Impact of visual rotations on heading direction and center of mass control during steady state gait.

Visual information is essential to navigate the environment and maintain postural stability during gait. Visual field rotations alter the perceived heading direction and center of mass (CoM) trajectory. This interaction, referred to as visual coupling, is poorly characterized during steady-state gait. Moreover, it is unclear how visual field rotations affect CoM control relative to the continuously changing base of support (BoS). This study aimed to characterize the role of visual information in heading and mediolateral (ML) balance control during unperturbed, steady-state gait. Sixteen healthy participants walked on an instrumented treadmill, naïve to sinusoidal low-frequency (0.1 Hz) rotations of the virtual environment. Rotations had a 1) high (CMH) or 2) low amplitude (CML), or were 3) periodical left-right manipulations (PM) with 10 second intervals. Coupling between CoM trajectory and visual manipulations was in-phase and showed strong cross-correlations on group level (CML: 0.88, CMH: 0.91 and PM: 0.95) and moderate to strong on individual level (CML: 0.52 ± 0.15, CMH: 0.56 ± 0.17 and PM: 0.80 ± 0.07). Higher manipulation amplitudes induced stronger CoM trajectory deviations. The margin of stability (MoSML), characterizing ML balance control, decreased towards the deviation direction and increased at the opposite side. Furthermore, a pelvis and feet reorientation towards the manipulation direction was observed. We concluded that visual information is continuously used to determine and adjust heading direction during steady-state gait. To facilitate these adjustments, the body was reorientated and the CoM-ML shifted closer to the lateral BoS boundary towards the adjusted heading direction, while preserving CoM excursion.

Efficacy of Walking Adaptability Training on Walking Capacity in Ambulatory People With Motor Incomplete Spinal Cord Injury: A Multicenter Pragmatic Randomized Controlled Trial.

BACKGROUND AND OBJECTIVE: Balance and walking capacity are often impaired in people with motor incomplete spinal cord injury (iSCI), frequently resulting in reduced functional ambulation and participation. This study aimed to assess the efficacy of walking adaptability training compared to similarly dosed conventional locomotor and strength training for improving walking capacity, functional ambulation, balance confidence, and participation in ambulatory people with iSCI. METHODS: We conducted a 2-center, parallel-group, pragmatic randomized controlled trial. Forty-one people with iSCI were randomized to 6 weeks of (i) walking adaptability training (11 hours of Gait Real-time Analysis Interactive Lab (GRAIL) training-a treadmill in a virtual reality environment) or (ii) conventional locomotor and strength training (11 hours of treadmill training and lower-body strength exercises). The primary measure of walking capacity was maximal walking speed, measured with an overground 2-minute walk test. Secondary outcome measures included the Spinal Cord Injury Functional Ambulation Profile (SCI-FAP), the Activities-specific Balance Confidence (ABC) scale, and the Utrecht Scale for Evaluation of Rehabilitation-Participation (USER-P). RESULTS: No significant difference in maximal walking speed between the walking adaptability (n = 17) and conventional locomotor and strength (n = 18) training groups was found 6 weeks after training at follow-up (-0.05 m/s; 95% CI = -0.12-0.03). In addition, no significant group differences in secondary outcomes were found. However, independent of intervention, significant improvements over time were found for maximal walking speed, SCI-FAP, ABC, and USER-P restrictions scores. Conclusions. Our findings suggest that walking adaptability training may not be superior to conventional locomotor and strength training for improving walking capacity, functional ambulation, balance confidence, or participation in ambulatory people with iSCI. TRIAL REGISTRATION: Dutch Trial Register; Effect of GRAIL training in iSCI.

Assessment of Foot Strike Angle and Forward Propulsion with Wearable Sensors in People with Stroke.

