One-year retention of gait speed improvement in stroke survivors after treatment with a wearable home-use gait device.

Background: Gait impairments after stroke are associated with numerous physical and psychological consequences. Treatment with the iStride® gait device has been shown to facilitate improvements to gait function, including gait speed, for chronic stroke survivors with hemiparesis. This study examines the long-term gait speed changes up to 12 months after treatment with the gait device. Methods: Eighteen individuals at least one-year post-stroke completed a target of 12, 30-minute treatment sessions with the gait device in their home environment. Gait speed was measured at baseline and five follow-up sessions after the treatment period: one week, one month, three months, six months, and 12 months. Gait speed changes were analyzed using repeated-measures ANOVA from baseline to each follow-up time frame. Additional analysis included comparison to the minimal clinically important difference (MCID), evaluation of gait speed classification changes, and review of subjective questionnaires. Results: Participants retained an average gait speed improvement >0.21 m/s compared to baseline at all post-treatment time frames. Additionally, 94% of participants improved their gait speed beyond the MCID during one or more post-treatment measurements, and 88% subjectively reported a gait speed improvement. Conclusion: Treatment with the gait device may result in meaningful, long-term gait speed improvement for chronic stroke survivors with hemiparetic gait impairments. Clinical trial registration: https://clinicaltrials.gov/ct2/show/NCT03649217, identifier NCT03649217.

Gait Device Treatment Using Telehealth for Individuals With Stroke During the COVID-19 Pandemic: Nonrandomized Pilot Feasibility Study.

BACKGROUND: During the COVID-19 pandemic, rehabilitation providers and consumers adopted telehealth practices at unprecedented rates. Multiple prepandemic studies demonstrate the feasibility and comparable efficacy between in-clinic and remote treatment for certain impairments caused by stroke, such as upper extremity weakness and impaired motor function. However, less guidance has been available regarding gait assessment and treatment. Despite this limitation, safe and effective gait treatment is fundamental to optimizing health and well-being after stroke and should be considered a treatment priority, including during the COVID-19 pandemic. OBJECTIVE: This study explores the feasibility of using telehealth to deliver gait treatment using a wearable gait device, the iStride device, to stroke survivors during the 2020 pandemic. The gait device is used to treat hemiparetic gait impairments caused by stroke. The device alters the user's gait mechanics and creates a subtle destabilization of the nonparetic limb; therefore, supervision is required during its usage. Before the pandemic, treatment with the gait device had been provided in person to appropriate candidates using a combination of physical therapists and trained personnel. However, upon the emergence of the COVID-19 pandemic, in-person treatment was halted in adherence to pandemic guidelines. This study investigates the feasibility of 2 remote delivery treatment models with the gait device for stroke survivors. METHODS: Participants were recruited during the first half of 2020 after the onset of the pandemic and included 5 individuals with chronic stroke (mean age 72 years; 84 months post stroke). Four participants were previous gait device users who transitioned to the telehealth delivery model to continue their gait treatment remotely. The fifth participant performed all study-related activities, from recruitment through follow-up, remotely. The protocol included virtual training for the at-home care partner, followed by 3 months of remote treatment with the gait device. Participants were instructed to wear gait sensors during all treatment activities. To assess feasibility, we monitored the safety of the remote treatment, compliance with protocol activities, acceptability of the telehealth treatment delivery, and preliminary efficacy of the gait treatment. Functional improvement was measured using the 10-Meter Walk Test, the Timed Up and Go Test, and the 6-Minute Walk Test, and quality of life was assessed using the Stroke-Specific Quality of Life Scale. RESULTS: No serious adverse events occurred, and participants rated high acceptance of the telehealth delivery. Protocol compliance averaged 95% of treatment sessions, 100% of assessments, and 85% of sensor usage during treatment. After 3 months of treatment, the average improvement in each functional outcome exceeded the minimal clinically important difference or minimal detectable change value. CONCLUSIONS: Remote treatment delivery with the gait device appeared feasible with care partner support. Gait treatment using telehealth may be useful to offset negative immobility impacts for those requiring or preferring remote care during the pandemic or otherwise. TRIAL REGISTRATION: ClinicalTrials.gov NCT04434313; https://clinicaltrials.gov/ct2/show/NCT04434313.

