A Review of Wearable Optical Fiber Sensors for Rehabilitation Monitoring.

As the global aging population increases, the demand for rehabilitation of elderly hand conditions has attracted increased attention in the field of wearable sensors. Owing to their distinctive anti-electromagnetic interference properties, high sensitivity, and excellent biocompatibility, optical fiber sensors exhibit substantial potential for applications in monitoring finger movements, physiological parameters, and tactile responses during rehabilitation. This review provides a brief introduction to the principles and technologies of various fiber sensors, including the Fiber Bragg Grating sensor, self-luminescent stretchable optical fiber sensor, and optic fiber Fabry-Perot sensor. In addition, specific applications are discussed within the rehabilitation field. Furthermore, challenges inherent to current optical fiber sensing technology, such as enhancing the sensitivity and flexibility of the sensors, reducing their cost, and refining system integration, are also addressed. Due to technological developments and greater efforts by researchers, it is likely that wearable optical fiber sensors will become commercially available and extensively utilized for rehabilitation.

National Institutes of Health Research Plan on Rehabilitation: Analysis and Progress.

OBJECTIVE: To summarize the progress toward the National Institutes of Health (NIH) Research Plan on Rehabilitation goals and the methods by which tracking occurred. DESIGN: Each grant award was manually coded by NIH staff for research plan goals, type of science categories (eg, basic, applied, infrastructure, etc), and if applicable, training, and then validated by NIH institute and center (IC) experts. Data for years 2015 through 2017 were used to develop a coding algorithm to automatically code grants in 2018 for validation by NIH IC experts. Additional data for all years (2015-2018) were also analyzed to track changes and progress. SETTING: The research utilized administrative data from NIH Reporter and internal NIH databases. PARTICIPANTS: The data sample included research grants and programs funded from fiscal years 2015 through 2018. The year 2015 was considered a baseline year as the research plan was published in 2016. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The primary outcome measures were substantial growth in NIH funding and numbers of awards for rehabilitation research, across most research plan goals and types of science, as well as validation of an automatic algorithm for coding grants. RESULTS: Number of grants, funding dollars, funding mechanisms, patent data, scientific influence and translational science, research plan goals, and type of science categories were tracked across years (2015-2018). Algorithm validation is presented for 2018 data. CONCLUSIONS: NIH advanced the goals stated in the Research Plan on Rehabilitation, but gap areas remain. Though funding in this portfolio is growing, continued focus and participation by the field is needed to advance rehabilitation science.

Transfer of motor skill between virtual reality viewed using a head-mounted display and conventional screen environments.

BACKGROUND: Virtual reality viewed using a head-mounted display (HMD-VR) has the potential to be a useful tool for motor learning and rehabilitation. However, when developing tools for these purposes, it is important to design applications that will effectively transfer to the real world. Therefore, it is essential to understand whether motor skills transfer between HMD-VR and conventional screen-based environments and what factors predict transfer. METHODS: We randomized 70 healthy participants into two groups. Both groups trained on a well-established measure of motor skill acquisition, the Sequential Visual Isometric Pinch Task (SVIPT), either in HMD-VR or in a conventional environment (i.e., computer screen). We then tested whether the motor skills transferred from HMD-VR to the computer screen, and vice versa. After the completion of the experiment, participants responded to questions relating to their presence in their respective training environment, age, gender, video game use, and previous HMD-VR experience. Using multivariate and univariate linear regression, we then examined whether any personal factors from the questionnaires predicted individual differences in motor skill transfer between environments. RESULTS: Our results suggest that motor skill acquisition of this task occurs at the same rate in both HMD-VR and conventional screen environments. However, the motor skills acquired in HMD-VR did not transfer to the screen environment. While this decrease in motor skill performance when moving to the screen environment was not significantly predicted by self-reported factors, there were trends for correlations with presence and previous HMD-VR experience. Conversely, motor skills acquired in a conventional screen environment not only transferred but improved in HMD-VR, and this increase in motor skill performance could be predicted by self-reported factors of presence, gender, age and video game use. CONCLUSIONS: These findings suggest that personal factors may predict who is likely to have better transfer of motor skill to and from HMD-VR. Future work should examine whether these and other predictors (i.e., additional personal factors such as immersive tendencies and task-specific factors such as fidelity or feedback) also apply to motor skill transfer from HMD-VR to more dynamic physical environments.

Fall inducing movable platform (FIMP) for overground trips and slips.

