Factors predicting successful outcome for ozone chemonucleolysis in lumbar disk herniation

Objectives: The aim of this study was to retrospectively investigate factors predicting a successful outcome after ozone chemonucleolysis (OCN) in patients with radicular pain and poor response to conservative treatments. Methods: Univariable and multivariable logistic regression analysis was used to identify the predictors of good outcome after OCN. Good outcome was defined as 33% Oswestry Disability Index (ODI) reduction (model 1) or 13-point ODI improvement (model 2) at 1 month after OCN. Results: Two hundred seventy-three patients were analyzed. A significant pain reduction (pre-operative Numerical Rating Scale [NRS] 6.7 ± 1.5, postoperative NRS 2.6 ± 2.2, P < 0.0001) and ODI improvement (pre-operative ODI 39 ± 13.7, postoperative ODI 21.4 ± 13.8, P < 0.0001) was obtained 1 month after OCN. Pain duration (< 1 year), type of disk herniation based on Michigan State University classification (MSU), stages of disk degeneration revealed by discogram and absence of foraminal stenosis (bony or ligament flavum hypertrophy) appeared as predictors of successful outcome. Age, gender, previous spine surgery, level site of disk herniation, presence of uncontained lumbar disk herniation, and vertebral Modic changes were not statistically associated with the outcome. Both the models showed a good accuracy (model 1, area under the curve [AUC] = 0.84 ± 0.027, 95% confidence interval [CI] = 0.79 to 0.89; model 2, AUC = 0.86 ± 0.024, 95% CI = 0.81 to 0.91). Conclusions: OCN is an effective treatment for radicular pain due to disk herniation. Pain duration (< 1 year), MSU disk herniation type (1A, 1B, 1C, 2A, and 2B), disk degeneration grade 2, and absence of foraminal stenosis are all associated with the successful outcome and should be carefully evaluated before OCN.