196. Longitudinal changes of the sagittal plane after posterior spinal fusion of adolescent idiopathic scoliosis in Lenke 5 and 6 from baseline to two-year follow-up

Abstract

BACKGROUND CONTEXT The coronal plane in adolescent idiopathic scoliosis (AIS) has been extensively studied. However, studies investigating the changes in sagittal parameters before and after posterior spinal fusion in Lenke types 5 and 6 are scarce. Sagittal plane assessment of lumbar lordosis (LL), pelvic tilt (PT) and pelvic incidence (PI) in AIS Lenke 5 & 6 has not been fully delineated. PURPOSE The purpose of this study was to report on the spinopelvic parameters over 2 years. AIS Lenke 5 & 6 pts who underwent PSF were stratified into 3 groups based on amount of preop lumbar lordosis (low LL 60). Sagittal plane and spinopelvic parameters were followed longitudinally over 2 years postop. STUDY DESIGN/SETTING This study was a retrospective review of a prospectively collected multicenter database of patients with AIS who underwent spinal fusion. PATIENT SAMPLE Multicenter database of AIS patients, Lenke 5 and 6, who underwent PSF with 2-year follow-up and radiographic data were included. OUTCOME MEASURES Radiographic spinopelvic parameters including lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT) and thoracolumbar kyphosis (TL kyphosis). METHODS Baseline, 6-week, 6-month, 1-year and 2-year follow-up radiographs were analyzed for sagittal plane parameters (LL, PI, PT and TL kyphosis). Lenke 5 & 6 pts were stratified according to LL into 3 groups; low LL 60. Patients within each LL group were followed from preop to 2 years after PSF for changes in TL kyphosis, LL, PI and PT. RESULTS A total of 242 Lenke 5 (L5) and 223 Lenke 6 (L6) patients were studied. In the L5 pts, the average preop LL was −56 (−24 to −93), average preop PT was 9.3 (−10-26). In L5 pts with preop LL 60 (n=94), postop LL increased to 6 months then plateaued while PT trended down from 6 weeks to 2 years. L6 patients had an average preop LL of-55 (−21 to −91), average preop PT 10(−6 to 52). L6 pts with preop LL 60 (n= 71) LL increased from 6 weeks to 6 months back to preop value and remained unchanged at 2 yrs. PI did not change over time but lumbar lordosis increased over the 2 years. CONCLUSIONS There is an inverse relationship between LL and PT in patients with Lenke types 5&6 when longitudinally tracked over 2 years postoperatively. PI did not change but lumbar lordosis increased over 2 years. When lumbar lordosis increases, sagittal plane adapts to PSF and improves over time. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.