One-Hole Split Endoscopy Versus Open Laminectomy for Single-Level Thoracic Ossification of the Ligamentum Flavum: A Multicenter Propensity Score-Matched Cohort Study

<title>Abstract</title> <p>Background Thoracic ossification of the ligamentum flavum (TOLF) is an important cause of thoracic myelopathy and is commonly treated by open posterior decompression. One-hole split endoscopy (OSE) may reduce surgical trauma, but multicenter comparative evidence with quantitative evaluation of paraspinal muscle preservation and local alignment remains limited. Methods This multicenter retrospective cohort study included 216 patients with single-level TOLF treated at four tertiary hospitals between January 2019 and January 2024. Patients underwent OSE decompression (n = 72) or open laminectomy alone (n = 144). A 1:2 propensity score matching (PSM) analysis was performed, yielding 62 OSE patients and 124 open-surgery patients. Perioperative outcomes, 1-year neurological recovery, radiographic decompression, local Cobb angle change, paraspinal muscle relative functional cross-sectional area (rfCSA), and complications were compared. Results After PSM, baseline covariates were well balanced. Compared with open laminectomy, OSE required a longer operative time but resulted in less blood loss, lower postoperative drainage, and a shorter hospital stay (all P &lt; 0.001). The 1-year JOA recovery rate was comparable between OSE and open surgery (68.7% ± 12.5% vs. 65.3% ± 13.2%; mean difference, 3.40%; 95% CI, -0.52 to 7.32; P = 0.089). OSE was associated with less local Cobb angle progression, better preservation of multifidus and erector spinae rfCSA, and a lower overall complication rate (16.1% vs. 34.7%, P = 0.010). Preoperative JOA score &lt; 7, modified Sato type III, Epstein grade IV, and grade 2 preoperative intramedullary T2 hyperintensity were independent risk factors for poor neurological recovery, whereas surgical approach was not. Conclusions In strictly selected patients with single-level TOLF without obvious instability, OSE achieved neurological recovery and decompression comparable to open laminectomy while reducing surgical trauma, preserving paraspinal muscle morphology, limiting local Cobb angle progression, and lowering overall complications. OSE may be a minimally invasive option when indications are carefully controlled and thoracic endoscopic expertise is available.</p>