[Significance of staged lateral lumbar interbody fusion in the treatment of degenerative lumbar scoliosis with sagittal imbalance].

Objective: To investigate the clinical and radiological outcomes of staged lateral lumbar interbody fusion (LLIF) combined with posterior fusion and fixation in the treatment of degenerative lumbar scoliosis (DLS) with sagittal imbalance, and to quantitatively evaluate the contribution of LLIF to deformity correction in the staged treatment strategy.

Methods: Between January 2018 and January 2022, 35 patients with DLS accompanied by sagittal imbalance underwent stageⅠLLIF combined with stageⅡposterior fusion and fixation. There were 13 males and 22 females, aged from 56 to 79 years with a mean of (68.63±7.03) years, with a disease duration of (36.89±14.41) months. The visual analogue score (VAS) and Oswestry disability index (ODI) were used to evaluate changes in low back and leg pain as well as functional status preoperatively and postoperatively. Imaging parameters were assessed preoperatively, after stageⅠsurgery, after stageⅡsurgery, and at the final follow-up.

Results: All patients were followed up for a mean of(24.20±7.36) months. The mean operation time was (294.14±35.15) min, and the total blood loss was (584.14±197.58) mL. The mean number of LLIF levels per patient was (3.23±0.55), and the mean number of posterior fixation levels was (6.80±1.84). The low back pain VAS score decreased from (6.29±0.99) preoperatively to(2.54±0.70) at the final follow-up, with a statistically significant difference(P<0.01). The leg pain VAS score decreased from (6.14±1.06) preoperatively to (2.03±0.75) at the final follow-up, with a statistically significant difference (P<0.01). The ODI score improved from (68.54±12.36)% preoperatively to (26.74±8.37)% at the final follow-up, with a statistically significant difference (P<0.01). Compared with preoperative values, sagittal and coronal plane deformities were significantly corrected after staged surgery and were well maintained at the final follow-up. In the staged treatment protocol, stageⅠLLIF contributed 67.17% of the total correction for Cobb angle, 56.65% for lumbar lordosis (LL)angle, 52.69% for sagittal vertical axis (SVA) correction, and 56.21% for pelvic incidence (PI)-LL mismatch correction. Postoperative complications occurred in 12 patients.

Conclusion: StageⅠmultilevel lateral LLIF combined with stageⅡposterior fusion and fixation achieves favorable clinical and radiological outcomes in the treatment of DLS with sagittal imbalance. In the staged procedure, stageⅠmultilevel LLIF plays a crucial role in the correction of coronal and sagittal plane deformities and shows potential advantage of simplifying the stageⅡsurgical strategy.