Overview
The axis is the most commonly fractured cervical vertebra, and odontoid fractures (mainly type II) are its most common fractures; they are especially common in the elderly after low-energy falls (Campbell). Posterior C1-C2 fusion with a C1 lateral mass screw and a C2 isthmic screw connected by rods, with autologous iliac graft, is the authors' preferred method for most C1-C2 injuries; it is stable and can be used even with a fractured posterior C1 ring (Campbell). Because C1-C2 fusion causes functional loss of motion, motion-preserving options are preferred when possible (Campbell).
Indications
Odontoid fractures (Campbell, Rockwood)
Anderson and D'Alonzo: type I tip avulsion; type II through the base or waist; type III extending into the C2 body. Grauer subtypes of type II: IIA transverse, IIB oblique anterosuperior to posteroinferior (ideal for anterior odontoid screw), IIC oblique anteroinferior to posterosuperior with anterior comminution.
Poor healing of type II fractures reflects poor vascularity at the base of the dens. Type II fractures in the elderly carry 30-40% mortality at 1 year regardless of treatment (Campbell).
Factors affecting outcome: fracture type, initial displacement more than 2 mm, angulation more than 15 degrees and age, particularly over 80 (Campbell).
Under 80 years: surgery is most often recommended if displacement is more than 2-3 mm or angulation more than 15 degrees and surgical risk is acceptable; options are posterior C1-C2 fusion (Harms) or anterior odontoid screw (Campbell).
Over 80 years, frail or minimally displaced: a rigid collar remains acceptable; fibrous union with radiographic stability is common (Campbell, Rockwood).
Rockwood lists general surgical indications in young patients: displacement over 5 mm, angulation over 10 degrees, neurologic deficit, significant comminution, or polytrauma in which external immobilization is poorly tolerated. Halo vests in elderly patients have been associated with dysphagia, aspiration, pneumonia and high mortality in some series.
Atlas fractures and transverse ligament injury (Campbell)
Gehweiler classification: type 1 anterior arch; 2 posterior arch; 3 combined (Jefferson), 3A with intact and 3B with disrupted transverse atlantal ligament (TAL); 4 lateral mass; 5 transverse process.
Types 1, 2, 3A and 5: rigid collar for 6-8 weeks.
Type 3B with midsubstance TAL tear (Dickman type I): posterior C1-C2 fusion. Bony TAL avulsion (Dickman type II): direct C1 osteosynthesis (Technique 48.5) to preserve motion, only in isolated C1 fractures.
The rule of Spence (combined lateral mass overhang more than 6.9 mm, later 8.1 mm) misses 61% of TAL ruptures; MRI is much more sensitive.
Fractures at other cervical levels occur in 30-70% of patients with C1 fractures.
Preoperative Planning (Campbell, Rockwood)
Review CT carefully for C1 lateral mass and C2 isthmus size and the course of the vertebral artery; CT angiography helps.
Look for a ponticulus posticus (bony bridge over the vertebral artery on C1, present in up to 16%), which must not be mistaken for a screw starting point (Campbell, Rockwood).
Structures at risk anterior to the C1 lateral mass: internal carotid artery and hypoglossal nerve (Campbell).
Achieve reduction preoperatively when possible; intraoperatively, an anteriorly displaced C1 ring can be pulled back with a sublaminar wire or cable or towel clips under fluoroscopy (Rockwood).
Technique 48.6: Posterior C1-C2 Fusion with C1 Lateral Mass Screws (Harms) (Campbell)
Positioning and exposure
Induce anesthesia with the awake patient already on a rotating frame; do not anesthetize and then move a patient with an unstable spine. Use a Mayfield pin head holder and turn the patient prone with the bed.
Shave to the inion; prepare and drape the posterior head and neck and the posterior iliac crest.
Score the skin from the foramen magnum to C3 and inject dilute epinephrine (1 mg in 500 mL saline) into the dermis and paraspinal muscles.
Dissect with electrocautery to the skull and the spinous processes down to C3 (the C1 spinous process is only a midline tubercle).
Expose the occiput just above the foramen magnum subperiosteally.
Expose the posterior C1 ring 15 mm from the midline or to the vertebral artery sulcus, whichever is less. Keep cautery on bone; do not cauterize the thin atlanto-occipital membrane. The C1-C2 ligamentum flavum is thin or absent.
Expose the bifid C2 spinous process, elevating muscle attachments so they can be sutured back through bone at closure; expose the C2 laminae and lateral masses, preserving the C2-3 facet capsules.
The C2 nerve (greater occipital nerve) crosses behind the C2 isthmus in a dense venous plexus. Mobilize the plexus cephalad with bipolar cautery and a small angled curette until the medial border of the isthmus is visible; expect bleeding (Gelfoam or Surgicel with cottonoids; reverse Trendelenburg helps). The authors do not sacrifice the nerve.
