Statistical method for evaluating human thoracolumbar spinal curves in the sagittal plane: a preliminary report

This study was conducted to develop a statistical method of analyzing human thoracolumbar curves in the sagittal plane. Spinal tracings were obtained from 30 women by recording directly from the body surface, using a draftsman's flexible rule, transferring curves to graph paper, and making cubic spline and principal component analyses. Results were: an accurate method of analyzing spinal curves; accurate analysis of curves at an average overall residual standard deviation of 0.7 mm; component analysis suggesting that this method can be used to establish normal values for specific populations of known age, race, and sex, and to categorize individual curves.