Spine Surgeon NYU School of Medicine New Canaan, CT, US
Introduction: Novel parameters and realignment schema have centered on pelvic incidence to improve outcomes in ASD surgery. We sought to determine an ordered realignment approach when addressing PI-based parameters to produce better long-term outcomes.
Methods: Included: ASD patients with 2Y data. Outcomes included: Smith et al Best Clinical Outcome(BCO: ODI < 15 and SRS-Total score>4.5). Patients ranked based on baseline T1PA, categorized into Low and High Global Deformity, then ranked and categorized by Low and High PI(pelvic incidence). Hierarchical Approach: using conditional inference tree(CIT) analysis, thresholds for L1PA were derived based on meeting BCO. Patients meeting L1PA threshold were isolated, and realignment in other parameters(PI-based Relative Lordosis, PI-based Sacral Slope, L4-S1, Lordosis Distribution Index(LDI: L4-S1/L1-S1), L4PA) was examined to identify which had the greatest effect on meeting BCO. ANCOVA and multivariable regression, controlling for age, invasiveness and baseline disability and deformity, assessed outcome rates for the hierarchical approach for each deformity group.
Results: 445 ASD patients included. Low Global Low PI patients saw lower rates of mechanical complications, PJF, and more likely to achieve BCO(OR: 5.2,[1.8-15.1]) when correcting L1PA and L4PA. Properly distributing lordosis through L4-S1 best aided Low Global High PI patients, demonstrating lower odds of mechanical complications(OR: 0.1,[0.08-0.9]) and increasing likelihood of meeting BCO(OR: 7.1,[1.8-28.9]). Addressing L4PA in High Global Low PI group after correction of L1PA led to lower rates of mechanical complications(0% vs 12%,p < .001), reoperation(10% vs. 29%,p=.04) and higher rates of meeting BCO(23% vs. 9%,p=.03). High Global High PI cohort saw lower rates of mechanical complications, reoperations(7% vs 23%,p=.02), and higher odds of achieving BCO(OR: 4.8,[1.4-16.3]).
Conclusion : An individualized approach to presentation of deformity produced tremendous clinical benefits while minimizing mechanical complication and reoperation rates. These realignment strategies better enable spine surgeons to tailor correction to each patient presenting for correction of adult spinal deformity.
