Techniques for measuring weight bearing during standing and walking

Deep learning approach to estimate foot pressure distribution in walking with application for a cost-effective insole system

Background

Foot pressure distribution can be used as a quantitative parameter for evaluating anatomical deformity of the foot and for diagnosing and treating pathological gait, falling, and pressure sores in diabetes. The objective of this study was to propose a deep learning model that could predict pressure distribution of the whole foot based on information obtained from a small number of pressure sensors in an insole.

Methods

Twenty young and twenty older adults walked a straight pathway at a preferred speed with a Pedar-X system in anti-skid socks. A long short-term memory (LSTM) model was used to predict foot pressure distribution. Pressure values of nine major sensors and the remaining 90 sensors in a Pedar-X system were used as input and output for the model, respectively. The performance of the proposed LSTM structure was compared with that of a traditionally used adaptive neuro-fuzzy interference system (ANFIS). A low-cost insole system consisting of a small number of pressure sensors was fabricated. A gait experiment was additionally performed with five young and five older adults, excluding subjects who were used to construct models. The Pedar-X system placed parallelly on top of the insole prototype developed in this study was in anti-skid socks. Sensor values from a low-cost insole prototype were used as input of the LSTM model. The accuracy of the model was evaluated by applying a leave-one-out cross-validation.

Results

Correlation coefficient and relative root mean square error (RMSE) of the LSTM model were 0.98 (0.92 ~ 0.99) and 7.9 ± 2.3%, respectively, higher than those of the ANFIS model. Additionally, the usefulness of the proposed LSTM model for fabricating a low-cost insole prototype with a small number of sensors was confirmed, showing a correlation coefficient of 0.63 to 0.97 and a relative RMSE of 12.7 ± 7.4%.

Conclusions

This model can be used as an algorithm to develop a low-cost portable smart insole system to monitor age-related physiological and anatomical alterations in foot. This model has the potential to evaluate clinical rehabilitation status of patients with pathological gait, falling, and various foot pathologies when more data of patients with various diseases are accumulated for training.

The impact of walker height positions and their influence on triceps activity and energy conservation: a pilot study

Background/Aims

Millions of adults use walkers for functional mobility. Inappropriate walker use is associated with incorrect height, forward-leaning posture, and increased energy expenditure. Few studies have investigated the impact of walker positions and their influence on triceps activity. The present study assessed walker height and baseline positioning for individuals with a 50% weight bearing restriction of the lower extremity, and implications for energy conservation.

Methods

A total of 38 young adults (mean age = 24.95 years; 84.2% female; 15.8% male) participated in this study with a two-wheeled walker. Participants executed five walker positions while maintaining 50% weight bearing of the lower extremity to determine the effect on triceps electromyography activity.

Results

Triceps electromyography activity did significantly change across the five walker positions assessed (X2 [df=37, P<0.001]). This study showed that the median electromyography activity for positions B (median=0.268) and A (median=0.280) was significantly less than the median electromyography activity for position E (median=0.452; P<0.001). The effect sizes for comparisons of positions B and E (r=0.49) as well as A and E were the largest (r=0.53).

Conclusions

These findings suggest an elbow angle of 26–35° (position B), followed by an elbow angle of 15–25° (position A), with the walker in line with the heels of the participant, to be superior in minimising exertion of the triceps.

RELIABILITY OF WIRELESS INSOLE BAROPODOMETRY OF NORMAL INDIVIDUAL'S GAIT

Objective:

The plantar pressure distribution can be assessed quantitatively by computerized baropodometry such as carpet or insole. An insole-type system with wireless transmission was developed and plantar pressure results were previously validated by force platform. However, the reproducibility of the system had not been determined. Our objective was to evaluate the reliability of the results in different gait cycles, clinical characteristics and in different plantar anatomical sites.

Methods:

41 healthy adults (age, 34 ± 13 years; body mass index, 25 ± 5 kg/m²; 26 [63%], male, 26 [63%] practicing physical activity) were evaluated. Baropodometer evaluations were performed in 3 walking cycles with 100 m each, and the reliability between the cycles was examined. Pressure points on the heel, first metatarsal, fifth metatarsal and total plantar pressure were analyzed and compared.

Results:

Moderate agreement was identified between the second and third cycles (ICC, 0.66; 95% CI, 0.14-0.83). Physical activity practitioners showed higher total plantar pressure (70.8 vs 68.2 Kpa; p = 0.04) and higher pressure in the heel (70.7 vs 68.1 Kpa; p = 0.036) in relation to sedentary ones.

Conclusion:

The insole was able to assess plant pressure with moderate reliability from the adaptation period. Level of Evidence III, Case control study - Investigating a diagnostic test.

Accelerometry-Based Step Count Validation for Horse Movement Analysis During Stall Confinement

Quantitative tracking of equine movement during stall confinement has the potential to detect subtle changes in mobility due to injury. These changes may warn of potential complications, providing vital information to direct rehabilitation protocols. Inertial measurement units (IMUs) are readily available and easily attached to a limb or surcingle to objectively record step count in horses. The objectives of this study were: (1) to compare IMU-based step counts to a visually-based criterion measure (video) for three different types of movements in a stall environment, and (2) to compare three different sensor positions to determine the ideal location on the horse to assess movement. An IMU was attached at the withers, right forelimb and hindlimb of six horses to assess free-movement, circles, and figure-eights recorded in 5 min intervals and to determine the best location, through analysis of all three axes of the triaxial accelerometer, for step count during stall confinement. Mean step count difference, absolute error (%) and intraclass correlation coefficients (ICCs) were determined to assess the sensor's ability to track steps compared to the criterion measure. When comparing sensor location for all movement conditions, the right-forelimb vertical-axis produced the best results (ICC = 1.0, % error = 6.8, mean step count difference = 1.3) followed closely by the right-hindlimb (ICC = 0.999, % error = 15.2, mean step count difference = 1.8). Limitations included the small number of horse participants and the lack of random selection due to limited availability and accessibility. Overall, the findings demonstrate excellent levels of agreement between the IMU's vertical axis and the video-based criterion at the forelimb and hindlimb locations for all movement conditions.

A novel walking cane with haptic biofeedback reduces knee adduction moment in the osteoarthritic knee

Knee osteoarthritis is a leading cause of ambulatory disability in adults. The most prescribed mobility aid, the walking cane, is often underloaded and therefore fails to reduce knee joint loading and provide symptomatic relief. For this study, a novel walking cane with haptic biofeedback was designed to improve cane loading and reduce the knee adduction moment (KAM). To determine; 1) the short-term efficacy of a novel walking cane using haptic biofeedback to encourage proper cane loading and 2) the effects of the novel cane on KAM. Cane loading and KAM, peak knee adduction moment (PKAM), and knee adduction angular impulse (KAAI)) while walking were calculated under five conditions: 1) naïve, 2A) after scale training (apply 20%BW to cane while standing, using a beam scale), 2B) scale recall (attempt to load the cane to 20%BW), 3A) after haptic training (vibrotactile biofeedback delivered when target cane load achieved), and 3B) haptic recall (attempt to load the cane to 20%BW with vibrotactile biofeedback delivered). Compared to the naïve condition all interventions significantly increased cane loading and reduced PKAM and KAAI. No differences between haptic recall and scale recall condition were observed. The haptic biofeedback cane was shown to be an effective and simple way to increase cane loading and reduced knee loading. Haptic biofeedback and scale training were equally effective at producing immediate short-term improvements in cane loading and knee loading. Future studies should examine the long-term effects of scale training and canes with haptic biofeedback on knee joint health, pain, and osteoarthritis disease progression.

