Is multilevel MIS-TLIF with bilateral facetectomy a lordosing procedure? A retrospective cohort of 3-level MIS-TLIF.

Objective: Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is a common surgery that has been extensively reported. However, publications on 3-level MIS-TLIF are sparse, and the effects of multilevel MIS-TLIF on sagittal balance remain controversial. This study aimed to analyze the outcomes and variables involved in the correction of sagittal imbalance by multilevel MIS-TLIF.

Methods: Consecutive patients who underwent 3-level MIS-TLIF were retrospectively analyzed. Demographics and clinical outcomes were evaluated. Standard radiological and spinopelvic parameters were measured pre- and postoperatively, and at the last follow-up. A linear regression model was used to examine the correlation between preoperative segmental lordosis (SL) and the degree of sagittal correction. An optimal cutoff of preoperative SL to predict the change in sagittal correction was determined by receiver operating characteristic (ROC) analysis.

Results: Forty-seven patients (mean follow-up 24.63 ± 12.69 months) were included. Postoperatively, all patients showed clinical improvements, demonstrated by the Oswestry Disability Index and visual analog scale. The overall SL at the last follow-up was slightly nonsignificantly increased (1.23°, p = 0.267), while the other spinopelvic parameters, including lumbar lordosis (p = 0.008), sacral slope (p < 0.001), pelvic tilt (p = 0.002), and pelvic incidence-lumbar lordosis mismatch (p = 0.006), all improved significantly compared with preoperatively. The preoperative SL was negatively correlated with the change in SL at the last follow-up (r2 = 0.2591, p = 0.0003), and the cutoff value was 26.89° (area under the ROC curve = 0.7836, p = 0.0087). The 24 patients who had a less lordotic lumbar spine (i.e., preoperative SL ≤ 27°) demonstrated significant improvement in spinopelvic parameters, whereas the other 23 patients (SL > 27°) had a slight, insignificant decrease of spinopelvic parameters.

Conclusions: Multilevel MIS-TLIF improved sagittal balance and SL with satisfactory patient-reported clinical outcomes at 2 years postoperatively. Multilevel MIS-TLIF was more effective in increasing lordosis in patients whose lumbar spine had a smaller preoperative lordotic curve (SL ≤ 27°).