The Comprehensive Systematic Review of Association of Smoking Status to Risk of Pseudarthrosis after Spinal Arthrodesis

Abstract

Introduction: Pseudarthrosis, or nonunion, following spinal arthrodesis is a significant complication that leads to pain, instrumentation failure, and often requires revision surgery. Smoking is widely suspected as a key modifiable risk factor, yet the strength, consistency, and modifiers of this association across diverse surgical contexts require comprehensive synthesis. This systematic review aims to consolidate the evidence on the relationship between smoking status and pseudarthrosis risk after spinal fusion surgery (Ravi S. Nunna et al., 2021; Yang Li et al., 2021).

Methods: A systematic literature search was conducted following predefined screening criteria. We included observational studies (cohort, case-control), systematic reviews, and meta-analyses involving adult patients (≥18 years) undergoing spinal arthrodesis, with clear definitions of smoking status and pseudarthrosis assessment. Case reports, editorials, and animal studies were excluded. Data on smoking exposure, pseudarthrosis definition, risk measures, surgical characteristics, and study design were extracted from 59 included sources (Nunna et al., 2021; Boonsirikamchai et al., 2024).

Results: The majority of high-quality evidence demonstrates a significant association between smoking and increased pseudarthrosis risk. Pooled meta-analyses indicate smokers have approximately a 91% increased risk of nonunion (Risk Ratio 1.91, 95% CI 1.56–2.35) and 45% reduced odds of successful fusion (Odds Ratio 0.55, 95% CI 0.45–0.67) (Nunna et al., 2021; Yang Li et al., 2021). This risk is modified by factors including graft type (stronger effect with autograft), use of biological adjuncts like rhBMP-2 (which mitigates risk), surgical technique, and number of levels fused. Smoking also prolongs time to union and interacts adversely with other factors like ketorolac use (Jesse Li et al., 2018).

Discussion: The evidence robustly supports smoking as a major independent risk factor for pseudarthrosis, though its impact is context-dependent. Heterogeneity in findings can be explained by variations in surgical stabilization, use of biological enhancers, follow-up duration, and procedural complexity. The biological mechanisms involve nicotine-induced impairment of osteoblast function and vascular perfusion. Critical gaps remain in standardized smoking quantification and adjustment for confounders.

Conclusion: Smoking significantly elevates the risk of pseudarthrosis following spinal arthrodesis, particularly in lumbar posterolateral fusions using autograft. Preoperative smoking cessation should be strongly encouraged as a modifiable risk-reduction strategy. Surgical planning should consider mitigation strategies, such as using rhBMP-2 or more robust instrumentation in smokers. Future research requires standardized smoking metrics and longer-term outcome assessments.