Avaliação da distribuição do peso corporal em hemiparéticos: medidas posturográficas versus o instrumento Avaliação da Simetria e Transferência de Peso

RESUMO A assimetria na distribuição do peso corporal (DPC) é um achado comum após um acidente vascular cerebral. Embora a posturografia seja considerada o padrão-ouro para a detecção da assimetria da DPC, exige equipamentos e conhecimentos específicos, limitando seu uso na prática clínica. Por outro lado, a Escala de Avaliação da Simetria e Transferência de Peso (ASTP) é um método simples para identificar a assimetria na DPC. Entretanto, não foi testado se seus resultados estão relacionados às medidas posturográficas. Assim, o objetivo desse estudo foi avaliar a validade concorrente por meio da identificação do grau de associação entre a ASTP e as medidas posturográficas da DPC em indivíduos com hemiparesia. Sessenta indivíduos, com hemiparesia [mediana (min-max)] 58 (33-86) anos e 24 (6-29) meses desde o primeiro AVC, foram avaliados. zA DPC foi avaliada por meio da ASTP e da posturografia (percentual da DPC sobre o membro não parético). A mediana do escore ASTP foi 23 (14-27), “capacidade parcialmente boa de simetria e transferência de peso”. A posturografia revelou 59% de apoio do peso corporal (50-97) sobre o lado não parético. Além disso, identificou uma proporção maior de indivíduos assimétricos do que a ASTP (29 vs. 8; p=0,003). Não houve correlação significativa entre ASTP e %DPC (rho=0,001, p=0,992). Concluiu-se que a ASTP não está relacionada à assimetria na DPC estimada pela posturografia, sugerindo a necessidade de uma reavaliação de sua utilidade clínica.

Reliability of upright weight-bearing distribution measures obtained by computed baropodometry for participants with and without post-stroke hemiparesis

Background/Aims

Measurements from force platforms and digital scales have been applied to classify weight-bearing distribution in post-stroke hemiparesis. However, an intermediate tool – computed baropodometry – is breaking new ground in this field of diagnosis, with a need to report its reliability. Intra-test and test/retest reliabilities of the percentage of total body weight borne by the predominantly used hemibody calculated from computed baropodometry in participants with and without chronic hemiparesis was investigated in this study.

Methods

A total of 40 participants were evaluated and combined for age and sex in two different groups. Repeated measures were taken to analyse differences among records obtained from averages during 5, 10 or 20 seconds (intra-test reliability) and between the test and 1-week retest (test/retest reliability) for both groups. The analysis of variance, intra-class correlation coefficient and data plotted by Bland-Altman method were administrated.

Results

The intra-test analysis did not show differences among records obtained from different time durations (5, 10 and 20 seconds). Excellent to moderate intra-class correlation coefficient values (0.794 to 0.644) between test and retest were observed in the hemiparesis group from the records obtained by short to the longer lasting time durations, while for control groups, intra-class correlation coefficient values (0.661 to 0.748) were classified as moderate.

Conclusions

Acceptable reliability was found for all participants. Moreover, improved repeatability was reported when the measures were obtained by shorter time periods for both groups.

A novel device to measure static hindlimb weight-bearing forces in pronograde rodents

BACKGROUND

Joint pain is composed of both spontaneous and movement-induced pain. In animal models, static bodyweight distribution is a surrogate for spontaneous joint pain. However, there are no commercially-available instruments that measure static bodyweight distribution in normal, pronograde rodents.

NEW METHOD

We designed a Static Horizontal Incapacitance Meter (SHIM) to measure bodyweight distribution in pronograde standing rodents. We assessed the device for feasibility, repeatability, and sensitivity to quantify hindlimb bodyweight distribution. Mice and rats with unilateral inflammatory pain induced by subcutaneous injections of capsaicin or Complete Freund's Adjuvant (CFA) into the plantar surface of the left hind paw were used to measure static weight-bearing. The ability to attenuate inflammatory pain-associated weight-bearing asymmetry was tested by administering a non-steroidal anti-inflammatory drug, meloxicam.

RESULTS

The SHIM's ability to detect significant reductions in limb loading on the injected hindlimb in mice and rats was validated using both acute and sub-chronic pain models. Treatment with meloxicam partially reversed CFA-induced effects.

COMPARISON WITH EXISTING METHODS

In contrast with assays that measure kinetic or static weight-bearing forces (e.g., walking, or standing at a 45 ° incline), the SHIM allows evaluation of weight-bearing in rodents that are standing at rest in their normal pronograde position.

CONCLUSIONS

The SHIM successfully detected: (a) asymmetric weight-bearing in acute and sub-chronic pain models; and (b) the analgesic effects of meloxicam. This study provides a novel tool to objectively evaluate limb use dysfunction in rodents.

A multiscale model to predict current absolute risk of femoral fracture in a postmenopausal population

Osteoporotic hip fractures are a major healthcare problem. Fall severity and bone strength are important risk factors of hip fracture. This study aims to obtain a mechanistic explanation for fracture risk in dependence of these risk factors. A novel modelling approach is developed that combines models at different scales to overcome the challenge of a large space-time domain of interest and considers the variability of impact forces between potential falls in a subject. The multiscale model and its component models are verified with respect to numerical approximations made therein, the propagation of measurement uncertainties of model inputs is quantified, and model predictions are validated against experimental and clinical data. The main results are model predicted absolute risk of current fracture (ARF0) that ranged from 1.93 to 81.6% (median 36.1%) for subjects in a retrospective cohort of 98 postmenopausal British women (49 fracture cases and 49 controls); ARF0 was computed up to a precision of 1.92 percentage points (pp) due to numerical approximations made in the model; ARF0 possessed an uncertainty of 4.00 pp due to uncertainties in measuring model inputs; ARF0 classified observed fracture status in the above cohort with AUC = 0.852 (95% CI 0.753-0.918), 77.6% specificity (95% CI 63.4-86.5%) and 81.6% sensitivity (95% CI 68.3-91.1%). These results demonstrate that ARF0 can be computed using the model with sufficient precision to distinguish between subjects and that the novel mechanism of fracture risk determination based on fall dynamics, hip impact and bone strength can be considered validated.

The Reliability and Validity of the Loadsol® under Various Walking and Running Conditions

The assessment of loading during walking and running has historically been limited to data collection in laboratory settings or with devices that require a computer connection. This study aims to determine if the loadsol^®—a single sensor wireless insole—is a valid and reliable method of assessing force. Thirty (17 male and 13 female) recreationally active individuals were recruited for a two visit study where they walked (1.3 m/s) and ran (3.0 and 3.5 m/s) at a 0%, 10% incline, and 10% decline, with the visits approximately one week apart. Ground reaction force data was collected on an instrumented treadmill (1440 Hz) and with the loadsol^® (100 Hz). Ten individuals completed the day 1 protocol with a newer 200 Hz loadsol^®. Intraclass correlation coefficients (ICC3,k) were used to assess validity and reliability and Bland–Altman plots were generated to better understand loadsol^® validity. Across conditions, the peak force ICCs ranged from 0.78 to 0.97, which increased to 0.84–0.99 with the 200 Hz insoles. Similarly, the loading rate ICCs improved from 0.61 to 0.97 to 0.80–0.96 and impulse improved from 0.61 to 0.97 to 0.90–0.97. The 200 Hz insoles may be needed for loading rate and impulse in running. For both walking and running, the loadsol^® has excellent between-day reliability (>0.76).

COMplex Fracture Orthopedic Rehabilitation (COMFORT) - Real-time visual biofeedback on weight bearing versus standard training methods in the treatment of proximal femur fractures in the elderly: study protocol for a multicenter randomized controlled trial

Background

Proximal femur fractures are a common injury after low energy trauma in the elderly. Most rehabilitation programs are based on restoring mobility and early resumption of weight-bearing. However, therapy compliance is low in patients following lower extremity fractures. Moreover, little is known about the relevance of gait parameters and how to steer the rehabilitation after proximal femur fractures in the elderly. Therefore, the aim of this prospective, randomized controlled trial is to gain insight in gait parameters and evaluate if real-time visual biofeedback can improve therapy compliance after proximal femur fractures in the elderly.

