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Uneven ground, slopes, stairs, sidewalks are constraining situations that must be overcome by transfemoral amputees (TFA). However, most of prosthetic systems do not have ankle mobility, the connection between the prosthetic knee and the prosthetic foot being a rigid part. A certain flexibility is allowed by the energy storage restitution feet thanks to their stiffness. But they do not allow a complete adaptation to daily encountered walking situations, like walking on slopes (ascent and descent) or downstairs [1]. Furthermore, TFA have a high risk of falling, with more than 50% of them reporting falling at least once in a year [2]. This risk is increased by the lack of musculature due to the amputation and the lack of mobility of the prosthetic ankle during the swing phase [3]. The aim of this study was to evaluate whether a microprocessor-controlled knee-ankle system (MPK_NEW) can help improve walking in transfemoral amputees. Eleven TFA with an activity level of d4602 (International Classification of Function, Disability and Health) or higher and wearing a microprocessor knee able to control stance and swing phases (MPK_HAB), for at least 3 months, were included in this study. They wore both prostheses (MPK_HAB and MPK_NEW) for 4 weeks, starting randomly with one or the other. At the end of each period, a quantified gait analysis (level ground, 12% slopes ascent and descent, downstairs) was performed using VICON® optoelectronic system (Vicon Motion Systems, Oxford Metrics, UK, sampling at 100 Hz) with 54 full-body markers-set. Flat Foot Time (FFT, where the ankle angle in the sagittal plane was within ± 1.25° of its orientation at 20% of the gait cycle) and Minimum Toe Clearance (MTC, minimum distance between the foot and the ground during the swing phase) were calculated for both prostheses. Student or Wilcoxon test were performed to assess significance at 0.05. Fig. 1 A shows an increase in flat-foot time for all walking situations with the MPK_NEW prosthesis, which was significant (*,p_value < 0.01) for all situations but the slope ascent one. Fig. 1B shows a significant increase in MTC (*, p_value < 0.01) when walking at level ground and ascent slope with the MPK_NEW prosthesis. Fig. 1. Comparison of FFT and MTC for each prosthesis in different walking situations [Display omitted] The knee-ankle synergy allows plantar and dorsal flexion during the stance and swing phases, increasing FFT (stance stability) and MTC (swing phase security) in various daily situations. This was consistent with the literature observed on transtibial amputees and approaching the behavior of asymptomatic subjects [4–6]. Thus, this new prosthetic system may improve stability and security for TFA [4,7], allowing them to better adapt to their daily environment. [ABSTRACT FROM AUTHOR]

Daily locomotion with a manual wheelchair includes curvilinear movements. However, little is known about the resisting forces in play during turning manoeuvres where the wheels are generally both rolling and swivelling. This study aimed at quantifying the swivelling resistance parameters of several wheels on different surfaces and to evaluate the effect of the curvature radius on these parameters. A specific test bench was designed allowing the swivelling resistance parameters of a wheel rolling while swivelling to be determined. Seven wheels (3 front and 4 rear wheels), three surfaces (plywood, linoleum and carpet), two loads (25 and 45 kg) and five curvature radii (from 0 to 0.4 m) were tested through a full factorial design experiment. Results showed that the wheel type was the most influential factor on swivelling resistance parameters, followed by the surface and the curvature radius. The effect of the load on swivelling resistance parameters was found negligible when compared to the influence of other factors. A predictive model for swivelling resistance parameters of the different wheel/surface combinations was proposed, as a function of the curvature radius. This study allowed the swivelling resistance parameters of different wheel/surface combinations to be quantified, as a function of the curvature radius of the wheel trajectory. Combined with data on rolling resistance, these data could now be used to assess energy losses during real life ambulation or to achieve more realistic behaviour in virtual rehabilitation environment. Swivelling resistances are increased by carpet surfaces compared to tile surfaces. Conversely to rolling resistance, castors wheels are less prone to swivelling resistance than rear wheels The swivelling resistance of a wheel rolling while swivelling is decreased compared to a pure swivelling movement. Combined with data on rolling resistance, these data on swivelling resistance would allow energy loss during daily life activity to be determined or as input data for the control of wheelchair simulator in virtual environment used for rehabilitation. [ABSTRACT FROM AUTHOR]

