Analysis of Risk Factors for Postoperative Progressive Segment Degeneration at the Decompression and Non-decompression Segments after Minimally Invasive Lumbar Decompression Surgery: A 5-year Follow-up Study.

Introduction: The risk factors for the development of progressive segment degeneration (PSD) after decompression surgery are still unknown. In this study, the risk factors for PSD in patients who undergo decompression surgery for lumbar spinal stenosis with and without coexisting spondylolisthesis and scoliosis were examined, focusing on decompression and non-decompression segments. Methods: We reviewed the data of patients with >5 years of postoperative follow up. Radiographic PSD was defined as either the development of an anterolisthesis or retrolisthesis of >3 mm or a decrease in disc height of >3 mm during the 5-year follow up. On the basis of intervertebral segments, the association between PSD and other preoperative clinical findings was analyzed. Results: Overall, 840 lumbar segments (L1-L2 to L5-S1) in 168 patients, with a mean age of 69.5±9.2 years, met the inclusion criteria. PSD was observed in 162 (19.3%) lumbar segments. A logistic regression model identified that Cobb angle ≥10° (OR 2.53, 95% CI 1.50-4.24), spondylolisthesis ≥3 mm (OR 4.447, 95% CI 2.06-9.58), and level of segments were more likely to have PSD at the non-decompression level; additionally, lateral listhesis ≥3 mm (OR 2.91, 95% CI 1.08-7.81) was more likely to have PSD in the decompression segments. In clinical outcomes in patients with PSD at baseline and the 5-year follow-up, no significant difference was found. Conclusions: Even though PSD does not correlate with worsening symptoms, our study confirms that a higher degree of pre-existing disc degeneration is indicative of a higher PSD in 5 years.