Restoration of Spinopelvic Alignment After Reduction of High-grade Spondylolisthesis: Myth or Reality? A Systematic Review of the literature and Meta-analysis.

STUDY DESIGN: Systematic review and meta-analysis of literature.

OBJECTIVE: The aim of the presented study is to assess whether the reduction of high-grade spondylolisthesis (HGS) through the correction of lumbosacral kyphosis leads to a decrease in the sagittal spinopelvic compensatory mechanisms.

SUMMARY OF BACKGROUND DATA: HGS is as an anterior translation of a vertebra, >50%. It is also characterized by a kyphotic deformity of the affected level. This combination of translation and kyphosis leads to compensatory mechanisms on the sagittal plane [pelvic retroversion, increased lumbar lordosis (LL), reduction in thoracic kyphosis (TK)].

METHODS: A systematic search of electronic databases was conducted. Inclusion criteria were diagnosis of HGS (Meyerding >II, Slip% >50%), partial or complete reduction surgery (with a significant decrease in Slip%), and report of spinopelvic parameters (pelvic incidence, pelvic tilt, or sacral slope). Clinical and radiographic outcomes were extracted and summarized. Meta-analyses were performed to estimate the differences between preoperative and postoperative spinopelvic alignment measures. P<0.05 was considered significant.

RESULTS: Eighteen studies were included. PT showed a statistically significant decrease of -2.1217 (95% CI: -3.4803 to -0.7630), while SS showed a significant increase of 4.8349 (95% CI: 2.7462-6.9236). Conversely, both LL and TK showed nonsignificant changes, -4.7043 (95% CI: -10.4535 to 1.0449) and 6.3881 (95% CI: -0.8344 to 13.6106), respectively. VAS significantly decreased by -3.1950 (95% CI: -4.9462 to -1.4439).

CONCLUSIONS: The meta-analysis showed mild, yet statistically significant, decrease of PT and an increase in SS after HGS reduction. Conversely, nonstatically significant decrease in LL and an increase in TK occurred. The clinical significance of these results remains questionable.

LEVEL OF EVIDENCE: Level IV.