Methods

This is a two-arm, parallel-design, prospective, randomized controlled trial. Inclusion criteria are age ≥ 60 years, a proximal femur fracture following low energy trauma, and unrestricted-weight bearing. Exclusion criteria are cognitive impairment and limited mobility before trauma. Participants are randomized into either the control group, which receives care as usual, or the intervention group, which receives real-time visual biofeedback about weight-bearing during gait in addition to care as usual. Spatiotemporal gait parameters will be measured in 94 participants per group during a 30-m walk with an ambulatory biofeedback system (SensiStep). The progress of rehabilitation will be evaluated by the primary outcome parameters maximum peak load and step duration in relation to the discharge date. Secondary outcome parameters include other spatiotemporal gait parameters in relation to discharge date. Furthermore, the gait parameters will be related to three validated clinical tests: Elderly Mobility Scale; Functional Ambulation Categories; and Visual Analogue Scale. The primary hypothesis is that participants in the intervention group will show improved and faster rehabilitation compared to the control group.

Discussion

The first aim of this multicenter trial is to investigate the normal gait patterns after proximal femur fractures in the elderly. The use of biofeedback systems during rehabilitation after proximal femur fractures in the elderly is promising; therefore, the second aim is to investigate the effect of real-time visual biofeedback on gait after proximal femur fractures in the elderly. This could lead to improved outcome. In addition, analysis of the population may indicate characteristics of subgroups that benefit from feedback, making a differentiated approach in rehabilitation strategy possible.

Trial registration

TrialRegister.nl, NTR6794. Registered on 31 October 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2612-9) contains supplementary material, which is available to authorized users.

Real-time visual biofeedback to improve therapy compliance after total hip arthroplasty: A pilot randomized controlled trial

BACKGROUND

Previous studies have shown limited therapy compliance in weight-bearing in patients following total hip arthroplasty.

RESEARCH QUESTION

The purpose of this pilot RCT is to determine the immediate and late effect of real-time, visual biofeedback on weight-bearing during rehabilitation after THA in elderly.

METHODS

24 participants who underwent THA were randomized to either the control or the intervention group. The intervention group received real-time, visual biofeedback on weight-bearing during training with the physical therapist during hospitalization and at twelve weeks follow up.

RESULTS

Without biofeedback, therapy compliance was limited. Significant improvement in peak load was found in the intervention group in the early postoperative phase. In contrast to the control group, the peak load at twelve weeks was significantly higher in the intervention group compared to the pre-operative peak load, indicating a lasting effect of early biofeedback. Other gait parameters were not significantly different in the early postoperative phase. In the intervention group a longer walking distance was observed and the use of walking aids was reduced at twelve weeks.

SIGNIFICANCE

Biofeedback systems could be promising to improve outcomes and reduce costs in future rehabilitation programs after THA.

Real-time visual biofeedback during weight bearing improves therapy compliance in patients following lower extremity fractures

BACKGROUND

Individuals with lower extremity fractures are often instructed on how much weight to bear on the affected extremity. Previous studies have shown limited therapy compliance in weight bearing during rehabilitation. In this study we investigated the effect of real-time visual biofeedback on weight bearing in individuals with lower extremity fractures in two conditions: full weight bearing and touch-down weight bearing.

METHODS

11 participants with full weight bearing and 12 participants with touch-down weight bearing after lower extremity fractures have been measured with an ambulatory biofeedback system. The participants first walked 15m and the biofeedback system was only used to register the weight bearing. The same protocol was then repeated with real-time visual feedback during weight bearing. The participants could thereby adapt their loading to the desired level and improve therapy compliance.

RESULTS

In participants with full weight bearing, real-time visual biofeedback resulted in a significant increase in loading from 50.9±7.51% bodyweight (BW) without feedback to 63.2±6.74%BW with feedback (P=0.0016). In participants with touch-down weight bearing, the exerted lower extremity load decreased from 16.7±9.77kg without feedback to 10.27±4.56kg with feedback (P=0.0718). More important, the variance between individual steps significantly decreased after feedback (P=0.018).

CONCLUSIONS

Ambulatory monitoring weight bearing after lower extremity fractures showed that therapy compliance is low, both in full and touch-down weight bearing. Real-time visual biofeedback resulted in significantly higher peak loads in full weight bearing and increased accuracy of individual steps in touch-down weight bearing. Real-time visual biofeedback therefore results in improved therapy compliance after lower extremity fractures.

Technical Aspects and Validation of a New Biofeedback System for Measuring Lower Limb Loading in the Dynamic Situation

Background: A variety of techniques for measuring lower limb loading exists, each with their own limitations. A new ambulatory biofeedback system was developed to overcome these limitations. In this study, we described the technical aspects and validated the accuracy of this system. Methods: A bench press was used to validate the system in the static situation. Ten healthy volunteers were measured by the new biofeedback system and a dual-belt instrumented treadmill to validate the system in the dynamic situation. Results: Bench press results showed that the sensor accurately measured peak loads up to 1000 N in the static situation. In the healthy volunteers, the load curves measured by the biofeedback system were similar to the treadmill. However, the peak loads and loading rates were lower in the biofeedback system in all participants at all speeds. Conclusions: Advanced sensor technologies used in the new biofeedback system resulted in highly accurate measurements in the static situation. The position of the sensor and the design of the biofeedback system should be optimized to improve results in the dynamic situation.

Biofeedback in Partial Weight Bearing: Validity of 3 Different Devices

Study Design Controlled laboratory study to assess criterion-related validity, with a cross-sectional within-subject design. Background Patients with orthopaedic conditions have difficulties complying with partial weight-bearing instructions. Technological advances have resulted in biofeedback devices that offer real-time feedback. However, the accuracy of these devices is mostly unknown. Inaccurate feedback can result in incorrect lower-limb loading and may lead to delayed healing. Objectives To investigate validity of peak force measurements obtained using 3 different biofeedback devices under varying levels of partial weight-bearing categories. Methods Validity of 3 biofeedback devices (OpenGo science, SmartStep, and SensiStep) was assessed. Healthy participants were instructed to walk at a self-selected speed with crutches under 3 different weight-bearing conditions, categorized as a percentage range of body weight: 1% to 20%, greater than 20% to 50%, and greater than 50% to 75%. Peak force data from the biofeedback devices were compared with the peak vertical ground reaction force measured with a force plate. Criterion validity was estimated using simple and regression-based Bland-Altman 95% limits of agreement and weighted kappas. Results Fifty-five healthy adults (58% male) participated. Agreement with the gold standard was substantial for the SmartStep, moderate for OpenGo science, and slight for SensiStep (weighted ± = 0.76, 0.58, and 0.19, respectively). For the 1% to 20% and greater than 20% to 50% weight-bearing categories, both the OpenGo science and SmartStep had acceptable limits of agreement. For the weight-bearing category greater than 50% to 75%, none of the devices had acceptable agreement. Conclusion The OpenGo science and SmartStep provided valid feedback in the lower weight-bearing categories, and the SensiStep showed poor validity of feedback in all weight-bearing categories. J Orthop Sports Phys Ther 2016;46(11):-1. Epub 12 Oct 2016. doi:10.2519/jospt.2016.6625.

Biofeedback in Partial Weight Bearing: Usability of Two Different Devices from a Patient's and Physical Therapist's Perspective

Background

Partial weight bearing is frequently instructed by physical therapists in patients after lower-limb trauma or surgery. The use of biofeedback devices seems promising to improve the patient’s compliance with weight-bearing instructions. SmartStep and OpenGo-Science are biofeedback devices that provide real-time feedback. For a successful implementation, usability of the devices is a critical aspect and should be tested from a user’s perspective.

