Influence of thigh cluster configuration on the estimation of hip axial rotation

The non-invasive estimation of hip axial rotation is prone to error. Most of this is likely to originate from soft tissue artefact (STA) at the thigh. The purpose of this study was to evaluate the relative performance of four different thigh cluster configurations. Three were novel configurations whilst one represented the Helen Hayes convention. Twenty able-bodied adults performed two alternative motor tasks involving hip axial rotation: gait and an isolated longitudinal rotation task. Kinematic data were acquired using a three-dimensional motion analysis system (VICON 512, Oxford Metrics, Oxford, England). Indirect criteria were used to evaluate STA. Hip axial rotation kinematic profiles during gait were highly sensitive to thigh cluster configuration. For the longitudinal rotation task, the various thigh clusters were only capable of estimating, at best, up to 60% of the reference amount of movement. The Helen Hayes convention was associated with the greatest degree of STA. Whilst none of the clusters represented an optimal solution, a non-rigid configuration on the distal thigh provided a more favourable alternative. The main limitation associated with this study was the absence of a true gold standard measure of hip axial rotation.Until future work provides further insight, one must remain cautious when using estimates of hip axial rotation for purposes of research or clinical interpretation

Defining the knee joint flexion–extension axis for purposes of quantitative gait analysis : an evaluation of methods

Minimising measurement variability associated with hip axial rotation and avoiding knee joint angle cross-talk are two fundamental objectives of any method used to define the knee joint flexion–extension axis for purposes of quantitative gait analysis. The aim of this experiment was to compare three different methods of defining this axis: the knee alignment device (KAD) method, a method based on the transepicondylar axis (TEA) and an alternative numerical method (Dynamic). The former two methods are common approaches that have been applied clinically in many quantitative gait analysis laboratories; the latter is an optimisation procedure. A cohort of 20 subjects performed three different functional tasks (normal gait; squat; non-weight bearing knee flexion) on repeated occasions. Three-dimensional hip and knee angles were computed using the three alternative methods of defining the knee joint flexion–extension axis. The repeatability of hip axial rotation measurements during normal gait was found to be significantly better for the Dynamic method ( p < 0.01). Furthermore, both the variance in the knee varus–valgus kinematic profile and the degree of knee joint angle cross-talk were smallest for the Dynamic method across all functional tasks. The Dynamic method therefore provided superior results in comparison to the KAD and TEA-based methods and thus represents an attractive solution for orientating the knee joint flexion–extension axis for purposes of quantitative gait analysis

Human Free-Walking Model For A Real-Time Interactive Design Of Gaits

This paper presents a human walking model built from experimental data based on a wide range of normalized velocities. The model is structured in two levels. At a first level, global spatial and temporal characteristics (normalized length and step duration) are generated. At the second level, a set of parameterized trajectories produce both the position of the body in the space and the internal body configuration in particular the pelvis and the legs. This is performed for a standard structure and an average configuration of the human body. Th