BACKGROUND: The study of falls and fall prevention/intervention devices requires the recording of true falls incidence. However, true falls are rare, random, and difficult to collect in real world settings. A system capable of producing falls in an ecologically valid manner will be very helpful in collecting the data necessary to advance our understanding of the neuro and musculoskeletal mechanisms underpinning real-world falls events. METHODS: A fall inducing movable platform (FIMP) was designed to arrest or accelerate a subject's ankle to induce a trip or slip. The ankle was arrested posteriorly with an electromagnetic brake and accelerated anteriorly with a motor. A power spring was connected in series between the ankle and the brake/motor to allow freedom of movement (system transparency) when a fall is not being induced. A gait phase detection algorithm was also created to enable precise activation of the fall inducing mechanisms. Statistical Parametric Mapping (SPM1D) and one-way repeated measure ANOVA were used to evaluate the ability of the FIMP to induce a trip or slip. RESULTS: During FIMP induced trips, the brake activates at the terminal swing or mid swing gait phase to induce the lowering or skipping strategies, respectively. For the lowering strategy, the characteristic leg lowering and subsequent contralateral leg swing was seen in all subjects. Likewise, for the skipping strategy, all subjects skipped forward on the perturbed leg. Slip was induced by FIMP by using a motor to impart unwanted forward acceleration to the ankle with the help of friction-reducing ground sliding sheets. Joint stiffening was observed during the slips, and subjects universally adopted the surfing strategy after the initial slip. CONCLUSION: The results indicate that FIMP can induce ecologically valid falls under controlled laboratory conditions. The use of SPM1D in conjunction with FIMP allows for the time varying statistical quantification of trip and slip reactive kinematics events. With future research, fall recovery anomalies in subjects can now also be systematically evaluated through the assessment of other neuromuscular variables such as joint forces, muscle activation and muscle forces.

Implementation of Wearable Sensing Technology for Movement: Pushing Forward into the Routine Physical Rehabilitation Care Field.

While the promise of wearable sensor technology to transform physical rehabilitation has been around for a number of years, the reality is that wearable sensor technology for the measurement of human movement has remained largely confined to rehabilitation research labs with limited ventures into clinical practice. The purposes of this paper are to: (1) discuss the major barriers in clinical practice and available wearable sensing technology; (2) propose benchmarks for wearable device systems that would make it feasible to implement them in clinical practice across the world and (3) evaluate a current wearable device system against the benchmarks as an example. If we can overcome the barriers and achieve the benchmarks collectively, the field of rehabilitation will move forward towards better movement interventions that produce improved function not just in the clinic or lab, but out in peoples' homes and communities.

Improved Active Disturbance Rejection Control for Trajectory Tracking Control of Lower Limb Robotic Rehabilitation Exoskeleton.

Neurological disorders such as cerebral paralysis, spinal cord injuries, and strokes, result in the impairment of motor control and induce functional difficulties to human beings like walking, standing, etc. Physical injuries due to accidents and muscular weaknesses caused by aging affect people and can cause them to lose their ability to perform daily routine functions. In order to help people recover or improve their dysfunctional activities and quality of life after accidents or strokes, assistive devices like exoskeletons and orthoses are developed. Control strategies for control of exoskeletons are developed with the desired intention of improving the quality of treatment. Amongst recent control strategies used for rehabilitation robots, active disturbance rejection control (ADRC) strategy is a systematic way out from a robust control paradox with possibilities and promises. In this modern era, we always try to find the solution in order to have minimum resources and maximum output, and in robotics-control, to approach the same condition observer-based control strategies is an added advantage where it uses a state estimation method which reduces the requirement of sensors that is used for measuring every state. This paper introduces improved active disturbance rejection control (I-ADRC) controllers as a combination of linear extended state observer (LESO), tracking differentiator (TD), and nonlinear state error feedback (NLSEF). The proposed controllers were evaluated through simulation by investigating the sagittal plane gait trajectory tracking performance of two degrees of freedom, Lower Limb Robotic Rehabilitation Exoskeleton (LLRRE). This multiple input multiple output (MIMO) LLRRE has two joints, one at the hip and other at the knee. In the simulation study, the proposed controllers show reduced trajectory tracking error, elimination of random, constant, and harmonic disturbances, robustness against parameter variations, and under the influence of noise, with improvement in performance indices, indicates its enhanced tracking performance. These promising simulation results would be validated experimentally in the next phase of research.