Effective retraining of foot elevation and forward propulsion is a critical aspect of gait rehabilitation therapy after stroke, but valuable feedback to enhance these functions is often absent during home-based training. To enable feedback at home, this study assesses the validity of an inertial measurement unit (IMU) to measure the foot strike angle (FSA), and explores eight different kinematic parameters as potential indicators for forward propulsion. Twelve people with stroke performed walking trials while equipped with five IMUs and markers for optical motion analysis (the gold standard). The validity of the IMU-based FSA was assessed via Bland-Altman analysis, ICC, and the repeatability coefficient. Eight different kinematic parameters were compared to the forward propulsion via Pearson correlation. Analyses were performed on a stride-by-stride level and within-subject level. On a stride-by-stride level, the mean difference between the IMU-based FSA and OMCS-based FSA was 1.4 (95% confidence: -3.0; 5.9) degrees, with ICC = 0.97, and a repeatability coefficient of 5.3 degrees. The mean difference for the within-subject analysis was 1.5 (95% confidence: -1.0; 3.9) degrees, with a mean repeatability coefficient of 3.1 (SD: 2.0) degrees. Pearson's r value for all the studied parameters with forward propulsion were below 0.75 for the within-subject analysis, while on a stride-by-stride level the foot angle upon terminal contact and maximum foot angular velocity could be indicative for the peak forward propulsion. In conclusion, the FSA can accurately be assessed with an IMU on the foot in people with stroke during regular walking. However, no suitable kinematic indicator for forward propulsion was identified based on foot and shank movement that could be used for feedback in people with stroke.

Validation of an algorithm to assess regular and irregular gait using inertial sensors in healthy and stroke individuals.

Background: Studies using inertial measurement units (IMUs) for gait assessment have shown promising results regarding accuracy of gait event detection and spatiotemporal parameters. However, performance of such algorithms is challenged in irregular walking patterns, such as in individuals with gait deficits. Based on the literature, we developed an algorithm to detect initial contact (IC) and terminal contact (TC) and calculate spatiotemporal gait parameters. We evaluated the validity of this algorithm for regular and irregular gait patterns against a 3D optical motion capture system (OMCS). Methods: Twenty healthy participants (aged 59 ± 12 years) and 10 people in the chronic phase after stroke (aged 61 ± 11 years) were equipped with 4 IMUs: on both feet, sternum and lower back (MTw Awinda, Xsens) and 26 reflective makers. Participants walked on an instrumented treadmill for 2 minutes (i) with their preferred stride lengths and (ii) once with irregular stride lengths (±20% deviation) induced by light projected stepping stones. Accuracy of the algorithm was evaluated on stride-by-stride agreement of IC, TC, stride time, length and velocity with OMCS. Bland-Altman-like plots were made for the spatiotemporal parameters, while differences in detection of IC and TC time instances were shown in histogram plots. Performance of the algorithm was compared between regular and irregular gait with a linear mixed model. This was done by comparing the performance in healthy participants in the regular vs irregular walking condition, and by comparing the agreement in healthy participants with stroke participants in the regular walking condition. Results: For each condition at least 1,500 strides were included for analysis. Compared to OMCS, IMU-based IC detection in both groups and condition was on average 9-17 (SD ranging from 7 to 35) ms, while IMU-based TC was on average 15-24 (SD ranging from 12 to 35) ms earlier. When comparing regular and irregular gait in healthy participants, the difference between methods was 2.5 ms higher for IC, 3.4 ms lower for TC, 0.3 cm lower for stride length, and 0.4 cm/s higher for stride velocity in the irregular walking condition. No difference was found on stride time. When comparing the differences between methods between healthy and stroke participants, the difference between methods was 7.6 ms lower for IC, 3.8 cm lower for stride length, and 3.4 cm/s lower for stride velocity in stroke participants. No differences were found on differences between methods on TC detection and stride time between stroke and healthy participants. Conclusions: Small irrelevant differences were found on gait event detection and spatiotemporal parameters due to irregular walking by imposing irregular stride lengths or pathological (stroke) gait. Furthermore, IMUs seem equally good compared to OMCS to assess gait variability based on stride time, but less accurate based on stride length.

A DEDICATED AMPUTEE SPORTS PROGRAMME IMPROVES PHYSICAL FUNCTIONING AND SPORTS PARTICIPATION.

