The effects of experimentally-induced fatigue on gait parameters during obstacle crossing: A systematic review.

Striking an obstacle while walking can be dangerous, reflecting the higher risks of losing one's balance, tripping and falling. Particular situations during which internal resources are limited, such as in a fatigued state, may impair performance when crossing obstacles, enhancing the risks of falls or accidents. Our goal was thus to review the effects of experimentally-induced fatigue (EIF) on gait parameters during obstacle crossing by healthy individuals. We systematically searched PubMed and Web of Science databases using 'fatigue', 'obstacle crossing' and their equivalent terms to extract data from studies investigating this domain. Nine studies were found. First, EIF-related effects on kinetics, EMG and obstacle contacts have been poorly studied. Second, consistent and inconsistent results were found in the kinematic outcomes after EIF. Consistent results included reductions in stride duration and increased step width. Inconsistent results included gait velocity (no-effect vs increased), leading and trailing-foot vertical clearance (reduced vs increased) and horizontal distance from foot to the obstacle before obstacle avoidance (no-effect vs increased). These findings should be interpreted cautiously, however, due to the heterogeneity of the obstacle crossing and EIF protocols.

Spatio-temporal gait parameters obtained from foot-worn inertial sensors are reliable in healthy adults in single- and dual-task conditions.

Inertial measurement units (IMUs) are increasingly popular and may be usable in clinical routine to assess gait. However, assessing their intra-session reliability is crucial and has not been tested with foot-worn sensors in healthy participants. The aim of this study was to assess the intra-session reliability of foot-worn IMUs for measuring gait parameters in healthy adults. Twenty healthy participants were enrolled in the study and performed the 10-m walk test in single- and dual-task ('carrying a full cup of water') conditions, three trials per condition. IMUs were used to assess spatiotemporal gait parameters, gait symmetry parameters (symmetry index (SI) and symmetry ratio (SR)), and dual task effects parameters. The relative and the absolute reliability were calculated for each gait parameter. Results showed that spatiotemporal gait parameters measured with foot-worn inertial sensors were reliable; symmetry gait parameters relative reliability was low, and SR showed better absolute reliability than SI; dual task effects were poorly reliable, and taking the mean of the second and the third trials was the most reliable. Foot-worn IMUs are reliable to assess spatiotemporal and symmetry ratio gait parameters but symmetry index and DTE gait parameters reliabilities were low and need to be interpreted with cautious by clinicians and researchers.

Validity of wearable actimeter computation of total energy expenditure during walking in post-stroke individuals.

BACKGROUND: Recent studies reported that wearable sensor devices show low validity for assessing the amount of energy expenditure in individuals after stroke. OBJECTIVE: We aimed to evaluate the validity of energy expenditure calculation based on the product of energy cost and walked distance estimated by wearable devices in individuals after hemispheric stroke. METHODS: We recruited individuals with hemispheric stroke sequelae who were able to walk without human assistance. The participants wore a tri-axial accelerometer (Actigraph GT3x) and a pedometer (ONStep 400) on the unaffected hip in addition to a respiratory gas exchange analyzer (METAMAX 3B) during 6min of walking at their self-selected walking speed and mode. The energy expenditure was calculated from the product of energy cost measured by the METAMAX 3B and the distance estimated by wearable devices. It was compared to the energy expenditure measured by the METAMAX 3B and the energy expenditure values recorded by the devices according to the manufacturer's algorithms. The validity was investigated by Bland-Altman analysis (mean bias [MB], root mean square error [RMSE], limits of agreement [95%LoA]), and Pearson correlation analysis (r). RESULTS: We included 26 participants (mean [SD] age 64.6 [14.8] years). With the pedometer, the energy expenditure calculated from the product of energy cost and walked distance showed high accuracy and agreement with METAMAX 3B values (MB=-1.6kcal; RMSE=4.1kcal; 95%LoA=-9.9; 6.6kcal; r=0.87, P<0.01) but low accuracy and agreement with Actigraph GT3x values (MB=15.7kcal; RMSE=8.7kcal; 95%LoA=-1.3; 32.6kcal; r=0.44, P=0.02) because of poorer estimation of walked distance. With the pedometer, this new method of calculation strongly increased the validity parameter values for estimating energy expenditure as compared with the manufacturer's algorithm. CONCLUSIONS: This new method based on the energy cost and distance estimated by wearable devices provided better energy expenditure estimates for the pedometer than did the manufacturer's algorithm. The validity of this method depended on the accuracy of the sensor to measure the distance walked by an individual after stroke.

