Predicting spinal column profile from surface topography via 3D non-contact surface scanning

PLOS ONE RESEARCH ARTICLE Predicting spinal column profile from surface topography via 3D non-contact surface scanning Lionel Rayward ID1, Mark Pearcy ID1, Maree Izatt ID1, Daniel Green2, Robert Labrom1,3, Geoffrey Askin1,4, J. Paige Little ID1* a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 1 Biomechanics and Spine Research Group, School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane City, Australia, 2 Sealy of Australia, Wacol, Australia, 3 Wesley Hospital, Auchenflower, Australia, 4 Mater Health Services, South Brisbane, Australia * Abstract Introduction OPEN ACCESS Citation: Rayward L, Pearcy M, Izatt M, Green D, Labrom R, Askin G, et al. (2023) Predicting spinal column profile from surface topography via 3D non-contact surface scanning. PLoS ONE 18(3): e0282634. https://doi.org/10.1371/journal. pone.0282634 Editor: Kevin M. Moerman, National University of Ireland Galway, Galway, Ireland, IRELAND Received: May 19, 2022 Accepted: February 17, 2023 Published: March 23, 2023 Copyright: © 2023 Rayward et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 3D Non-Contact surface scanning (3DSS) is used in both biomechanical and clinical studies to capture accurate 3D images of the human torso, and to better understand the shape and posture of the spine–both healthy and pathological. This study sought to determine the efficacy and accuracy of using 3DSS of the posterior torso, to determine the curvature of the spinal column in the lateral lying position. Methods A cohort of 50 healthy adults underwent 3DSS and Magnetic Resonance Imaging (MRI) to correlate the contours of the external spine surface with the internal spinal column. The correlation analysis was composed of two phases: (1) MRI vertebral points vs MRI external spine surface markers; and (2) MRI external spine surface markers vs 3DSS external spine surface markers. The first phase compared the profiles of fiducial markers (vitamin capsules) adhered to the skin surface over the spinous processes against the coordinates of the spinous processes–assessing the linear distance between the profiles, and similarity of curvature, in the sagittal and coronal planes. The second phase compared 3DSS external spine surface markers with the MRI external spine surface markers in both planes, with further qualitative assessment for postural changes. Data Availability Statement: The data relevant to this study are available at https:// researchdatafinder.qut.edu.au/display/n17685. Results Funding: The study equipment, study consumables, infrastructure, computing equipment and facilities are all supported (ownership/upkeep) by JPL’s academic institution, through research group funds (not linked to individual project/ person). The clinical imaging equipment is supported by a local public hospital (ownership/ upkeep). JPL receives salary support from her The distance between the MRI vertebral points and MRI external spine surface markers showed strong statistically significant correlation with BMI in both sagittal and coronal planes. Kolmogorov-Smirnov (KS) tests showed similar no significant difference in curvature, k, in almost all participants on both planes. In the second phase, the coronal 3DSS external spine surface profiles were statistically different to the MRI external spine surface markers in 44% of participants. Qualitative assessment showed postural changes between MRI and 3DSS measurements in these participants. PLOS ONE | https://doi.org/10.1371/journal.pone.0282634 March 23, 2023 1 / 14 PLOS ONE academic institution, which is in part contributed by Sealy of Australia. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist. Predicting spinal column profile from surface topography Conclusion These study findings demonstrate the utility and accuracy of using anatomical landmarks overlaid on the spinous processes, to identify the position of the spinal bones using 3DSS. Using this method, it will be possible to predict the internal spinal curvature from surface topography, provided that the thickness of the overlaying subcutaneous adipose layer is considered, thus enabling postural analysis of spinal shape and curvature to be carried out in biomechanical and clinical studies without the need for radiographic imaging. Introduction Three dimensional (3D) non-contact structured light surface scanners capture calibrated images of 3D objects, enabling virtual 3D reconstruction to be created with a high level of accuracy. The technology rapidly projects light onto an object while simultaneously recording images and detecting how the light distorts to patch together a 3D object. This versatile technology has seen applications across a multiplicity of disciplines, with examples including digital preservation of heritage listed buildings and sculptures [1], design of custom apparel [2]; analysing the biomechanics of a golf swing [3]; and in custom designing and reverse engineering car parts [4]. In certain healthcare applications, 3D surface scanning (3DSS) provides an appealing alternative to radiographic imaging due to its affordability, portability, ease of operation, and absence of ionising radiation exposure [5]. Examples of this application include evaluation of biomechanical and postural parameters, such as chest wall deformities [6], asymmetric muscular development [7], and measuring trunk posture for orthotic brace design [8]. An emerging application is the measurement of scoliosis severity by capturing surface topography of the torso to produce an external spinal contour [9]. Even so, it remains in question whether external surface topography can be used to derive meaningful clinical parameters describing the spinal column, and prior studies using surface topography to evaluate spinal deformity parameters have found varying results, with some finding surface metrics do not relate to clinical deformity angles [10] and others finding good correlation between the two modalities [11, 12]. While Yıldırım et al. [10] found a strong correlation between surface derived spinal contours and Cobb angle for 42 scoliosis patients, Hong et al. [11] noted that surface topography is most reliable for mild and non-progressive curves. 3DSS of the human body is similarly relevant for the study of healthy human biomechanics. Wu et al. [12] used 3DSS to capture body shape when creating a predictive model to assess sleep comfort, however, only scanned participants while standing and thus estimated lying alignment from computational modelling. Huysmans et al. [13] similarly evaluated the alignment of the spine using a poin (...truncated)