Effects of electrical stimulation of antagonist muscles on shoulder joint adduction force and grip strength.

[Purpose] This study aimed to determine whether applying electrical stimulation to the deltoid and extensor digitorum muscles could lead to a reduction in fixation force during shoulder joint adduction and grip strength. [Participants and Methods] Fifteen healthy adult males participated in this study. In the shoulder adduction force experiment, the middle fibers of the deltoid muscle of the dominant arm were electrically stimulated. In the grip strength experiment, the extensor digitorum muscle of the dominant arm was electrically stimulated. The forces exerted with and without the electrical stimulation were measured. [Results] The torque of the shoulder adduction force decreased significantly with electrical stimulation, while no significant change was observed in normalized grip strength with electrical stimulation. [Conclusion] The response of antagonist muscles to electrical stimulation varied according to location.

Inducing unstable walking conditions through visual and auditory stimuli.

[Purpose] Falls can significantly affect elderly individuals. However, most current methods used to detect and analyze high-risk conditions make use of simulated falling movements for data collection, which may not accurately represent actual falls. The present study aimed to induce natural falls using visual and auditory stimuli to create unstable walking conditions. [Participants and Methods] Two experiments were performed. The first experiment focused on inducing unstable walking using visual stimuli; whereas, the second experiment combined visual and auditory stimuli. To investigate the effects of stimuli on the induction of unstable walking, our results were compared with those of normal walking conditions. In addition, the two experimental conditions were compared to identify the most effective stimuli. [Results] Both experiments revealed a decrease in step length, an increase in step time and width, and an increase in the coefficient of variation of measurements, indicating an induced walking pattern with a higher risk of falls. Furthermore, combining visual and auditory stimuli caused deterioration of inter-limb coordination, as observed through an increased phase coordination index, thus resulting in further instability during walking. [Conclusion] Visual and auditory stimuli induced unstable walking. In particular, the combination of visual and auditory stimuli with a 0.8-s rhythm increased instability.

Investigation of factors influencing low physical activity levels in community-dwelling older adults with chronic pain: a cross-sectional study.

Low levels of physical activity in individuals with chronic pain can lead to additional functional impairment and disability. This study aims to investigate the predictors of low physical activity levels in individuals with chronic pain, and to determine the accuracy of the artificial neural network used to analyze these predictors. Community-dwelling older adults with chronic pain (n = 103) were surveyed for their physical activity levels and classified into low, moderate, or high physical activity level groups. Chronic pain-related measurements, physical function assessment, and clinical history, which all influence physical activity, were also taken at the same time. Logistic regression analysis and analysis of multilayer perceptron, an artificial neural network algorithm, were performed. Both analyses revealed that history of falls was a predictor of low levels of physical activity in community-dwelling older adults. Multilayer perceptron analysis was shown to have excellent accuracy. Our results emphasize the importance of fall prevention in improving the physical activity levels of community-dwelling older adults with chronic pain. Future cross-sectional studies should compare multiple analysis methods to show results with improved accuracy.

Development of Hallux Valgus Classification Using Digital Foot Images with Machine Learning.

Hallux valgus, a frequently seen foot deformity, requires early detection to prevent it from becoming more severe. It is a medical economic problem, so a means of quickly distinguishing it would be helpful. We designed and investigated the accuracy of an early version of a tool for screening hallux valgus using machine learning. The tool would ascertain whether patients had hallux valgus by analyzing pictures of their feet. In this study, 507 images of feet were used for machine learning. Image preprocessing was conducted using the comparatively simple pattern A (rescaling, angle adjustment, and trimming) and slightly more complicated pattern B (same, plus vertical flip, binary formatting, and edge emphasis). This study used the VGG16 convolutional neural network. Pattern B machine learning was more accurate than pattern A. In our early model, Pattern A achieved 0.62 for accuracy, 0.56 for precision, 0.94 for recall, and 0.71 for F1 score. As for Pattern B, the scores were 0.79, 0.77, 0.96, and 0.86, respectively. Machine learning was sufficiently accurate to distinguish foot images between feet with hallux valgus and normal feet. With further refinement, this tool could be used for the easy screening of hallux valgus.

Improving Fall Detection Devices for Older Adults Using Quality Function Deployment (QFD) Approach.

Engineering invention must be in tandem with public demands. Often it is difficult to identify the priorities of consumers where technological advancement is needed. In line with the global challenge of increasing fall prevalence among older adults, providing prevention solutions is the key. This study aims at developing an improved fall detection device using an approach called Quality Function Deployment (QFD). The goal is to investigate features to incorporate in existing device from consumer's perspectives. A three-phases design process is constructed; (1) Questionnaire, (2) Ishikawa Method, and (3) QFD. The proposed method begins with identifying customer needs as the requirement analysis, followed by a method to convert them to design specifications to be added in a fall detection device using QFD tool. As the top feature is monitoring balance, the new improved fall detection devices incorporating balance features will help older adults to monitor their level of risk of falling.