Polymer Optical Fiber-Based Integrated Instrumentation in a Robot-Assisted Rehabilitation Smart Environment: A Proof of Concept.

Advances in robotic systems for rehabilitation purposes have led to the development of specialized robot-assisted rehabilitation clinics. In addition, advantageous features of polymer optical fiber (POF) sensors such as light weight, multiplexing capabilities, electromagnetic field immunity and flexibility have resulted in the widespread use of POF sensors in many areas. Considering this background, this paper presents an integrated POF intensity variation-based sensor system for the instrumentation of different devices. We consider different scenarios for physical rehabilitation, resembling a clinic for robot-assisted rehabilitation. Thus, a multiplexing technique for POF intensity variation-based sensors was applied in which an orthosis for flexion/extension movement, a modular exoskeleton for gait assistance and a treadmill were instrumented with POF angle and force sensors, where all the sensors were integrated in the same POF system. In addition, wearable sensors for gait analysis and physiological parameter monitoring were also proposed and applied in gait exercises. The results show the feasibility of the sensors and methods proposed, where, after the characterization of each sensor, the system was implemented with three volunteers: one for the orthosis on the flexion/extension movements, one for the exoskeleton for gait assistance and the other for the free gait analysis using the proposed wearable POF sensors. To the authors' best knowledge, this is the first time that optical fiber sensors have been used as a multiplexed and integrated solution for the simultaneous assessment of different robotic devices and rehabilitation protocols, where such an approach results in a compact, fully integrated and low-cost system, which can be readily employed in any clinical environment.

Head-Mounted Display-Based Application for Cognitive Training.

Virtual Reality (VR) has had significant advances in rehabilitation, due to the gamification of cognitive activities that facilitate treatment. On the other hand, Immersive Virtual Reality (IVR) produces outstanding results due to the interactive features with the user. This work introduces a VR application for memory rehabilitation by walking through a maze and using the Oculus Go head-mounted display (HMD) technology. The mechanics of the game require memorizing geometric shapes while the player progresses in two modes, autonomous or manual, with two levels of difficulty depending on the number of elements to remember. The application is developed in the Unity 3D video game engine considering the optimization of computational resources to improve the performance in the processing and maintaining adequate benefits for the user, while the generated data is stored and sent to a remote server. The maze task was assessed with 29 subjects in a controlled environment. The obtained results show a significant correlation between participants' response accuracy in both the maze task and a face-pair test. Thus, the proposed task is able to perform memory assessments.

A Multi-Modal Person Perception Framework for Socially Interactive Mobile Service Robots.

In order to meet the increasing demands of mobile service robot applications, a dedicated perception module is an essential requirement for the interaction with users in real-world scenarios. In particular, multi sensor fusion and human re-identification are recognized as active research fronts. Through this paper we contribute to the topic and present a modular detection and tracking system that models position and additional properties of persons in the surroundings of a mobile robot. The proposed system introduces a probability-based data association method that besides the position can incorporate face and color-based appearance features in order to realize a re-identification of persons when tracking gets interrupted. The system combines the results of various state-of-the-art image-based detection systems for person recognition, person identification and attribute estimation. This allows a stable estimate of a mobile robot's user, even in complex, cluttered environments with long-lasting occlusions. In our benchmark, we introduce a new measure for tracking consistency and show the improvements when face and appearance-based re-identification are combined. The tracking system was applied in a real world application with a mobile rehabilitation assistant robot in a public hospital. The estimated states of persons are used for the user-centered navigation behaviors, e.g., guiding or approaching a person, but also for realizing a socially acceptable navigation in public environments.

Upper Limb Physical Rehabilitation Using Serious Videogames and Motion Capture Systems: A Systematic Review.

The use of videogames and motion capture systems in rehabilitation contributes to the recovery of the patient. This systematic review aimed to explore the works related to these technologies. The PRISMA method (Preferred Reporting Items for Systematic reviews and Meta-Analyses) was used to search the databases Scopus, PubMed, IEEE Xplore, and Web of Science, taking into consideration four aspects: physical rehabilitation, the use of videogames, motion capture technologies, and upper limb rehabilitation. The literature selection was limited to open access works published between 2015 and 2020, obtaining 19 articles that met the inclusion criteria. The works reported the use of inertial measurement units (37%), a Kinect sensor (48%), and other technologies (15%). It was identified that 26% used commercial products, while 74% were developed independently. Another finding was that 47% of the works focus on post-stroke motor recovery. Finally, diverse studies sought to support physical rehabilitation using motion capture systems incorporating inertial units, which offer precision and accessibility at a low cost. There is a clear need to continue generating proposals that confront the challenges of rehabilitation with technologies which offer precision and healthcare coverage, and which, additionally, integrate elements that foster the patient's motivation and participation.