Progress in vibrotactile threshold evaluation techniques: a review.

Vibrotactile threshold (VT) testing has been used for nearly a century to investigate activation of human somatosensory pathways. This use of vibrotactile stimuli provides a versatile tool for detecting peripheral neuropathies, and has been broadly used for investigation of carpal tunnel syndrome. New applications include investigation of drug-induced neuropathies and diabetes-related neuropathies. As a feedback device, the vibrotactile stimuli could be used as an information delivery system for rehabilitative feedback devices for upper limb musculoskeletal disorders or as information channels for the visually impaired. This review provides a comprehensive review of the advancement in VT measurement techniques over time and a comparison of these techniques in terms of various hardware features used and the testing protocols implemented. The advantages and limitations of these methods have been discussed along with specific recommendations for their implementation and suggestions for incorporation into clinical practice.

Can mHealth Technology Help Mitigate the Effects of the COVID-19 Pandemic?

Goal: The aim of the study herein reported was to review mobile health (mHealth) technologies and explore their use to monitor and mitigate the effects of the COVID-19 pandemic. Methods: A Task Force was assembled by recruiting individuals with expertise in electronic Patient-Reported Outcomes (ePRO), wearable sensors, and digital contact tracing technologies. Its members collected and discussed available information and summarized it in a series of reports. Results: The Task Force identified technologies that could be deployed in response to the COVID-19 pandemic and would likely be suitable for future pandemics. Criteria for their evaluation were agreed upon and applied to these systems. Conclusions: mHealth technologies are viable options to monitor COVID-19 patients and be used to predict symptom escalation for earlier intervention. These technologies could also be utilized to monitor individuals who are presumed non-infected and enable prediction of exposure to SARS-CoV-2, thus facilitating the prioritization of diagnostic testing.

Center of pressure in a walking boot shifts posteriorly in patients following lower leg fracture.

BACKGROUND: Studies have shown that the ambulatory behavior and amount of weight bearing performed by lower leg fracture patients, increases over time. It is likely that gait features, such as center of pressure (CoP), also change over time. RESEARCH QUESTION: The purpose of this study was to characterize changes in CoP exhibited by lower leg fracture patients wearing a walking boot during the recovery period. METHODS: Approximately 2 weeks post-surgery, seven lower leg fracture patients were fitted with a MaxTrax walking boot which was integrated with the Ambulatory Tibia Load Analysis System, an underfoot load monitoring system. Patients wore the walking boot for 2-12 weeks resulting in continuous load data during the recovery period. Ambulation was filtered from the raw data and daily average CoP values were calculated by averaging the CoP vectors from all steps in a given day. RESULT: In general, the CoP vector varied in both the x and y directions during the initial stages of recovery but was more uniform during the later stages of healing. In 6/7 patients, the CoP in the y direction was closer to the forefoot during the initial stages of healing but shifted posteriorly as time post-surgery increased. The single patient that did not exhibit a posterior shift in CoP was also the only patient to develop a non-union. CoP in the x direction show a less clear trend. CoP in the x direction exhibited a medial shift in 5 patients and a lateral shift in 2 patients. SIGNIFICANCE: During lower leg fracture recovery in a walking boot, the CoP in the y direction shifts posteriorly as time post-surgery increases and CoP monitoring may become a useful tool to monitor individual patient healing progression.

Evaluating How Post-Bronchodilator Vital Capacities Affect the Diagnosis of Obstruction in Pulmonary Function Tests.

