The ‘Lumbar Fusion Outcome Score’ (LUFOS): a new practical and surgically oriented grading system for preoperative prediction of surgical outcomes after lumbar spinal fusion in patients with degenerative disc disease and refractory chronic axial low back pain

Abstract

In order to evaluate the predictive effect of non-invasive preoperative imaging methods on surgical outcomes of lumbar fusionfor patients with degenerative disc disease (DDD) and refractory chronic axiallow back pain (LBP), the authors conducted a retrospective review of 45 patients with DDD and refractory LBP submitted to anterior lumbar interbody fusion (ALIF) at a single center from 2007 to 2010. Surgical outcomes -as measured by Visual Analog Scale (VAS/back pain) and Oswestry Disability Index (ODI)- were evaluated pre-operatively and at 6weeks, 3 months, 6months, and 1year post-operatively. Linear mixed-effects models were generated in order to identify possible preoperative imaging characteristics (includingbone scan/99mTc scintigraphyincreased endplate uptake, Modic endplate changes, and disc degeneration graded according to Pfirrmann classification)which may be predictive of long-term surgical outcomes . After controlling for confounders, a combined score, the Lumbar Fusion Outcome Score (LUFOS), was developed. The LUFOS grading system was able to stratify patients in two general groups (Non-surgical: LUFOS 0 and 1; Surgical: LUFOS 2 and 3) that presented significantly different surgical outcomes in terms of estimated marginal means of VAS/back pain (p = 0.001) and ODI (p = 0.006) beginning at 3months and continuing up to 1year of follow-up. In conclusion, LUFOS has been devised as anew practical and surgically oriented grading system based on simple keyparameters from non-invasive preoperative imaging exams (magnetic resonance imaging/MRI and bone scan/99mTc scintigraphy) which has been shown to be highly predictive of surgical outcomes of patients undergoing lumbar fusion for treatment for refractory chronic axialLBP.