One-hole split endoscopy versus open laminectomy for single-level thoracic ossification of the ligamentum flavum: a multicenter propensity score-matched cohort study

Thoracic ossification of the ligamentum flavum (TOLF) is an important cause of thoracic myelopathy. One-hole split endoscopy (OSE) offers a single-incision posterior decompression strategy, but multicenter evidence comparing neurological recovery, paraspinal-muscle preservation, and local alignment with open laminectomy remains limited. This multicenter retrospective cohort included 216 patients with single-level TOLF treated at four tertiary hospitals (OSE, n = 72; open laminectomy, n = 144). Deterministic 1:2 propensity-score matching retained 66 OSE and 132 open patients. The primary outcome was 1-year mJOA recovery. Secondary outcomes included perioperative measures, Cobb-angle progression, paraspinal-muscle rfCSA, back-pain VAS, and complications. Matched-set GEE was used for the primary comparisons; 1:1 matching and full-cohort overlap weighting were used as sensitivity analyses. The 1-year mJOA recovery rate was 62.35% ± 20.16% after OSE and 63.12% ± 17.81% after open laminectomy (difference, − 0.77%; 95% CI, − 6.85 to 5.31; P = 0.804). OSE required longer surgery but was associated with less blood loss (83.1 ± 20.9 vs. 330.2 ± 69.4 mL), shorter hospitalization (5.18 ± 1.24 vs. 9.71 ± 2.10 days), smaller 1-year Cobb-angle progression (1.30° ± 1.56° vs. 4.33° ± 2.04°), and less 3-month multifidus and erector-spinae rfCSA reduction (all P < 0.001). After baseline adjustment, 1-year back-pain VAS was lower after OSE (difference, − 0.55; 95% CI, − 0.94 to − 0.16; P = 0.006). Postoperative clinical complications were less frequent after OSE in the primary matched cohort (7.6 vs. 18.9%; P = 0.024), although this association was attenuated in full-cohort weighted analyses. At 18–37 months, differences in paraspinal-muscle preservation and local alignment remained evident. Both approaches produced substantial neurological improvement, and no statistically significant between-group difference in 1-year mJOA recovery was detected. OSE was consistently associated with lower blood loss, shorter hospitalization, greater preservation of paraspinal-muscle rfCSA, and less local Cobb-angle progression. OSE may therefore be considered a minimally invasive option for appropriately selected patients in experienced centers.