Reduction versus In-situ fusion for Adult High-Grade Spondylolisthesis: A Systematic Review and Meta-analysis.

BACKGROUND: Surgical management of high-grade spondylolisthesis remains controversial. Both reduction and in-situ fusion are available options, but it remains unclear which approach provides better outcomes. OBJECTIVE: To conduct a systematic review and meta-analysis on studies reporting outcomes following reduction or in-situ fusion for adult high-grade spondylolisthesis. METHODS: PubMed, Embase, Web of Science, and Cochrane databases were last searched on 06/24/2019. A total of 1236 studies were identified after excluding duplicates. After screening, 15 studies were included in the meta-analysis. Random-effects models were used to pool the effect estimates. RESULTS: A total of 188 patients were analyzed. Compared to reduction, in-situ fusion had a higher mean estimated blood loss (584 mL vs 451 mL) and a clinically higher incidence of neurological (48% vs 15%), pseudarthrosis (13% vs 8%) and infectious (20% vs 10%) complications; however, these differences were statistically non-significant. Reduction, on the other hand, was associated with a clinically higher incidence of overall complications (32% vs 25%), dural tears (22% vs 7%); provided better pain relief (mean difference [MD] = 5.24 vs 4.77) and a greater change in pelvic tilt (MD = 5.33 vs 2.60); yet, these differences were not statistically significant; however, patients who underwent reduction had a significantly greater decline in ODI scores (MD = 55.7 vs 11.5; p-interaction < 0.01) and greater change in slip angle (MD = 25.0 vs 11.4; p-interaction = 0.01) CONCLUSION: In the management of adult high-grade spondylolisthesis, both approaches appear to be safe and effective. However, reduction appeared to offer better disability relief and spinopelvic parameter correction than in-situ fusion.