Atlantoaxial fixation

Last revised by Joachim Feger on 9 Jan 2022

Atlantoaxial fixation refers to various surgical techniques to stabilize the atlantoaxial complex.

The first effort of an atlantoaxial stabilization was made by Mixter and Osgood in 1910 by fixation of the spinous processes with a heavy silk thread 1,2

Posterior cervical fusion by atlantoaxial laminar wiring was first described by Gallie in 1939 3,4 later by Brooks and Jenkins 5 and Sonntag. Interlaminar clamp fixation was introduced in 1984 6. Posterior transarticular screw fixation was first reported by Margerl in 1986 7. The posterior cervical fusion methods with screw-plate and screw-rod interfaces were initially introduced by Goel 8,9 and later modified by several authors including Harms and colleagues 10.

Anterior transarticular screw fixation was first reported by Barbour 1971 11,12.

Atlantoaxial fixation is indicated in the setting of atlantoaxial instability including 1,3:

Contraindications of atlantoaxial fixation include 1,3:

  • posterior transarticular screw fixation
    • anomalous or aberrant vertebral artery
    • extensive fractures of the posterolateral structures
  • posterior clamp fixation
    • Jefferson or Hangman fracture
    • osteoporosis of the laminae
    • degenerative changes of posterior elements
    • surgical procedures requiring posterior decompression

The procedure and technique involve screw fixation from an anterolateral or posterior approach as well as different posterior cervical fusion techniques of the atlantoaxial joint either with wires, clamps, screw-plate or screw-rod interfaces. Choice of technique will depend on the injury, local anatomy and other patient-related factors as well as preference and skills of the surgeon.

A rough overview of the surgical procedure concerning the different approaches includes the following 1,3:

  • standard Smith-Robinson approach
  • screw entry point location distal to the C1-C2 joint surfaces
  • screw trajectory approximately 30° posteriorly and 20° laterally angulated through the lateral atlantoaxial joints
  • cannulated screw insertion under fluoroscopic guidance
  • variably decortication of the atlantoaxial joints and bone graft placement
  • posterior transarticular screw fixation (Magerl technique)
    • screw entry point location in the mediolateral midpoint of the C2 pars slightly cranial to the C2-C3 facet joint
    • screw trajectory approximately through the second lower quarter of the atlas tubercle and the anterior arch
    • K-wire placement under fluoroscopic view
    • cannulated screw insertion under fluoroscopic guidance
  • posterior cervical fusion with screw-plate or screw-rod interface (Goel-Harms technique)
    • screw-rod or screw-plate instrumentation with C1 lateral mass and C2 pars, pedicle or laminar screws
    • variably bone graft insertion between the C1 posterior arch and C2 lamina and sublaminar wiring and/or intraarticular C1-C2 facet joint decortication and fusion
  • posterior clamp fixation
    • hook placement on the superior C1 and inferior C2 laminar surface and tightening
    • preferably intermediary bone graft placement
  • posterior spinal wiring
    • Gallie technique
      • wire cerclage around the posterior arch of the atlas and the spinous process of the axis
      • autologous bone craft placed on C2 spinous process and leaned against C1 posterior arch
    • Brooks-Jenkins technique
      • two separate bevelled interlaminar bone grafts
      • bilateral sublaminar wires
    • modified Gallie technique (Sonntag technique) 1
      • single inferior-superior sublaminar passage of the wire cerclage
      • autologous bone craft placement notched between the posterior arch C1 and spinous process C2 after decortication of the respective surfaces

Complications of atlantoaxial fixation techniques generally include complications of spinal surgery and the following:

Plain radiographs can assess implant position and vertebral alignment.

In addition to the exact position of implants, CT might detect complications and characterize bony fusion.

MRI can be used to evaluate the spinal canal in the setting of suspected complications 1.

The postoperative radiological report should include a description of the following features:

  • implanted hardware
  • bone grafts if present
  • position of screws especially with relation to the following structures
    • spinal canal
    • intervertebral foramen
    • foramina transversarium
  • complications

Posterior clamp fixation and posterior wiring with the Gallie technique offer good stability in flexion and extension but poor stability concerning rotational stability 1. The Brook-Jenkins technique offers more rotational stability, but also an increased risk of neural or dural injury due to the necessity of bilateral sublaminar passage of the cable or wire 1. The Sonntag technique or modified Gallie technique features similar rotational stability with a high rate of bony fusion.

The posterior transarticular screw fixation can completely obliterate the rotational motion of the atlantoaxial joint but carries the risk of screw malpositioning with the concomitant spinal cord, hypoglossal nerve or vertebral artery injury 1. Posterior atlantoaxial fusion with screw-plate or screw-rod interfaces features a very high fusion rate with minimal complications allowing for minimally more rotational movement than the transarticular screw fixation 1. The procedure is technically demanding but anatomic alignment is not needed before instrumentation 1.

Anterior transarticular screw fixation might be of advantage in situations where a posterior approach is not desired due to aberrant vertebral artery or extensive posterolateral structures but carries the risk of postoperative laryngeal edema.

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