Objective: People with a lower-limb amputation often have a sedentary lifestyle and increasing physical activity is important to optimize their health and quality of life. To achieve this the Amputee Parateam programme was developed. Amputee Parateam is a sports programme that addresses important physical, environmental, and social barriers for sports participation. This programme was evaluated in terms of various aspects of physical functioning and health. Design: Repeated measures design. Patients: Thirteen participants with a lower-limb amputation, with a median age of 51 (interquartile range (IQR) 40-63). Methods: Measurements were performed at T0 (baseline), T1 (after 6 weeks) and T2 (follow-up after 12 months). Outcome measures were walking ability, functional mobility, daily activity, health-related quality of life, and adherence to sports at follow-up. Results: Walking ability and functional ability significantly improved between T0 and T1. Adherence to sports at follow-up was high, with 11/13 participants still practicing sports weekly. There were no significant changes in daily activity or health-related quality of life. Conclusions: The Amputee Parateam programme successfully improved walking ability and functional mobility and resulted in a high adherence to sports among the participants. However, these improvements in physical capacity did not lead to less sedentary behaviour in daily life.

Automated spatial localization of ankle muscle sites and model-based estimation of joint torque post-stroke via a wearable sensorised leg garment.

Assessing a patient's musculoskeletal function during over-ground walking is a primary objective in post-stroke rehabilitation, due to the importance of walking recovery for everyday life. However, the quantitative assessment of musculoskeletal function currently requires lab-constrained equipment, and labor-intensive analyses, which hampers assessment in standard clinical settings. The development of fully wearable systems for the online estimation of muscle-tendon forces and resulting joint torque would aid clinical assessment of motor recovery, it would enhance the detection of neuro-muscular anomalies and it would consequently enable highly personalized treatments. Here, we present a wearable technology that combines (1) a soft garment for the human leg sensorized with 64 flexible and dry electromyography (EMG) electrodes, (2) a generalized and automated algorithm for the localization of leg muscle sites, and (3) an EMG-driven musculoskeletal modeling framework for the estimation of ankle dorsi-plantar flexion torques. Our results showed that the automated clustering algorithm could detect muscle locations in both healthy and post-stroke individuals. The estimated muscle-specific EMG envelopes could be used to drive forward person-specific musculoskeletal models and estimate resulting joint torques accurately across all healthy and post-stroke individuals and across different walking speeds (R2  > 0.82 and RMSD  < 0.16). The technology we proposed opens new avenues for automated muscle localization and quantitative musculoskeletal function assessment during gait in both healthy and neurologically impaired individuals.

Orthopedic footwear has a positive influence on gait adaptability in individuals with hereditary motor and sensory neuropathy.

BACKGROUND: Individuals with Hereditary Motor and Sensory Neuropathy (HMSN) are commonly provided with orthopedic footwear to improve gait. Although orthopedic footwear has shown to improve walking speed and spatiotemporal parameters, its effect on gait adaptability has not been established. RESEARCH QUESTION: What is the effect of orthopedic footwear on gait adaptability in individuals with HMSN? METHODS: Fifteen individuals with HMSN performed a precision stepping task on an instrumented treadmill projecting visual targets, while wearing either custom-made orthopedic or standardized footwear (i.e. minimally supportive, flexible sneakers). Primary measure of gait adaptability was the absolute Euclidean distance [mm] between the target center and the middle of the foot (absolute error). Secondary outcomes included the relative and variable error [mm] in both anterior-posterior (AP) and medial-lateral (ML) directions. Dynamic balance was assessed by the prediction of ML foot placement based on the ML center of mass position and velocity, using linear regression. Dynamic balance was primarily determined by foot placement deviation in terms of root mean square error. Another aspect of dynamic balance was foot placement adherence in terms of the coefficient of determination (R2). Differences between the footwear conditions were analyzed with a paired t-test or Wilcoxon signed-rank test (α = 0.05). RESULTS: The absolute error, relative error (AP) and variable error (AP and ML) decreased with orthopedic footwear, whereas the relative error in ML-direction slightly increased. As for dynamic balance, no effect on foot placement deviation or adherence was found. SIGNIFICANCE: Gait adaptability improved with orthopedic compared to standardized footwear in people with HMSN, as indicated by improved precision stepping. Dynamic balance, as a possible underlying mechanism, was not affected by orthopedic footwear.

