Impact of Posterior Spinal Fusion on Pulmonary Function in Patients With Severe Adolescent Idiopathic Scoliosis (Major Cobb Angle ≥90°).

Abstract

Curve severity is a recognized factor associated with impaired pulmonary function in patients with severe adolescent idiopathic scoliosis (AIS). Despite significant curve correction achieved after posterior spinal fusion, reports on the extent of potential pulmonary function improvement in these patients remain inconsistent. Therefore, we aimed to evaluate the changes in pulmonary function test (PFT) parameters in patients with severe AIS after posterior spinal fusion. This study involved 18 severe AIS patients with major main thoracic curves (<i>major Cobb angle ≥90°</i>), who underwent posterior spinal fusion between 2019 and 2023, with a minimum 24-month follow-up. Primary PFT parameters measured preoperatively and at the most recent observation postoperatively were forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), and total lung capacity (TLC). Moderate to severe pulmonary impairment (<i>MSPI</i>) is defined as a predicted FVC/FEV₁ of ≤65%. Patients were classified into having <i>normal pulmonary function/mild pulmonary impairment</i> (<i>normal/mild PI</i>) and <i>MSPI</i>. Postoperatively, patients were further categorized into having <i>improved pulmonary function</i> or <i>stable pulmonary function</i> based on the transition of their pulmonary function classification. The mean final follow-up duration was 37.9 ± 15.1 months. The major Cobb angle improved from 101.5° (93.0°-115.3°) to 45.0° (35.0°-58.0°) postoperatively (<i>p</i> < 0.001). There were increments of 14.7 ± 8.3% in predicted FVC and 15.2 ± 9.6% in predicted FEV₁ postoperatively. The predicted FVC and FEV₁ increased from 53.6 ± 11.9% and 50.1 ± 13.4% (preoperative) to 68.3 ± 7.9% and 65.3 ± 10.5% (postoperative), respectively (<i>p</i> < 0.001). Seven patients (50.0%) (<i>based on FVC classification</i>) and 6 patients (40.0%) (<i>based on FEV</i> _<i>1</i> <i>classification</i>) with <i>MSPI</i> showed postoperative improvement in pulmonary function by transitioning to <i>normal/mild PI</i>. The remaining patients exhibited stable pulmonary function, and none experienced deterioration. Patients with severe AIS demonstrated significant improvements in pulmonary function parameters after posterior spinal fusion. None experienced postoperative deterioration, whereas approximately 40.0% to 50.0% of those with <i>MSPI</i> improved to the <i>normal/mild PI</i> category. Level III. See Instructions for Authors for a complete description of levels of evidence.