It is not just about the frontal plane: sagittal parameters impact curve progression in AIS patients undergoing brace treatment.

Abstract

Retrospective cohort study. The purpose of this study was to explore the association between pre-brace and in-brace sagittal parameters and curve progression. To date, there has been no published research focused on spinopelvic sagittal parameters and bracing outcomes in AIS. We hypothesize that sagittal spinopelvic parameters are associated with curve progression at 2years. This study included AIS patients with a pre-brace (PB) major curve between 20° and 45°. The outcome was defined as > 10° curve progression or surgery within 2years of brace initiation. Spinopelvic parameters included C7-Central Sacral Vertebral Line shift (C7-CSVL), thoracic trunk shift, lumbar lordosis (LL), pelvic incidence (PI), T2-T12 thoracic kyphosis (TK) pelvic incidence-lumbar lordosis (PI-LL) mismatch, sagittal vertical axis (SVA), and pelvic tilt (PT). Of 50 patients included in this review, [70% Rigo (RCSO) and 30% Boston (BSO)], 16 (32%) patients demonstrated progression (23% of patients with RCSO vs 53% with BSO; p = 0.034). In patients with more than 30% major coronal curve correction (CCC), 23% had progression. 45% of patients progressed when they achieved ≤ 30% correction (p = 0.108). Among PB sagittal parameters and adjusting for coronal curve, patients with an abnormal PB SVA had 3.1 times increased risk of treatment failure compared with patients who had a normal PB SVA. Patients with PB hypo-LL had a 2.8 times increased risk of treatment failure compared with patients who had normal or hyper-LL. Among IB sagittal parameters, patients who had a normal PB PI-LL had a 3.9 times increased risk of treatment failure when they became mismatched in-brace (IB). Patients who had normal pre-brace kyphosis who became hypo-kyphotic IB had an 8.4 times increased risk of treatment failure compared with patients who maintained normal TK or became hyper-kyphotic. These data suggest that we should pay careful attention to sagittal parameters prior to and during brace treatment as braces can control these parameters. Level III.