Improved walking capacity after complementary ankle-foot surgery and gait training in a person with an incomplete tetraplegia; a case report.

INTRODUCTION: The population of people with a spinal cord injury (SCI) is changing to a diverse population with an increasing number of incomplete lesions. Often, these individuals have the capacity to walk, but experience disabling gait impairments. CASE PRESENTATION: The course of a 34-year-old male with a chronic incomplete traumatic cervical SCI who initially could walk no more than a few steps with supervision or a wheeled walker is described. He participated in a clinical trial with Targeted Epidural Spinal Stimulation (TESS). After this trial, he was able to walk with a wheeled walker and bilateral orthosis over a distance of 100 meters. Despite these improvements, his main complaints were (1) difficulty to correctly preposition the feet, and (2) pain in his toe and calf muscles. An interdisciplinary approach and the use of structured gait analysis formed the basis for shared decision-making with the team and the patient to perform ankle-foot surgery followed by 2-month gait training with a body weight support system. After this trajectory his walking distance increased to 250 meters, with a wheeled walker; but now without orthosis and with an increased walking speed compared to pre-surgery. Additionally, there was reduction of pain and he experienced no disturbances during sleeping, washing and clothing anymore. DISCUSSION: This case shows that surgical interventions can improve the gait capacity even in case of chronic incomplete SCI. Furthermore, training with a body weight support system after medical-technical interventions is useful to utilize the full potential of these interventions.

The effect of walking with reduced trunk motion on dynamic stability in healthy adults.

BACKGROUND: Most people with Parkinson's disease (PD) walk with a smaller mediolateral base of support (BoS) compared to healthy people, but the underlying mechanisms remain unknown. Reduced trunk motion in people with PD might be related to this narrow-based gait. Here, we study the relationship between trunk motion and narrow-based gait in healthy adults. According to the extrapolated center of mass (XCoM) concept, a decrease in mediolateral XCoM excursion would require a smaller mediolateral BoS to maintain a constant margin of stability (MoS) and remain stable. RESEARCH QUESTION: As proof of principle, we assessed whether walking with reduced trunk motion results in a smaller step width in healthy adults, without altering the mediolateral MoS. METHODS: Fifteen healthy adults walked on a treadmill at preferred comfortable walking speed in two conditions. First, the 'regular walking' condition without any instructions, and second, the 'reduced trunk motion' condition with the instruction: 'Keep your trunk as still as possible'. Treadmill speed was kept the same in the two conditions. Trunk kinematics, step width, mediolateral XCoM excursion and mediolateral MoS were calculated and compared between the two conditions. RESULTS: Walking with the instruction to keep the trunk still significantly reduced trunk kinematics. Walking with reduced trunk motion resulted in significant decreases in step width and mediolateral XCoM excursion, but not in the mediolateral MoS. Furthermore, step width and mediolateral XCoM excursion were strongly correlated during both conditions (r = 0.887 and r = 0.934). SIGNIFICANCE: This study shows that walking with reduced trunk motion leads to a gait pattern with a smaller BoS in healthy adults, without altering the mediolateral MoS. Our findings indicate a strong coupling between CoM motion state and the mediolateral BoS. We expect that people with PD who walk narrow-based, have a similar mediolateral MoS as healthy people, which will be further investigated.

Quantitative assessment of plantar pressure patterns in relation to foot deformities in people with hereditary motor and sensory neuropathies.