Do gait and muscle activation patterns change at middle-age during split-belt adaptation?

Advancing age affects gait adaptability, but it is unclear if such adaptations to split-belt perturbations are already affected at middle-age. Changes in neuromuscular control, that already start at middle-age, may underlie the age-related changes in gait adaptation. Thus, we examined the effects of age on adaptations in gait and muscle activation patterns during split-belt walking in healthy young and middle-aged adults. Young (23.3 ± 3.13 years) and middle-aged adults (55.3 ± 2.91 years) walked on an instrumented split-belt treadmill. Both age groups adapted similarly by reducing asymmetry in step length and double support time. Surface EMG was recorded from eight leg muscles bilaterally. Principal Component Analysis (PCA) was applied to the EMG data of all subjects, for the fast and slow leg separately, to identify muscle activation patterns. The principal components consisted of i.e. temporal projections that were analyzed with Statistical Parametric Mapping (SPM). The functional muscle groups, identified by PCA, increased activation during early adaptation and post-adaptation, and decreased activation over time similarly in both age groups. Extra activation peaks of the plantar- and dorsiflexors suggest a role in gait modulation during split-belt walking. Both young and middle-aged adults re-established gait symmetry and showed adaptation effects in the muscle activation patterns. Since the adaptation of muscle activation patterns parallels adaptation of gait symmetry, changes in muscle activation likely underlie the changes in step parameters during split-belt adaptation. In conclusion, split-belt adaptation, in terms of gait and muscle activation patterns, is still preserved at middle-age, suggesting that age-related differences occur later in the lifespan.

Reduction of Prolonged Excessive Pressure in Seated Persons With Paraplegia Using Wireless Lingual Tactile Feedback: A Randomized Controlled Trial.

Pressure ulcers (PU) are known to be a high-cost disease with a risk of severe morbidity. This paper evaluates a new clinical strategy based on an innovative medical device [Tongue Display Unit (TDU)] that implements perceptive supplementation in order to reduce prolonged excessive pressure, recognized as one of the main causes of PU. A randomized, controlled, and parallel-group trial was carried out with 12 subjects with spinal cord injuries (SCI). Subjects were assigned to the control (without TDU, [Formula: see text]) or intervention (with TDU, [Formula: see text]) group. Each subject took part in two sessions, during which the subject, seated on a pressure map sensor, watched a movie for one hour. The TDU was activated during the second session of the intervention group. Intention-to-treat analysis showed that the improvement in adequate weight shifting between the two sessions was higher in the intervention group (0.84 [0.24; 0.89]) than in the control group (0.01 [-0.01; 0.09]; [Formula: see text]) and that the ratio of prolonged excessive pressure between the two sessions was lower in the intervention group (0.74 [0.37; 1.92]) than in the control group (1.72 [1.32; 2.56]; [Formula: see text]). The pressure map sensor was evaluated as being convenient for use in daily life; however, this was not the case for the TDU. This paper shows that persons with SCI could benefit from a system based on perceptive supplementation that alerts and guides the user on how to adapt their posture in order to reduce prolonged excessive pressure, one of the main causes of PU.

Clinical workflow for personalized foot pressure ulcer prevention.

Foot pressure ulcers are a common complication of diabetes because of patient's lack of sensitivity due to neuropathy. Deep pressure ulcers appear internally when pressures applied on the foot create high internal strains nearby bony structures. Monitoring tissue strains in persons with diabetes is therefore important for an efficient prevention. We propose to use personalized biomechanical foot models to assess strains within the foot and to determine the risk of ulcer formation. Our workflow generates a foot model adapted to a patient's morphology by deforming an atlas model to conform it to the contours of segmented medical images of the patient's foot. Our biomechanical model is composed of rigid bodies for the bones, joined by ligaments and muscles, and a finite element mesh representing the soft tissues. Using our registration algorithm to conform three datasets, three new patient models were created. After applying a pressure load below these foot models, the Von Mises equivalent strains and "cluster volumes" (i.e. volumes of contiguous elements with strains above a given threshold) were measured within eight functionally meaningful foot regions. The results show the variability of both location and strain values among the three considered patients. This study also confirms that the anatomy of the foot has an influence on the risk of pressure ulcer.

iProprio: a smartphone-based system to measure and improve proprioceptive function.

