Factors affecting reduction in low-grade lumbosacral spondylolisthesis

Lumbosacral spondylolisthesis (LSS) is a common disorder that often requires a stabilization and fusion procedure. The aim of this study was to determine the early neuroimaging-detected results of instrumentation-assisted (in situ) fusion with no attempt at surgical reduction of the deformity in patients with low-grade LSS. The neuroimaging results were evaluated to determine the extent of reduction and its correlation with different parameters.

Thirty patients with low-grade LSS underwent short-segment transpedicular screw fixation; surgical reduction was not attempted. All patients underwent plain anteroposterior and lateral lumbar radiography, flexion-extension lateral lumbar radiography, and computerized tomography and magnetic resonance imaging of the lumbar spine before and after surgery. Postoperative measurements were determined on the late (9 to 12-month) postoperative radiographs. The findings were recorded and grouped. Correlation analysis was performed among the radiological findings, body mass index, age, and sex. Paired-sample t-tests were performed for each paired group to determine statistically significant differences. There was no significant difference in extent of deformity reduction in patients with different lordotic angles, sagittal-plane rotation angles, and intervertebral disc heights. The extent of reduction was statistically significant at the L4-5 level (p < 0.05), in patients younger than 50 years of age (p < 0.05), and in those in whom the facet joint angle was increased (p < 0.05).

The authors found that in cases of low-grade LSS, short-segment posterior stabilization (in situ fusion and fixation) does not require surgical reduction and in fact is associated with a measurable reduction when used as the sole treatment.