A novel wearable device to deliver unconstrained, unpredictable slip perturbations during gait.

BACKGROUND: Task-specific perturbation training is a widely studied means of fall prevention, utilizing techniques that induce slips or slip-like perturbations during gait. Though effective, these methods only simulate narrow ranges within the larger space of possible slipping conditions encountered in daily life. Here we describe and test a novel, wearable apparatus designed to address these limitations and simulate a diverse range of slipping disturbances. METHODS: The device consists of wireless triggering and detachable outsole components that provide adequate friction with the floor when secured to the wearer's foot, but suddenly create a low-friction surface underfoot upon release. "Benchtop" tests were carried out to quantify device triggering characteristics (i.e. cutting temperature, release delay) and the resulting friction reduction. The device was also tested on six healthy young adults (3 female, age 23 ± 2.4 years), who walked with and without the device to observe how gait kinematics and spatiotemporal parameters were influenced, then performed 12 walking trials ending with a slip delivered by the device. Each participant also completed a survey to obtain opinions on device safety, device comfort, slip realism, and slip difficulty. A linear mixed effects analysis was employed to compare subject spatiotemporal parameters with and without the apparatus, as well as correlation coefficients and root mean square errors (RMSE) to assess the impact of the device on lower limb gait kinematics. Slip onset phases, distances, directions, velocities, and recovery step locations were also calculated. RESULTS: This device rapidly diminishes available friction from static coefficients of 0.48 to 0.07, albeit after a substantial delay (0.482 ± 0.181 s) between signal reception and outsole release. Strong correlations (R > 0.93) and small RMSE between gait kinematics with and without the device indicate minimal effects on natural gait patterns, however some spatiotemporal parameters were significantly impacted. A diverse range of slip perturbations and recovery steps were successfully elicited by the device. CONCLUSIONS: Our results highlight the efficacy and utility of a wearable slipping device to deliver diverse slip conditions. Such an apparatus enables the study of unconstrained slips administered across the gait cycle, as well as during different locomotor behaviors like turning, negotiating slopes, and level changes.

Harnessing smartphone technology and three dimensional printing to create a mobile rehabilitation system, mRehab: assessment of usability and consistency in measurement.

BACKGROUND: Residual sensorimotor deficits are common following stroke. While it has been demonstrated that targeted practice can result in improvements in functional mobility years post stroke, there is little to support rehabilitation across the lifespan. The use of technology in home rehabilitation provides an avenue to better support self-management of recovery across the lifespan. We developed a novel mobile technology, capable of quantifying quality of movement with the purpose of providing feedback to augment rehabilitation and improve functional mobility. This mobile rehabilitation system, mRehab, consists of a smartphone embedded in three dimensional printed items representing functional objects found in the home. mRehab allows individuals with motor deficits to practice activities of daily living (ADLs) and receive feedback on their performance. The aim of this study was to assess the usability and consistency of measurement of the mRehab system. METHODS: To assess usability of the mRehab system, four older adults and four individuals with stroke were recruited to use the system, and complete surveys to discuss their opinions on the user interface of the smartphone app and the design of the 3D printed items. To assess the consistency of measurement by the mRehab system, 12 young adults were recruited and performed mRehab ADLs in three lab sessions within 1 week. Young adults were chosen for their expected high level of consistency in motor performance. RESULTS: Usability ratings from older adults and individuals with stroke led us to modify the design of the 3D printed items and improve the clarity of the mRehab app. The modified mRehab system was assessed for consistency of measurement and six ADLs resulted in coefficient of variation (CV) below 10%. This is a commonly used CV goal for consistency. Two ADLs ranged between 10 and 15% CV. Only two ADLs demonstrated high CV. CONCLUSIONS: mRehab is a client-centered technology designed for home rehabilitation that consistently measures performance. Development of the mRehab system provides a support for individuals working on recovering functional upper limb mobility that they can use across their lifespan.

Development and Validation of Ambulosono: A Wearable Sensor for Bio-Feedback Rehabilitation Training.

