The significance of facet joint cross-sectional area on magnetic resonance imaging in relationship to cervical degenerative spondylolisthesis.

BACKGROUND CONTEXT: Characteristic changes of the facet joints, including synovial cysts, facet joint hypertrophy, and facet joint effusions, on magnetic resonance imaging (MRI) and computed tomography have been associated with lumbar degenerative spondylolisthesis. The cervical facets have not been examined for associations with cervical degenerative spondylolisthesis similar to those seen in the lumbar spine.

PURPOSE: To define abnormalities of the facet joints seen on supine MRI that correlate with cervical spondylolisthesis seen on upright radiographs.

STUDY DESIGN: Retrospective radiographic review of consecutive patients with a universally applied standard.

PATIENT SAMPLE: A total of 204 consecutive patients from a single institution, with both an MRI and upright radiographs, were reviewed.

OUTCOME MEASURES: Sagittal plane displacement on upright lateral radiographs was compared with MRI. The total area of the facet joint and the amount of facet joint asymmetry were measured on an axial MRI.

METHODS: The data were analyzed to determine a significant association between the cervical degenerative spondylolisthesis and the following: facet joint asymmetry, increased total area of the facet joint, and age.

RESULTS: Degenerative spondylolisthesis was seen in 26 patients at C3-C4 and in 27 patients at C4-C5. Upright radiographs identified significantly more degenerative spondylolisthesis than MRIs at levels C3-C4 and C4-C5, 26 versus 6 (p<.001) at C3-C4 and 27 versus 11 (p<.001) at C4-C5. Patients with degenerative spondylolisthesis were more likely to be older, have a larger total facet area, and more facet asymmetry at C3-C4 and C4-C5 (p<.05).

CONCLUSIONS: Supine MRIs underestimate sagittal displacement compared with upright lateral radiographs. Asymmetric facet hypertrophy at C3-C4 and C4-C5 is associated with degenerative spondylolisthesis on upright lateral films even in the absence of anterolisthesis on supine MRIs.