Purpose: Among the different resistances occurring during wheelchair locomotion and that limit the user autonomy, bearing resistance is generally neglected, based on a few studies carried out in static conditions and by manufacturer's assertion. Therefore, no special attention is generally paid to the mounting and the maintenance of manual wheelchair bearings. However, the effect of inadequate mounting or maintenance on wheelchair bearing resistance has still to be clarified. This study aimed at filling this gap by developing and validating a specific device allowing the measurement of wheelchair bearing friction, characterized by low speed velocities, with an accuracy lower than 0.003 Nm. Methods: The bearing resistance measured by the device was compared to free deceleration measurement, intra and inter operator reproducibility were assessed. A factorial experiment allowed the effects of various functioning parameters (axial and radial loads, velocity) to be classified. Results: The device allowed significant differences in the bearing resistance of static and rotating conditions to be measured, even if a relatively high proportionality was found between both conditions. The factorial experiment allowed the expected impact of the radial load on bearing resistance as well as the predominant effect of the axial load to be demonstrated. Conclusions: As a consequence, it appeared that the control of the axial load is compulsory for measurement purposes or during wheel mounting, to avoid significant increase of global resistance during wheelchair locomotion. The findings of this study could help enhancing the models which assess manual wheelchair mechanical power from its settings and use conditions. [ABSTRACT FROM AUTHOR]

This article presents an examination and validation of a method to measure the field deceleration of a manual wheelchair (MWC) and to calculate the rolling resistances properties of the front and rear wheels. This method was based on the measurements of the MWC deceleration for various load settings from a 3D accelerometer. A mechanical model of MWC deceleration was developed which allowed computing the rolling resistance factors of front and rear wheels on a tested surface. Four deceleration sets were conducted on two paths on the same ground to test the repeatability. Two other deceleration sets were conducted using different load settings to compute the rolling resistance parameters (RPs). The theoretical decelerations of three load settings were computed and compared with the measured decelerations. The results showed good repeatability (variations of measures represented 6–11% of the nominal values) and no statistical difference between the path results. The rolling RPs were computed and their confidence intervals were assessed. For the last three sets, no significant difference was found between the theoretical and measured decelerations. This method can determine the specific rolling resistance properties of the wheels of a MWC, and be employed to establish a catalogue of the rolling resistance properties of wheels on various surfaces. [ABSTRACT FROM PUBLISHER]

This article proposes a simple and convenient method for assessing the subject-specific rolling resistance acting on a manual wheelchair, which could be used during the provision of clinical service. This method, based on a simple mathematical equation, is sensitive to both the total mass and its fore-aft distribution, which changes with the subject, wheelchair properties, and adjustments. The rolling resistance properties of three types of front casters and four types of rear wheels were determined for two indoor surfaces commonly encountered by wheelchair users (a hard smooth surface and carpet) from measurements of a three-dimensional accelerometer during field deceleration tests performed with artificial load. The average results provided by these experiments were then used as input data to assess the rolling resistance from the mathematical equation with an acceptable accuracy on hard smooth and carpet surfaces (standard errors of the estimates were 4.4 and 3.9 N, respectively). Thus, this method can be confidently used by clinicians to help users make trade-offs between front and rear wheel types and sizes when choosing and adjusting their manual wheelchair. [ABSTRACT FROM AUTHOR]