BACKGROUND: Although the ratio of FEV1 to the vital capacity (VC) is universally accepted as the cornerstone of pulmonary function test (PFT) interpretation, FVC remains in common use. We sought to determine what the differences in PFT interpretation were when the largest measured vital capacity (VCmax) was used instead of the FVC. METHODS: We included 12,238 consecutive PFTs obtained for routine clinical care. We interpreted all PFTs first using FVC in the interpretation algorithm and then again using the VCmax, obtained either before or after administration of inhaled bronchodilator. RESULTS: Six percent of PFTs had an interpretive change when VCmax was used instead of FVC. The most common changes were: new diagnosis of obstruction and exclusion of restriction (previously suggested by low FVC without total lung capacity measured by body plethysmography). A nonspecific pattern occurred in 3% of all PFT interpretations with FVC. One fifth of these 3% produced a new diagnosis of obstruction with VCmax. The largest factors predicting a change in PFT interpretation with VCmax were a positive bronchodilator response and the administration of a bronchodilator. Larger FVCs decreased the odds of PFT interpretation change. Surprisingly, the increased numbers of PFT tests did not increase odds of PFT interpretation change. CONCLUSIONS: Six percent of PFTs have a different interpretation when VCmax is used instead of FVC. Evaluating borderline or ambiguous PFTs using the VCmax may be informative in diagnosing obstruction and excluding restriction.

Durability evaluation of biopolymer coating on titanium alloy substrate.

For this study, a commercially available phosphorylcholine (PC) polymer was applied to Ti6Al4V ELI. A multivariate approach to design a statistically significant array of experiments was employed to evaluate and estimate optimization of PC-immobilization process factors. The seven process factors analyzed were (1) power level for RFGD plasma treatment, (2) duration of plasma treatment, (3) concentration of PC solution used to coat samples, (4) rate at which samples were dipped in/out of the solution, (5) temperature for curing, (6) relative humidity level during curing, and (7) duration of curing. Imaging and analysis of the coating were done via fluorescence microscopy (FM), confirming the uniform coverage of PC polymer on titanium substrate. The process factors were evaluated by three measured responses: initial thickness, coating durability and degree of cross-linked coating, which were assessed by FM, a spray test and extraction in IPA, respectively. Variations in PC solution concentration showed no impact on fouling resistance of the resultant coating. It was hypothesized that the PC-application process factors could be optimized to yield favorable outcomes in durability and degree of cross-linked coating responses. The resulting statistical model indicates that PC solution concentration, dip rate, and cure temperature are the three greatest singular effects on both durability and degree of cross-linking. In addition, plasma treatment of the substrate with O2 was effective in enhancing the degree of cross-linking of the polymer surface.

Using a pilot study to establish experimental methods for inexpensive instrumented insoles used in dynamic skiing analysis.

Loss of balance leads to increased likelihood of falling for human locomotion. Determining the likelihood of falling for skiing locomotion is challenging because, unlike walking, normal locomotion is not clearly defined. One of the first learned styles of skiing is wedge style (WS). WS affords relatively easier balancing and speed control due to a wide base of support and greater resistance to forward movement, respectively. As skiers become more familiar with WS, their sensory, cognition, and actuation improve and they are able to apply more advanced styles, namely parallel style (PS), which requires refined balance. This paper studies the effects of WS and PS, on a single subject pilot study, and how they effect the likelihood of falling. A traditional laboratory setting was not suitable because of extreme difficulty and expense required to mimic the environment. Specially designed instrumented insoles were used to capture force data in a mountain environment.

Forward kinematics using IMU on-body sensor network for mobile analysis of human kinematics.

The feasibility of large network inertial measurement units (IMUs) are evaluated for purposes requiring feedback. A series of wireless IMUs were attached to a human lower-limb laboratory model outfitted with joint angle encoders. The goal was to discover if large networks of wireless IMUs can give realtime joint orientation data while still maintaining an acceptable degree of accuracy.

Kinetic Gait Analysis Using a Low-Cost Insole.

Abnormal gait caused by stroke or other pathological reasons can greatly impact the life of an individual. Being able to measure and analyze that gait is often critical for rehabilitation. Motion analysis labs and many current methods of gait analysis are expensive and inaccessible to most individuals. The low-cost, wearable, and wireless insole-based gait analysis system in this study provides kinetic measurements of gait by using low-cost force sensitive resistors. This paper describes the design and fabrication of the insole and its evaluation in six control subjects and four hemiplegic stroke subjects. Subject-specific linear regression models were used to determine ground reaction force plus moments corresponding to ankle dorsiflexion/plantarflexion, knee flexion/extension, and knee abduction/adduction. Comparison with data simultaneously collected from a clinical motion analysis laboratory demonstrated that the insole results for ground reaction force and ankle moment were highly correlated (all >0.95) for all subjects, while the two knee moments were less strongly correlated (generally >0.80). This provides a means of cost-effective and efficient healthcare delivery of mobile gait analysis that can be used anywhere from large clinics to an individual's home.

