Forced vital capacity and maximal respiratory pressures in patients with mild and moderate scoliosis.

Lung function and maximal respiratory pressures of 24 adolescent females with mild-to-moderate idiopathic scoliosis (spinal curvature 10-60 degrees) were determined and compared with 38 age- and sex-matched controls. Twelve patients with moderate scoliosis (Cobb angle 35-60 degrees) had significantly reduced mean values for FVC (% predicted) and maximal inspiratory pressure (MIP), as compared to the controls. Twelve patients with mild scoliosis (Cobb angle less than 35 degrees) had normal mean values for FVC and maximal respiratory pressures, but five individual patients had FVC values less than 80% predicted. All but one of the patients with mild scoliosis had normal MIP values. FVC (% predicted) was significantly correlated with the degree of spinal curvature (r = -0.466; P less than 0.05) but was not related to MIP. These results indicate that reduced FVC values do occur in patients with mild-to-moderate idiopathic scoliosis and suggest that these low FVC values can be attributed to the rib cage deformity rather than to an inability to generate adequate inspiratory pressures.