Background: The analysis of biomechanical parameters derived from the body center of mass (BCoM) 3D motion allows for the characterization of gait impairments in people with lower-limb amputation, assisting in their rehabilitation. In this context, magneto-inertial measurement units are promising as they allow to measure the motion of body segments, and therefore potentially of the BCoM, directly in the field. Finding a compromise between the accuracy of computed parameters and the number of required sensors is paramount to transfer this technology in clinical routine.Research Question: Is there a reduced subset of instrumented segments (BSN) allowing a reliable and accurate estimation of the 3D BCoM acceleration transfemoral amputees?Methods: The contribution of each body segment to the BCoM acceleration was quantified in terms of weight and similarity in ten people with transfemoral amputation. First, body segments and BCoM accelerations were obtained using an optoelectronic system and a full-body inertial model. Based on these findings, different scenarios were explored where the use of one sensor at pelvis/trunk level and of different networks of segment-mounted sensors for the BCoM acceleration estimation was simulated and assessed against force plate-based reference acceleration.Results: Trunk, pelvis and lower-limb segments are the main contributors to the BCoM acceleration in transfemoral amputees. The trunk and shanks BSN allows for an accurate estimation of the sagittal BCoM acceleration (Normalized RMSE ≤ 13.1 %, Pearson's correlations r ≥ 0.86), while five segments are necessary when the 3D BCoM acceleration is targeted (Normalized RMSE ≤ 13.2 %, Pearson's correlations r ≥ 0.91).Significance: A network of three-to-five segments (trunk and lower limbs) allows for an accurate estimation of 2D and 3D BCoM accelerations. The use of a single pelvis- or trunk-mounted sensor does not seem advisable. Future studies should be performed to confirm these results where inertial sensor measured accelerations are considered. [ABSTRACT FROM AUTHOR]

Objective Manual wheelchair (MWC) allows active disabled people to recover mobility but constrains both cardiorespiratory and upper-limb musculoskeletal systems. User morphology, experience and propulsion strategy as well as environment and wheelchair settings can affect the constraints sustained by the upper limbs. Choosing and configuring a wheelchair is a difficult task, which requires the analysis of multiple factors. Due to this difficulty, the process sometimes results in non-optimized wheelchair settings. The present work describes a method which simulates the wheelchair behavior from a mechanical model. The ability of this method to provide a better understanding of the effect of various wheelchair settings on propulsion difficulty is illustrated through an example. Material/patients and methods At first, appropriate representations (or “models”) need to be developed. In this study, the user was modeled by his center of mass position with respect to drive wheels; the MWC was modeled by an assembly of solids characterized by their weight, geometry and material; and the environment was modeled by a flat surface characterized by roughness and inclination. Through mechanical analysis, the MWC settings and movements were linked to the user efforts and energy losses. As inputs for the simulation, the efforts applied by one subject were previously measured during straightforward propulsion using specific instrumented MWC. Finally, various propulsion scenarios were numerically simulated, in which wheelchair settings were changed, keeping every other experimental conditions constant. Scenarios where instability occurred were discarted. Results Simulation allowed defining an appropriate wheelchair configuration (mainly defined by a backward position of the user and large castor radii) where energy losses were decreased by 2.5 times with respect to the 3.3 Joules per propulsion cycle observed during experiments. Discussion – conclusion When choosing and configuring a wheelchair, tradeoffs often need to be found between energetic performance and other mandatory aspects, like stability. Through numerical simulation, optimization can be developed to assist in defining a set of MWC setting that takes into account the necessary tradeoffs. Nowadays, similar analysis can be applied to hard smooth/carpet surfaces, turning motion, ramps and cross slopes. More complex subject-specific musculoskeletal models are developed for better precision and understanding. [ABSTRACT FROM AUTHOR]

In recent years, inertial measurement units (IMUs) have been proposed as an alternative to force platforms and pressure sensors for gait events (i.e., initial and final contacts) detection. While multiple algorithms have been developed, the impact of gait event timing errors on temporal parameters and asymmetry has never been investigated in people with transfemoral amputation walking freely on level ground. In this study, five algorithms were comparatively assessed on gait data of seven people with transfemoral amputation, equipped with three IMUs mounted at the pelvis and both shanks, using pressure insoles for reference. Algorithms' performance was first quantified in terms of gait event detection rate (sensitivity, positive predictive value). Only two algorithms, based on shank mounted IMUs, achieved an acceptable detection rate (positive predictive value > 99%). For these two, accuracy of gait events timings, temporal parameters, and absolute symmetry index of stance-phase duration (SPD-ASI) were assessed. Whereas both algorithms achieved high accuracy for stride duration estimates (median errors: 0%, interquartile ranges < 1.75%), lower accuracy was found for other temporal parameters due to relatively high errors in the detection of final contact events. Furthermore, SPD-ASI derived from IMU-based algorithms proved to be significantly different to that obtained from insoles data. Graphical abstract Gait event detection with IMU in people with transfemoral amputation: initial contact (IC) and final contact (FC) events at the sound (s) and prosthetic (p) side are identified. Five algorithms were implemented using either shank-mounted or pelvis-mounted IMUs. Gait events were used to estimate temporal parameters (stride duration, stance phase duration [SPD], and double support time) and SPD asymmetry. [ABSTRACT FROM AUTHOR]