Aim

To describe the usability from the physical therapists’ and a patients’ perspective of Smartstep and OpenGo-Science to provide feedback on partial weight bearing during supervised rehabilitation of patients after lower-limb trauma or surgery.

Methods

In a convergent mixed-methods design, qualitative and quantitative data were collected. Usability was subdivided into user performance, satisfaction and acceptability. Patients prescribed with partial weight bearing and their physical therapists were asked to use SmartStep and OpenGo-Science during supervised rehabilitation. Usability was qualitatively tested by a think-aloud method and a semi-structured interview and quantitatively tested by the System-Usability-Scale (SUS) and closed questions. For the qualitative data thematic content analyses were used.

Results

Nine pairs of physical therapists and their patients participated. The mean SUS scores for patients and physical therapists were for SmartStep 70 and 53, and for OpenGo-Science 79 and 81, respectively. Scores were interpreted with the Curved Grading Scale. The qualitative data showed that there were mixed views and perceptions from patients and physical therapists on satisfaction and acceptability.

Conclusion

This study gives insight in the usability of two biofeedback devices from the patient’s and physical therapist’s perspective. The overall usability from both perspectives seemed to be acceptable for OpenGo-Science. For SmartStep, overall usability seemed only acceptable from the patient’s perspective.

Implication

The study findings could help clinicians to decide which biofeedback device is appropriate for their given situation and provide information for future development of biofeedback devices.

Agreement of spatio-temporal gait parameters between a vertical ground reaction force decomposition algorithm and a motion capture system

INTRODUCTION

A ground reaction force decomposition algorithm based on large force platform measurements has recently been developed to analyze ground reaction forces under each foot during the double support phase of gait. However, its accuracy for the measurement of the spatiotemporal gait parameters remains to be established.

OBJECTIVE

The aim of the present study was to establish the agreement between the spatiotemporal gait parameters obtained using (1) a walkway (composed of six large force platforms) and the newly developed algorithm, and (2) an optoelectronic motion capture system.

METHODS

Twenty healthy children and adolescents (age range: 6-17 years) and 19 healthy adults (age range: 19-51 years) participated in this study. They were asked to walk at their preferred speed and at a speed that was faster than the preferred one. Each participant performed three blocks of three trials in each of the two walking speed conditions.

RESULTS

The spatiotemporal gait parameters measured with the algorithm did not differ by more than 2.5% from those obtained with the motion capture system. The limits of agreement represented between 3% and 8% of the average spatiotemporal gait parameters. Repeatability of the algorithm was slightly higher than that of the motion capture system as the coefficient of variations ranged from 2.5% to 6%, and from 1.5% to 3.5% for the algorithm and the motion capture system, respectively.

CONCLUSION

The proposed algorithm provides valid and repeatable spatiotemporal gait parameter measurements and offers a promising tool for clinical gait analysis. Further studies are warranted to test the algorithm in people with impaired gait.

Short-time weight-bearing capacity assessment for non-ambulatory patients with subacute stroke: reliability and discriminative power

Background

Weight-bearing capacity (WBC) on the hemiparetic leg is crucial for independent walking, and is thus an important outcome to monitor after a stroke. A specific and practical assessment in non-ambulatory patients is not available. This is of importance considering the increasing administration of high intensive gait training for the severely impaired stroke population. The aim was to develop a fast and easy-to-perform assessment for WBC on a foot pressure plate to be used in clinical routine.

Methods

WBC was assessed in the frontal plane in 30 non-ambulatory patients with subacute stroke and 10 healthy controls under 3 conditions: static, dynamic, and rhythmic. Force–time curves for the hemiparetic leg (patients with stroke) and the non-dominant leg (healthy controls) were normalised as a percentage of body weight (%BW), and the means analysed over 60, 30, and 15 s (static) and the mean of the peak values for 15, 10, 5, 4, and 3 repetition trials (dynamic, rhythmic). The data were tested for discriminative power and reliability. Dynamic and rhythmic tests could discriminate between patients with stroke and healthy controls over all periods (15, 10, 5, 4, and 3 repetitions) (p < 0.001), but not the static test (60 s, p = 0.639; 30 s, p = 0.708; 15 s, p = 0.685). Excellent relative intra-session [intra-class correlation (ICC) >0.829] and inter-session reliability (ICC = 0.740) were found for 3 repetitions in the dynamic test with acceptable absolute reliability [standard error of measurement (SEM) <5 %BW, minimal detectable difference (MDD) <12.4 %BW] and no within- or between-test differences (trial 1, p = 0.792; trial 2, p = 0.067; between trials, p = 0.102).

Conclusions

Three dynamic repetitions of loading the hemiparetic leg are sufficient to assess WBC in non-ambulatory patients with subacute stroke. This is an important finding regarding the implementation of a fast and easy-to-perform assessment for routine clinical usage in patients with limited standing ability.

Could be the predominantly-used hemibody related to the weight bearing distribution modified by the chronic hemiparesis after stroke?

Since the first Broca publications issued from 1970s, lateralized functions in the human brain have urged the researchers to postulate hypothesis based in the right-left asymmetries and, according to some theories, the lateralization of the voluntary motor control could represent a solution to avoid redundant process optimizing space and time. Supported by this idea, the clinicians and researchers tend to concept that the chronic hemiplegic stroke patients learn to use predominantly the non-affected hemibody after stroke in which is more convenient to execute their daily life activities, modifying their natural preference in some cases. Although could seems reasonable conceptualize the non-affected side as the predominantly-used hemibody for motor tasks after stroke (convenience hypothesis), evidences point to exist also hemiplegic patients that developed a predominantly use of the affected side. To float an idea, in terms of weight bearing distribution during upright position, the researchers have found patients overloading the non-affected hemibody, as expected; but also patients overloading the affected hemibody, not presenting necessarily Pusher's syndrome cases. Given the evidences, we could propose a severity-modulated predominance hypothesis which complements the convenience hypothesis. According to our complementary hypothesis, the severity of the motor disability presented in the hemiparesis condition (light, moderate and heavy severity) could determine a predominant use defined by preference (light to moderate severity) or convenience (moderate to heavy severity). In this hypothesis, we postulate ideas from a rehabilitation perspective to be incorporated in treatment programs.

Reliability of a digital weighing scale relative to the Nintendo Wii in measuring limb load asymmetry

Background/Aims:

Limb load asymmetry (LLA) is common in clinical conditions related to the lower limbs such as degenerative joint disease, soft tissue injuries, joint replacements, amputations and stroke. However, the measurement of LLA is limited in clinical practice as the equipment used is expensive and not readily available in most health care settings. The digital weighing scale is proposed as an inexpensive alternative method of measuring LLA and the objective of this study was to investigate the reliability and accuracy of a digital weighing scale relative to the Nintendo Wii in measuring limb load asymmetry during static standing.

Methods:

Twenty-four participants (12 participants with knee osteoarthritis (OA) and 12 healthy participants) were recruited through convenient sampling from a public university teaching hospital. The participants were required to perform a quiet standing task during the measurement of LLA. The measurements were taken over three trials during both eyes-open (EO) and eyes-closed (EC) resting conditions. LLA was measured in kilograms and computed with a symmetry index. Intra-class correlation coefficient (ICC) (3, 1) analysis, standard error of measurement and coefficient of variation were performed to assess reliability. The Bland-Altman plot was used to test the degree of agreement between digital weighing scales and the Nintendo Wii.

Results:

The digital weighing scale showed an excellent reliability of 0.983 and 0.988 in EC and EO conditions, respectively. The Bland-Altman plot showed good agreement between digital weighing scales and the Nintendo Wii in measuring LLA.

