Alteration of Facet Joint Orientation and Asymmetry With Time in Lumbar Disc Herniation

Abstract

In the previous studies, the facet tropism and its relation to the development of lumbar disc herniation (LDH) were investigated. However, these studies have shown inconsistent conclusions. The aim of this study was to investigate the alteration of facet joint angle and (a)symmetry in LDH. Fifty-four patients with LDH were included. In the first and second computed tomography images, all facet angles were measured from the similar axial slice by the same observer who was blinded with regard to the date of computed tomography scan. Total reproducibility of the variability was found to be ±1.85 degrees. Thirty-one patients had a change in the orientation of at least 1 facet joint. The mean rate of the change in the facet orientation varied from 2.69 to 3.63 degree/y. The most common observed change in the orientation was sagittalization. Females, taller patients, cases with median herniation, and patients with longer course of LDH had a higher risk of this change (P=0.011). The facet asymmetry was found to develop in 7 patients and to recover in 7 patients (P=0.002). The facet orientation could change and the facet asymmetry could develop or recover in the same patient with time in LDH. These results could explain contradictory results in the literature.