Anatomical, biomechanical, and practical considerations in posterior occipitocervical instrumentation

Abstract 

Background context

Patients with cervical myelopathy secondary to craniocervical instability commonly present with spinal cord compression secondary to a combination of static forces and gross instability. Craniocervical arthrodesis is therefore indicated in the treatment of the majority of these conditions. In order to facilitate arthrodesis, techniques for occipitocervical instrumentation have been developed.

Purpose

To systematically review the anatomy, biomechanics, and practical considerations involved in posterior occipitocervical instrumentation.

Study design

Retrospective literature review.

Patient sample

Not applicable.

Outcome measures

Not applicable.

Methods

Retrospective literature review.

Results

The anatomic elements of the craniocervical junction include the occipital bone, occipital condyles, atlas (C1), and axis (C2). The occiput–C1 and C1–C2 motion segments possess unique mechanical properties. Occipitocervical instrumentation constructs are comprised of points of fixation and longitudinal elements, each with characteristic strengths and weaknesses.

Conclusions

Analysis of the anatomy, available points of fixation, and the movements to be controlled leads to the choice of a longitudinal element which can control movement by incorporating the strongest points of fixation. By going through this process for each patient, an informed decision may be made regarding the optimal occipitocervical instrumentation construct.

Keywords: Posterior, Occipitocervical, Instability, Instrumentation, Anatomy, Biomechanics, Techniques