Potential to fall of bipeds using foot kinematics.

This research compares normal to unexpected slipping gaits of healthy adults to detect potential to fall. Using various x, y, and z position analyses, including a Root Mean Squared Error (RMSE), significant differences are shown between normal and unexpected slipping gaits. Our results show that after heel strike of the slipping foot, the recovery foot rapidly changes position to restore balance and lower falling potential. We found RMSE of the recovery foot is significantly greater than the slipping foot, and that potential to fall is easily quantifiable through comparing normal to unexpected gaits. This research provides a solid foundations for a generalized understanding of fall potential for various gaits.

A feasibility study of an upper limb rehabilitation system using Kinect and computer games.

A new low-cost system for rehabilitation of the impaired upper limb for stroke survivors is presented. A computer game was developed specifically for this purpose and the user's impaired upper extremity is tracked using a downward-pointed Kinect, an inexpensive motion capture system commercially available from Microsoft. A Kalman filter was implemented to reduce data jittering. Patients are required to move their impaired arm, sliding it on top of a transparent support, in order to play the game. The game is personalized to the patient through specific settings that adapt to the patient's range of motion and motor control at the start of the game as well as performance during the game. The final score is proportional to the arm's movement speed. A feasibility study was carried out with one stroke survivor. The game was played for ten days and usability surveys were answered before and after the study. The patient was engaged with the game, found it easy to understand and reported willingness to use it in the home environment and enjoyment of the use in the clinic.

Flow characteristics of continuous-flow left ventricular assist devices in a novel open-loop system.

Fluid-pumping technology is a mature engineering subject area with a well-documented knowledge base. However, the pump design optimization techniques accepted in industry are geared toward steady-state constant-flow conditions. In contrast, the implantation of a continuous-flow pump to aid the output of the human left ventricle subjects the device to perpetual variation. This study measures pressure-flow performance characteristics for both axial- and centrifugal continuous-flow rotary blood pumps across a wide range of pressure differential values under uniform conditions by means of a novel open-loop flow system. The axial-flow devices show lower hydraulic efficiency. All pumps yield best efficiency point at a head to flow coefficient ratio of approximately 1.7. The open-loop flow system accounts for the dynamic changes associated with human heart physiology and allows for more precise characterization of existing heart pumps and those in development.

A laboratory insole for analysis of sensor placement to determine ground reaction force and ankle moment in patients with stroke.

An insole system was constructed with 32 sensors inside a size 10 men's shoe. This system allows evaluation of the contributions of individual sensors spread throughout the surface area of the insole. The kinetic variables of interest in this initial study are ground reaction force and anterior-posterior ankle moment. Use of all 32 sensors are able to replicate the shape of the ground reaction force and ankle moment in a stroke patient who has regained a more normal gait, but less so in a stroke patient with impaired gait. Subsets of sensors can now be evaluated in order to ultimately identify an optimum set of sensors for determining kinetic variables necessary to classify presence or absence of a particular gait abnormality or other pathology.

The effect of partial weight bearing in a walking boot on plantar pressure distribution and center of pressure.

Physicians routinely prescribe partial weight bearing in a walking boot following fractures of the lower limbs in order to produce the needed mechanical environment to facilitate healing. Plantar pressure measurements can provide key information regarding the mechanical environment experienced by lower limb bones. The effect of walking boots on plantar pressure distribution has been well reported, however, the combined effects of partial weight bearing and walking boots on plantar pressure distribution and center of pressure is unknown. Thirteen healthy volunteers with no known gait pathologies were fitted with a multi-pressure sensor insole that recorded their plantar pressure distribution during four walking trials: (i) normal walking, (ii) full weight bearing in a walking boot, (iii) 27 kg partial weight bearing in a walking boot and (iv) 9 kg partial weight bearing in a walking boot. Results demonstrated that changing from trial (i) to (iv) resulted in a posterior shift in weight distribution; the percentage of total weight experienced at the heel increased while the percentage of total weight experienced at the forefoot (both medial and lateral) and the hallux decreased. Center of pressure trajectories also shifted more posteriorly. Additionally, while in a walking boot the gait during full and partial weight bearing resulted in more even foot loading.