Manual wheelchair (MWC) locomotion exposes the user's upper-body to large and repetitive loads, which can lead to upper limbs pain and injuries. A thinner understanding of the influence of MWC settings on propulsion biomechanics could allow for a better adaptation of MWC configuration to the user, thus limiting the risk of developing such injuries. Advantageously compared to experimental studies, simulation methods allow numerous configurations to be tested. Recent studies have developed predictive locomotion simulation using optimal control methods. However, those models do not consider MWC anteroposterior stability, potentially resulting in unreasonable propulsion strategies. To this extent, this study aimed at confirming if constraining MWC anteroposterior stability in the optimal control formulation could lead to a different simulated movement. For this purpose, a four-link rigid-body system was used in a forward dynamics optimization paired with an anteroposterior stability constraint to predict MWC locomotion dynamics of the upper limbs during both startup and steady-state propulsion. Simulation results indicated the occurrence of MWC tipping when stability was not constrained, and that the constrained optimal control algorithm predicted different propulsion strategies. Hence, further proceedings of MWC locomotion simulation and optimal control investigations should take the anteroposterior stability into account to achieve more realistic simulations. Additionally, the implementation of the anteroposterior stability constrains unexpectedly resulted in a reduction of the computational time. [ABSTRACT FROM AUTHOR]

Purpose:Wheelchair locomotion is constraining for the upper limbs and involves a set of motor tasks that need to be learnt by a novice user. To understand this integration process, we investigated the evolution of shoulder kinetics during start-up and propulsion within the initial phase of low-intensity uninstructed training. Materials and methods:Seventeen novice able-bodied subjects performed a 120-min uninstructed practice distributed over 4 weeks. During the initial and final sessions, upper limbs kinematics and hand-rim kinetics were continuously collected. Inverse kinematics and dynamics coupled to a three-dimensional linked-segment model were used to compute shoulder net moments. Results:Participants increased the speed of the wheelchair with practice. In average, an increase of shoulder net moments and mechanical work during the push phase was observed. Conversely, during the recovery phase, participants slightly increased shoulder power but maintained a similar level of shoulder loading. However, individual evolutions allowed the definition of two groups defined as: “increasers”, who increased shoulder loading and mechanical work versus “decreasers”, who managed to limit shoulder loading while improving the wheelchair speed. Conclusion:These findings underline that individual adaptation strategies are essential to take into account when designing a rehabilitation protocol for wheelchair users. Implications for RehabilitationThe learning process of manual wheelchair locomotion is essential for the assimilation of motor tasks leading individuals to select their propulsion technique.Novice users display different learning strategies: some people increase shoulder loading very early but others spontaneously manage to increase the wheelchair speed while maintaining a constant level of shoulder loading.Wheelchair rehabilitation programs should be individualized to take into account the subject-specific learning strategy. [ABSTRACT FROM PUBLISHER]

During manual wheelchair (MWC) locomotion, the user's upper limbs are subject to heavy stresses and fatigue because the upper body is permanently engaged to propel the MWC. These stresses and fatigue vary according to the environmental barriers encountered outdoors along a given path. This study aimed at conducting a systematic review of the literature assessing the biomechanics of MWC users crossing various situations, which represent physical environmental barriers. Through a systematic search on PubMed, 34 articles were selected and classified according to the investigated environmental barriers: slope; cross-slope; curb; and ground type. For each barrier, biomechanical parameters were divided into four categories: spatiotemporal parameters; kinematics; kinetics; and muscle activity. All results from the different studies were gathered, including numerical data, and assessed with respect to the methodology used in each study. This review sheds light on the fact that certain situations (cross-slopes and curbs) or parameters (kinematics) have scarcely been studied, and that a wider set of situations should be studied. Five recommendations were made at the end of this review process to standardize the procedure when reporting materials, methods, and results for the study of biomechanics of any environmental barrier encountered in MWC locomotion: (i) effectively reporting barriers' lengths, grades, or heights; (ii) striving for standardization or a report of the approach conditions of the barrier, such as velocity, especially on curbs; (iii) reporting the configuration of the used MWC, and if it was fitted to the subject's morphology; (iv) reporting rotation sequences for the expression of moments and kinematics, and when used, the definition of the musculoskeletal model; lastly (v) when possible, reporting measurement uncertainties and model reconstruction errors. [ABSTRACT FROM AUTHOR]

