Three-dimensional shape analysis of the scoliotic spine using invariant shape parameters.

Abstract Use of calibrated stereoradiographs or other three-dimensional measuring systems enables a three-dimensional shape analysis of the spine. In the present study the shape of the spinal midline in the case of deformities such as scoliosis is investigated. The shape analysis is performed with reference to differential geometry of spatial curves. The resulting spatial shape parameters are invariant, i.e. independent of the coordinate system chosen. The relation of these parameters to conventional measures such as the Cobb angle is discussed.