It is well known that proprioception is necessary to maintain balance control. Although proprioceptive exercices have shown to have beneficial effects on balance, the joint position sense is not easy to measure and patient cannot practise self-measurement. This article proposes a new system specifically desinged to allow measure and improve proprioceptive function. This so-called `iProprio' system uses inertial sensors included in a smartphone, wireless communication and voice command to allow joint position sense measurment in autonomous way and provide a configurable vibrotactile biofeedback for end-users at home. A proof-of-concept study was performed to assess the effectiveness of iProprio on sixteen young healthy subjects. Results showed that they were able to take advantage of vibrotactile biofeedback to increase knee joint repositioning accuracy and consistency. Results suggest that iProprio can be used for rehabilitation proprioceptive home exercices.

Results with the Roseland(®) HAC trapeziometacarpal prosthesis after more than 10 years.

The Roseland(®) hydroxyapatite-coated prosthesis is a total trapeziometacarpal joint prosthesis used for the surgical treatment of thumb basal joint arthritis. The aim of this retrospective study was to evaluate its long-term outcomes. Fifty-one patients (64 thumbs) underwent trapeziometacarpal joint replacement with this prosthesis. The mean follow-up was 12.5 years. Survival rate of the prosthesis was 91%. There was either no pain or only occasional pain in 91% of cases. The mean QuickDASH score was 27.6. Abnormal radiographic findings were present in 70% of cases. Since they were often asymptomatic, no further treatment was carried out. Complications were common (25%) and occurred early on but could often be treated without surgery. The long-term results with the Roseland(®) HAC prosthesis are satisfactory in terms of pain relief and function. However, the high complication rate is a major concern.

Influence of the calcaneus shape on the risk of posterior heel ulcer using 3D patient-specific biomechanical modeling.

Most posterior heel ulcers are the consequence of inactivity and prolonged time lying down on the back. They appear when pressures applied on the heel create high internal strains and the soft tissues are compressed by the calcaneus. It is therefore important to monitor those strains to prevent heel pressure ulcers. Using a biomechanical lower leg model, we propose to estimate the influence of the patient-specific calcaneus shape on the strains within the foot and to determine if the risk of pressure ulceration is related to the variability of this shape. The biomechanical model is discretized using a 3D Finite Element mesh representing the soft tissues, separated into four domains implementing Neo Hookean materials with different elasticities: skin, fat, Achilles' tendon, and muscles. Bones are modelled as rigid bodies attached to the tissues. Simulations show that the shape of the calcaneus has an influence on the formation of pressure ulcers with a mean variation of the maximum strain over 6.0 percentage points over 18 distinct morphologies. Furthermore, the models confirm the influence of the cushion on which the leg is resting: a softer cushion leading to lower strains, it has less chances of creating a pressure ulcer. The methodology used for patient-specific strain estimation could be used for the prevention of heel ulcer when coupled with a pressure sensor.

[Repair of a facial nerve substance loss by interposition of a collagen neurotube]. / Réparation d'une perte de substance du nerf facial par neurotube en collagène.

We are exposing the case of a 22 year-old patient presenting a wound of the right cheek, with a palsy of the right corner of the mouth. He has been sent to us 6 days after the trauma for secondary exploration. A section of the buccal branch of the right facial nerve with a 1cm gap has been brought out. We have bypassed the loss of substance with a collagen absorbable biological conduit. The 6-months clinical and electromyographic follow-up has shown a clear improvement of the function of the orbicularis oris, as well as its reinnervation by the buccal branch of the right facial nerve.

Wegoto: A Smartphone-based approach to assess and improve accessibility for wheelchair users.

This paper proposes a description of a Smartphone-based approach to assess and improve accessibility for wheelchair users. The developed system employs a dedicated Smartphone application that records various complementary sensor measurements (acceleration, deceleration, inclination, orientation, speed, GPS position) and permits obstacle denunciation. Then, accessibility information are reported on maps in a Geographic Information System which can calculate the most accessible route for wheelchair users taking into account their profiles and capabilities. A case study involving a wheelchair-dependent paraplegic was performed to preliminary assess the feasibility of our Smartphone-based approach to provide an accessibility index for wheelchair users. Although preliminary, our results do suggest that the Wegoto system could be used as an innovative assistive navigation system for wheelchair users and ultimately could help to improve their autonomy and quality of life.

