Resident Physician Barrow Neurological Institute Phoenix, Arizona, United States
Introduction: Multilevel lateral lumbar interbody fusion (LLIF) has become increasingly popular for the treatment of adult spinal deformity (ASD). Occasionally, the L5-S1 disc space can be spared while still addressing the primary deformity. However, concerns exist about restoring the upper lumbar lordosis without addressing L5-S1. We investigated sagittal alignment outcomes following L5-S1 sparing LLIF surgery for ASD.
Methods: We retrospectively identified patients undergoing L1-5 and L2-5 LLIFs for ASD. Patients were selected if they met one of the following criteria: coronal cobb angle (CCA) > 20, pelvic incidence-lumbar lordosis mismatch (PI-LL) > 10, pelvic tilt (PT) > 20, or sagittal vertical axis (SVA) > 5. Pre- and post-operative standing scoliosis x-rays were measured to evaluate changes in sagittal alignment.
Results: 46 patients were included. 12 patients underwent L1-5 LLIF; 34 patients underwent L2-5 LLIF. Following surgery, patients were found to have increased overall LL (42.4 vs. 38.5, p = 0.012) and proximal LL (10.8 vs. 6.2, p < 0.001). Segmental lordosis at L2-3, L3-4, and L4-5 increased (p < 0.05); segmental lordosis at L5-S1 decreased (18.5 vs. 20.5, p = 0.043). Lordosis distribution index decreased (78.8 vs. 93.6, p < 0.001). The number of vertebrae in lordosis (NVL) increased from 3.7 to 4.4 (p < 0.001). The apex of lordosis shifted from L4-5 to L4 (p = 0.043). Total GAP score and the number of patients matching their ideal Roussouly type did not change significantly.
Conclusion : Following L5-S1 sparing multilevel LLIFs, patients exhibited an increase in the proximal and overall lumbar lordosis without a significant change in the distal lumbar lordosis. They also exhibited an increase in NVL and a cranial shift in the apex of lumbar lordosis. Overall, these changes resulted in redistribution of lumbar lordosis to the proximal lumbar spine without significantly changing overall sagittal balance, GAP score, or Roussouly match/mismatch rate.