Expose only the caudal edge of the C1 ring laterally and mobilize the plexus and C2 nerve caudally to expose the C1 lateral mass below the ring and vertebral artery.
Confirm reduction fluoroscopically.
Screw placement
C1 lateral mass screw (Goel, Harms and Melcher): start just caudal to the C1 ring, 3-4 mm lateral to the medial edge of the lateral mass. Drill with a hand drill 10 degrees medially and slightly cephalad to a point just posterior to the anterior margin of the dens on the lateral view (unicortical). Insert a polyaxial screw with a 10-mm smooth shank to the drilled depth.
C2 isthmic screw (Magerl-type): place a Penfield No. 4 to see the medial cortex of the isthmus and choose an entry point on the inferior facet of C2 that directs the drill up the center of the isthmus on the lateral view. Open the cortex with a burr. Typical trajectory 25 degrees medial and 20-30 degrees cephalad, but anatomy varies. Drill under fluoroscopy to the posterior margin of the C2 foramen transversarium.
Insert a polyaxial screw that stops at the posterior foramen transversarium; this gives good fixation without crossing into the C2 body near the vertebral artery.
Cut and contour the rods, seat them and tighten the blockers.
Fusion and closure
Harvest iliac crest graft.
Decorticate the C1 and C2 laminae with a high-speed burr and lay morselized autograft over them.
Do not pack bone over the atlanto-occipital membrane: compression there may cause apnea from brainstem compression. Obtain meticulous hemostasis for the same reason. Facet decortication and packing increase bleeding and usually are not needed with posterior autograft.
Check final alignment; close the fascia to bone over a drain, securely reattaching at C2, and close with a subcuticular suture.
Postoperative care
Rigid cervical orthosis for 6-8 weeks; remove the drain on the first postoperative day; follow with flexion-extension radiographs (Campbell).
Alternatives for C2 Fixation (Campbell)
Technique | Key points |
|---|---|
C2 translaminar screws (Wright, Technique 48.7) | Crossing screws from the base of the spinous process into the contralateral lamina, one slightly more caudal and steeper; usually 25-35 mm. Lower vertebral artery risk, risk of dural or cord injury. Biomechanically equivalent to Harms for C1-C2 but not for occiput-C2; useful when the isthmus cannot take a screw or with vertebral artery injury |
C2 pedicle screw | Longer, more medial, crosses the course of the vertebral artery into the body; 8-10% of patients (especially women) lack safe anatomy. Little clinical gain over the isthmic screw |
C1-C2 transarticular screws (Magerl and Seemann, Technique 48.8) | 3.5-mm screws, usually 34-43 mm, through the C2 isthmus across the facet into the anterior C1 lateral mass. Anatomic constraints in up to 23%; a high-riding vertebral artery is a contraindication. Excellent rotational stability; collar 8-12 weeks |
Wiring (Gallie, Brooks-Jenkins) | Mainly adjunctive. Gallie gives a posterior force on C1 but poor rotational control; Brooks bone block resists rotation better |
Direct C1 Osteosynthesis (Technique 48.5, Shatsky et al.) (Campbell)
For isolated unstable C1 ring fractures with bony TAL avulsion.
Position as above with bite blocks for an open-mouth view; reverse Trendelenburg and shoulder taping reduce the fracture by ligamentotaxis.
Place bilateral C1 lateral mass screws as above (monoaxial screws aid reduction), connect with a slightly bowed rod and compress to reduce lateral mass displacement.
Rigid orthosis for 8-12 weeks; CT to confirm reduction and screw position.
Complications
Vertebral artery injury (lateral dissection beyond 15 mm at C1, misdirected C2 screws) (Campbell).
Internal carotid artery or hypoglossal nerve injury from overlong C1 screws (Campbell).
Venous plexus bleeding around the C2 nerve (Campbell).
Brainstem compression from graft over the atlanto-occipital membrane (Campbell).
C1-C2 fusion causes functional loss of motion; consider motion-preserving treatment when appropriate (Campbell).
References
Williams KD. Fractures, dislocations, and fracture-dislocations of the spine. In: Azar FM, Sawyer JR, Throckmorton TW, eds. Campbell's Operative Orthopaedics. 15th ed. Philadelphia: Elsevier; 2026. Chapter 48, Techniques 48.5-48.9.
Le HV, Schoenfeld AJ, Vander Voort WD, Bono CM. Cervical spine fractures and dislocations. In: Tornetta P III, Ricci WM, Ostrum RF, McKee MD, Ollivere BJ, de Ridder VA, eds. Rockwood and Green's Fractures in Adults. 10th ed. Philadelphia: Wolters Kluwer; 2024. Chapter 48. (Turkish edition: Erişkin Kırıkları.)