[Pulmonary function and movement of the thoracic cage in mild idiopathic thoracic scoliosis]

It has not yet been studied whether there is a threshold in the degree of scoliotic deformity, above which the pulmonary function is impaired. Neither has it been confirmed whether the pulmonary dysfunction has some relation to the development of scoliosis and its deterioration, if the impairment of pulmonary function does exists in patients with subclinically mild scoliosis. To elucidate these problems, the author investigated the respiratory function and the movement of the thoracic cage as well, in scoliotic patients with mild involvement on their thoracic spine. The results were as follows. In cases with mild deformity of less than fourty degrees, residual volume and functional residual capacity were increased and static lung compliance was decreased, but vital capacity remained within normal limits. Increased residual volume was observed even in the very mild case with a curvature of as much as ten degrees. No correlation was found between the degree of pulmonary dysfunction and the prognosis of scoliosis. The author believed that prognosis of scoliosis could not be predicted by testing the pulmonary functions alone. The movement of the thoracic cage was greater in the concave side of scoliosis than in the convex side on both tidal breathing and vital capacity measurement maneuver. Both the degree of deformity represented by Cobb's angle and that of rib hump correlated significantly with the restriction of the movement of the thoracic cage on the convex side of scoliotic deformity.