Instrumented insole vs. force plate: a comparison of center of plantar pressure.

Instrumented insoles allow analysis of gait outside of the confines of a motion analysis lab and capture motion data on every step. This study assesses the concurrent validity of center of plantar pressure (COPP) measurements during walking, and shows that our custom instrumented insoles compare favorably to an Advanced Mechanical Technology Inc. (AMTI) force plate in a clinical motion laboratory, particularly when the large difference in price is considered (an insole is nearly two orders of magnitude less expensive than a force plate). Deploying inexpensive insoles such as ours for ubiquitous health monitoring allows measurement of gait in more typical environments. This affords the opportunity to evaluate the gait of older adults in the home environment, and a future opportunity of providing real-time feedback corresponding to changes in gait.

A wireless sensory feedback system for real-time gait modification.

Current rehabilitation technology and techniques have proven effective at modifying and correcting gait abnormalities. They are however limited to laboratory and clinical settings, under the supervision of a specialist. Conventional techniques for quantifying gait asymmetries can be combined with sensory feedback methods to provide an intuitive and inexpensive feedback system for extra-clinical rehabilitation. A wireless feedback system has been designed to collect gait information, process it in real-time, and provide corrective feedback to the user. The corrective feedback can be presented through visual, audible, or vibrotactile methods, or a combination thereof. Initial results have led to improvement in the sensory interface of the device to maximize the corrective influence on inexperienced subjects. These preliminary findings suggest that the wireless feedback device can influence the gait of the user, and effectively adapt to their personal feedback preferences.

Liquid cooling system for the vibro-tactile threshold device.

Vibrotactile threshold testing has been used to investigate activation of human somatosensory pathways. A portable vibrotactile threshold testing device called the Vibrotactile Threshold Evaluator for the Workplace (VTEW) was designed for screening of carpal tunnel syndrome in the workplace, and initially contained a small fan for cooling. During subject testing, the device is operated intermittently, which causes the linear actuator to warm the tactile probe. The probe causes discomfort for some subjects. During testing, the probe heated to 42 °C within 90 seconds of continuous operation. A liquid cooling system was implemented to dissipate heat from the probe. The liquid cooling system maintains a steady state temperature of 36 °C for continuous actuation of the probe. The liquid cooling system is capable of maintaining a safe operating temperature, without adding erroneous vibrations to the device. However, the cooling system deters the portability of the device. Further research will investigate how to make the liquid cooling system portable and implements vibrotactile threshold testing in the workplace to quickly evaluate whether or not a person has early symptoms of carpal tunnel syndrome.

Insole sensor system for real-time detection of biped slip.

The study of bipedal gait is important for two primary reasons: biomimetic robotics and human gait rehabilitation. Both fields have numerous models describing bipedal locomotion that require a no-slip interaction with the ground for accuracy. This paper presents a low cost wearable sensor system capable of identifying slip in real time, which could afford rehabilitative analysts important information on the nature of patient falls, and provide robot designers a feedback ability with which to implement an active traction control system. The system can functionally provide better than 90% detection rates when calibrated to an individual.

Just enough measurement: a proposed paradigm for designing medical instrumentation.

Our research group hypothesizes that one way to provide low-cost healthcare delivery efficiently is through the use of a large number of inexpensive sensors that can provide meaningful medical data. Typical development of medical instrumentation pursues increased resolution and higher accuracy - accompanied by a corresponding increase in cost; it is no secret that high costs impose a heavy burden on healthcare. We seek to invert the adage that quality is more important than quantity by extracting high quality biomedical information from a large quantity of low-cost measurements, and to demonstrate this using measurement instrumentation developed in our lab for extra-clinical assessment and rehabilitation tools. This will be discussed in terms of our initial experiments in evaluating balance and postural stability. This is an area of critical clinical importance: 2.6 million non-fatal fall injuries in persons over age 65 resulted in direct health care costs of $19 billion (in 2000) in the U.S., and the number of persons over age 65 in the U.S. is projected to more than double between 2000 and 2030.