CLINICAL OUTCOMES AFTER INDIRECT DECOMPRESSION THROUGH ANTERIOR APPROACHES VERSUS DIRECT DECOMPRESSION WITH POSTERIOR APPROACHES IN LUMBAR INTERBODY FUSION: A PROPENSITY-MATCHED ANALYSIS USING DATA FROM THE CANADIAN SPINE OUTCOMES AND RESEARCH NETWOR

Lumbar interbody fusion (LIF) is a surgical treatment for degenerative diseases of the lumbar spine. It can be achieved via posterior or anterior approaches. Though posterior approaches are more commonly used, anterior approaches are garnering popularity due to their improved rates of fusion and decreased risk of iatrogenic neurological injury since decompression is achieved indirectly. To date, there is limited comparative evidence supporting the superiority of one surgical approach over another in terms of long-term clinical outcomes. Our objective was to compare long-term (>1 year) outcomes between anterior (indirect decompression) and posterior (direct decompression) approaches to lumber interbody fusion (LIF) surgery by means of a matched cohort using a nationwide, multicenter observational registry. This was a one-to-one propensity score matched analysis. Data were collected for adult patients with a degenerative diagnosis who underwent anterior or posterior LIF between January 1st, 2015, and February 15th, 2022, from the Canadian Spine Outcomes and Research Network national registry, a nationwide multicentre database compiling prospectively collected data from 18 tertiary care academic and non-academic hospitals across Canada. Baseline variables were used in a logistic regression model for calculating the propensity score for being in the anterior or posterior cohort. Patient-reported outcome measures (PROMs) were compared and included numerical rating scales (NRS) for leg and back pain, Oswestry Disability Index (ODI), and the short form (SF)-12 survey at 12 months and 24 months after surgery; and adverse events. There were 1,339 patients who met inclusion criteria. Sixty-seven patients were in the anterior cohort and 1,272 were in the posterior cohort. Before matching, patients in the anterior cohort were significantly younger and had a lower BMI. Following matching, 55 patient pairs were identified, and the mean (SD) ages were 60 (10.5) and 62 (10.7) years (p=0.25), the mean (SD) BMI 27.8 (5.46) and 27.3 (4.88) kg/m2 (p=0.61), and the proportion of females 56.4% and 54.6% (p=0.84) for anterior and posterior cohorts, respectively. At 1-year follow up, patients in the anterior cohort had significantly less back pain (2 vs. 4 NRS, p=0086), however this difference did not persist at 2-years of follow-up. Using prospectively collected data from a large nationwide registry in Canada, we demonstrated that anterior LIF through indirect decompression is associated with less back pain at 1-year follow-up compared to the standard posterior (direct decompression) approaches, but at 2-years follow-up both approaches yielded similar pain relief.