Differences in Sagittal Balance in Patients with and without Degenerative Spondylolisthesis Who are Surgically Treated for Spinal Stenosis. A Comparative Study

Author(s): Bougiouklis Dimitrios, Patsiaouras Thomas

Introduction: In pathogenesis of degenerative spondylolisthesis (DS) and its development, several predisposing factors have been advocated. However, the role of lumbar sagittal alignment has not been well studied yet. The purpose of this retrospective study was to analyze the sagittal spinopelvic alignment and to compare these parameters between patients with and without degenerative spondylolisthesis who were surgically treated for lumbar spinal stenosis.

Materials and Methods: Between 2008-2018, we studied 68 patients who underwent surgery for lumbar spinal canal stenosis. 34 of these patients, suffered by DS (group 1), and the other 34, age- and gender-matched patients, not presented DS (group 2). Surgical treatment was realized after six months of unsuccessful conservative treatment. Spinopelvic parameters including pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), L4 slope, L5 slope, thoracic kyphosis (TK), lumbar lordosis (LL), segmental lumbar lordosis (SLL) and sagittal balance were compared between the two groups. In the group 1, the slippage grade (% slip) was also evaluated.

Results: PI, SS, L4 slope, L5 slope, TK and LL in the group 1 were significantly greater than those in the group 2, and PI had positive correlation with % slip (p<0.05). The SLL of patients with DS was significantly lower than those without DS. In the group 1, there was a strong correlation between the PI and the SS (p<0.001), rather than with the PT (p<0.01). Between the two groups there was no significant difference in PT.

Conclusions: In patients with degenerative spondylolisthesis, PI was significantly greater than that in patients without DS and PI had positive correlation with the percentage of slippage. Greater PI turns to be a predisposing factor to the development and the progression of vertebral sliding. On the other hand, patients who suffered by degenerative lumbar stenosis without sliding, have a normal PI. In patients with DS, a predisposing condition for an anterior displacement of L4 on L5, was represented by the increased vertical inclination of the S1 endplate. In these patients, segmental lordosis was increased at the levels above L4/L5.

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