Exploring the Influence Factors of Pelvic Tilt Restoration After Surgical Treatment of Lumbar Degenerative Diseases: Value of Preoperative Standing-Sitting Radiograph

Study Design Single-center retrospective study. Objectives In lumbar degenerative diseases (LDD), pelvic retroversion compensates for sagittal malalignment. Surgical restoration of lumbar lordosis (LL) may reduce increased pelvic tilt (PT), while the influence factors of PT restoration (rPT) remain unclear. This study aimed to identify potential factors affecting rPT in LDD surgery and its correlation to postoperative clinical outcome. Methods 161 LDD patients underwent surgical treatment were included. Sagittal parameters were measured in whole spine radiographs in standing and sitting. Changes from standing to sitting were denoted as Δ. The LL restoration (rLL) and rPT was calculated as postoperative - preoperative values. Clinical outcomes were evaluated using the visual analogue scale (VAS) and Oswestry Disability Index (ODI). The influence factors of rPT were analyzed, and the sagittal parameters affecting post-operative ODI, leg pain VAS and low back pain VAS was examined. Results rLL (r=-0.403), PT (r=-0.375), SS (r=0.400), L4-S1 lordosis (r=0.324), LL (r=0.319) and TPA (r=-0.291) in standing, ΔPT (r=0.304) and ΔSS (r=-0.254) was significantly related to rPT. A predictive formula for rPT was developed as rPT= -0.265×PT- 0.114×rLL+ 0.112×ΔPT+ 2.841° (R 2 =0.350, P<0.001). Postoperatively, low back pain VAS was related to PT (r=0.358, p<0.01) and PI-LL (r=0.246, p<0.05), and ODI was related to SVA (r=0.253, p<0.05). Conclusion LL restoration, preoperative PT, and ΔPT were identified as predictors of rPT. This study revealed the potential clinical value of standing-sitting radiograph in surgical planning of LDD, and further highlights the importance of restoring sagittal balance in lumbar surgery.