebral Artery Injury. Non-operative and adjunct immobilisation: Halo Vest Application and Management.