Effect of postoperative lumbar sagittal alignment on the development of adjacent instability

Objective: This study investigated the effect of postoperative lumbar sagittal alignment on the development of adjacent segment instability. Methods: The patients were retrospectively divided into two groups (hypolordotic and hyperlordotic) using the lumbar lordosis on lateral lumbosacral view. Diagnosis of adjacent segment instability depended on the dynamic lateral views of the lumbosacral spine. Results: Thirteen (21.7%) cases developed adjacent segment instability during the 6-year follow-up. The two groups had no significant difference in rates of developing adjacent segment instability. Conclusion: Restoring the lordosis of the lumbar curve during one motion segment fusion does not prevent the development of adjacent instability.