A survey of physical and occupational therapists' views on lumbar loading movements.

[Purpose] To identify the lumbar loading movements necessary in clinical practice. [Participants and Methods] A questionnaire survey was conducted among physical and occupational therapists in Japan. There were no exclusion criteria regarding the number of years of experience, age, or field of employment. The participants were randomly selected and administered the questionnaire. They were asked to list and rank the lumbar loadings they considered necessary. [Results] A total of 739 respondents participated in the survey. The results of this nationwide survey indicated that the lifting movement of heavy objects in the trunk flexion position was the most common movement (for 354 participants). [Conclusion] The main loading movements of the lumbar spine were reported to be heavy lifting movements (in the trunk flexion position) and trunk rotation movements. As perspectives, we aim to conduct an analytical study of some of lumbar spine loading movements outlined in this study, using a musculoskeletal simulator and electromyography.

Identification of the cause of fall during the pre-impact fall period.

[Purpose] This study aimed to develop and validate a method for identifying factors that may cause a fall during the pre-impact fall period using wearable sensors. [Participants and Methods] The participants were 23 young people from the public data set (mean age, 23.4 years). Acceleration and angular velocity information obtained from sensors attached to the participant's waist was used to generate the pre-impact fall. The cause of the fall (slip, trip, fainting, get up, sit down) was then classified with and without the addition of activity of daily living data using three different support vector machine. In addition, we investigated the influence of lead time (0-2.0s) on accuracy. [Results] The quadratic and cubic support vector machine identified the activity of daily living and fall patterns more accurately than the linear support vector machine, and the cubic support vector machine was better for classification, although the difference was slight. The greatest accuracy for predicting the cause of the fall (87.9%) was obtained when the cubic support vector machine was used, activity of daily living was factored into the analysis, and the lead time was 0.25 sec. [Conclusion] Support vector machine can identify the cause of the fall during the pre-impact fall period. Appropriate individualized interventions may be designed based on the most likely cause of fall as identified by this analysis method.

Effect of Knee Orthosis Pressure Variation on Muscle Activities during Sit-to-Stand Motion in Patients with Knee Osteoarthritis.

It is yet not known whether the variation in knee orthotics pressure would lead to changes in muscle activity during-sit-to-stand postural transition in patients with knee osteoarthritis (OA). Participants in this analytical study were patients with knee OA. The research design was a cross-sectional study. They were enrolled in the study through a sample of convenience method. The primary outcome measure was surface electromyography for measuring muscle activity while changing knee orthotics pressure during sit-to-stand motion. Data were summarized with mean and standard deviation while Friedman's test was performed for multiple comparison of variables, at a significance level of p = 0.05. Seven elderly patients with knee osteoarthritis (mean age 71.4 ± 11.8 years) participated in the study. Moderate orthotics (7.3 mmHg) led to a significant increase in the percentage maximum voluntary contraction (MVC) of tibialis anterior compared to that obtained without orthotics. Rectus femoris, vastus medialis, vastus lateralis, and biceps femoris tended to increase the % MVC with an increase in wearing pressure. It was therefore concluded that the muscle activity during sit-to-stand motion could be increased in patients with knee osteoarthritis by wearing flexible orthotics with varying pressure.

Foot Position Measurement during Assistive Motion for Sit-to-Stand Using a Single Inertial Sensor and Shoe-Type Force Sensors.

Assistive motion for sit-to-stand causes lower back pain (LBP) among caregivers. Considering previous studies that showed that foot position adjustment could reduce lumbar load during assistive motion for sit-to-stand, quantitative monitoring of and instructions on foot position could contribute toward reducing LBP among caregivers. The present study proposes and evaluates a new method for the quantitative measurement of foot position during assistive motion for sit-to-stand using a few wearable sensors that are not limited to the measurement area. The proposed method measures quantitative foot position (anteroposterior and mediolateral distance between both feet) through a machine learning technique using features obtained from only a single inertial sensor on the trunk and shoe-type force sensors. During the experiment, the accuracy of the proposed method was investigated by comparing the obtained values with those from an optical motion capture system. The results showed that the proposed method produced only minor errors (less than 6.5% of body height) when measuring foot position during assistive motion for sit-to-stand. Furthermore, Bland-Altman plots suggested no fixed errors between the proposed method and the optical motion capture system. These results suggest that the proposed method could be utilized for measuring foot position during assistive motion for sit-to-stand.