Conclusions:

The digital weighing scale is a reliable tool to measure LLA and has excellent potential to be used in clinical settings.

Reliability of the measures of weight-bearing distribution obtained during quiet stance by digital scales in subjects with and without hemiparesis

Described as an alternative way of assessing weight-bearing asymmetries, the measures obtained from digital scales have been used as an index to classify weight-bearing distribution. This study aimed to describe the intra-test and the test/retest reliability of measures in subjects with and without hemiparesis during quiet stance. The percentage of body weight borne by one limb was calculated for a sample of subjects with hemiparesis and for a control group that was matched by gender and age. A two-way analysis of variance was used to verify the intra-test reliability. This analysis was calculated using the differences between the averages of the measures obtained during single, double or triple trials. The intra-class correlation coefficient (ICC) was utilized and data plotted using the Bland-Altman method. The intra-test analysis showed significant differences, only observed in the hemiparesis group, between the measures obtained by single and triple trials. Excellent and moderate ICC values (0.69-0.84) between test and retest were observed in the hemiparesis group, while for control groups ICC values (0.41-0.74) were classified as moderate, progressing from almost poor for measures obtained by a single trial to almost excellent for those obtained by triple trials. In conclusion, good reliability ranging from moderate to excellent classifications was found for participants with and without hemiparesis. Moreover, an improvement of the repeatability was observed with fewer trials for participants with hemiparesis, and with more trials for participants without hemiparesis.

Evaluation of limb load asymmetry using two new mathematical models

Quantitative measurement of limb loading is important in orthopedic and neurological rehabilitation. In current practice, mathematical models such as Symmetry index (SI), Symmetry ratio (SR), and Symmetry angle (SA) are used to quantify limb loading asymmetry. Literatures have identified certain limitations with the above mathematical models. Hence this study presents two new mathematical models Modified symmetry index (MSI) and Limb loading error (LLE) that would address these limitations. Furthermore, the current mathematical models were compared against the new model with the goal of achieving a better model. This study uses hypothetical data to simulate an algorithmic preliminary computational measure to perform with all numerical possibilities of even and uneven limb loading that can occur in human legs. Descriptive statistics are used to interpret the limb loading patterns: symmetry, asymmetry and maximum asymmetry. The five mathematical models were similar in analyzing symmetry between limbs. However, for asymmetry and maximum asymmetry data, the SA and SR values do not give any meaningful interpretation, and SI gives an inflated value. The MSI and LLE are direct, easy to interpret and identify the loading patterns with the side of asymmetry. The new models are notable as they quantify the amount and side of asymmetry under different loading patterns.

Accuracy of a digital weight scale relative to the nintendo wii in measuring limb load asymmetry

[Purpose] The aim of the present study was to investigate the accuracy of a digital weight scale relative to the Wii in limb loading measurement during static standing. [Methods] This was a cross-sectional study conducted at a public university teaching hospital. The sample consisted of 24 participants (12 with osteoarthritis and 12 healthy) recruited through convenient sampling. Limb loading measurements were obtained using a digital weight scale and the Nintendo Wii in static standing with three trials under an eyes-open condition. The limb load asymmetry was computed as the symmetry index. [Results] The accuracy of measurement with the digital weight scale relative to the Nintendo Wii was analyzed using the receiver operating characteristic (ROC) curve and Kolmogorov-Smirnov test (K-S test). The area under the ROC curve was found to be 0.67. Logistic regression confirmed the validity of digital weight scale relative to the Nintendo Wii. The D statistics value from the K-S test was found to be 0.16, which confirmed that there was no significant difference in measurement between the equipment. [Conclusion] The digital weight scale is an accurate tool for measuring limb load asymmetry. The low price, easy availability, and maneuverability make it a good potential tool in clinical settings for measuring limb load asymmetry.

Patient compliance with postoperative lower extremity touch-down weight-bearing orders at a level I academic trauma center

After lower extremity fracture or surgery, physicians often prescribe limited weight bearing. The current study was performed to evaluate teaching and compliance of touch-down weight bearing (defined as 25 lb) at a level I academic trauma center. A survey was distributed to physical therapists (PTs) from the orthopedic ward to gauge their training methods and their confidence in patients' ability to comply. Patients with recommended touch-down weight bearing were then evaluated on the day of discharge and again at their first follow-up appointment using the SmartStep weight-bearing measurement device (Andante Medical Devices, Inc, White Plains, New York). Fifteen PTs completed the survey (average of 14 years in practice). Inconsistency was observed in weight-bearing teaching methods: verbal cues were used 87% of the time, tactile methods were used 41%, demonstration was used 23%, and a scale was used only 1%. Limited confidence was found in the instruction efficacy by those surveyed. Twenty-one patients were seen the day of discharge and 18 of those were seen at first follow-up. At discharge, average minimum and maximum weight bearing were 3.2 and 30.2 lb, respectively. Only 31% of steps were within an acceptable range of 15 to 35 lb. At first follow-up, average minimum and maximum weight bearing were 12.2 and 50.8 lb, respectively. Only 27% of steps were within the acceptable range. The majority of steps were less than the prescribed weight at discharge, whereas the majority of steps were greater than the prescribed weight at first follow-up. These data suggest that more uniform and effective teaching methods for prescribed weight-bearing orders are warranted assuming compliance is an important clinical objective.

Use of bathroom scales in measuring asymmetry of hindlimb static weight bearing in dogs with osteoarthritis

OBJECTIVE

The study assessed the use and reliability of bathroom scales as an objective measurement tool, and setting a normal variance of static weight bearing between hindlimbs.

METHODS

Two groups of dogs were tested: a healthy control group (n = 21) and a group (n = 43) of dogs with confirmed osteoarthritis in at least one stifle joint, with or without hip joint osteoarthritis. Static weight bearing was evaluated manually and measured with two bathroom scales. An orthopaedic examination was done and dynamic weight bearing was measured using a force platform. Radiographs were taken to confirm the presence of osteoarthritis, and dogs were divided into groups of severe and non-severe osteo- arthritic changes. Reliability by repeatability was tested using analysis of variance, and the congruity between static weight bearing and other evaluation methods with Kappa statistics and proportion of agreement.

RESULTS

The difference between the hindlimbs proportional to the body weight in control dogs was 3.3% (± 2.7%). The repeatability of measuring static weight bearing in the hindlimbs of osteoarthritic dogs with bathroom scales was 81% with osteoarthritic limbs, and 70% for unaffected limbs. The sensitivity of static weight bearing measurements using bathroom scales was 39% and specificity 85%.

CLINICAL SIGNIFICANCE

Bathroom scales are a reliable, simple, and cost-effective objective method for measuring static weight bearing and can be used as an outcome measure when rehabilitating dogs with osteoarthritic changes in the hindlimbs.

Effect of age on partial weight-bearing training

Biofeedback devices are increasingly used to train orthopedic patients to comply with partial weight-bearing instructions for an injured or postoperative extremity. In a previous study, the authors showed that biofeedback was effective in training young participants. However, because many partial weight-bearing orthopedic patients are of advanced age, the current study was designed to test the effect of age on partial weight-bearing training. Fifty asymptomatic participants aged between 20 and 78 years completed 3 interventions: (1) verbal instructions on weight bearing, (2) training with a bathroom scale, and (3) training with a biofeedback device. Participants given only verbal touchdown weight-bearing instructions (25 lb) initially bore an average of 61.25±4.80 lb. This was reduced to 51.50±4.47 lb after training with a bathroom scale and further reduced to 30.01±2.33 lb after biofeedback training. Likewise, participants given verbal partial weight-bearing instructions (75 lb) initially bore an average of 89.06±5.58 lb. No improvement was observed with the use of a bathroom scale (average, 88.47±4.75 lb). After training with the biofeedback device, weight bearing improved to an average of 68.11±2.46 lb. Mixed-model analysis revealed that age was not a significant predictor of compliance. However, a higher body mass index and male sex were predictive of worse compliance and heavier weight bearing. Biofeedback training leads to superior compliance to weight-bearing instructions compared with verbal instructions or training with a bathroom scale. Because partial weight-bearing instructions are commonly given to orthopedic patients, biofeedback training may be appropriately considered in any age group with similar effect.