BACKGROUND: Hereditary motor and sensory neuropathies (HMSN), also known as Charcot-Marie-Tooth disease, are characterized by affected peripheral nerves. This often results in foot deformities that can be classified into four categories: (1) plantar flexed first metatarsal, neutral hindfoot, (2) plantar flexed first metatarsal, correctable hindfoot varus, (3) plantar flexed first metatarsal, uncorrectable hindfoot varus, and (4) hindfoot valgus. To improve management and for the evaluation of surgical interventions, a quantitative evaluation of foot function is required. The first aim of this study was to provide insight into plantar pressure of people with HMSN in relation to foot deformities. The second aim was to propose a quantitative outcome measure for the evaluation of surgical interventions based on plantar pressure. METHODS: In this historic cohort study, plantar pressure measurements of 52 people with HMSN and 586 healthy controls were evaluated. In addition to the evaluation of complete plantar pressure patterns, root mean square deviations (RMSD) of plantar pressure patterns from the mean plantar pressure pattern of healthy controls were calculated as a measure of abnormality. Furthermore, center of pressure trajectories were calculated to investigate temporal characteristics. Additionally, plantar pressure ratios of the lateral foot, toes, first metatarsal head, second/third metatarsal heads, fifth metatarsal head, and midfoot were calculated to measure overloading of foot areas. RESULTS: Larger RMSD values were found for all foot deformity categories compared to healthy controls (p < 0.001). Evaluation of the complete plantar pressure patterns revealed differences in plantar pressure between people with HMSN and healthy controls underneath the rearfoot, lateral foot, and second/third metatarsal heads. Center of pressure trajectories differed between people with HMSN and healthy controls in the medio-lateral and anterior-posterior direction. The plantar pressure ratios, and especially the fifth metatarsal head pressure ratio, differed between healthy controls and people with HMSN (p < 0.05) and between the four foot deformity categories (p < 0.05). CONCLUSIONS: Spatially and temporally distinct plantar pressure patterns were found for the four foot deformity categories in people with HMSN. We suggest to consider the RMSD in combination with the fifth metatarsal head pressure ratio as outcome measures for the evaluation of surgical interventions in people with HMSN.

Examining the role of intrinsic and reflexive contributions to ankle joint hyper-resistance treated with botulinum toxin-A.

BACKGROUND: Spasticity, i.e. stretch hyperreflexia, increases joint resistance similar to symptoms like hypertonia and contractures. Botulinum neurotoxin-A (BoNT-A) injections are a widely used intervention to reduce spasticity. BoNT-A effects on spasticity are poorly understood, because clinical measures, e.g. modified Ashworth scale (MAS), cannot differentiate between the symptoms affecting joint resistance. This paper distinguishes the contributions of the reflexive and intrinsic pathways to ankle joint hyper-resistance for participants treated with BoNT-A injections. We hypothesized that the overall joint resistance and reflexive contribution decrease 6 weeks after injection, while returning close to baseline after 12 weeks. METHODS: Nine participants with spasticity after spinal cord injury or after stroke were evaluated across three sessions: 0, 6 and 12 weeks after BoNT-A injection in the calf muscles. Evaluation included clinical measures (MAS, Tardieu Scale) and motorized instrumented assessment using the instrumented spasticity test (SPAT) and parallel-cascade (PC) system identification. Assessments included measures for: (1) overall resistance from MAS and fast velocity SPAT; (2) reflexive resistance contribution from Tardieu Scale, difference between fast and slow velocity SPAT and PC reflexive gain; and (3) intrinsic resistance contribution from slow velocity SPAT and PC intrinsic stiffness/damping. RESULTS: Individually, the hypothesized BoNT-A effect, the combination of a reduced resistance (week 6) and return towards baseline (week 12), was observed in the MAS (5 participants), fast velocity SPAT (2 participants), Tardieu Scale (2 participants), SPAT (1 participant) and reflexive gain (4 participants). On group-level, the hypothesis was only confirmed for the MAS, which showed a significant resistance reduction at week 6. All instrumented measures were strongly correlated when quantifying the same resistance contribution. CONCLUSION: At group-level, the expected joint resistance reduction due to BoNT-A injections was only observed in the MAS (overall resistance). This observed reduction could not be attributed to an unambiguous group-level reduction of the reflexive resistance contribution, as no instrumented measure confirmed the hypothesis. Validity of the instrumented measures was supported through a strong association between different assessment methods. Therefore, further quantification of the individual contributions to joint resistance changes using instrumented measures across a large sample size are essential to understand the heterogeneous response to BoNT-A injections.

The Influence of Stride Selection on Gait Parameters Collected with Inertial Sensors.

