Impact of Physical Flexibility Changes on Respiratory Function after Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis Surgery

Introduction: Corrective scoliosis surgery in patients with adolescent idiopathic scoliosis (AIS) increases thoracic volume but does not improve respiratory function (RF). This study evaluates the effect of physical flexibility (PF) improvement af-ter scoliosis surgery on RF. Methods: This study reviewed the records of 61 consecutive patients with AIS (56 female and 5 male; mean +/- standard deviation age: 14.8 +/- 2.2 years, range: 11-20 years) who had undergone posterior spinal fusion (PSF) of the thoracic curve. PF evaluated as finger-floor distance (FFD) was measured preoperatively and one year after surgery. After dividing the co-hort into the PF improvement group and the PF nonimprovement group, RF changes at two years postoperative were statis-tically compared. Using logistic regression analysis, we evaluated the impact of a PF improvement on % forced vital capac-ity (%FVC) two years after surgery. Results: The rate of patients with increased FVC, %FVC, and forced expiratory volume 1.0 second two years after sur-gery was 79%, 51%, and 80%, respectively. The PF improvement group exhibited a significantly higher gain in %FVC ver-sus the PF nonimprovement group (P=0.043). Moreover, PF improvement significantly prevented a %FVC decrease (odds ratio 8.43, 95% confidence interval 1.92-59.70; P<0.001), with an adjusted odds ratio of 11.86 (P<0.001). Conclusions: Patients with diminished PF after PSF for AIS may be less likely to achieve postoperative %FVC improve-ment. As increased postsurgical %FVC had a positive effect on physical function, treatment strategies that focus on main-taining and increasing PF are desirable from an RF viewpoint.