Purpose: During manual wheelchair (MWC) skill acquisition, users adapt their propulsion technique through changes in biomechanical parameters. This evolution is assumed to be driven towards a more efficient behavior. However, when no specific training protocol is provided to users, little is known about how they spontaneously adapt during overground MWC locomotion. For that purpose, we investigated this biomechanical spontaneous adaptation within the initial phase of low-intensity uninstructed training. Materials and methods: Eighteen novice able-bodied subjects were enrolled to perform 120 min of uninstructed practice with a field MWC, distributed over 4 weeks. Subjects were tested during the very first minutes of the program, and after completion of the entire training protocol. Spatiotemporal parameters, handrim forces, motor force, rolling resistance and fore-aft stability were investigated using an instrumented field wheelchair. Results: Participants rapidly increased linear velocity of the MWC, thanks to a higher propulsive force. This was achieved thanks to higher handrim forces, combined with an improved fraction of effective force for startup but not for propulsion. Despite changes in mechanical actions exerted by the user on the MWC, rolling resistance remained constant but the stability index was noticeably altered. Conclusion: Even if no indication is given, novice MWC users rapidly change their propulsion technique and increase their linear speed. Such improvements in MWC mobility are allowed by a mastering of the whole range of stability offered by the MWC, which raises the issue of safety on the MWC. The learning process of manual wheelchair locomotion induces adaptations for novice users, who change their propulsion technique to improve their mobility. Several wheelchair biomechanical parameters change during the learning process, especially wheelchair speed, handrim forces, motor force, rolling resistance and fore-aft stability. Fore-aft stability on the wheelchair rapidly reached the tipping limits for users. Technical solutions that preserve stability but do not hinder mobility have to beimplemented, for instance by adding anti-tipping wheels rather than moving the seat forwards with respect to the rear wheels axle. [ABSTRACT FROM AUTHOR]

Multibody kinematic optimization is frequently used to assess shoulder kinematics during manual wheelchair (MWC) propulsion, but multiple kinematics chains are available. It is hypothesized that these different kinematic chains affect marker tracking, shoulder kinematics, and resulting musculotendon (MT) lengths. In this study, shoulder kinematics and MT lengths obtained from four shoulder kinematic chains (open-loop thorax-clavicle-scapula-humerus (M1), closed-loop with contact ellipsoid (M2), scapula rhythm from regression equations (M3), and a single ball-and- socket joint between the thorax and the humerus (M4) were compared. Right-side shoulder kinematics from seven subjects were obtained with 34 reflective markers and a scapula locator using an optoelectronic motion capture system while propelling on a MWC simulator. Data were processed based on the four models. The results showed the impact of shoulder kinematic chains on all studied variables. Marker reconstruction errors were found to be similar between M1 and M2 and lower than for M3 and M4. Few degrees-of-freedom (DoF) were noticeably different between M1 and M2, but all shoulder DoFs were significantly affected between M1 and M4. As a consequence of differences in joint kinematics, MT lengths were affected by the kinematic chain definition. The contact ellipsoid (M2) was found as a good trade-off between marker tracking and penetration avoidance of the scapula. The regression-based model (M3) was less efficient due to limited humerus elevation during MWC propulsion, as well as the ball-and-socket model (M4) which appeared not suitable for upper limbs activities, including MWC propulsion. [ABSTRACT FROM AUTHOR]

