Thursday, September 27, 2018 1:05 PM–2:05 PM Lumbar Spine Surgery: What You Need to Know: 116. Preoperative lumbosacral alignment and its correlation to lordosis change in one- and two-level degenerative fusions

Abstract

BACKGROUND CONTEXT As the evidence for maintenance of spinopelvic alignment in degenerative spinal conditions continues to grow, an understanding of postsurgical alignment changes based on patient and treatment factors may help guide surgical decision making in individual patients undergoing short segment lumbar spinal fusion procedures. PURPOSE The purpose of this study was to assess lordosis alignment changes after one or two level lumbar spinal fusions by preoperative alignment. STUDY DESIGN/SETTING A retrospective, multicenter, IRB-approved study measuring lumbosacral alignment before and after short-segment lumbar fusions was performed by 24 surgeons at 18 institutions across the United States. PATIENT SAMPLE A total of 578 patients were enrolled in the study. Inclusion required prior treatment with a one- or two-level spinal fusion in the lumbar spine for a non-deformity indication with available pre- and postoperative standing evaluable lateral radiographs. OUTCOME MEASURES Alignment measures included lumbar lordosis (LL) (L1–S1), pelvic tilt (PT) and pelvic incidence (PI), which were assessed at each time point. METHODS Alignment measurements were made using NuVaMap (NuVasive, Inc. San Diego, CA, USA) software. Preoperative alignment measures (LL, PI, & PT) were tested against postoperative LL and PT changes. Statistical significance was defined at p RESULTS A weak, but significant correlation was found between preoperative PI and postoperative change in LL, where a higher PI was associated with less LL increase compared to those with a lower PI. PI quartile differences in LL change showed a mean LL decrease if 0.9° for those in the higher PI quartile compared with a mean increase of 1.0° for those in the lowest PI quartile (p=.003). Additionally, there was an inverse correlation between preoperative LL and postoperative change in LL, where a lower preoperative LL predicted a greater increase in LL change postoperatively (r2=0.211, p CONCLUSIONS In a large, multicenter evaluation of lumbosacral alignment change in patients who underwent one- or two-level fusions for degenerative conditions, alignment change was shown to be significantly influenced by preoperative PI and LL, with patients having a higher preoperative PI or LL at greater risk of having a reduction in LL after short-segment fusions compared to those with a lower preoperative LL or PI. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.