A MATHEMATICAL EXPRESSION OF 3-DIMENSIONAL CONFIGURATION OF THE SCOLIOTIC SPINE

Three-dimensional configuration of the scoliotic spine was mathematica lly expressed by a spatial curve passing through each vertebral centro id (''vertebral body line''). Three-dimensional location of the verteb ral centroid was determined from digitization on the frontal and sagit tal roentgenograms. Cobb angle, which is clinically used for measuring scoliosis curvature, was calculated in space to evaluate scoliosis de formity three-dimensionally In forty-five scoliotic spines, regardless of curvature and curve patterns, the spinal configurations were excel lently approximated by vertebral body lines. Vertebral body lines swer ved from the sagittal plane at the end vertebrae, but aligned on a cer tain plane within the scoliosis region. Three-dimensional Cobb angle, which was larger than that in the frontal plane, can be utilized to ev aluate the scoliosis deformity.