Better Spine Stabilization With Circumferential Fixation

When posterior ligaments and facet capsules are intact, anterior fixation stabilizes spine

WEDNESDAY, March 30 (HealthDay News) -- Circumferential fixation after a C5 corpectomy provides superior spine stabilization to anterior fixation or posterior fixation without anterior cage when facet capsules and posterior ligaments (PLs) are disrupted, according to a study published in the April 1 issue of Spine.

Youssef R. Karam, M.D., from the University of Iowa in Iowa City, and colleagues compared the cervical spine rigidity achieved by anterior, posterior, and circumferential fixation after a C5 corpectomy, and evaluated the effect of facet capsule integrity and PL disruption on biomechanical stability. Pure moment applications in six directions were tested on nine cadaveric cervical spines in five situations: intact spine; after a C5 corpectomy and anterior fixation; and after the disruption of PLs, C4-C5, and C5-C6 facet capsules with anterior fixation, circumferential fixation, or posterior fixation without anterior cage. The angular movement of C4 with respect to C6 was also measured.

The investigators found that, after a C5 corpectomy, anterior fixation resulted in higher rigidity than the intact spine for all loads in flexion and left lateral bending, and at 0.5 Nm and 1.0 Nm loads in right axial rotation and lateral bending when PLs and capsule facets were intact. In cases with facet capsule and PL disruption, circumferential fixation was more stable than anterior fixation, in the coronal and axial planes but not in the sagittal plane, and was more stable than posterior fixation without anterior cage in the sagittal plane, but not coronal and axial planes.

"Our study demonstrated that circumferential fixation results in a more rigid construct than anterior-only or posterior fixation without anterior cage," the authors write.

This study was supported by a research grant from DePuy Spine.

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