OBJECTIVE: The primary objective of this study is to examine the effects smoking status on rhBMP-2 supplementation in spinal fusion constructs.
METHODS: Patient records were reviewed retrospectively for a consecutive set of patients who underwent first-time posterolateral, instrumented fusion of the lumbar spine for degenerative spinal disease. All operations included arthrodesis supplementation with rhBMP-2. All patients were followed for at least 2 years. The primary endpoint of this study was reoperation for pseudarthrosis, instrumentation failure, or adjacent segment disease. After a rigorous sensitivity analysis, the measure of association was calculated with a multivariable logistic regression controlling for smoking, age, and number of spinal levels fused.
RESULTS: Of the 110 patients in the study population, 82 (74.6%) were nonsmokers and 28 (25.5%) were smokers. Among perioperative predictors, smokers were younger in age (53.9 ± 9.6 vs. 61.1 ± 13.1 years; P = 0.008) and had shorter length of inpatient hospital stay (4.1 ± 1.8 vs. 5.3 ± 3.0; P = 0.039). After a mean follow-up of 59 months, the 32% incidence of reoperation for pseudarthrosis, instrumentation failure, or adjacent segment among smokers was statistically significantly higher than the 13.4% incidence in nonsmokers (P = 0.027). Following multivariable logistic regression, the odds of reoperation among smokers was 4.75-fold higher than for nonsmokers (P = 0.009; 95% confidence interval, 1.48-15.24).
CONCLUSIONS: While rhBMP-2 supplements arthrodesis of instrumented lumbar fusion constructs, smoking status ascertains the strongest predictor of reoperation for pseudarthrosis, instrumentation failure, and adjacent segment
