Anthropometric Scaling Research Articles

Froude number fractions to increase walking pattern dynamic similarities: Application to plantar pressure study in healthy subjects

The purpose of this study was to determine if using similar walking velocities obtained from fractions of the Froude number (N(Fr)) and leg length can lead to kinematic and kinetic similarities and lower variability. Fifteen male subjects walked on a treadmill at 0.83 (VS(1)) and 1.16ms(-1) (VS(2)) and then at two similar velocities (V(Sim27) and V(Sim37)) determined from two fractions of the N(Fr) (0.27 and 0.37) so that the average group velocity remained unchanged in both conditions (VS(1)=V (Sim27)andVS(2)=V (Sim37)). N(Fr) can theoretically be used to determine walking velocities proportional to leg lengths and to establish dynamic similarities between subjects. This study represents the first attempt at using this approach to examine plantar pressure. The ankle and knee joint angles were studied in the sagittal plane and the plantar pressure distribution was assessed with an in-shoe measurement device. The similarity ratios were computed from anthropometric parameters and plantar pressure peaks. Dynamically similar conditions caused a 25% reduction in leg joint angles variation and a 10% significant decrease in dimensionless pressure peak variability on average of five footprint locations. It also lead to heel and under-midfoot pressure peaks proportional to body mass and to an increase in the number of under-forefoot plantar pressure peaks proportional to body mass and/or leg length. The use of walking velocities derived from N(Fr) allows kinematic and plantar pressure similarities between subjects to be observed and leads to a lower inter-subject variability. In-shoe pressure measurements have proven to be valuable for the understanding of lower extremity function. Set walking velocities used for clinical assessment mask the effects of body size and individual gait mechanics. The anthropometric scaling of walking velocities (fraction of N(Fr)) should improve identification of unique walking strategies and pathological foot functions.

Considerations of anthropometric, tissue volume, and tissue mass scaling for improved patient specificity of skeletal S values.

It is generally acknowledged that reference man (70 kg in mass and 170 cm in height) does not adequately represent the stature and physical dimensions of many patients undergoing radionuclide therapy, and thus scaling of radionuclide S values is required for patient specificity. For electron and beta sources uniformly distributed within internal organs, the mean dose from self-irradiation is noted to scale inversely with organ mass, provided no escape of electron energy occurs at the organ boundaries. In the skeleton, this same scaling approach is further assumed to be correct for marrow dosimetry; nevertheless, difficulties in quantitative assessments of marrow mass in specific skeletal regions of the patient make this approach difficult to implement clinically. Instead, scaling of marrow dose is achieved using various anthropometric parameters that presumably scale in the same proportion. In this study, recently developed three-dimensional macrostructural transport models of the femoral head and humeral epiphysis in three individuals (51-year male, 82-year female, and 86-year female) are used to test the abilities of different anthropometric parameters (total body mass, body surface area, etc.) to properly scale radionuclide S values from reference man models. The radionuclides considered are 33P, 177Lu, 153Sm, 186Re, 89Sr, 166Ho, 32P, 188Re, and 90Y localized in either the active marrow or endosteal tissues of the bone trabeculae. S value scaling is additionally conducted in which the 51-year male subject is assigned as the reference individual; scaling parameters are then expanded to include tissue volumes and masses for both active marrow and skeletal spongiosa. The study concludes that, while no single anthropometric parameter emerges as a consistent scaler of reference man S values, lean body mass is indicated as an optimal scaler when the reference S values are based on 3D transport techniques. Furthermore, very exact patient-specific scaling of radionuclide S values can be achieved if measurements of spongiosa volume and marrow volume fraction (high-resolution CT with image segmentation) are known in both the patient and the reference individual at skeletal sites for which dose estimates are sought. However, the study indicates that measurements of the spongiosa volume alone may be sufficient for reasonable patient-specific scaling of S values for the majority of radionuclides of interest in internal-emitter therapy.

Sex differences and action scaling in overhead reaching.