Improving lower limb weight distribution asymmetry during the squat using Nintendo Wii Balance Boards and real-time feedback

Weight-bearing asymmetry (WBA) may be detrimental to performance and could increase the risk of injury; however, detecting and reducing it is difficult in a field setting. This study assessed whether a portable and simple-to-use system designed with multiple Nintendo Wii Balance Boards (NWBBs) and customized software can be used to evaluate and improve WBA. Fifteen elite Australian Rules Footballers and 32 age-matched, untrained participants were tested for measures of WBA while squatting. The NWBB and customized software provided real-time visual feedback of WBA during half of the trials. Outcome measures included the mean mass difference (MMD) between limbs, interlimb symmetry index (SI), and percentage of time spent favoring a single limb (TFSL). Significant reductions in MMD (p = 0.028) and SI (p = 0.007) with visual feedback were observed for the entire group data. Subgroup analysis revealed significant reductions in MMD (p = 0.047) and SI (p = 0.026) with visual feedback in the untrained sample; however, the reductions in the trained sample were nonsignificant. The trained group showed significantly less WBA for TFSL under both visual conditions (no feedback: p = 0.015, feedback: p = 0.017). Correlation analysis revealed that participants with high levels of WBA had the greatest response to feedback (p < 0.001, ρ = 0.557). In conclusion, WBA exists in healthy untrained adults, and these asymmetries can be reduced using real-time visual feedback provided by an NWBB-based system. Healthy, well-trained professional athletes do not possess the same magnitude of WBA. Inexpensive, portable, and widely available gaming technology may be used to evaluate and improve WBA in clinical and sporting settings.

Is it possible to train patients to limit weight bearing on a lower extremity?

Orthopedic patients are often instructed on how much weight to bear on an injured or postoperative extremity. Although specific weight-bearing instructions are given to a majority of lower-extremity orthopedic patients, the ability of patients to comply with these instructions is questioned in the medical literature. This study compared the effectiveness of new forms of clinical interventions designed to train patients on weight bearing, focusing on the use of biofeedback devices designed to offer real-time feedback to partial weight-bearing patients. Twenty healthy patients aged 20 to 30 years completed 3 interventions: (1) verbal instructions on weight bearing, (2) training with a bathroom scale, and (3) training with a biofeedback device.Patients given touchdown weight-bearing instructions (25 lb) initially bore an average of 63.57±6.24 lb when given verbal instructions. This was reduced to 44.75±5.69 lb after training with a bathroom scale (P<.001), and was further reduced to 26.2±1.57 lb with biofeedback training (P=.011). Likewise, patients given partial weight-bearing instructions (75 lb) initially bore an average of 92.28±7.85 lb. No improvement occurred with the use of a bathroom scale (at 75 lb), which showed an average of 90.82±7.19 lb (P=1.000). Training with a biofeedback device improved the average weight bearing to 69.67±3.18 lb (P=.014).Biofeedback training led to superior compliance with touchdown and partial weight-bearing instructions. Because partial weight-bearing instructions are commonly given to orthopedic patients, training with such a device may be appropriately considered.

Comparação entre medidas de descarga, simetria e transferência de peso em indivíduos com e sem hemiparesia

Avaliação da Simetria e Transferência de Peso (ASTP) foi indicada para se fazer associação entre simetria e atividades funcionais nas hemiparesias, apontando simétricos como mais capacitados. Contudo, tais relações não são claras e divergem com evidências que sugerem assimetrias como estratégias funcionais. Assim, objetivou-se verificar se as medidas subjetivamente determinadas pela ASTP concordam com medidas calculas pela descarga de peso entre os pés. Realizou-se estudo observacional do tipo transversal para amostra de sujeitos com hemiparesia (n=20) pareados por idade e gênero a controles (n=20). Os participantes submeteram-se a procedimentos para obtenção de escore determinado pela ASTP e para cálculo da razão de simetria (RS) na descarga de peso entre os pés obtido por meio de duas balanças digitais. Os resultados obtidos pela ASTP identificaram apenas um sujeito com hemiparesia apresentando simetria, dentre os quatro sujeitos identificados pela RS como simétricos. Ainda, a ASTP não diferenciou assimetrias com sobrecarga para o lado afetado e apresentou correlação significativa somente quando os escores foram analisados com os valores de RS<1(sobrecarga para o lado não afetado). Conclui-se que a ASTP não foi concordante em identificar sujeitos hemiparéticos com descarga de peso compatível com simetria. Ainda, não identificou sobrecargas para o lado afetado que poderia conduzir a análises equivocadas da associação entre simetria e desempenho funcional.

Is it correct to always consider weight-bearing asymmetrically distributed in individuals with hemiparesis?

Injuries may cause unilateral deterioration of brain areas related to postural control resulting in lateralized motor disability with abnormal asymmetry in weight-bearing distribution. Although overloading toward the nonaffected limb has been described as the preferred posture among individuals with hemiparesis, characterization of the weight-bearing asymmetry is poorly and indirectly described. Therefore, this study aimed to describe weight-bearing distribution during upright stance, establishing criteria to consider asymmetry in hemiparesis when analyzed within the limits defined by controls matched by age and gender. Forty subjects with (n = 20) or without hemiparesis (n = 20) were included in procedures to record weight-bearing values between hemibodies, and these values were used to calculate a symmetry ratio. Control presented 95% confidence interval (CI) of the mean for symmetry ratio ranging from 0.888 to 1.072, defining limits to symmetry. Four subjects with hemiparesis (20%) had symmetry ratios inside limits defined by controls (i.e., weight-bearing symmetrically distributed), and 11 (55%) subjects without hemiparesis showed symmetry ratios outside the limits, suggesting asymmetrical weight-bearing distribution. It was concluded that asymmetry, when present in a control group, was more frequently overloading nonpredominantly used hemibody (nondominant side), differing from a hemiparesis group commonly forced to assume the nonaffected side as the predominantly used hemibody and where the overload was observed.

Reliability of an inexpensive and portable dynamic weight bearing asymmetry assessment system incorporating dual Nintendo Wii Balance Boards

Weight bearing asymmetry (WBA) during dynamic tasks is prevalent in a variety of clinical populations. However, accurate measurement has previously been out of reach of the clinician due to the costly equipment and technical expertise required. The aim of this study was to assess the test-retest reliability of WBA data obtained using an inexpensive and simple to use dual force plate system incorporating unmodified Nintendo Wii Balance Boards (NWBB) and customized software. A secondary outcome measure, individual limb COP path velocity, which represents the postural sway under each limb was also examined. Twenty-three participants performed squats both with and without visual WBA feedback on two separate occasions. Weight-bearing asymmetry as a percentage of body mass and individual limb center of pressure (COP) path velocity were recorded during these trials, with intraclass correlation coefficient (ICC(2,1)) analysis performed to assess test-retest reliability. This system provided reliable values for both outcome measures when performed with and without real-time visual feedback of WBA (ICC(2,1) range=0.75-0.91). In conclusion, recording WBA and COP path velocity data using NWBB is reliable. Given that tens of millions of NWBB have been sold worldwide, and that reprogramming them for clinical purposes is within the reach of most software developers, similar systems may soon become commonplace in the clinical setting.

