Efficacy of Varying Surgical Approaches on Achieving Optimal Alignment in Adult Spinal Deformity Surgery.

Abstract

The Roussouly, SRS-Schwab, and GAP classifications define alignment by spinal shape and deformity severity. The efficacy of different surgical approaches and techniques to successfully achieve these goals is not well understood. Identify the impact of surgical approach and/or technique on meeting complex realignment goals in adult spinal deformity(ASD) corrective-surgery. Retrospective. Included: ASD patients fused to pelvis with two-year(2Y) data. Patients were categorized by: 1)Roussouly: matching current and theoretical spinal shapes; 2)improving in SRS-Schwab modifiers(0, +, ++); 3)improving GAP Proportionality by 2Y. ANCOVA and multivariable logistic regression analyses controlling for age, levels fused, baseline deformity, and three-column osteotomy usage compared the effect of different surgical approaches, interbody and osteotomy use on meeting realignment goals. 693 ASD patients were included. By surgical approach, 65.7% were posterior-only and 34.3% underwent anterior-posterior(AP) approach with 76% receiving an osteotomy(21.8% 3CO). By 2Y, 34% matched Roussouly, 58% improved in GAP, 45% in SRS-Schwab PT, 62% SVA, and 70% PI-LL. Combined approaches were most effective for improvement in PT(OR: 1.7,[1.1-2.5]) and GAP(OR: 2.2,[1.5-3.2]). Specifically, ALIFs below L3 demonstrated higher rates of improvement versus TLIFs in Roussouly(OR: 1.7, [1.1-2.5]) and GAP(OR: 1.9, [1.3-2.7]). Patients undergoing PSO at L3 or L4 were more likely to improve in PT(OR: 2.0,[1.0-5.2]) and PI-LL(OR: 3.8[1.4-9.8]). Clinically, patients undergoing combined approach demonstrated higher rates of meeting SCB in ODI by 2Y while minimizing rates of PJF, most often with an ALIF at L5-S1(ODI-SCB: OR: 1.4,[1.1-2.0];PJF: OR: 0.4,[0.2-0.8]). Among patients undergoing ASD realignment, optimal lumbar shape and proportion can be achieved more often with a combined approach. While TLIFs incorporating a three-column osteotomy at L3 and L4 can restore lordosis and normalize pelvic compensation, ALIFs at L5-S1 were most likely to achieve complex realignment goals with an added clinical benefit and mitigation of junctional failure.