Quantifying changes in 3D surface rotations after surgical correction of adolescent idiopathic scoliosis

A plethora of measurements are available to characterise scoliosis, but a mismatch remains between cosmesis, radiological parameters and patient functional outcomes. Better assessment of cosmesis, through quantitative techniques, may help address this mismatch. We propose a new method of quantifying external scoliotic deformity, by assessing rotation in transverse slices across the length of the torso, using 3D photography. Patterns of segmental rotations across the spine were seen to be highly individual, and changes were observed after surgery. Along the length of the spine, pre-operatively, the range of rotations within individuals varied from 10.4° (Individual minimum 0.4° to maximum 10.8°) to 21.8° (Individual minimum of -5.2° to maximum of 16.6°). Post-operatively, this decreased, with individual rotational ranges as low as 2.6°, and individual decreases of up to 10.2° in total range. With further development, this technique has the potential to provide a useful quantitative and qualitative tool for assessing external deformity and surgical correction, possibly providing a non-irradiating diagnostic and monitoring tool to augment clinical imaging.