AOSpine Needs Assessment

Help shape the future of AOSpine education

If you are not a member but would like to contribute by telling us about your educational needs, please enter your e-mail address by using the button below and we will contact you.
Thank you for your valuable input.

Pipsa Ylanko, AOSpine Global Education Manager

General Editor: Luiz Vialle

Authors: Ronald Lehman, Daniel Riew, Klaus Schnake

Occipitocervical trauma - C1-C2, Dislocation Anterior C1-C2 fusion

back to Spine overview

Glossary

Authors: Ronald Lehman, Daniel Riew, Klaus Schnake

1 Introduction top

enlarge

C1 and C2 are anatomically unlike any other vertebrae in the spine. Their unique anatomy allows for 50% one's flexion-extension motion at the occipital C1 joint and 50% of one's rotational motion at the C1-C2 joint. Consequently, they are the most important vertebrae for cervical range of motion.

When treating fractures of these two vertebrae, every effort should be made to avoid arthrodesing these two joints. However, for dislocations, fusion would be the best option.

The goals of treatment are to stabilize the spine until the fractures have healed or to perform an arthrodesis in cases where stability cannot be achieved after healing is completed (such as with ligament ruptures).

If closed reduction and immobilization is not possible, one should consider open reduction and internal fixation followed by subsequent removal of instrumentation for cases that will become stable once the fractures have healed.

The vertebral artery trajectory must be fully evaluated prior to any surgery in this area.

2 Reduction top

Reduction may be performed by gentle traction, especially in acute cases. If not achieved or in more delayed cases, surgical reduction is indicated.

This involves soft tissue release (ligaments, capsule and scar tissues fond in delayed presentation) followed by gentle manipulation.

The final reduction must be confirmed using a C-arm.

3 Wires and structural bone grafts top

enlarge

The oldest technique involved wires and structural autograft. This is rarely used and will not be described here.

4 Magerl technique top

enlarge

Magerl first described the use of trans articular screws. This is a relatively simple and inexpensive way to fixate the C1-C2 joint. The disadvantage is that screw insertion requires fluoroscopy. Furthermore, the C2 pars must be large enough to accommodate a 3.5 mm diameter screw.

5 Goel and Harms technique top

enlarge

Goel and subsequently Harms described the use of C1 lateral mass and separate C2 fixation techniques.


enlarge

C1

C1 can be fixed using either lateral mass screws that start just caudal to the posterior arch or that start on top of the posterior arch and then capture the lateral mass. The latter can only be used if the posterior arch is thick enough to allow for the screw.


enlarge

C2

C2 can be fixed using either of the three techniques:


enlarge

Be aware that some posterior arches have a ponticulus posticus that appears to be a thick posterior arch, but in fact is a small bridge of bone that overlies the vertebral artery.


enlarge

This X-ray shows the ponticulus posticus.


enlarge

Rod placement

Since there are only two screws on each side there is no need for rod bending. A straight rod is placed and tightened. Keep the rods as short as possible.


enlarge

If there is spreading of the ring of C1, or a laterally displaced intra articular fracture, one can use the C1 lateral mass screws to reduce the displacement. After placement of bilateral C1and C2 screws and rods, one can place a cross link and compress the rods together, thereby reducing the fracture.


enlarge

An alternative in patients who have an anatomic reduction of the lateral mass fracture, but in whom C1 lateral mass fixation is not possible, one can instrument up to the skull but only fuse the C1-C2 joint. Once the fractures have healed, the instrumentation can be removed.

6 Posterior fusion top

enlarge

Cancellous allograft placed dorsally over the lamina does not work in the vast majority of cases and should be avoided. One can place cancellous allograft intra-articulary after decorticating.

To decorticate the joint, reflect the C2 nerve cranially.


enlarge

Burr into the joint or use a curette to scrape the articular cartilage. Be aware that the vertebral artery can in some cases be just below the articular surface of C2. This can be verified by CT scan.


enlarge

If an intra-articular fusion is not performed, one must use a structural cortical cancellous graft to bridge the C1 posterior arch to the C2 lamina. Auto iliac crest bone graft is the most reliable.


enlarge

Bone grafting following Goel/Harms technique

Fashion the bone graft as illustrated.


enlarge

If a Goel/Harms technique has been used, place a wire under the left rod over the graft and under the right rod and cinch it in place to push the graft onto the decorticated C1 posterior arch and C2 lamina.


enlarge

Add additional cancellous autograft strips to fill the voids between the lamina of C2 and the structural autograft.


enlarge

Bone grafting following trans-articular screw insertion

The bone graft is identical as for the Goel/Harms technique, but the wiring technique differs. Since there are no rods, the graft is secured with wires. A loop of wire is passed under the arch of C1, and the two free ends are passed through this loop.


enlarge

A second wire is passed through the spinous process of C2.


enlarge

After decorticating the C1 posterior arch and the C2 lamina, the graft is placed and the two wires are twisted together over the graft.


enlarge

Add additional cancellous autograft strips to fill the voids between the lamina of C2 and the structural autograft.

v1.0 2016.12.01