Relationship between the Degree of Thoracic Deformity and the Angle Formed by a Line Connecting the Sternum and the Spinous Process of the Vertebrae in Individuals with Severe Motor and Intellectual Disorders

[Purpose] The purpose of this study was to examine the relationship between the degree of thoracic deformity (TD) and the angle formed by a line drawn on transverse plane computed tomography (CT) images, connecting the sternum and the spinous process of the vertebrae at the level of the xiphisternum, and the perpendicular line from the floor (ANGLE), in individuals with severe motor and intellectual disorders (SMID). [Subjects] Twenty seven individuals with SMID were examined. [Methods] CT transverse images were acquired at the level of the xiphisternum of each patient. Two protocols were used to measure the anteroposterior (AP) and laterolateral (LL) diameters. The largest AP diameters were measured along a perpendicular line from the floor (protocol 1) and the line from the midline of the sternum to the spinous process of the vertebrae (protocol 2). The largest LL diameters were measured along the lines perpendicular to the AP diameters in each protocol. The ratios of the AP to LL diameters and the difference between the ratios of protocols 1 and 2 (DIFFERENCE) were calculated. [Results] Moderate to good correlation between DIFFERENCE and ANGLE was observed, and DIFFERENCE became larger with increasing ANGLE. [Conclusions] These results show that ANGLE indicates the degree of TD.