Effect of 3D printed foot orthoses stiffness and design on foot kinematics and plantar pressures in healthy people

Background Foot orthoses (FOs) have been widely prescribed to alter various lower limb disorders. FOs’ geometrical design and material properties have been shown to influence their impact on foot biomechanics. New technologies such as 3D printing provide the potential to produce custom shapes and add functionalities to FOs by adding extra-components. Research question The purpose of this study was to determine the effect of 3D printed FOs stiffness and newly design postings on foot kinematics and plantar pressures in healthy people. Methods Two pairs of ¾ length prefabricated 3D printed FOs were administered to 15 healthy participants with normal foot posture. FOs were of different stiffness and were designed so that extra-components, innovative flat postings, could be inserted at the rearfoot. In-shoe multi-segment foot kinematics as well as plantar pressures were recorded while participants walked on a treadmill. One-way ANOVAs using statistical non-parametric mapping were performed to estimate the effect of FOs stiffness and then the addition of postings during the stance phase of walking. Results Increasing FOs stiffness altered frontal and transverse plane foot kinematics, especially by further reducing rearfoot eversion and increasing the rearfoot abduction. Postings had notable effect on rearfoot frontal plane kinematics, by enhancing FOs effect. Looking at plantar pressures, wearing FOs was associated with a shift of the loads from the rearfoot to the midfoot region. Higher peak pressures under the rearfoot and midfoot (up to +31.7 %) were also observed when increasing the stiffness of the FOs. Significance 3D printing techniques offer a wide range of possibilities in terms of material properties and design, providing clinicians the opportunity to administer FOs that could be modulated according to pathologies as well as during the treatment by adding extra-components. Further studies including people presenting musculoskeletal disorders are required

Effets de l'inclinaison naturelle du tronc sur le contrôle de l'équilibre orthostatique, l'initiation de la marche et la marche

Ce mémoire a pour objectif d'étudier les effets de l'inclinaison naturelle du tronc dans le plan sagittal sur le contrôle de la posture orthostatique, l'initiation de la marche et la marche. Des sujets en bonne santé sont classés en groupes, en mesurant l'angle de leur tronc par rapport à la verticale et en utilisant le modèle clinique de Sohier et Haye (1989). Deux études préliminaires ont précisé la méthodologie. Pour l'étude du contrôle postural, les moments articulaires à la cheville, à la hanche et en L5 ainsi que la position antéropostérieure (AP) du centre de masse du haut du corps par rapport aux hanches permettent d'expliquer les différences de régulation posturale observées entre les groupes, quelle que soit la classification. L'étude de l'initiation de la marche présente les moments articulaires du membre d'appui à la cheville, au genou, à la hanche et en L5 au cours de l'exécution du premier pas. Bien que les paramètres spatiotemporels, la dynamique du tronc et la composante AP de la force de réaction au sol soient similaires entre les groupes, ces moments présentent des caractéristiques spécifiques à l'inclinaison du tronc. L'étude de la phase d'appui de la marche montre que les moments articulaires des membres inférieurs et en L5 sont affectés par l'inclinaison naturelle du tronc et qu'il existe des asymétries entre les membres inférieurs en fin de phase d'appui, quelle que soit la classification. En conclusion, ce mémoire montre les effets de l'inclinaison naturelle du tronc sur les trois tâches motrices étudiées. En l'absence de système d'analyse gestuelle, le modèle clinique apparaît être une alternative intéressante à la classification expérimentale.The objective of this work is to study the effects of natural trunk inclination in the sagittal plane on the standing posture control, gait initiation and gait. Young and able-bodied subjects are classified into groups, from the measure of their trunk angle with respect to vertical axis, and from the clinical model proposed by Sohier and Haye in 1989. Two preliminary studies were needed to specify the methodology. For the study of the standing posture, the moments at the ankle, hip and L5 and the anteroposterior (AP) position of the center of mass of the HAT with respect to hip axis allow to explain the differences observed in the postural control for the two respective trunk inclinations, whatever the classification used. The study of gait initiation explains the net moments of the standing limb at the ankle, knee, hip and L5 during the execution of the first step. Although the spatiotemporal parameters, trunk dynamics and AP component of the ground reaction force are similar between the groups, these net moments present characteristics that are specific to the trunk inclination. The study of the stance phase of gait shows that the net moments of the lower limbs and L5 are affected by the natural trunk inclination and that gait asymmetries appear between the lower limbs, only at the end of the stance phase, whatever the classification used. In conclusion, this work shows the effects of the natural trunk inclination in the sagittal plane on the three motor tasks studied. Moreover, the results indicate that, in the absence of motion analysis system, the clinical model appears to be an interesting alternative to the experimental classification.VALENCIENNES-BU Sciences Lettres (596062101) / SudocSudocFranceF