Wearable technology-based measurement systems hold potential for the therapeutic and rehabilitation management of patients with various chronic diseases. The purpose of this study was to assess the accuracy and test⁻retest reliability of a new-generation wearable sensor-based system, dubbed Ambulosono, for bio-feedback training. The Ambulosono sensor system was cross-validated by comparing its functionality with the iPod touch (4th generation) sensor system. Fifteen participants underwent a gait test to measure various gait parameters while wearing both the iPod-based and Ambulosono sensors simultaneously. The physically measured values (i.e., the true values) of step length, distance traveled, velocity, and cadence were then compared to those obtained via the two-sensor systems using the same calculation algorithms. While the mean percentage error was <10% for all measured parameters, and the intra-class correlation coefficient revealed a high level of agreement between trials for both sensor systems, it was found that the Ambulosono sensor system outperformed the iPod-based system in some respects. The Ambulosono sensor system possessed both reliability and accuracy in obtaining gait parameter measurements, which suggests it can serve as an economical alternative to the iPod-based system that is currently used in various clinical rehabilitation programs.

Verification of a Portable Motion Tracking System for Remote Management of Physical Rehabilitation of the Knee.

Rehabilitation following knee injury or surgery is critical for recovery of function and independence. However, patient non-adherence remains a significant barrier to success. Remote rehabilitation using mobile health (mHealth) technologies have potential for improving adherence to and execution of home exercise. We developed a remote rehabilitation management system combining two wireless inertial measurement units (IMUs) with an interactive mobile application and a web-based clinician portal (interACTION). However, in order to translate interACTION into the clinical setting, it was first necessary to verify the efficacy of measuring knee motion during rehabilitation exercises for physical therapy and determine if visual feedback significantly improves the participant's ability to perform the exercises correctly. Therefore, the aim of this study was to verify the accuracy of the IMU-based knee angle measurement system during three common physical therapy exercises, quantify the effect of visual feedback on exercise performance, and understand the qualitative experience of the user interface through survey data. A convenience sample of ten healthy control participants were recruited for an IRB-approved protocol. Using the interACTION application in a controlled laboratory environment, participants performed ten repetitions of three knee rehabilitation exercises: heel slides, short arc quadriceps contractions, and sit-to-stand. The heel slide exercise was completed without feedback from the mobile application, then all exercises were performed with visual feedback. Exercises were recorded simultaneously by the IMU motion tracking sensors and a video-based motion tracking system. Validation showed moderate to good agreement between the two systems for all exercises and accuracy was within three degrees. Based on custom usability survey results, interACTION was well received. Overall, this study demonstrated the potential of interACTION to measure range of motion during rehabilitation exercises for physical therapy and visual feedback significantly improved the participant's ability to perform the exercises correctly.

[Kinematics and workspace analysis of a spherical exoskeleton parallel mechanism].

Based on the biomechanical simulation curve of OpenSim, an open source software of biomechanical model, a spherical exoskeleton parallel mechanism with two degrees of freedom for hip joint is proposed in this paper for the rehabilitation therapy of patients with impaired leg motor function or elderly people with walking dysfunction. Firstly, the parallel mechanism is modeled and the position inverse solution of the parallel mechanism is obtained using inverse kinematics analysis. The velocity analysis expression of the mechanism is derived by deriving the inverse kinematics solution. The model is imported into the mechanical system dynamics analysis software ADAMS and matrix processing analysis software MATLAB to carry out simulation experiments. The correctness of the velocity analysis is verified by comparing the velocity simulation results of the two methods. Then, three singular types of the mechanism are analyzed according to the obtained Jacobian matrix. According to the inverse solution of the mechanism, the reachable workspace of the mechanism is obtained by programming in MATLAB with given mechanism parameters and restriction conditions. Finally, the prototype platform is built. The experimental results show that the exoskeleton hip joint using this parallel mechanism can satisfy the requirement of rotation angle of human hip joint movement, but also can be good to assist patients with leg flexion-extension movement and adduction-abduction movement, and it is helpful to carry out corresponding rehabilitation training. It also has theoretical significance and application value for the research work of human hip exoskeleton parallel mechanism.

[Application and Development of Rehabilitation System of Intelligent Lower Limb Rehabilitation Based on Intelligent Medical Treatment].

