Interbody cage use on successful spinal correction in pedicle subtraction osteotomy for adult spinal deformity surgery: a systematic review and meta-analysis of comparative studies.

INTRODUCTION

Adult spinal deformity (ASD) often necessitates high-grade osteotomies to achieve adequate correction and durable arthrodesis, yet guidance on adjunctive interbody cage use remains fragmented. This systematic review aims to aggregate and critically appraise clinical and radiographic outcomes of interbody cage use in Schwab grade 3 and 4 osteotomies to provide evidence-based guidance for complex ASD correction.

METHODS

We conducted a PROSPERO-registered systematic review and meta-analysis (CRD420251068532) of comparative studies to evaluate perioperative characteristics of ASD patients undergoing corrective high-grade osteotomies. We queried PubMed, EMBASE, and CINAHL databases through June 7th, 2025. Inclusion criteria were studies that examined ASD patients who underwent high-grade osteotomy and reported postoperative metrics such as blood loss, final degree of correction, and complication rates. A random-effects binary and continuous model for meta-analysis was performed using risk ratios.

RESULTS

Four comparative studies (n = 367; 50.41% male; mean age 57.75 ± 11.1 years) were included. Baseline mean preoperative sagittal vertical axis (SVA), Visual Analog Pain scores (VAS), and Oswestry Disability Index scores (ODI) for the total cohort were 19.40 cm ± 10.90 cm, 57.26 ± 25.13, and 61.91 ± 17.74, respectively. There was no significant difference in operative time regardless of cage use (mean time Cage: 461.76 ± 158.65 min; No Cage: 452.47 ± 169.04 min, mean difference (MD): 22.01; CI [- 13.92, 57.94] p = 0.23). There was no significant difference in intraoperative blood loss regardless of cage use (mean Cage: 1,576.29 ml ± 483.58 ml; No Cage: 1,513.64 ml ± 844.41 ml; MD: 49.53; CI [- 127.65, 226.72], p = 0.584). Osteotomies with cage use had a significantly lower postoperative SVA compared to cageless osteotomies (mean Cage SVA: 5.20 ± 2.55 cm; No Cage: 5.81 ± 2.50 cm; p = 0.03). There was no significant difference in ODI regardless of cage use (mean ODI Cage: 29.04 ± 5.84; No Cage: 35.42 ± 5.46 cm; p = 0.116). When comparing outcomes between patients with or without cages, no differences were seen in instances of rod fractures (6.94% vs 4.64%), proximal junctional kyphosis (15.61% vs 14.9%), or proximal junctional failure (4.05% vs 4.12%) respectively (p > 0.05).

CONCLUSION

ASD patients who underwent high-grade osteotomies with an interbody cage had lower postoperative SVA compared to patients who underwent cageless osteotomies. No differences were seen in operative time, blood loss, complication rates, or patient-reported outcomes between groups. Cage use may benefit patients at higher risk for nonunion or mechanical failure. Further prospective studies are needed to better define the role of cages in ASD correction.