The use of statistical modelling to identify important parameters for the shape of the torso following surgery for adolescent idiopathic scoliosis

Abstract

The surgical strategy in adolescent idiopathic scoliosis (AIS) aims to recreate the symmetry of the torso. This requires the minimisation of both the size of the scoliosis and the angulation between the sides of the torso, along with the recreation of a normal thoracic kyphosis. This study uses predictive modelling to identify the significance of the value of the pre‐operative parameters, and the change in the magnitude of the parameters as a result of an operation on the shape of the torso using the ‘most prominent points’; two areas of maximum prominence on either side of the spine with x, y and z coordinates. The pre‐operative values, and the change in magnitude between the pre and post‐operative values, for scoliosis, kyphosis and skin angulation from a group of Lenke 1 convex to the right AIS were analysed with measures collected using Integrated Spine Imaging System 2 surface topography and compared with those without visible spinal deformity. The models best explained the z coordinate and least well explained the x coordinate, although there was a contribution to all of the models that remained unexplained. The parameters that affected the position of the coordinates in the model differed between the models. This confirms that surgically altering the shape of the spine and torso whilst correcting an AIS does not lead to a symmetrical torso. There are as yet, undefined factors which contribute to the shape of the torso and which if identified and corrected surgically would lead to greater symmetry post‐operatively.

Statistical modelling of how the sagittal alignment of the cervical spine is affected by adolescent idiopathic scoliosis and how scoliosis surgery changes that

“…An understanding of the different alignment between the cervical and thoracic spines are also critical to the prevention of proximal junctional kyphosis and failure, where, following surgery for AIS there is segmental kyphosis over the cervicothoracic junction which in the worst case can lead to spinal cord injury (Hart et al, 2013). More advanced mathematical modelling techniques have been used previously to describe the cervical spine alignment in an adult population without spinal deformity (Diebo et al, 2016) and with regards to the 3D shape of the torso in AIS (Gardner, Berryman, & Pynsent, 2021). These techniques have not, however, been applied to cervical spine alignment in the setting of AIS.…”