An in-shoe device to measure plantar pressure during daily human activity

In this work, we report the development of a novel device, integrated into a shoe, to monitor plantar pressure under real-life conditions by reducing the spatial and temporal resolution. The device consists of a shoe insole with seven pressure-sensitive conductive rubber sensors and a wireless data transmission unit incorporated into a smaller measurement unit. One advantage of this approach is that the mass and volume of the measurement unit are less than 1/10th and 1/50th, respectively, of that reported for other devices. A comparison experiment was conducted for validation of the device using the F-scan system, and the initial test of the device was conducted by recording unobstructed gaits of one young adult subject and two elderly subjects. Each subject performed a straight, level walking trial at a comfortable speed for 7 m without any assistive device while wearing the in-shoe device. Changes in the plantar pressure during gait were recorded. Compared with the young subject, the pressure under the heel of the elderly subject was found to be smaller and less steep. This in-shoe device can be used to monitor plantar pressure during daily living and is expected to be useful in various clinical applications.

Design and test of a novel closed-loop system that exploits the nociceptive withdrawal reflex for swing-phase support of the hemiparetic gait

A novel closed-loop system for improving gait in hemiparetic patients by supporting the production of the swing phase using electrical stimulations evoking the nociceptive withdrawal reflex was designed. The system exploits the modular organization of the nociceptive withdrawal reflex and its stimulation site- and gait-phase modulation in order to evoke movements of the hip, knee, and ankle joints during the swing phase. A modified model-reference adaptive controller (MRAC) was designed to select the best stimulation parameters from a set of 12 combinations of four electrode locations on the sole of the foot and three different stimulation onset times between heel-off and toe-off. It was hypothesized that the MRAC system would result in a better walking pattern compared with an open-loop preprogrammed fixed pattern of stimulation (FPS) controller. Thirteen chronic or subacute hemiparetic subjects participated in a study to compare the performance of the two control schemes. Both control schemes resulted in a more functional gait compared to no stimulation (P < 0.05) with a weighted joint angle peak change of 4.0 ± 1.6 (mean ± Standard deviation) degrees and 3.1 ± 1.4 degrees for the MRAC and FPS schemes, respectively. This indicates that the MRAC scheme performed better than the FPS scheme (P < 0.001) in terms of reaching the control target.

Footscan pressure insoles: accuracy and reliability of force and pressure measurements in running

In the current investigation, the accuracy and reliability of two pairs of Footscan pressure insoles (500 Hz, RSscan, Belgium) was assessed, with four female (pair 1) and four male (pair 2) participants each performing 16 running trials (3.8m/s ± 5%). Intraclass Correlation Coefficients (ICC) revealed that the reliability of the force and pressure data was generally excellent (ICC>0.75). In comparison with impact and propulsive force data collected simultaneously with a force plate (AMTI, 500 Hz), insole data were significantly lower (p<0.05). Therefore, despite the excellent reliability of measurements, the accuracy of the impact and propulsive forces taken with the Footscan pressure insole is low. It is concluded that data collected without appropriate calibration should be used with caution, particularly if the aim is to use the data for a comparison of absolute force and pressure magnitudes with criterion values.

[Partial weight-bearing in rehabilitation. Strategies for instruction and limitations]

Following trauma or surgery on the musculoskeletal system the primary aim is always as complete a restitution of mobility as possible. By mobilization with partial weight-bearing this is possible. The preferred way of teaching partial weight-bearing is the use of conventional bathroom scales. This method proves to be simple as well as time and cost-saving, but the transferability to the patient's daily life is questionable. Training and control of partial weight-bearing under dynamic conditions, such as normal walking, and walking up and down stairs seem to be very important. Different investigations have shown that the minority of subjects recruited could manage to maintain the given load of partial weight-bearing. Furthermore, the actual resulting moments within the joints, caused by muscles, fascia and tendons, are not considered in presets of partial weight-bearing, as only external forces (ground reaction forces) are measured. However, the problems in teaching partial weight-bearing have to be contrasted with the as yet unexplained issue of postoperative partial versus full weight-bearing.

Musculoskeletal biomechanics in sit-to-stand and stand-to-sit activities with stroke subjects: a systematic review

INTRODUCTION: Sit-to-stand and stand-to-sit are two of the most mechanically demanding activities undertaken in daily life and which are usually impaired in stroke subjects. OBJECTIVES: To determine the distinguishing characteristics in musculoskeletal biomechanical outcomes of the sit-to-stand and stand-to-sit activities with stroke subjects, with an emphasis on the clinical management of stroke disabilities, in a systematic review. MATERIAL AND METHODS: An extensive literature search was performed with the MEDLINE, CINAHL, EMBASE, PEDro, LILACS, and SciELO databases, followed by a manual search, to select studies on musculoskeletal biomechanical outcomes in both activities with stroke subjects, without language restrictions, and published until December/2007. RESULTS: Out of the 432 studies, only 11 reported biomechanical outcomes of both activities and none reached the total score on the selected quality parameters. The majority of the experimental studies which compared groups did not achieve acceptable scores on their methodological quality (PEDRo). The investigated conditions and interventions were also restricted. Only one study compared biomechanical outcomes between the activities, but only evaluated the time spent to perform them. Few musculoskeletal biomechanical outcomes have been investigated, being weight bearing on the lower limbs and duration of the activities the most investigated. CONCLUSION: There is little information regarding musculoskeletal biomechanical outcomes during these activities with stroke subjects and no definite conclusions can be drawn regarding the particularities of these outcomes on their performance with stroke survivors.

Weight bearing on the affected lower limb in residents of a geriatric rehabilitation hospital

OBJECTIVES

The purpose of the study was to determine whether and to what extent the treatment goal of enhancement of weight bearing on an affected lower limb is achieved in the gait rehabilitation of patients with poststroke hemiparesis, postprosthetic fitting due to unilateral transtibial amputation, or postunilateral hip or knee arthroplasty.

DESIGN

Nonrandomized prepost study. Subjects were 26 residents of a geriatric rehabilitation hospital in the initial stage of gait rehabilitation after poststroke hemiparesis (n = 9), unilateral total hip or knee joint replacement (n = 11), or unilateral transtibial amputation with a fitted prosthesis (n = 6). Weight bearing on the hindfoot and forefoot of the affected limb was measured by using the SmartStep system version 2.2.0, at least once a week, both before and immediately after a gait-training session. Measurements were performed with the patients using their assistive devices.

RESULTS

In the patients with hemiparesis, there was no significant difference found between the initial pretraining maximal weight bearing on the afflicted limb (39% and 50% of body weight on the hindfoot and forefoot, respectively) and that at discharge (47% and 50% of body weight, respectively). In patients after hip or knee arthroplasty and in those who underwent prosthetic fitting, there was a substantial increase found in the loading of the forefoot, but not of the hindfoot, from the initial evaluation to the time of discharge (from 43% to 54% of body weight, P = 0.05, in the arthroplasty group, and from 49.6% to 69.5%, P = 0.09, in the prosthetic group).

CONCLUSIONS

For elderly individuals belonging to the studied diagnostic groups, the goal of enhancing normal weight bearing on the afflicted limb during the time course of 2-3 wks might be unrealistic.

Embedded capacitive sensor system for hip surgery rehabilitation: online measurements and long-term stability

We are developing an embedded system that measures the force between foot and insole with a low-cost laminated capacitive sensor matrix. The system is intended to guide a hip surgery patient to train the operated leg with a suitable force. In this paper, we present an embedded measurement system, which is able to estimate the total plantar force in real-time and to give instant feedback to a user. We also present a method for compensating the drift of capacitive sensors. A 5-hour long test measurement was made in order to validate the system. According to the preliminary test, the compensation method effectively prevents the drift of the baseline of the force reading.

