Correlation of Cobb's angle with pulmonary function in idiopathic scoliosis

Abstract

Background: Idiopathic scoliosis, which accounts for the 80-85% of all lateral spine curvatures, distorts the chest wall anatomy and results in functional pulmonary disability. Aims and Objectives: The aim of this study is to evaluate the pulmonary function in patients with asymptomatic idiopathic scoliosis and matched controls and to study the correlation between the degree of spinal deformity (Cobb’s angle) and pulmonary function test (PFT) parameters. Materials and Methods: This study included 35 (27 males and 8 females) patients with idiopathic scoliosis in the age group of 15-30 years, with mean Cobb’s angle 62°. Standing anteroposterior X-rays of the spine were taken. The radiographs were assessed and angle of curvature was measured by the Cobb’s method. PFT parameters were recorded and compared with matched controls, and their correlation with Cobb’s angle was studied. The data were analyzed with the Student’s unpaired t-test and Pearson’s correlation coefficient. Results: Pulmonary parameters such as tidal volume, vital capacity (VC), forced VC (FVC), forced expiratory volume in first second (FEV1), maximum mid-expiratory flow rate, peak expiratory flow rate, and maximum voluntary ventilation were significantly reduced in scoliosis patients than controls, and they were inversely correlated with Cobb’s angle. However, the mean FEV1/FVC ratio at rest in scoliosis patients was within normal limits and the ratio was not correlated with Cobb’s angle. Conclusion: Thus, it can be concluded that patients with idiopathic scoliosis show reduced lung volumes and capacity on PFT and the pulmonary parameters show strong inverse correlation with the severity of the spinal deformity (Cobb’s angle).