General Editor: Luiz Vialle

Authors: Ronald Lehman, Daniel Riew, Klaus Schnake

Occipitocervical trauma - Odontoid, AAII Anterior C1-C2 trans articular screws

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1 Introduction top


This procedure can be used to achieve additional stability in osteoporotic bone when odontoid screw fixation alone is insufficient.

It generally serves as an alternative to posterior C1-C2 fusion, in particular when prone positioning is contraindicated.

The advantage of this screw is that it requires less muscle dissection than a posterior trans articular screw.

2 Preoperative evaluation top

A preoperative CT image must be evaluated to determine if this screw is possible.

3 Approach top


When C1-C2 screws are used as an adjunct to odontoid screws, then these screws are inserted using the same approach as the odontoid screws.

If these screws are used as a stand alone procedure, the standard anterolateral approach to the cervical spine is utilized for the insertion of anterior trans articular C1-C2 screws.

The surgery is performed withe the patient placed supine.

4 Screw insertion top


Screw entry point

The starting hole for the screw is 7-8 mm distal to the C1-C2 joint.

It is 3-5 mm lateral to the medial boarder of the C1-C2 joint.


Screw trajectory

K-wires are inserted and directed approximately 30° laterally and 30° posteriorly across the joint.


Screw insertion

Drill, tap, measure and insert the cannulated screws under fluoroscopic guidance (3.5 or 4.0 mm cortex screws, typically 15-20 mm long). The screw should not perforate the dorsal cortex of C1, nor should it violate the occipital cervical joint.

A radiolucent retractor is useful to visualize the joint.


K-wires are removed.

v1.0 2016.12.01