Withdrawal reflexes examined during human gait by ground reaction forces: site and gait phase dependency

The objective of this study was to investigate the modulation of the nociceptive withdrawal reflex during gait measured using Force Sensitive Resistors (FSR). Electrical stimulation was delivered to four locations on the sole of the foot at three different time points between heel-off and toe-off. Peak force changes were measured by FSRs attached to the big toe, distal to the first and fourth metatarsophalangeal joints, and the medial process of the calcaneus on both feet. Force changes were assessed in five gait sub-phases. The painful stimulation led to increased ipsilateral unloading (10 +/- 1 N) and contralateral loading (12 +/- 1 N), which were dependent on stimulation site and phase. In contrast, the hallux of the ipsilateral foot plantar flexed, thus facilitating the push-off. The highest degree of plantar flexion (23 +/- 10 N; range, 8-44 N) was seen in the second double support phase following the stimulation. Site and phase modulation of the reflex were detected in the force signals from all selected anatomical landmarks. In the kinematic responses, both site and phase modulation were observed. For stimulations near toe-off, withdrawal was primarily accomplished by ankle dorsiflexion, while the strategy for stimulations at heel-off was flexion of the knee and hip joints.

Psychometric properties of the modified Emory Functional Ambulation Profile in stroke patients

OBJECTIVE

To examine the test-retest reliability, convergent and predictive validity and responsiveness of the modified Emory Functional Ambulation Profile (mEFAP) in assessing gait function in stroke patients undergoing rehabilitation.

SUBJECTS

Forty subacute stroke inpatients were enrolled in the validity and responsiveness study. Twenty chronic patients participated in the reliability study.

SETTING

Rehabilitation department of a medical centre.

DESIGN

In the validity and responsiveness study, patients were tested using the mEFAP, 10-m walking speed test, Barthel Index and Rivermead Mobility Index at admission and at discharge. For the reliability study, the patients completed the mEFAP twice one week apart.

RESULTS

The patients' performances on the mEFAP were moderately to highly correlated with results of the 10-m walking speed test and Rivermead Mobility Index (absolute correlation coefficients > or = 0.67), indicating good convergent validity. Patients' performance on the mEFAP at admission was moderately correlated with the Barthel Index and Rivermead Mobility Index scores at discharge (Spearman's rank correlation coefficients = -0.52 and -0.78, respectively), indicating good predictive validity. The standardized response mean of the mEFAP was 1.1 (P < 0.0001), suggesting good responsiveness. The intraclass correlation coefficient ICC(3,1) for the mEFAP was 0.997, indicating excellent test retest reliability.

CONCLUSIONS

Our results provide strong evidence that the mEFAP has good reliability, validity and responsiveness for assessing stroke patients undergoing rehabilitation. The mEFAP is a useful scale for measuring walking function and recovery in stroke patients.

Accuracy and repeatability of the Pedar Mobile system in long-term vertical force measurements

Portable insole pressure systems can be used to measure the vertical force during long-term (hours) measurements to determine the patient's amount of weight bearing during daily activities in the hospital and at home. Especially for long-term measurements, the amount and duration of loading pressure insoles can have a large influence on the accuracy, as previous studies found a time-dependent behavior after a relatively short period (minutes) of constant loading. Therefore, this study assessed the accuracy and repeatability of a portable capacitive insole system (Pedar, Novel(GmbH)) to measure vertical force during long-term loading. Static loading experiments were performed during which the Pedar insoles were loaded with 5 and 10 N/cm2 for 7 h. Dynamic loading experiments were performed with one Pedar insole which was cyclically loaded with 300, 500 and 1000 N during two sessions of 1200 load cycles. The static and dynamic experiments were repeated 3 days later. Accuracy, due to offset drift, decreased in time during the start of the static experiments (percent error: -1.9% to 0.3% at hour 0; 26.3% to 34% at hour 7). The percent error for the dynamic experiments ranged from -16% to -19%, from -3% to -7% and from -8% to approximately 0% when the insole was loaded with 300, 500 and 1000 N, respectively. The amount of drift ranged from 12 to 62 N for the 500 and 1000 N loads, respectively. The mean day-to-day percentage difference for the static and dynamic experiments ranged from -2.3% to 0.5%, and from -2.9% to 3.0%, respectively. The results indicate that drift correction is necessary for accurate assessment of vertical force by the Pedar Mobile system to determine the amount of weight bearing during long-term measurements.

Medial-lateral balance during stance phase of straight and circular walking of human subjects

Right and left balance during human locomotion has been estimated by the distance between locations of the sequential right and left heel-strikes, or step width. During the stance phase of human locomotion one leg maintains medial-lateral balance for the progression. We focused our attention on this point, and medial-lateral balance during straight-ahead and circular walking was investigated by recording sole-floor reaction force from five anatomically discrete points of human sole; calcaneus, 1st, 3rd, 5th metatarsals and great toe. Forces from these points were recorded during straight walking and circular walking. Medial-lateral balance was obtained by subtracting force at 5th metatarsal from force at 1st metatarsal (x-axis vector). The foot takes off the floor from medial balance in most steps, although in some steps the foot takes off from lateral balance at slower walking speed at 2 km/h or 4 km/h, showing variable patterns of x-axis vector. At faster walking speed at 6 km/h or 8 km/h body weight shifted to 1st metatarsal before taking off the floor. During circular walking body weight shift to 1st metatarsal in the outer foot, and to 5th metatarsal in the inner foot in most cases.

Validity of the Pedar Mobile system for vertical force measurement during a seven-hour period

Objective measurement of weight bearing during a long-term period can give insight into the postoperative loading of the lower extremity of orthopedic patients to avoid complications. This study investigated the validity of vertical ground reaction force measurements during a long-term period using the Pedar Mobile insole pressure system, by comparing it with a Kistler force platform. In addition, the validity of a new sensor drift correction algorithm to correct for offset drift in the Pedar signal was evaluated. Ground reaction force data were collected during dynamic and static conditions from five healthy subjects every hour for 7 h. A mean offset drift of 14.6% was found after 7 h. After applying the drift correction algorithm the Pedar system showed a high accuracy for the second peak in the ground reaction force-time curve (1.1 to 3.4% difference, p>0.05) and step duration (-2.0 to 4.4% difference, p>0.05). Less accuracy was found for the first peak in the ground reaction force-time curve (5.2 to 12.0% difference; p<0.05 for the first 3 h, p>0.05 for the last 4 h) and, consequently, in the vertical force impulse (5.5 to 11.0% difference, p>0.05). The Pedar Mobile system appeared to be a valid instrument to measure the vertical force during a long-term period when using the drift correction program described in this study.

Analysis of human locomotion by recording sole-floor reaction forces from anatomically discrete points

Sole-floor reaction forces were recorded from five anatomically discrete points to analyze characteristics of human locomotion. Strain gauge of 14 mm diameter were firmly attached to the sole of bare-foot for recording force changes from the following five points: (1) medial process of calcaneus, (2) head of 1st metatarsal, (3) head of 3rd metatarsal, (4) head of 5th metatarsal and (5) great toe. Fifteen healthy adults were asked to walk at 2, 4, 6 and 8 km/h and to run at 8 km/h on the treadmill. Sole-floor reaction forces from 1st to 5th metatarsals show reciprocal changes during stance phase, while force from 1st metatarsal is strong 5th metatarsal shows weak reaction and vice versa. This phenomenon may be an expression of locomotor program to maintain vertical stability of the body during stance phase. There was a linear relation between walking speeds and sum of force from the five points, although sum of forces from three metatarsals did not change significantly during the walking speeds, indicating mainly calcaneus and great toe contribute to increasing walking speed. During running the sum of force from the three metatarsals increased sharply, joining the other two points to increase thrust.