Evaluation of a Smartphone-based audio-biofeedback system for improving balance in older adults--a pilot study.

This study was designed to assess the effectiveness of a Smartphone-based audio-biofeedback (ABF) system for improving balance in older adults. This so-called "iBalance-ABF" system that we recetly developed is "all-inclusive" in the sense that its three main components of a balance prosthesis, (i) the sensory input unit, (ii) the processing unit, and (iii) the sensory output unit, are entirely embedded into the Smartphone. The underlying principle of this system is to supply the user with supplementary information about the medial-lateral (ML) trunk tilt relative to a predetermined adjustable "dead zone" through sound generation in earphones. Six healthy older adults voluntarily participated in this pilot study. Eyes closed, they were asked to stand upright and to sway as little as possible in two (parallel and tandem) stance conditions executed without and with the use of the iBalance-ABF system. Results showed that, without any visual information, the use of the Smartphone-based ABF allowed the older healthy adults to significantly decrease their ML trunk sway in the tandem stance posture and to mitigate the destabilizing effect induced by this particular stance. Although an extended study including a larger number of participants is needed to confirm these data, the present results are encouraging. They do suggest that Smartphone-based ABF system could be used for balance training and rehabilitation therapy in older adults.

Effect of saccades in tongue electrotactile stimulation for vision substitution applications.

The visual substitution paradigm aims to facilitate the life of blind people. Generally one uses electro-stimulating devices where electrodes are arranged into arrays to stimulate the skin or the tongue mucosa to send signals of visual type to the subjects. When an electro-stimulation signal is applied continuously (e.g. when static visual scenes are displayed for a long period of time), the receptors of the affected region can get saturated and the patient may lose the displayed information. We propose here some mechanisms that ameliorate the quality of perception of the electro-stimulation information. The electrical signal is encoded as 2D scenes projected onto the tongue via a Tongue Display Unit, i.e. an electro-tactile stimulator formed by a 12×12 matrix of electrodes. We propose to apply stochastic saccades on this signal. Our assumption is that this eye-inspired mechanism should make the visual substitution more efficient (by improving the perception) because of the reduction of the tactile receptors saturation. The influence of saccades was evaluated by a series of experiments. Results revealed a benefit on the persistence of perception due to saccades. This work helps to prevent the saturation of receptors on the tongue. Therefore increasing the quality of vision by the way of the electro-stimulation. It allows new enhancement features to retinal prosthesis devices which suffer from the same phenomenon.

Electrotactile vision substitution for 3D trajectory following.

Navigation for blind persons represents a challenge for researchers in vision substitution. In this field, one of the used techniques to navigate is guidance. In this study, we develop a new approach for 3D trajectory following in which the requested task is to track a light path using computer input devices (keyboard and mouse) or a rigid body handled in front of a stereoscopic camera. The light path is visualized either on direct vision or by way of a electro-stimulation device, the Tongue Display Unit, a 12 × 12 matrix of electrodes. We improve our method by a series of experiments in which the effect of the modality of perception and that of the input device. Preliminary results indicated a close correlation between the stimulated and recorded trajectories.

Effects of a gait training session combined with a mass on the non-paretic lower limb on locomotion of hemiparetic patients: a randomized controlled clinical trial.

BACKGROUND: Results of recent studies have suggested that restraint of non-paretic lower limb movement could improve locomotion in hemiplegic patients. The aim of this study was therefore to determine if a mass applied to the non-paretic lower limb during a single gait training session (GTS) would specifically improve spatio-temporal, kinematic and kinetic gait parameters (GP) of the paretic lower limb. METHODS: Sixty chronic hemiplegic subjects were included in this randomized study. Each participated in one of four GTS conditions: overground or on a treadmill while wearing or not wearing an ankle mass. All subjects were assessed before, immediately after and 20 min after the end of the GTS using 3D gait analysis. RESULTS: The results showed that restraining the non-paretic lower limb during a GTS had no specific effect on GP of the paretic limb, whereas it increased braking force of the non-paretic limb. CONCLUSION: Restraining the non-paretic lower limb of hemiparetic patients with a mass applied to the ankle does not seem to be an effective approach to improve paretic lower limb parameters during a single GTS.