Disc Height Narrowing Could Not Stabilize the Mobility at the Level of Cervical Spondylolisthesis: A Retrospective Study of 83 Patients with Cervical Single-Level Spondylolisthesis

STUDY DESIGN: A retrospective study at a single academic institution. PURPOSE: We aimed to understand the pathogenesis of cervical spondylolisthesis by analyzing whether narrowing of the disc height stabilizes the slipped disc level according to the degenerative cascade. OVERVIEW OF LITERATURE: According to Kirkaldy-Willis’ degenerative cascade, the narrowing of the disc height at slipped level contributes to intervertebral stability in lumbar spondylolisthesis. Conversely, the pathogenesis of cervical spondylolisthesis is unknown due to a scarcity of reports on the condition. METHODS: The images of 83 patients with cervical single-level spondylolisthesis were studied. We looked at 52 slipped levels for anterior slippage and 31 for posterior slippage. The imaging parameters included slippage in the neutral, flexed, and extended positions, axial facet joint orientation, sagittal facet slope, global cervical alignment, C2–C7 angle, C2–C7 sagittal vertical axis, range of motion (ROM), and slipped disc angle ROM. RESULTS: With the narrowing of the intervertebral disc height, slippage in the flexed position of both anterior and posterior spondylolisthesis increased. However, in both anterior and posterior spondylolisthesis, disc height narrowing did not show stability. The narrowing of the intervertebral disc height was found to be a risk factor for a translation of slippage of 1.8 mm or more in flexion-extension motion in anterior spondylolisthesis in multivariate regression analysis. CONCLUSIONS: Narrowing the intervertebral disc height did not stabilize the translation of slippage in flexion-extension motion in cervical spondylolisthesis. Instead, narrowing of the disc height was associated with a translation of slippage of 1.8 mm or more in flexion-extension motion in cases of anterior slippage. Therefore, we discovered that degenerative cascade stabilization for cervical spondylolisthesis was difficult to achieve.