Are We Getting Better at Achieving Optimal Lumbar Segmental Sagittal Alignment in Complex Adult Spine Deformity Surgery?

Overview

abstract

STUDY DESIGN: Retrospective multicenter study. OBJECTIVE: To investigate how advances in spine realignment have impacted lumbar segmental alignment. SUMMARY OF BACKGROUND DATA: The understanding of spine alignment and adult spinal deformity (ASD) management continues to advance. It remains unknown how these advances have influenced lumbar segmental alignment changes in the setting of surgical correction. METHODS: Patients undergoing primary thoracolumbar fusion for ASD were stratified based on enrolment in two distinct multicenter registries; forming an 'Early' (2008-2017) and a 'Late cohort' (2018-present). Patients were further stratified based on pelvic incidence (PI) and Roussouly type. Segmental alignment was determined based on published values of asymptomatic individuals. Pelvic incidence-based alignment and Roussouly-based alignment were determined in alignment with previously published normative values. Means comparisons tests and multivariate analyses compared segmental and regional parameters between groups. RESULTS: One thousand two hundred forty patients included (622 EARLY, 618 LATE). The mean age was 61.4±14.5 years, body mass index (BMI) was 28.0±5.8 kg/m 2 , and Charlson comorbidity index (CCI) was 1.55±1.70. 70.2% of patients were female sex. LATE consistently displayed better L5 to S1 alignment across all PI and Roussouly types ( P =0.001). However, EARLY demonstrated better L4 to 5 alignment ( P =0.001). Improved alignment in L5 to S1, L4 to 5, and L3 to 4 was associated with achieving minimum clinically important difference in ODI scores and decreased risk of mechanical complications. Both cohorts demonstrated low rates of matching L4 to S1 regional and overall lumbar lordosis L1 to S1 alignment, with no differences between both groups. By lordosis distribution index, both groups had predominantly hyperlordotic maldistribution postop, but LATE had more 'Aligned' patients (15.9 vs. 11%, P <0.001). CONCLUSIONS: Over the past 15 years, surgeons seem to be better at restoring ideal lumbar segmental sagittal alignment in ASD patients. However, idealized correction does not seem to be uniform across all lumbar segments, representing an opportunity for further improvement. LEVEL OF EVIDENCE: Level III.