Different methods exist to select strides that represent preferred, steady-state gait. The aim of this study was to identify the effect of different stride-selection methods on spatiotemporal gait parameters to analyze steady-state gait. A total of 191 patients with hip or knee osteoarthritis (aged 38-85) wearing inertial sensors walked back and forth over 10 m for two minutes. After the removal of strides in turns, five stride-selection methods were compared: (ALL) include all strides, others removed (REFERENCE) two strides around turns, (ONE) one stride around turns, (LENGTH) strides <63% of median stride length, and (SPEED) strides that fall outside the 95% confidence interval of gait speed over the strides included in REFERENCE. Means and SDs of gait parameters were compared for each trial against the most conservative definition (REFERENCE). ONE and SPEED definitions resulted in similar means and SDs compared to REFERENCE, while ALL and LENGTH definitions resulted in substantially higher SDs of all gait parameters. An in-depth analysis of individual strides showed that the first two strides after and last two strides before a turn were significantly different from steady-state walking. Therefore, it is suggested to exclude the first two strides around turns to assess steady-state gait.

Comparison of ground reaction force and marker-based methods to estimate mediolateral center of mass displacement and margins of stability during walking.

Dynamic balance control during human walking can be described by the distance between the mediolateral (ML) extrapolated center of mass (XCoM) position and the base of support, the margin of stability (MoS). The ML center of mass (CoM) position during treadmill walking can be estimated based on kinematic data (marker-based method) and a combination of ground reaction forces and center of pressure positions (GRF-based method). Here, we compare a GRF-based method with a full-body marker-based method for estimating the ML CoM, ML XCoM and ML MoS. Fifteen healthy adults walked on a dual-belt treadmill at comfortable walking speed for three minutes. Kinetic and kinematic data were collected and analyzed using a GRF-based and marker-based method to compare the ML CoM, ML XCoM and ML MoS. High correlation coefficients (r > 0.98) and small differences (Root Mean Square Difference < 0.0072 m) in ML CoM and ML XCoM were found between the GRF-based and marker-based methods. The GRF-based method resulted in larger ML XCoM excursion (0.0118 ± 0.0074 m) and smaller ML MoS values (0.0062 ± 0.0028 m) than the marker-based method, but these differences were consistent across participants. In conclusion, the GRF-based method is a valid method to determine the ML CoM, XCoM and MoS. One should be aware of higher ML XCoM and smaller ML MoS values in the GRF-based method when comparing absolute values between studies. The GRF-based method strongly reduces measurement times and can be used to provide real-time CoM-CoP feedback during treadmill gait training.

Needs and wishes for the future lower limb exoskeleton: an interview study among people with spinal cord injury with community-based exoskeleton experience.

PURPOSE: Exoskeleton use by people with complete spinal cord injury (SCI) in daily life is challenging. To optimize daily exoskeleton use, a better understanding of the purpose of use and the accompanying improvements are needed. The perspective of experienced exoskeleton users could guide design improvements. METHODS: Face-to-face semi-structured interviews were held with 13 people with SCI with exoskeleton experience. Interviews were audio-taped, transcribed, and analysed thematically. RESULTS: Participants expressed three future purposes of exoskeleton use: for daily activities (e.g., stair climbing), exercise (e.g., staying healthy), and social interaction (e.g., standing at parties). Exoskeleton use during daily activities was the ultimate goal. Therefore, the future exoskeleton should be: easy to use, small and lightweight, tailor made, safe, comfortable, less distinctive, durable, and affordable. Improving the ease of use was relevant for all purposes, for all participants. The other suggestions for improvement varied depending on the purpose of use and the participant. CONCLUSION: Increasingly more advanced improvements are needed to transition from an exercise purpose to social interaction, and ultimately use during daily activities. In the current study, detailed suggestions for improvements have been made. Only when multiple of these suggestions are adjusted, can the exoskeleton be used to its full potential.IMPLICATIONS FOR REHABILITATIONThe use of an exoskeleton by people with a complete spinal cord injury in daily life is still in its infancy.To optimize daily exoskeleton use, a better understanding of the purpose of use and exoskeleton improvements is needed.More advanced improvements to future exoskeletons are needed to make a transition from use as an exercise device to use during social interaction and daily activities.Improving the ease of use of future exoskeletons is considered a priority by experienced users, followed by making the exoskeleton small, lightweight, and tailor made.