Knee joint angle sensing in healthy young adults using flexible orthosis with different wearing pressure.

[Purpose] To investigate the effects of a flexible brace, by analyzing whether its usage; the difference in wearing pressure could change the joint position sensation in healthy participants; and develop a flexible knee brace for patients with knee osteoarthritis. [Participants and Methods] The study included eight healthy males with 14 knee joints (mean age, 22.0 ± 3.1 years). To measure joint position sense, an "angle reproduction test" was performed in three experimental conditions: 1) participants not wearing the brace, 2) the brace was secured with an appropriate force, and 3) the brace was fully secured using hook-and-loop fasteners. [Results] No significant difference was observed among groups comprising of those not wearing, those wearing with the standard force, and those wearing with the tight force. When the maximum hook-and-loop fastener was squeezed, the sensory error in joint position was maximized at both 30° and 60° flexion. [Conclusion] Joint position sense improvement was confirmed to be poor by orthosis, and an error occurred in the joint position sense by increasing the wearing pressure in orthosis. In future, measurements should be performed on patients with knee osteoarthritis who have decreased joint position sense and verify the effect of different wearing pressures verified.

The Association of Falls with Instability: An Analysis of Perceptions and Expectations toward the Use of Fall Detection Devices Among Older Adults in Malaysia.

Background: Falls are a significant incident among older adults affecting one in every three individuals aged 65 and over. Fall risk increases with age and other factors, namely instability. Recent studies on the use of fall detection devices in the Malaysian community are scarce, despite the necessity to use them. Therefore, this study aimed to investigate the association between the prevalence of falls with instability. This study also presents a survey that explores older adults' perceptions and expectations toward fall detection devices. Methods: A cross-sectional survey was conducted involving 336 community-dwelling older adults aged 50 years and older; based on randomly selected participants. Data were analyzed using quantitative descriptive analysis. Chi-square test was conducted to investigate the associations between self-reported falls with instability, demographic and walking characteristics. Additionally, older adults' perceptions and expectations concerning the use of fall detection devices in their daily lives were explored. Results: The prevalence of falls was 28.9%, where one-quarter of older adults fell at least once in the past 6 months. Participants aged 70 years and older have a higher fall percentage than other groups. The prevalence of falls was significantly associated with instability, age, and walking characteristics. Around 70% of the participants reported having instability issues, of which over half of them fell at least once within 6 months. Almost 65% of the participants have a definite interest in using a fall detection device. Survey results revealed that the most expected features for a fall detection device include: user-friendly, followed by affordably priced, and accurate. Conclusions: The prevalence of falls in community-dwelling older adults is significantly associated with instability. Positive perceptions and informative expectations will be used to develop an enhanced fall detection incorporating balance monitoring system. Our findings demonstrate the need to extend the fall detection device features aiming for fall prevention intervention.

Spinal postural alignment measurements using markerless digital photography.

BACKGROUND: A device that can measure posture alignment repeatedly is important for the prevention of hyperkyphosis. OBJECTIVE: We devised a markerless measurement method for hyperkyphosis using digital photography and investigated the correlation with other noninvasive measurements and the validity and accuracy of this method. METHODS: The study included 27 participants. The craniovertebral angle in supine (CVAS) and craniohorizontal angle in supine (CHAS) were calculated from digital photographs of the head and neck areas of the studied subjects with ImageJ. The correlations of CVAS and CHAS with the kyphosis index (KI) and block method (BM) were investigated. Intrarater correlation coefficient and Bland-Altman analyses were used to verify the reliability and accuracy of the measured results. RESULTS: CHAS exhibited an excellent correlation with the KI and the BM. The intra- and interrater reliabilities of CHAS were almost perfect. Bland-Altman analysis revealed that CHAS was associated with minor addition errors. CONCLUSION: CHAS founded an excellent correlation and reliability with the conventional spinal postural alignment measurements. The addition error suggested that the manual was needed to confirm the landmark. The CHAS is a method used to measure the spinal postural alignment in a supine position without markers and without exposing the skin surface.

Optimal foot-position of caregiver based on muscle activity of lower back and lower limb while providing sit-to-stand support.

