Microdiscectomy for Lumbar Disc Herniation: A Single-Center Observational Study.

OBJECTIVE:To examine outcomes and complications following first-time lumbar microdiscectomy. METHODS:Prospective data for patients operated on between May 2007 and July 2016 were obtained from the Norwegian Registry for Spine Surgery. The primary outcome was change in Oswestry Disability Index (ODI) score at 1 year. Secondary endpoints were change in quality of life measured with EuroQol 5 Dimensions, back and leg pain measured with numeric rating scales, and perioperative complications within 3 months of surgery. RESULTS:For all enrolled patients (N = 1219) enrolled, mean improvement in ODI at 1 year was 33.3 points (95% confidence interval [CI] 31.7 to 34.9, P < 0.001). Mean improvement in EuroQol 5 Dimensions at 1 year of 0.52 point (95% CI 0.49 to 0.55, P < 0.001) represents a large effect size (Cohen's d = 1.6). Mean improvements in back pain and leg pain numeric rating scales were 3.9 points (95% CI 3.6 to 4.1, P < 0.001) and 5.0 points (95% CI 4.8 to 5.2, P < 0.001), respectively. There were 18 surgical complications in 1219 patients and 63 medical complications in 846 patients. The most common complication was micturition problems at 3 months following surgery (n = 25, 2.1%). In multivariate analysis, ODI scores of 21-40 (hazard ratio [HR] 14.5, 95% CI 1.1 to 27.9, P = 0.035), 41-60 (HR 27.5, 95% CI 13.4 to 41.7, P < 0.001), 61-80 (HR 47.4, 95% CI 33.4 to 61.4, P < 0.001) and >81 (HR 66.7, 95% CI 51.1 to 82.2, P < 0.001) were identified as positive predictors for ODI improvement at 1 year, whereas age ≥65 (HR -0.9, 95% CI -0.3 to -1.5, P = 0.004) was identified as a negative predictor for ODI improvement. CONCLUSIONS:Microdiscectomy for lumbar disc herniation is an effective and safe treatment.