Prevalence and Motion Characteristics of Degenerative Cervical Spondylolisthesis in the Symptomatic Adult

Study Design. Retrospective analysis of kinetic magnetic resonance images. Objective. To define the prevalence of degenerative cervical spondylolisthesis in symptomatic patients and to analyze the motion characteristics and influence on the spinal canal at the affected level. Summary of Background Data. When compared with lumbar spondylolisthesis, there are few studies evaluating cervical spondylolisthesis, and the prevalence and motion characteristics of cervical spondylolisthesis are not well defined. Methods. Four hundred sixty-eight symptomatic patients underwent upright cervical kinetic magnetic resonance images in neutral, flexion, and extension positions. Segmental displacement and intervertebral angles were measured in 3 positions using computer analysis software. Spondylolisthesis was defined as the vertebral displacement more than 2 mm, and graded based on the magnitude into 2 groups at each level: grade 1 (2-3 mm), grade 2 (> 3 mm). Instability was defined as segmental translational motion exceeding 3 mm. Results. Grade 1 and 2 spondylolisthesis at a minimum of 1 level were observed with a prevalence of 16.4% and 3.4% of all patients, respectively. The most affected levels were C4-C5 (6.2%) and C5-C6 (6.0%) followed by C3-C4 (3.6%) and C6-C7 (3.0%). Translational motion was greater in levels with grade 1 as compared with segments without spondylolisthesis, but there was no difference in angular motion between the 3 groups. Translational instability was observed with a prevalence of 16.7% in grade 2, 4.3% in grade 1, and 3.4% in segments without spondylolisthesis. Space available for the cord at the affected level was decreased and spinal cord compression grade was higher in grade 1 and grade 2 as compared with levels without spondylolisthesis. Conclusion. Cervical spondylolisthesis of at least 2 mm was observed in 20% of patients and was most common at C4-C5 and C5-C6. The presence of spondylolisthesis was associated with increased translational motion and decreased segmental spinal canal diameter.