Oral Posters: Thoraco-lumbar Degenerative
Presented by: O Tannous - View Audio/Video Presentation (Members Only)
O. Tannous(1), N. Nabizadeh(2), B. Nguyen(2), V. Zlomislic(2), S. Garfin(2), R.T. Allen(2)
(1) Georgetown University, Orthopaedics, Bethesda, MD, United States
(2) UCSD, Orthopaedics, San Diego, CA, United States
Purpose: Sagittal imbalance has been shown to negatively affect health related quality of life measures in patients with degenerative lumbar spine conditions. Over the past two decades, the incidence of lumbar fusion has increased significantly, however, understanding of the relationship between pelvic incidence (PI) and lumbar lordosis (LL) has not become widespread until recent years. The purpose of this study is to evaluate the prevalence of preoperative sagittal imbalance (defined as a PI-LL mismatch >10°) and the incidence of postoperative imbalance after varying forms of spinal fusion for lumbar degenerative spinal conditions.
Methods: Patients who underwent one- two- or three-level lumbar fusion at our institution between 2013 and 2015, with a minimum of 6 months of follow-up, were selected. Patients were grouped based on the type of lumbar fusion that was performed, i.e. posterolateral fusion only (PSF), anterior lumbar interbody fusion (ALIF), transforaminal lumbar interbody fusion (TLIF), and lateral lumbar interbody fusion (LLIF). Those undergoing revision surgery or without a degenerative lumbar condition were excluded. Pre-and post-operative radiographs were retrospectively reviewed; the PI and LL were measured on standing lateral lumbar radiographs at the preoperative and 6-month postoperative time points. The PI-LL mismatch was measured at both time points.
Results: 105 patients were selected based on the inclusion criteria. Overall, 56 patients (53%) had a preoperative PI-LL mismatch of >10 degrees (mean 23°) compared to 42 (40%) with a residual postoperative mismatch (mean 20.1°). Of the various forms of lumbar fusion, there were 7 PSF, 40 ALIF, 8 TLIF, and 50 LLIF. The mean preoperative PI-LL was 14.1° for PSF, 10.1° for ALIF, 13.9° for TLIF, and 14.6° for LLIF. Postoperatively, the mean PI-LL was 12.3° for PSF, 6.4° for ALIF, 13.2° for TLIF, and 8.3° for LLIF.
Conclusion: In this patient cohort, 53% of patients undergoing lumbar fusion for a degenerative condition, had a preoperative PI-LL mismatch of greater than 10°. A significant proportion of these patients are left with a postoperative mismatch. Patients undergoing PSF and TLIF are most likely to retain a postoperative PI-LL mismatch >10°, while those undergoing ALIF or LLIF are most likely to achieve postoperative sagittal balance.