Specifications of affordances is independent of the anthropometric scale of the perceiver. It is therefore predicted that sex differences disappear when perceptual performance is scaled relative to the relevant physical properties of the system formed by performer and environment in a particular action. 24 women and 30 men were compared for their ability to perceive the boundaries for overhead reaching for a ball suspended above them. Perceived and actual maximum action boundaries were measured in two height conditions, with and without wearing 15-cm high blocks under their feet. On average the men reached higher than the women; however, when perceived maximum reachable height was expressed as a ratio of actual maximum reachable height, the difference between the groups disappeared. The participants showed an identical fit between environment and performer in both height conditions. The results indicate that the specification of affordances for overhead reaching is independent of the height and the sex of the performer.

The anthropometric assessment of dysmorphic features in schizophrenia as an index of its developmental origins.

Evidence suggests that schizophrenia may be a disorder with origins in early intrauterine mal-development. We have constructed a comprehensive anthropometric scale for the evaluation of dysmorphic features as an index of the nature and timing of developmental disturbance. A detailed set of craniofacial and bodily measures was compiled and applied to 174 patients with schizophrenia and 80 matched control subjects. Patients had significantly higher scores on this scale and displayed multiple anomalies of the craniofacial region with an overall narrowing and elongation of the mid-face and lower face. Twelve craniofacial anomalies independently distinguished patients from controls and these variables correctly classified 95% of patients and 80% of control subjects. This new scale, while procedurally more exacting than the Waldrop scale, more clearly defines the topography of anomalies previously suspected in individuals with schizophrenia. These findings constitute direct evidence for disturbed craniofacial development in schizophrenia and indicate origins in the foetal period during which the characteristic human facial pattern evolves in close association with brain differentiation.

A nonhomogeneous anthropometric scaling method based on finite element principles

An anthropometric scaling technique is described which locates equivalent points on similarly shaped anatomical structures and quantifies the morphological differences of such geometries through the use of analytical strain parameters. The method is applicable to two or three-dimensional geometries with nonhomogeneous shape differences. The anatomical structures to be scaled are approximated by either four-noded tetrahedral or eight-noded hexahedral finite elements and equivalent points are located using shape functions. The method is demonstrated through its application to two human femora. Accuracy and limitations of the technique are discussed.

A technique for calculating in vivo ligament lengths with application to the human knee joint

This analysis is concerned with the development and application of a technique for calculating in vivo ligament length patterns for human joints as they move through a range of arbitrary orientations. The basis of this method is an anthropometric scaling procedure whereby locations of soft tissue origins and insertions in an “inaccessible” human subjecy body segment are determined by mathematically transforming their locations from a dissected cadaver specimen to their respective positions in the human subject. A detailed mathematical development of the technique is presented with the procedure being adapted to the knee joint. The conceptual validity and mathematical accuracy of the method is examined by its application to simple blocks of known geometry. The basic scaling technique and subsequent ligament length calculations are further tested by substituting dry skeletal bones in place of cadaver and human subject limbs so that results obtained by direct measurement could be compared with those theoretically predicted. The in vivo procedure is then applied to human subjects. A parametric analysis is utilized to examine the sensitivity of the technique to the input data. A discussion of possible sources of error is presented.

An anthropometric scaling method with application to the knee joint

This study is concerned with the development of an anthropometric scaling technique, with application to the human knee joint. The locations of soft tissue origins and insertions from a dissected limb are scaled to their relative positions which are inaccessible in the human subject limb, with the differences in geometry being modeled by a homogeneous deformation. This provides a spatial distribution of forces acting on the human subject limb, so that a force analysis may be performed at a particular static phase of a motion. Inherent in this method is a mathematical description of the rigid body motion of a body segment. The mathematical accuracy of the method was examined by scaling known geometries. The scaling scheme was then applied to dry skeletal tibias and femurs and its accuracy and sensitivity to various factors checked by comparison with direct measurements. The proposed method was compared with scaling by uniform dilatation, a scaling technique employed by Morrison (1970), and no scaling at all.