Musculoskeletal modelling of muscle activation and applied external forces for the correction of scoliosis

Abstract

BackgroundThis study uses biomechanical modelling and computational optimization to investigate muscle activation in combination with applied external forces as a treatment for scoliosis. Bracing, which incorporates applied external forces, is the most popular non surgical treatment for scoliosis. Non surgical treatments which make use of muscle activation include electrical stimulation, postural control, and therapeutic exercises. Electrical stimulation has been largely dismissed as a viable treatment for scoliosis, although previous studies have suggested that it can potentially deliver similarly effective corrective forces to the spine as bracing.MethodsThe potential of muscle activation for scoliosis correction was investigated over different curvatures both with and without the addition of externally applied forces. The five King’s classifications of scoliosis were investigated over a range of Cobb angles. A biomechanical model of the spine was used to represent various scoliotic curvatures. Optimization was applied to the model to reduce the curves using combinations of both deep and superficial muscle activation and applied external forces.ResultsSimulating applied external forces in combination with muscle activation at low Cobb angles (< 20 degrees) over the 5 King’s classifications, it was possible to reduce the magnitude of the curve by up to 85% for classification 4, 75% for classifications 3 and 5, 65% for classification 2, and 60% for classification 1. The reduction in curvature was less at larger Cobb angles. For King’s classifications 1 and 2, the serratus, latissimus dorsi, and trapezius muscles were consistently recruited by the optimization algorithm for activation across all Cobb angles. When muscle activation and external forces were applied in combination, lower levels of muscle activation or less external force was required to reduce the curvature of the spine, when compared with either muscle activation or external force applied in isolation.ConclusionsThe results of this study suggest that activation of superficial and deep muscles may be effective in reducing spinal curvature at low Cobb angles when muscle groups are selected for activation based on the curve type. The findings further suggest the potential for a hybrid treatment involving combined muscle activation and applied external forces at larger Cobb angles.

System identification for FES-based tremor suppression

“…In addition to the muscle dynamics, the joint dynamics of a human limb are commonly modelled by RBD in which the damping and elastic functions are linear [3,13,27]. This assumption has been used in previous research and is supported by experimental results over a wide range of movement.…”

Semiautomated 3D Spine Reconstruction from Biplanar Radiographic Images: Prediction of Intervertebral Loading in Scoliotic Subjects

“…Previous modeling works evaluated the thoracic region focusing on corrective treatments of scoliosis (Grealou et al, 2002; Aubin et al, 2003; Perie et al, 2003; Duke et al, 2005; Salmingo et al, 2012; Curtin and Lowery, 2014). Furthermore, spine models developed for load estimation were mostly oriented to explore lumbar region, describing thorax as a single rigid body (Stokes and Gardner-Morse, 1995; Shirazi-Adl et al, 2005; de Zee et al, 2007; Arjmand et al, 2009; Christophy et al, 2012; Han et al, 2012; Ghezelbash et al, 2016).…”

Repetitive Control of Electrical Stimulation for Tremor Suppression

“…Among a variety of models for the latter [24]- [27], a Hammerstein structure will be assumed due to its popularity in the literature [27], confirmed accuracy, structural simplicity, and correspondence with biophysics. The rigid body dynamics are commonly considered to exhibit linear elastic and damping, an assumption that has been experimentally verified in previous research [28]- [30]. This yields the following model definition:…”