Cervical degenerative spondylolisthesis: analysis of facet orientation and the severity of cervical spondylolisthesis

BACKGROUND CONTEXT: Previous studies have shown an association between the degree of cervical degenerative spondylolisthesis (DS) and spinal cord conditions of the cervical spine. However, there is no information available on the association between the severity of cervical DS and the orientation of the cervical facet joints. This study examined the association between the severity of cervical DS and facet tropism. PURPOSE: This study aimed to retrospectively explore the relationship between facet tropism and cervical DS and the effect of facet tropism on cervical DS. STUDY DESIGN: A retrospective review of radiographic and magnetic resonance imaging (MRI) findings in patients with or without cervical DS was carried out. PATIENT SAMPLE: A total of 200 patients from a single institution who underwent both MRI and radiography were reviewed. OUTCOME MEASURES: The facet angles at the C3-C4, C4-C5, and C5-C6 levels based on axial MRI in the two groups and the slippage degree at C4-C5 based on neutral lateral radiographs in the experimental group were measured and calculated. METHODS: One hundred patients with only C4-C5 level cervical DS who were treated in our hospital from January 2005 to August 2011 were selected as the experimental group. One hundred age and sex-matched spinal disease-free patients were selected as the control group from patients who presented for physical examinations. Comparative analysis of the obtained parameters was performed to determine significant differences between the examined levels in the two groups and to investigate the association between cervical DS and facet tropism. RESULTS: Facet tropism at C4-C5 was significantly greater than that at C3-C4 and C5-C6 in the experimental group (C4-C5 vs. C3-C4, p<.001; C4-C5 vs. C5-C6, p<.001), but there were no significant differences between the examined levels in the control group (p=.075). Facet tropism at C4-C5 in the moderate spondylolisthesis patients was significantly greater than that in the severe spondylolisthesis patients (p=.036), but facet tropism severity did not vary with the degree of spondylolisthesis in the experimental group (p=.108). CONCLUSIONS: This study revealed that facet tropism is universally present at the C3-C4, C4-C5, and C5-C6 levels and that the greatest degree of facet tropism exists in spondylolisthesis-affected levels. Although there was no significant correlation between facet tropism severity and the degree of spondylolisthesis, facet tropism was found to increase the risk of the development of spondylolisthesis. This finding suggested that facet tropism may play a significant role in cervical DS. (C) 2015 Elsevier Inc. All rights reserved.