Risk Factors for Adjacent Segment Degeneration and Disease after Lumbar Spine Fusion Surgery

Objective: Adjacent segment degeneration (ASD) after lumbar fusion is common, but some cases are asymptomatic. Radiologic ASD becomes symptomatic when it progresses to adjacent segment disease (ASDs). Debate continues regarding the factors contributing to ASD and ASDs. Thus, in this study, we investigated factors influencing ASD and ASDs in the rostral segment after fusion surgery.Methods: In 79 patients who underwent lumbar or lumbosacral spine fusion surgery between January 2012 and December 2014, we evaluated central canal stenosis progression (≥ moderate) and subsequent adjacent segment surgery over a minimum follow-up of 5 years.Results: Transpedicular screw fixation with interbody fusion was the only factor that demonstrated a significant association with the progression of central canal stenosis (≥moderate) (73.68% vs. 31.71%; p = 0.035). Disc degeneration of grade III or higher was the only factor significantly associated with additional surgery after fusion (29.41% vs. 6.67%; p = 0.035).Conclusion: Transpedicular fixation with interbody fusion is an independent risk factor for ASD, and preoperative disc degeneration ≥grade Ⅲ in the rostral segment is an independent risk factor for ASDs.