Adjacent segment degeneration may predict significantly worse leg pain outcomes after lumbar discectomy

Abstract

Objective: We assessed whether preoperative advanced multisegmental degeneration is associated with worse 1-year outcomes of primary single-level lumbar discectomy. Materials and methods: A literature-based scoring system was developed to quantify degeneration in the operated and adjacent lumbar segments, based on advanced phenotypes of common intervertebral disc–related degenerative features. Each segment received a score from 0 to 3: cranial and caudal ≥ 25% endplate damage (EPD) and Modic changes type I (MC1) were assigned 0.5 points each, and Pfirrmann grade ≥ 4 was assigned 1 point. The final adjacent segment degeneration score was calculated as the mean of the operated and adjacent segment scores. Prospectively collected data from primary single-level lumbar discectomy patients operated in a single center between 2017 and 2022 were retrospectively analyzed. Patients were stratified into none-to-mild (≤ 0.5), moderate (0.5 < score < 1.33), and severe (≥ 1.33) degeneration groups, using the 40th and 80th percentile cut-offs. A linear mixed-effects model was employed to assess between-group differences in 1-year improvements in low back (LBP) and leg pain (VAS, 0–100), disability (ODI), and quality of life (EQ-5D-3L). Results: Among the 140 patients included (mean age 45.3 years; 57.9% male), all PROMs improved overall. The severe group showed significantly smaller improvements from baseline to 1-year follow-up, with adjusted mean differences in change of 20.2 for LBP, 31.6 for leg pain, and 11.1 for disability relative to the none-to-mild reference group. Conclusion: Severe preoperative adjacent segment degeneration may be associated with smaller 1-year improvements in pain and disability after primary single-level lumbar discectomy.