To develop an intelligent lower limb rehabilitation instrument which could realize the quantification and visualization of lower limbs' raising angle and frequency, using the smart client to realize the remote control, autonomous data acquisition and the establishment of database. Doctors had the access to the database in order to adjust the rehabilitation program in time to meet the individual requirement. We realized the design of intelligent lower limb instrument based on the Andriod smartphone, which is suitable for clinical and family use.

Validating attentive locomotion training using interactive treadmill: an fNIRS study.

BACKGROUND: Existing treadmill-based locomotion training, which has been used for gait function recovery, still has limitations, such as less attentive training. Interactive treadmills (ITMs) were developed to overcome these limitations, but it has not yet been verified that ITMs can make the user pay closer attention to walk training. METHODS: An experimental comparison between ITMs and conventional treadmills was conducted by measuring the level of the user's attention using functional near-infrared spectroscopy (fNIRS). To consider the effect of task complexity on the subject's attention, we provided two (slow and fast) speed conditions for walking on both treadmills. RESULTS: Both the cortical activity images and oxygenated hemoglobin (oxyHb) changes showed that the level of attention to walking induced by the ITM was significantly higher than that induced by the conventional treadmill. We found that the walking speed on the ITM also affected the level of attention. CONCLUSION: ITM-based locomotion training would be a promising solution to the limitations of existing treadmill-based locomotion training currently used to improve gait function recovery. TRIAL REGISTRATION: DGIST-HR-150309-03-02 . Registered 01 March 2015.

Development, Dynamic Modeling, and Multi-Modal Control of a Therapeutic Exoskeleton for Upper Limb Rehabilitation Training.

Robot-assisted training is a promising technology in clinical rehabilitation providing effective treatment to the patients with motor disability. In this paper, a multi-modal control strategy for a therapeutic upper limb exoskeleton is proposed to assist the disabled persons perform patient-passive training and patient-cooperative training. A comprehensive overview of the exoskeleton with seven actuated degrees of freedom is introduced. The dynamic modeling and parameters identification strategies of the human-robot interaction system are analyzed. Moreover, an adaptive sliding mode controller with disturbance observer (ASMCDO) is developed to ensure the position control accuracy in patient-passive training. A cascade-proportional-integral-derivative (CPID)-based impedance controller with graphical game-like interface is designed to improve interaction compliance and motivate the active participation of patients in patient-cooperative training. Three typical experiments are conducted to verify the feasibility of the proposed control strategy, including the trajectory tracking experiments, the trajectory tracking experiments with impedance adjustment, and the intention-based training experiments. The experimental results suggest that the tracking error of ASMCDO controller is smaller than that of terminal sliding mode controller. By optimally changing the impedance parameters of CPID-based impedance controller, the training intensity can be adjusted to meet the requirement of different patients.

Use of an In-Home Body Weight Support System by a Child With Spina Bifida.

PURPOSE: To examine the feasibility of a new open-area body weight support system (BWSS) to act as both an "assistive" and a "rehabilitative" device within the home. INTERVENTION: A 5-year-old boy with spina bifida used the BWSS during self-selected activities for 10 weeks. Feasibility, behavioral, and clinical assessments provided a quantification of his activity in and out of the BWSS. OUTCOMES: On average, the child used the device on 2.7 days/week and for 67 minutes/day during intervention. When in the BWSS (assistive role), the child's locomotor activity and engagement in adapted sports activities increased. When not in the BWSS (rehabilitative role), the child's functional mobility and ambulatory ability increased. WHAT THIS CASE ADDS: The use of the open-area in-home BWSS was feasible for regular home use and associated with an increase in functional mobility for a child with spina bifida.

Reliability of StepWatch Activity Monitor to Measure Locomotor Activity in Youth With Lower Limb Salvage.

PURPOSE: The study purpose was to determine the minimum number of monitoring days necessary to reliably capture walking among individuals with lower limb salvage. METHODS: Nineteen participants with lower limb salvage wore an ankle-mounted motion sensor over a 7-day period to obtain step counts. Generalizability theory was used to examine the variance components in step counts (G study) and to determine the appropriate length of activity monitoring using various combinations of days (D study). RESULTS: Mean step counts were higher on weekends than on weekdays. Fifty percent of the total variance in step counts was accounted for by interindividual variability in walking (D study). Eighty percent was reached individually with 4 weekdays, 2 weekend days, or 3 week days + weekend days. CONCLUSION: The study provides data for an appropriate monitoring method to track walking outcomes of rehabilitation for individuals with lower limb salvage.