Sagittal spinopelvic alignment in 654 degenerative spondylolisthesis

Degenerative spondylolisthesis (DS) is common degenerative spinal disease. Recent studies highlighted relationship between DS and high pelvic incidence (PI). Moreover, impact of spinopelvic alignment on clinical outcomes has been emphasized. We aimed at describing epidemiologic and sagittal spinopelvic parameters in patients with DS, comparing them with asymptomatic volunteers, and determining a classification of DS patients. In this retrospective multicenter study of prospectively collected data, any adult patients treated for lumbar DS were included. Demographic data as well as radiographic parameters such as PI, pelvic tilt (PT), maximal lumbar lordosis (LLmax), lumbosacral lordosis, thoracic kyphosis, and C7tilt were recorded. DS patients were compared to 709 asymptomatic, age-matched volunteers. Cluster analyses were used to classify patients in homogenous groups. 654 patients were included (72 % female, 67 years). DS patients had greater PI (58.8A degrees vs. 53.2A degrees, p < 0.001) and C7tilt (p < 0.001). LLmax and lumbosacral lordosis were significantly smaller in the DS group. Cluster analysis allowed for the identification of 2 groups of patients according to C7tilt-159 patients with anterior C7tilt and 495 with normal C7tilt. In each group, 3 subgroups were found with different PI and sagittal spinopelvic parameters. Predominance of high PI and female gender was emphasized in DS population. Moreover, these findings highlighted the importance of sagittal alignment analysis in DS with 24 % of patients with anterior malalignment and in the remaining 76 % (normal C7Tilt), more than 50 % had pelvic retroversion. Consequently, DS sagittal malalignment should lead to specific surgical correction adapted to each subgroup of patients.