• The scapulothoracic ellipsoid mobilizer is promising for wheelchair biomechanics. • The ellipsoid-based model allows an improved kinematic reconstruction. • The ellipsoid-based and regression-based models display similar shoulder moments. • The ellipsoid-based model decreases the computational time. Several kinematic chains of the upper limbs have been designed in musculoskeletal models to investigate various upper extremity activities, including manual wheelchair propulsion. The aim of our study was to compare the effect of an ellipsoid mobilizer formulation to describe the motion of the scapulothoracic joint with respect to regression-based models on shoulder kinematics, shoulder kinetics and computational time, during manual wheelchair propulsion activities. Ten subjects, familiar with manual wheelchair propulsion, were equipped with reflective markers and performed start-up and propulsion cycles with an instrumented field wheelchair. Kinematic data obtained from the optoelectronic system and kinetic data measured by the sensors on the wheelchair were processed using the OpenSim software with three shoulder joint modeling versions (ellipsoid mobilizer, regression equations or fixed scapula) of an upper-limb musculoskeletal model. As expected, the results obtained with the three versions of the model varied, for both segment kinematics and shoulder kinetics. With respect to the model based on regression equations, the model describing the scapulothoracic joint as an ellipsoid could capture the kinematics of the upper limbs with higher fidelity. In addition, the mobilizer formulation allowed to compute consistent shoulder moments at a low computer processing cost. Further developments should be made to allow a subject-specific definition of the kinematic chain. [ABSTRACT FROM AUTHOR]

Objective Manual wheelchair (MWC) is a constraining form of locomotion for the musculoskeletal system and many MWC users are concerned by musculoskeletal disorders (MSD). Detecting and quantifying MWC related activities are of high interest for the day-to-day follow-up of patients using a MWC as a primary mode of locomotion. Indeed, it could assist clinician in early identification of MSD occurrence or optimizing the user environment (furnishing arrangements, etc). Since few years, several tools combining sensors and data processing algorithms were developed. However, the validation of these tools is difficult, in particular because video analysis used as a reference is both highly time consuming and sometimes inaccurate due to the cameras field of view. Hence, there is a need of an alternative reference method to facilitate the validation of such tools. As an alternative to video analysis, we propose to use an instrumented MWC, initially dedicated for investigating MWC biomechanics, as a new reference method for tasks identifications. Material/patients and methods This MWC was equipped with handrim dynamometers to measure handrim forces and two angular potentiometers fixed on rear wheels to determine the MWC trajectory. Data processing included data aggregation followed by multichannel symbolic representation based on force and velocity thresholds. Currently, the method was implemented for flat horizontal displacement and allowed distinguishing resting: start-up, propulsion, braking and turning motion various curvature radii. The method was tested on 18 able-bodied subjects during actual displacements. Results Results show that for most subjects, the method allowed identifying start-up, propulsion, braking and turning motion tasks. However, a specific adaptation of some thresholds was required for 2 subjects. Since the first subject kept his hands on the handrims during the recovery phase, making difficult the separation of the different tasks and the other subject used a desynchronized propulsion pattern between right and left upper-limbs (close to an alternative push strategy), which resulted in a failure of the identification of propulsion cycle. Discussion, conclusion Even if a real validation of this method against video analysis is still required, the results of the method are encouraging. Some works are still needed to include displacements on more various inclined surfaces and uneven terrain. [ABSTRACT FROM AUTHOR]

The analysis of the body center of mass (BCoM) 3D kinematics provides insights on crucial aspects of locomotion, especially in populations with gait impairment such as people with amputation. In this paper, a wearable framework based on the use of different magneto-inertial measurement unit (MIMU) networks is proposed to obtain both BCoM acceleration and velocity. The proposed framework was validated as a proof of concept in one transfemoral amputee against data from force plates (acceleration) and an optoelectronic system (acceleration and velocity). The impact in terms of estimation accuracy when using a sensor network rather than a single MIMU at trunk level was also investigated. The estimated velocity and acceleration reached a strong agreement (ρ > 0.89) and good accuracy compared to reference data (normalized root mean square error (NRMSE) < 13.7%) in the anteroposterior and vertical directions when using three MIMUs on the trunk and both shanks and in all three directions when adding MIMUs on both thighs (ρ > 0.89, NRMSE ≤ 14.0% in the mediolateral direction). Conversely, only the vertical component of the BCoM kinematics was accurately captured when considering a single MIMU. These results suggest that inertial sensor networks may represent a valid alternative to laboratory-based instruments for 3D BCoM kinematics quantification in lower-limb amputees. [ABSTRACT FROM AUTHOR]

