The influence of spinopelvic parameters on adjacent-segment degeneration after short spinal fusion for degenerative spondylolisthesis

OBJECTIVE Spinopelvic parameters, such as the pelvic incidence (PI) angle, sacral slope angle, and pelvic tilt angle, are important anatomical indices for determining the sagittal curvature of the spine and the individual variability of the lumbar lordosis (LL) curve. The aim of this study was to investigate the influence of spinopelvic parameters and LL on adjacent-segment degeneration (ASD) after short lumbar and lumbosacral fusion for single-level degenerative spondylolisthesis. METHODS The authors retrospectively reviewed the records of all short lumbar and lumbosacral fusion surgeries performed between August 2003 and July 2010 for single-level degenerative spondylolisthesis in their orthopedic department. RESULTS A total of 30 patients (21 women and 9 men, mean age 64 years) with ASD after lower lumbar or lumbosacral fusion surgery comprised the study group. Thirty matched patients (21 women and 9 men, mean age 63 years) without ASD comprised the control group, according to the following matching criteria: same diagnosis on admission, similar pathologic level (≤ 1 level difference), similar sex, and age. The average follow-up was 6.8 years (range 5–8 years). The spinopelvic parameters had no significant influence on ASD after short spinal fusion. CONCLUSIONS Neither the spinopelvic parameters nor a mismatch of PI and LL were significant factors responsible for ASD after short spinal fusion due to single-level degenerative spondylolisthesis.