Two-Step Validation of a New Wireless Inertial Sensor System: Application in the Squat Motion

The use of Inertial Measurement Units (IMUs) can provide embedded motion data to improve clinical application. The objective of this study was to validate a newly designed IMU system. The validation is provided through two main methods, a classical sensor validation achieved on a six-degrees-of-freedom hexapod platform with controlled linear and rotation motions and a functional validation on subjects performing squats with segmental angle measurement. The kinematics of the sensors were measured by using an optoelectronic reference system (VICON) and then compared to the orientation and raw data of the IMUs. Bland–Altman plots and Lin’s concordance correlation coefficient were computed to assess the kinematic parameter errors between the IMUs and VICON system. The results showed suitable precision of the IMU system for linear, rotation and squat motions

When motor simulation of disequilibrium increases postural stability

International audienc

Two-Step Validation of a New Wireless Inertial Sensor System: Application in the Squat Motion

The use of Inertial Measurement Units (IMUs) can provide embedded motion data to improve clinical application. The objective of this study was to validate a newly designed IMU system. The validation is provided through two main methods, a classical sensor validation achieved on a six-degrees-of-freedom hexapod platform with controlled linear and rotation motions and a functional validation on subjects performing squats with segmental angle measurement. The kinematics of the sensors were measured by using an optoelectronic reference system (VICON) and then compared to the orientation and raw data of the IMUs. Bland–Altman plots and Lin’s concordance correlation coefficient were computed to assess the kinematic parameter errors between the IMUs and VICON system. The results showed suitable precision of the IMU system for linear, rotation and squat motions

Urban legends in gait analysis

Impaired gait patterns are often compared to that of a group of able-bodied subjects. This latter group usually forms a gold standard. Variability in able-bodied gait parameters could reflect different normal locomotion patterns. Furthermore, a lack of statistical difference between patient data and control subjects can hide a perturbed gait pattern. This review on normal gait patterns discusses three well-accepted hypotheses, which can be called into question. These are that we all walk alike, gait is symmetrical and propulsion comes from the foot at push-off. This diversity in normal able-bodied locomotion patterns suggests different movement strategies making it difficult for an eventual comparison with pathological gait conditions

Trunk's natural inclination influences stance limb kinetics, but not body kinematics, during gait initiation in able men.

The imposing mass of the trunk in relation to the whole body has an important impact on human motion. The objective of this study is to determine the influence of trunk's natural inclination--forward (FW) or backward (BW) with respect to the vertical--on body kinematics and stance limb kinetics during gait initiation.Twenty-five healthy males were divided based on their natural trunk inclination (FW or BW) during gait initiation. Instantaneous speed was calculated at the center of mass at the first heel strike. The antero-posterior impulse was calculated by integrating the antero-posterior ground reaction force in time. Ankle, knee, hip and thoraco-lumbar (L5) moments were calculated using inverse dynamics and only peaks of the joint moments were analyzed. Among all the investigated parameters, only joint moments present significant differences between the two groups. The knee extensor moment is 1.4 times higher (P<0.001) for the BW group, before the heel contact. At the hip, although the BW group displays a flexor moment 2.4 times higher (P<0.001) before the swing limb's heel-off, the FW group displays an extensor moment 3.1 times higher (P<0.01) during the swing phase. The three L5 extensor peaks after the toe-off are respectively 1.7 (P<0.001), 1.4 (P<0.001) and 1.7 (P<0.01) times higher for the FW group. The main results support the idea that the patterns described during steady-state gait are already observable during gait initiation. This study also provides reference data to further investigate stance limb kinetics in specific or pathologic populations during gait initiation. It will be of particular interest for elderly people, knowing that this population displays atypical trunk postures and present a high risk of falling during this forward stepping