P85. Objective realignment guidelines in corrective ASD surgery accounting for reciprocal truncal and pelvic compensation

Abstract

BACKGROUND CONTEXT Despite increased recognition of the clinical benefit of optimal sagittal realignment among symptomatic ASD patients, persistent malalignment remains prevalent following corrective surgery. Following surgery it remains difficult to predict the changes in truncal inclination and pelvic retroversion depending on segmental and regional correction of the lumbar spine. PURPOSE Establish simultaneous focal and regional corrective guidelines accounting for reciprocal global and pelvic compensation STUDY DESIGN/SETTING Retrospective review of a prospective database PATIENT SAMPLE A total of 433 Surgical Adult Spinal Deformity (ASD) patients with 2-year follow-up. OUTCOME MEASURES Prediction of postoperative sagittal alignment (PT, SVA and TPA). METHODS Patients were included based on the presence of radiographic ASD and having undergone corrective realignment at minimum incorporating L1-pelvis. Established sagittal radiographic parameters, as well as segmental and regional (T10-L1, L1-L4, and L4-S1) Cobb angles were assessed prior to and following surgery. To distinguish the impact of the realignment on pelvic versus truncal inclination a virtual postoperative alignment was generated by combining postoperative alignment of the fused spine with the preoperative alignment on the unfused thoracic kyphosis and the preoperative pelvic retroversion. Incorporating virtual alignment, regression models were then generated to predict the relative impact of segmental (L4-L5) and regional (L1-L4) corrections on PT, SVA (virtual), and TPA. RESULTS A total of 433/667 patients were included (mean age 62.9 years, 81.3% women). Following surgical intervention significant improvement of sagittal alignment occurred; PI-LL (21° to 4°), PT (26° to 23°), SVA (79mm to 33mm) and TPA (26° to 19°)(all p CONCLUSIONS This study establishes that the overall impact of lumbar lordosis restoration is critically determined by the location of the correction. For any given amount of lordosis correction, a distal correction leads to a greater impact on global alignment and pelvic retroversion. More specifically, it can be assumed that 1° L4-S1 correction implies 1° change in TPA / 10mm change in SVA and 0.5° in PT. Based on regional objectives (PI-LL) and global perspectives (TPA/SVA and PT), preoperative planning can be adjusted to optimize realignment. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.