Head and trunk mass and center of mass position estimations in able-bodied and scoliotic girls

Abstract

Anthropometric tables are not applicable to calculate the scoliotic trunk mass and center of mass (COM). The purposes of this study were: (1) to estimate the head and trunk mass and COM in able-bodied and scoliotic girls using a force plate method, (2) to estimate head and trunk COM offset compared to those of the body, and (3) the use of mean ratios to estimate the head and trunk COM calculated in this study and that calculated according to a conventional three-dimensional (3D) method compared to the measured values. Twenty-one scoliotic and twenty able-bodied girls participated. The subjects stood upright with arms beside the trunk on a force plate that collected data at 60 Hz for a period of 5s. The anteroposterior and mediolateral positions of the body COM were obtained from the mean center of pressure values. The height of the body COM was estimated by the reaction board method. Afterwards a body segment was displaced and changes in force plate readings were recorded and applied to estimate the head and trunk mass and COM. Trunk offset was defined as the difference between the COM of the body and head and trunk. The measured head and trunk COM was compared to values obtained by the mean ratios calculated from this study and given by the conventional 3D method. The relative head and trunk mass and the anteroposterior trunk offset were larger in scoliotic girls. The force plate method gave similar results to measured COM values for both groups underlying its capability to provide a more accurate estimation of COM related values. Thus, the use of mean ratios of 0.5538 and 0.6438 obtained in this study to estimate the head and trunk mass and COM position in scoliotic girls can overcome the main drawbacks of current anthropometric methods, if direct measurements cannot be taken.

Head and Trunk Moments of Inertia of Able-Bodied and Unbraced Scoliotic Girls

“…This finding could be of clinical importance when loads are estimated on the spine since the HT's I values are usually calculated from anthropometric tables. According to Damavandi, Dalleau, Stylianides, Rivard, and Allard (2013), the HT's mass in scoliotic girls was 11.1% underestimated using the ratios of de Leva (1996) compared with a personalized developed force-plate method. In addition, the HT's K/segment length estimated by de Leva were 6.0% underestimated for the AP and ML axes compared with the proposed method.…”

Load bearing analysis on Lumbosacral Disc in Pre-operative and Post-operative Thoracic Scoliosis Patient

“…A study done by Damavandi et al, [1] on the head and trunk mass, and center of mass position estimations in able-bodied and scoliotic girls concluded that the pre-operative scoliotic girls have greater pelvic forward tilt and trunk inclination compared to normal subjects. Whereas, another study done by Park et al, [2] on the effect of scoliosis angle on sway on the center of gravity found that the whole-body balancing ability in pre-operative scoliosis patients is significantly different from normal persons.…”

Whole body balance control in Lenke 1 thoracic adolescent idiopathic scoliosis during level walking

“…Among these types, Lenke 1 involves a single main lateral curve of T5-T12, and has the highest incidence [4][5][6][7][8]. The deformed thoracic spinal curve has been shown to lead to compromised postural stability with an increased amount of static sway area during standing [9,10], as well as poor body segmental alignment during dynamic activities associated with increased center of mass (COM) displacement [11], and altered motions of the trunk and other segments [12][13][14][15][16][17].…”