Translation and validation of the System Usability Scale to a Dutch version: D-SUS.

PURPOSE: The System Usability Scale (SUS) is the most commonly used questionnaire to assess usability of healthcare innovations but is not available in Dutch (D-SUS). This study aims to translate the SUS to Dutch and to determine its internal consistency, test-retest reliability, and construct validity in healthcare innovations focused on rehabilitation technologies. METHODS: Translation of the SUS was performed according to the WHO recommendations. Fifty-four participants filled out the D-SUS and Dutch Quebec User Evaluation of Satisfaction with assistive Technology (D-QUEST) twice. Internal consistency was assessed by Cronbach's alpha. Test-retest reliability was evaluated by Gwet's agreement coefficient (Gwet's AC2) on item scale, and Pearson correlation coefficient (PCC) for the overall D-SUS scores. Construct validity was assessed with the PCC between the D-SUS and D-QUEST overall scores (Netherlands Trial Register, ID: NL9169). RESULTS: After translation, Cronbach's alpha was 0.74. Gwet's AC2 was 0.68 and the PCC between the first and second overall D-SUS scores was 0.75. No significant difference in D-SUS score between the two measurements was found. Repeatability coefficient was 18.4. The PCC between the D-SUS and D-QUEST overall scores was 0.49. CONCLUSIONS: The D-SUS is a valid and reliable tool for usability assessment of healthcare innovations, specifically rehabilitation technologies.

Successful implementation of new rehabilitation technologies is partially dependent on good system usability.The System Usability Scale is translated to Dutch (D-SUS) to evaluate usability of healthcare innovations in the Netherlands.The D-SUS is a reliable and valid method to measure usability of rehabilitation technologies and eHealth applications.

Impaired foot placement strategy during walking in people with incomplete spinal cord injury.

BACKGROUND: Impaired balance during walking is a common problem in people with incomplete spinal cord injury (iSCI). To improve walking capacity, it is crucial to characterize balance control and how it is affected in this population. The foot placement strategy, a dominant mechanism to maintain balance in the mediolateral (ML) direction during walking, can be affected in people with iSCI due to impaired sensorimotor control. This study aimed to determine if the ML foot placement strategy is impaired in people with iSCI compared to healthy controls. METHODS: People with iSCI (n = 28) and healthy controls (n = 19) performed a two-minute walk test at a self-paced walking speed on an instrumented treadmill. Healthy controls performed one extra test at a fixed speed set at 50% of their preferred speed. To study the foot placement strategy of a participant, linear regression was used to predict the ML foot placement based on the ML center of mass position and velocity. The accuracy of the foot placement strategy was evaluated by the root mean square error between the predicted and actual foot placements and was referred to as foot placement deviation. Independent t-tests were performed to compare foot placement deviation of people with iSCI versus healthy controls walking at two different walking speeds. RESULTS: Foot placement deviation was significantly higher in people with iSCI compared to healthy controls independent of walking speed. Participants with iSCI walking in the self-paced condition exhibited 0.40 cm (51%) and 0.33 cm (38%) higher foot placement deviation compared to healthy controls walking in the self-paced and the fixed-speed 50% condition, respectively. CONCLUSIONS: Higher foot placement deviation in people with iSCI indicates an impaired ML foot placement strategy in individuals with iSCI compared to healthy controls.

Using Sensor Technology to Measure Gait Capacity and Gait Performance in Rehabilitation Inpatients with Neurological Disorders.

The aim of this study was to objectively assess and compare gait capacity and gait performance in rehabilitation inpatients with stroke or incomplete spinal cord injury (iSCI) using inertial measurement units (IMUs). We investigated how gait capacity (what someone can do) is related to gait performance (what someone does). Twenty-two inpatients (11 strokes, 11 iSCI) wore ankle positioned IMUs during the daytime to assess gait. Participants completed two circuits to assess gait capacity. These were videotaped to certify the validity of the IMU algorithm. Regression analyses were used to investigate if gait capacity was associated with gait performance (i.e., walking activity and spontaneous gait characteristics beyond therapy time). The ankle positioned IMUs validly assessed the number of steps, walking time, gait speed, and stride length (r ≥ 0.81). The walking activity was strongly (r ≥ 0.76) related to capacity-based gait speed. Maximum spontaneous gait speed and stride length were similar to gait capacity. However, the average spontaneous gait speed was half the capacity-based gait speed. Gait capacity can validly be assessed using IMUs and is strongly related to gait performance in rehabilitation inpatients with neurological disorders. Measuring gait performance with IMUs provides valuable additional information about walking activity and spontaneous gait characteristics to inform about functional recovery.

