An optimal disc height changes for successful indirect decompression with OLIF.

This retrospective study included 63 patients in whom 104 vertebral levels were surgically involved. Data on the efficacy of oblique lumbar interbody fusion (OLIF) for canal and foraminal stenosis of the lumbar spine were analyzed for a follow-up period as long as one year post-surgery. The factors associated with successful indirect decompression were evaluated by measuring disc height and spinal canal width changes. Radiological assessments of anterior disc height (ADH), posterior disc height (PDH), lumbar lordotic angle (LL), segmental lordotic angle (SL), foraminal height (FH), cross-sectional area (CSA) of the spinal canal, cross-sectional foraminal area (CSF), and subsidence (SD) were conducted in this study. The comparison of pre- and postoperative values demonstrated significant increases in both mean CSA and CSF (p < 0.001). FH increased from 15.23 ± 3.48 mm to 18.78 ± 2.93 mm and was stable as long as one year post-surgery (p < 0.0001). The VAS leg score and Oswestry Disability Index (ODI) significantly improved after surgery (p < 0.05). Immediate and one-year postoperative FH changes were significantly associated with changes in one-year postoperative ADH, PDH, and VAS leg score (p < 0.05). The positive (+) group, comprised of those who demonstrated FH improvement at one year postoperatively, also demonstrated significantly greater ADH and PDH changes immediately postoperatively compared with the FH negative (-) group (6.46 mm vs. 4.52 mm, p = 0.038 and 3.59 vs. 2.40, respectively; both p-values < 0.001). The CSF positive (+) group also showed significantly greater immediate postoperative ADH and PDH changes (6.24 mm vs. 4.55 mm, p = 0.043, and 3.00 vs. 1.57, p = 0.010, respectively). OLIF provided satisfactory indirect decompression for at least one year after surgery. Based on the FH increases, our findings indicated that optimal surgical outcomes are achieved with > 3.0 mm PDH changes and no over-distraction of the disc space.