Objective Pressure insoles are developed to be placed in the shoes and provide embedded measurement of the pressure or/and normal ground reaction forces (NGrF). Recently, Pedoped ® insoles were commercialized and consists in only one sensor providing NGrF in real-time biofeedback. As NGrF represents about 90% of ground reaction forces during gait, this device permits to record the lower limb loading during walking, standing or in other daily living activities. Thus, these insoles could be a useful tool in rehabilitation when dealing with gait asymmetry or load recovery. As the first step to evaluate the reliability of these insoles, the accuracy of NGrF measurement with Pedoped ® insoles was assessed during gait of healthy subjects. Material/patients and methods Five healthy subjects were recruited. All subjects were wearing the same shoes with Pedoped ® insoles placed inside. Data collection was carried out in a motion capture laboratory equipped with 4 AMTI ® force platforms (PFF). Subjects were asked to stamp each foot on a PFF during one minute at self-selected speed. PFF and insoles data were synchronized by detecting the first NGrF above 20 N for the two systems. About sixty cycles were considered per insole to compare NGrF to PFF measurements. The mean error on NGrF over all cycles and insoles was computed and normalized by the maximum NGrF. Bland-Altman plots, RMSE and NRMSE, as well as Pearson correlation coefficient were computed. Results A mean error on NGrF of 31.7 N (SD: 31.9 N) was obtained between insoles and PFF. It corresponds to 3.6% (± 3.7%) of maximum NGrF during stamping. RMSE and NRMSE were of 45.4 N and 5.2% respectively. A 0.99 correlation coefficient was obtained. Bland-Altman plots highlighted that the higher the NGrF the higher the error. Discussion, conclusion Results suggested that the insoles are reliable compared to force platforms. However, highest errors seemed to be associated to calibration issues. Thus, more works must be conducted to evaluate their reliability in long time use, to estimate the intra and interoperator error, and to set up a validated protocol with injured patients. However the biofeedback of NGrF in real time with these embedded sensors open perspectives in rehabilitation. [ABSTRACT FROM AUTHOR]

Objective Even if properly fitted, the posture and gait of amputee people are disturbed, leading to compensations and over-solicitations of the contralateral limb. The recent commercialization of new generation ankle-foot (NG) prosthesis is not covered by French social security insurance. The evaluation of the service delivered by these medical devices was until now a combination of multidisciplinary evaluations and patient assessments, but needs objective evaluation. Several teams reported a benefit of NG feet, mainly in terms of joint mobility, walking speed and reduction in compensations. But the main subjective improvement is in balance, both in static (more comfortable waiting position) as well as in dynamic (quality and fluidity of walking), which was poorly evaluated in amputees with NG feet. The main objective of this research is to evaluate the relevance of these NG feet in terms of static stability, on both flat and inclined surfaces. Material/patients and methods Six transtibial subjects were included. Three NG feet (Elan ® , Propriofoot ® , Meridium ® ) and the patient's usual foot were successively tested. For each foot type, after socket and alignment validation by an expert prosthetist, an acclimatization period of 15 days at home was observed. After this period, clinical, instrumental (static acquisitions of 20 s on two force platforms, eyes open and closed, on flat ground and on 12% inclined slope uphill and downhill) and functional evaluations (Berg Balance Scale and Activity Specific Balance Scale) were performed. Participants observed a wash out period of 3 weeks with the usual foot before testing each NG foot. The static parameters collected were: lower limb joint angles, Center of Pressure (COP) variation, ground reaction forces (GRF), and functional scores. Results In static position, a larger prosthetic ankle dorsiflexion, less compensations of the amputed lower limb, better symmetry of the GRF and increase of CoP parameters (as length of trajectory and range) were found with NG feet, compared to ESR. Discussion, conclusion The absence of postural control leads to asymmetrical posture, leading to osteoarticular complications. Ankle mobility of NG feet may allow a better balance and improve destabilizations adaptations, above all on slope, and may reduce sound limb compensations. [ABSTRACT FROM AUTHOR]