[Purpose] In caregivers, low load posture is necessary to prevent lower back pain during patient handling activities such as sit-to-stand support. This study focused on the foot-position of caregivers as an adjustable and useful parameter. A wide stance decreases the stress on the lumbar vertebra. However, this foot-position increases loading of the spinae erector muscles. The aim of this study was to investigate the relationship of anterior-posterior and lateral-medial distances between feet and activity of the spinae erector muscles to determine the optimal foot-position for reducing stress on the lumbar vertebra without increasing spinae erector muscle load. [Participants and Methods] Five young male participants were asked to provide sit-to-stand support 10 times using nine normalized foot-positions with different anterior-posterior and lateral-medial distances. Surface electromyograms of the erector spinae and lower limb muscles were measured during sit-to-stand support. [Results] The results showed that the optimal foot-position (anterior-posterior 55%, lateral-medial 20% of body height) increased muscle activity within the lower limb muscles compared with the lower back muscles and did not increase loads on the erector spinae muscle. [Conclusion] Optimizing foot-position can reduce stress on the lumbar vertebra without increasing load on the spinae erector muscles.

Usefulness of a simulated experience method for transfer assistance for hemiplegia or limited range of motion in multiple joints.

[Purpose] To further the understanding of dysfunctions to which a simulated experience method could be applied, we clarified whether a simulated experience method can promote caregivers to utilize the abilities of care recipients with pseudo-hemiplegia or pseudo-limited range of motion (ROM) in multiple joints. [Participants and Methods] We studied transfer assistance in 60 nursing assistants from nursing home settings: 30 were assigned to the pseudo-hemiplegia (26 females, 4 males) and limited ROM in multiple joints (27 females, 3 males) groups. One healthy person was fitted with orthotic braces to mimic hemiplegia or limited ROM in multiple joints, each making it difficult to stand-up. Participants were randomized to either a simulated experience group (involving interventional help from a physical therapist between the first and second measurements) or a control group. The load difference on the lower limbs of the care recipient between two rounds of transfer assistance was examined. [Results] The difference between the second and first measurements was -5.9 ± 74.5 N for the control group and 107.9 ± 123.6 N for the simulated experience method in the pseudo-hemiplegia study, and -14.7 ± 64.7 N and 149.1 ± 132.4 N, respectively, for the pseudo-limited ROM-in-multiple-joints study. [Conclusion] The simulated experience method promoted transfer assistance of a care recipient with pseudo-hemiplegia or pseudo-limited ROM in multiple joints. These results suggest that hemiplegia and limited ROM in multiple joints are added as dysfunctions that can be applied to a simulated experience method in transfer assistance.

Inertial Sensor-Based Instrumented Cane for Real-Time Walking Cane Kinematics Estimation.

Falls are among the main causes of injuries in elderly individuals. Balance and mobility impairment are major indicators of fall risk in this group. The objective of this research was to develop a fall risk feedback system that operates in real time using an inertial sensor-based instrumented cane. Based on inertial sensor data, the proposed system estimates the kinematics (contact phase and orientation) of the cane. First, the contact phase of the cane was estimated by a convolutional neural network. Next, various algorithms for the cane orientation estimation were compared and validated using an optical motion capture system. The proposed cane contact phase prediction model achieved higher accuracy than the previous models. In the cane orientation estimation, the Madgwick filter yielded the best results overall. Finally, the proposed system was able to estimate both the contact phase and orientation in real time in a single-board computer.

3D Printed Robot Hand Structure Using Four-Bar Linkage Mechanism for Prosthetic Application.

Trans-radial prosthesis is a wearable device that intends to help amputees under the elbow to replace the function of the missing anatomical segment that resembles an actual human hand. However, there are some challenging aspects faced mainly on the robot hand structural design itself. Improvements are needed as this is closely related to structure efficiency. This paper proposes a robot hand structure with improved features (four-bar linkage mechanism) to overcome the deficiency of using the cable-driven actuated mechanism that leads to less structure durability and inaccurate motion range. Our proposed robot hand structure also took into account the existing design problems such as bulky structure, unindividual actuated finger, incomplete fingers and a lack of finger joints compared to the actual finger in its design. This paper presents the improvements achieved by applying the proposed design such as the use of a four-bar linkage mechanism instead of using the cable-driven mechanism, the size of an average human hand, five-fingers with completed joints where each finger is moved by motor individually, joint protection using a mechanical stopper, detachable finger structure from the palm frame, a structure that has sufficient durability for everyday use and an easy to fabricate structure using 3D printing technology. The four-bar linkage mechanism is the use of the solid linkage that connects the actuator with the structure to allow the structure to move. The durability was investigated using static analysis simulation. The structural details and simulation results were validated through motion capture analysis and load test. The motion analyses towards the 3D printed robot structure show 70-98% similar motion range capability to the designed structure in the CAD software, and it can withstand up to 1.6 kg load in the simulation and the real test. The improved robot hand structure with optimum durability for prosthetic uses was successfully developed.

Effects of the Characteristics and Duration of Chronic Pain on Psychosomatic Function in the Community-Dwelling Elderly Population.

