A reduced-order model of the spine to study pediatric scoliosis
- PDF / 2,677,707 Bytes
- 14 Pages / 595.276 x 790.866 pts Page_size
- 9 Downloads / 171 Views
ORIGINAL PAPER
A reduced‑order model of the spine to study pediatric scoliosis Sunder Neelakantan1 · Prashant K. Purohit1 · Saba Pasha2 Received: 30 March 2020 / Accepted: 30 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The S-shaped curvature of the spine has been hypothesized as the underlying mechanical cause of adolescent idiopathic scoliosis. In earlier work, we proposed a reduced-order model in which the spine was viewed as an S-shaped elastic rod under torsion and bending. Here, we simulate the deformation of S-shaped rods of a wide range of curvatures and inflection points under a fixed mechanical loading. Our analysis determines three distinct axial projection patterns of these S-shaped rods: two loop (in opposite directions) patterns and one Lemniscate pattern. We further identify the curve characteristics associated with each deformation pattern, showing that for rods deforming in a Loop1 shape the position of the inflection point is the highest and the curvature of the rod is smaller compared to the other two types. For rods deforming in the Loop2 shape, the position of the inflection point is the lowest (closer to the fixed base) and the curvatures are higher than the other two types. These patterns matched the common clinically observed scoliotic curves—Lenke 1 and Lenke 5. Our S-shaped elastic rod model generates deformations that are similar to those of a pediatric spine with the same sagittal curvature characteristics and it can differentiate between the clinically observed deformation patterns. Keywords Spine · Scoliosis · Sagittal profile · Classification · Rod mechanics
1 Introduction During the fast growth period around puberty, some pediatric spines deform in three dimensions leading to scoliosis (Burwell 2003; Castelein et al. 2005; Castelein and Veraart 1992; Weinstein et al. 2008). While the pathogenesis of this disease remains unknown (Gu et al. 2009; Liu et al. 2012), the side view of the S-shaped curvature of the fast-growing, flexible, immature, slender spines has been hypothesized as an underlying mechanical cause of adolescent scoliosis which also may impact the clinical management of the disease (Cheng et al. 2015; Pasha 2019a, b; Pasha and Baldwin 2019a; Schlösser et al. 2014). It has been clinically shown that at an early stage of scoliosis, the sagittal curvature of the spine is different between scoliotic and non-scoliotic subjects of similar age and sex (Schlösser et al. 2015). However, * Saba Pasha [email protected] 1
Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104, USA
Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
2
as the scoliosis changes the spinal alignment in three dimensions (Pasha et al. 2014a), even at an early stage of the disease (Brink et al. 2018), it is challenging to evaluate the role of the true sagittal alignment of the spine in induction of scoliosis. As the idiopathic scoliotic patients are oth
Data Loading...
