Head and Trunk Segment Moments of Inertia Estimation Using Angular Momentum Technique: Validity and Sensitivity Analysis

Abstract

Classical models to estimate the head and trunk (HT) moments of inertia (I) are limited to populations from which the anthropometric measures were obtained. The purposes of this study were to determine if the angular momentum technique can be used to estimate subject-specific HT's I values and test its validity and sensitivity. Twenty-three adults who participated in this study were divided into three morphological groups according to their body mass index (BMI). Using the proposed technique, the HT's I values were estimated for the whole sample and compared to three well-known methods to test its validity. The sensitivity of the proposed method was verified while applied to individuals with different BMI (i.e., lean, normal, and obese). The angular momentum technique gave I values within the range of those of the three methods for the entire sample. Statistical differences were identified between the lean and obese groups in relative radii of gyration for the anteroposterior and mediolateral axes ( P<0.05). Since the proposed technique makes no assumption on the mass distribution and segments' geometry, it appeared to be more sensitive to body morphology changes in estimating the HT's I values in lean and obese subjects compared to the classical methods.

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

“…The first objective was to estimate the HT segment's K and I values using the personalized in vivo angular momentum method described by Damavandi et al (2011) in able-bodied and scoliotic girls. These values were notably higher in the scoliotic girls for the AP and ML axes.…”

“…In this study, the personalized angular momentum method described by Damavandi et al (2011) was applied to estimate the HT's I values of able-bodied and scoliotic girls. The HT's K and I values were considerably higher in the scoliotic girls for the AP and ML axes compared with the able-bodied girls.…”

“…By way of intentional postural oscillating sway of the body at the ankles about the anteroposterior (AP), mediolateral (ML), and longitudinal (LG) axes, using force plate reaction moments and concurrent kinematic tracking of the HT measures, direct estimates of each subject's HT inertial properties may be derived (Damavandi et al, 2011).…”

“…An angular momentum method has been used to estimate the I values of the whole body less the feet (Damavandi, Barbier, et al, 2009) and the HT segment of able-bodied men (Damavandi, Stylianides, Farahpour, & Allard, 2011). Its validity and sensitivity was demonstrated while applied for individuals of lean and obese populations.…”

“…The objectives of this study were (a) to estimate the HT segment's radii of gyration (K) and I values using the personalized angular momentum method described by Damavandi et al (2011) in able-bodied and unbraced scoliotic girls, (b) to test if the use of mean constant ratios given by the conventional three-dimensional (3-D) method of de Leva (1996) and the ones calculated from this study for able-bodied and scoliotic girls under observation present similar I values of the HT segment compared to the experimental data, and (c) to determine the relationship between the HT's K and I values of the scoliotic subjects obtained from these methods and the Cobb angles. We assume that current anthropometric ratios do not accurately estimate the I of the unbraced scoliotic HT segment.…”