Radiological evaluation of spinopelvic parameters in patients with spondylolisthesis post fusion

Abstract

Objective: To determine and compare the radiological spinopelvic parameters (Lumbar Lordosis (LL), Sacral Slope (SS), Pelvic Tilt (PT), Pelvic Incidence (PI)) before and after MISS TLIF fusion in patients with low-grade spondylolisthesis. Methods: A descriptive, observational, and retrospective study with a sample of 20 patients (male predominance, 90% Meyerding Grade I). Spinopelvic parameters were measured on standing lateral radiographs pre- and post-surgery, analyzing the LL-PI mismatch. Statistical significance was evaluated using the Student's t-test. Results: No statistically significant changes were observed in postoperative LL, SS, or PT (e.g., LL pre 51.37º, post 48.73º, p=0.23). The LL-PI discrepancy ("mismatch") was null or insignificant (pre -7.61º, post -7.53º, Cohen's d=-0.0070), remaining within the acceptable range. Most fusions were at L4-L5. Conclusions: The MISS TLIF technique did not show a significant capacity to radiologically correct spinopelvic imbalance in this low-grade spondylolisthesis cohort. The postoperative clinical benefit is likely attributable to segmental stabilization and decompression, rather than active sagittal balance restoration.