Catastrophic thinking is related to pain intensity and the degree of disability and influences pain care significantly. However, only few studies have investigated the impact of catastrophic thinking on chronic pain (CP) in the community-dwelling elderly population. This study aimed to evaluate the characteristics of CP in the community-dwelling elderly population and to investigate the effects of different periods of CP on cognitive and psychological functions. A total of 187 community-dwelling elderly people met the inclusion criteria and were included in this cross-sectional study. The survey items included demographic data (age and gender), pain-related questionnaires, psychological and cognitive functions, and sleep status. The duration of CP was investigated using three categories: no pain and pain for ≤1 year and ≥1 year. A logistic regression analysis was performed to identify the factors most strongly associated with the presence of CP. The difference in each assessment was compared according to duration of CP among the three groups and analyzed using the chi-square test, Kruskal-Wallis test, and one-way analysis of variance. The PCS scores and depression scores were significantly higher in long duration of CP compared with no pain and pain for ≤1 year. The present study is consistent with the fear-avoidance model and was concluded that community-dwelling elderly people with CP are depressive and tend to magnify their pain with long duration of CP.

Reliability of laser-assisted hindfoot alignment evaluation.

[Purpose] A goniometer is frequently used for static measurement of hindfoot alignment. However, although goniometer measurements require experience, their reliability and validity remain controversial. We developed a hindfoot alignment measurement method by laser as an alternative measure. The purpose of this study was to examine the reliability of laser-assisted hindfoot alignment evaluation. [Participants and Methods] Two non-expert examiners (without medical knowledge), briefly trained in the use of laser-assisted hindfoot alignment evaluation, evaluated hindfoot alignment in 12 healthy participants. [Results] The ICC of the intra-rater reliability was 0.74 for both examiners and the ICC for inter-rater reliability was 0.43. [Conclusion] The good intra-rater and moderate inter-rater reliability of laser-assisted hindfoot alignment evaluation, when used by non-professionals, suggest the laser-assisted hindfoot alignment evaluation may be appropriate for use in clinical practice settings.

Validation of a Body-Conducted Sound Sensor for Respiratory Sound Monitoring and a Comparison with Several Sensors.

The ideal respiratory sound sensor exhibits high sensitivity, wide-band frequency characteristics, and excellent anti-noise properties. We investigated the body-conducted sound sensor (BCS) and verified its usefulness in respiratory sound monitoring through comparison with an air-coupled microphone (ACM) and acceleration sensor (B & K: 8001). We conducted four experiments for comparison: 1) estimation by equivalent circuit model of sensors and measurement by a sensitivity evaluation system; 2) measurement of tissue-borne sensitivity-to-air-noise sensitivity ratio (SRTA); 3) respiratory sound measurement through a simulator; and 4) actual respiratory sound measurement using human subjects. For 1), the simulation and measured values of all the sensors showed good agreement; BCS demonstrated sensitivity ~10 dB higher than ACM and higher sensitivity in the high-frequency segments compared with 8001. In 2), BCS showed high SRTA in the 600-1000 and 1200-2000-Hz frequency segments. In 3), BCS detected wheezes in the high-frequency segments of the respiratory sound. Finally, in 4), the sensors showed similar characteristics and features in the high-frequency segments as the simulators, where typical breathing sound detection was possible. BCS displayed a higher sensitivity and anti-noise property in high-frequency segments compared with the other sensors and is a useful respiratory sound sensor.

Relationship between surface electromyography of the spinae erector muscles and subjectively adjusted step length in the supporting standing-up motion.

[Purpose] Caregivers experience low back pain owing to frequent patient handling motions such as supporting the body while standing up. To prevent low back pain in caregivers, low load posture while engaging in patient handling motions is required. We determined the relationship between surface electromyography of the erector spinae muscles and subjective step length as "long" and "short" during the supporting standing-up motions of caregivers. [Participants and Methods] Ten young male participants were asked to perform supporting standing-up motion 10 times using two-step lengths comprised of subjective long and short steps. During supporting standing-up motion, we measured surface electromyograms of the erector spinae muscles and calculated the integral electromyographic values. [Results] The subjective long/short-step length normalized by body height did not differ across the participants. In addition, the subjective long-step length was longer than the subjective short-step length in all the participants. Integral electromyographic values for both the left and right erector spinae muscles in the short-step length were significantly lower than those in the long-step length when the data obtained from all the participants were used. [Conclusion] We considered that the load of the erector spinae muscle will be reduced if the short-step instead of the long-step instruction is given. In the future, instructions based on the subjective step-length variation in caregivers must be considered.