Correlation of an induced rotation model with the clinical categorisation of scoliotic deformity--a possible platform for prediction of scoliosis progression

Abstract

Aim: The primary aims were to develop a simplified three-dimensional model of the thoracolumbar spine and to predict the influence of axial rotation at different levels of the spine on the resultant scoliotic curve, using King's classification as a comparator.

Materials and methods: A three-dimensional mathematical model of the simplified thoracolumbar spine (constant size vertebral body without posterior elements) was developed using anatomical data from the published literature. The influence of rotational displacement of the motion segments at various levels of the spine was studied by applying different axial rotations, using a three-dimensional homogeneous transformation matrix method.

Results: The result of the model show the correlation of the deformity in lower regions of the spine (lumbar) with the geometrical changes in upper regions of the spine (thoracic), associated with the continuous alteration in direction of the vertebral axis of rotation along the spine. The final curvature of the scoliotic spine is influenced by both the degree of axial rotation in each region and the spatial deformation of the spine (e.g. kyphotic shape and extent of lateral deformity). Qualitatively, the model is capable of producing different categories of the spinal deformity based on King's classification.

Conclusion: A three-dimensional analysis of spinal shape demonstrates the important relationship between induced vertebral rotation and the resulting deformity. The effect of rotational displacement on the overall configuration of thoracolumbar spine during juvenile growth was assessed and demonstrates close correlation with deformities of the lower regions of spine.