PAIN AND FUNCTION ONE YEAR AFTER DECOMPRESSIVE DISC SURGERY: CASES AUGMENTED WITH THE DIAM INTERSPINOUS IMPLANT VERSUS THOSE RECEIVING MICRODISCECTOMY

Abstract

Purpose: To examine clinical outcomes after decompressive lumbar surgery for herniated nucleus pulposus (HNP) in two cohorts from a single surgeon: Microdiscectomy alone [MICRO] versus microdiscectomy augmented with the Device for Intervertebral Assisted Motion [DIAM™, Medtronic Sofamor Danek, Memphis, USA]. We hypothesized that DIAM-augmented microdiscectomy would provide superior outcomes to microdiscectomy alone given purported benefits for interspinous devices reported in the literature. Improvements would concur with clinically significant change. Methods: Two separate HNP patient groups were sourced from a single surgeon: MICRO [n = 47 (17F/30M); 45 years (SD 14.2; 22–75)] and DIAM [n = 29 (10F/19M); 42 years (SD 11.2; 20–64)]. Patient-reported outcomes for function [MICRO=Roland-Morris Questionnaire (RMQ); DIAM=Oswestry Disability Index (ODI)] and back and leg pain [visual analogue scale (VAS)] were serially examined at preoperative baseline, 4–6 weeks, 6 and 12 months postoperatively. Incidence of repeat surgery at the index segment was recorded. Data were reported using descriptive statistics, unpaired t-tests and repeated ANOVA (Scheffe's post-hoc test). Statistically meaningful differences were defined by p < 0.05. Results: MICRO cases had higher preoperative leg pain (by 19%; p < 0.01). Improvements in absolute function and leg pain at one year were better in the MICRO group (p < 0.01). Both groups showed clinically significant improvement for all variables at each time-point during the period of follow-up. MICRO cases had proportionally fewer repeat surgeries (3/47 versus 4/29). Conclusions: Significant improvements in function, back and leg pain were shown in both patient groups out to one year. Clinically important change to function, back and leg pain was achieved for the MICRO cases, while clinically important change to leg pain occurred in the DIAM group. MICRO cases required proportionally fewer repeat surgeries by one year postoperatively. Microdiscectomy augmented with DIAM did not result in superior outcomes in treatment of herniated nucleus pulposus compared with microdiscectomy alone.