Correlation between the sagittal spinopelvic alignment and degenerative lumbar spondylolisthesis: a retrospective study

Background: Pain and disability associated with degenerative lumbar spondylolisthesis (DLS) results in significant burden on both the patients quality of life and healthcare costs. Currently, there is controversy regarding the specificity of spinopelvic measures of sagittal plane alignment with respect to DLS. Moreover, the correlation among spinopelvic parameters of sagittal plane alignment remains to be clarified. Our aim in this study was to compare these measurements between patients with single-segment DLS at L5 and a control group with no history of DLS. Methods: Our study group was formed of 132 patients who underwent full length lateral view radiographs of the spine in a relaxed standing posture. Among these, DLS at L5 was identified in 72 patients, forming the DLS group, with no radiographic evidence of lumbar spine disease in the remaining 60 patients, forming the control group. The patient and control groups were balanced with regard to age and sex distribution. The following spinopelvic parameters of sagittal plane alignment were measured: angle of incidence (PI) and tilt (PT) of the pelvis; sacral slope (SS); thoracic kyphosis (TK); lumbar lordosis (LL); and the spinal sagittal vertical axis (SVA). The Meyerding grade of L5 slippage was quantified for each patient in the DLS group. Results: Measures of TK, PI, SS, and LL were significantly greater in the DLS than control group (P < 0.05), with no between-group difference in SVA and PT. In the DLS group, the grade of L5 slippage correlated with SS (r = 0.873, P < 0.0001), PI (r = 0.791, P < 0.0001) and LL (r = 0.790, P < 0.0001). Moreover, the measurement for 55 correlated more strongly with the PI (r = 0.94, P < 0.01) than the LL (r = 0.69, P < 0.01). Conclusion: Measurements of SS, PI, and LL were specifically associated with DLS, with measurements correlating positively with the grade of slippage.