Objective monitoring of functional recovery after total knee and hip arthroplasty using sensor-derived gait measures.

Background: Inertial sensors hold the promise to objectively measure functional recovery after total knee (TKA) and hip arthroplasty (THA), but their value in addition to patient-reported outcome measures (PROMs) has yet to be demonstrated. This study investigated recovery of gait after TKA and THA using inertial sensors, and compared results to recovery of self-reported scores of pain and function. Methods: PROMs and gait parameters were assessed before and at two and fifteen months after TKA (n = 24) and THA (n = 24). Gait parameters were compared with healthy individuals (n = 27) of similar age. Gait data were collected using inertial sensors on the feet, lower back, and trunk. Participants walked for two minutes back and forth over a 6m walkway with 180° turns. PROMs were obtained using the Knee Injury and Osteoarthritis Outcome Scores and Hip Disability and Osteoarthritis Outcome Score. Results: Gait parameters recovered to the level of healthy controls after both TKA and THA. Early improvements were found in gait-related trunk kinematics, while spatiotemporal gait parameters mainly improved between two and fifteen months after TKA and THA. Compared to the large and early improvements found in of PROMs, these gait parameters showed a different trajectory, with a marked discordance between the outcome of both methods at two months post-operatively. Conclusion: Sensor-derived gait parameters were responsive to TKA and THA, showing different recovery trajectories for spatiotemporal gait parameters and gait-related trunk kinematics. Fifteen months after TKA and THA, there were no remaining gait differences with respect to healthy controls. Given the discordance in recovery trajectories between gait parameters and PROMs, sensor-derived gait parameters seem to carry relevant information for evaluation of physical function that is not captured by self-reported scores.

Evaluation of Compensation Strategies for Gait Impairment in Patients With Parkinson Disease.

BACKGROUND AND OBJECTIVES: Compensation strategies are essential in Parkinson's disease (PD) gait rehabilitation. However, besides external cueing, these strategies have rarely been investigated systematically. We aimed to: (1) establish the patients' perspective on the efficacy and usability of five different compensation strategies; (2) quantify the efficacy of these strategies on spatiotemporal gait parameters; and (3) explore associations between the effects of specific strategies and patient characteristics. METHODS: We recruited persons with PD and self-reported disabling gait impairments for this lab-based, within-subject study. Clinimetrics included: questionnaires (NFOG-Q, VMIQ-2, GMSI), cognitive assessments (ANT, MoCA, Brixton), and physical examinations (MDS-UPDRS III, Mini-BEST, tandem gait, rapid turns test). Gait assessment consisted of six 3-minute trials of continuous walking around a 6-meter walkway. Trials comprised: 1) baseline gait; 2) external cueing; 3) internal cueing; 4) action observation; 5) motor imagery; and 6) adopting a new walking pattern. Spatiotemporal gait parameters were acquired using 3D motion capture analysis. Strategy efficacy was determined by the change in gait variability compared to baseline gait. Associated patient characteristics were explored using regression analyses. RESULTS: 101 participants (50 men; median[range] age: 66[47-91] years) were included. The effects of the different strategies varied greatly among participants. While participants with higher baseline variability showed larger improvements using compensation strategies, participants without freezing of gait, with lower MDS-UPDRS III scores, higher balance capacity and better performance in orienting attention, also showed greater improvements in gait variability. Higher MoCA scores were associated with greater efficacy of external cueing. DISCUSSION: Our findings support the use of compensation strategies in gait rehabilitation for PD, but highlight the importance of a personalized approach. Even patients with high gait variability are able to improve through the application of compensation strategies, but certain levels of cognitive and functional reserve seem necessary to optimally benefit from them. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that gait compensation strategies can be effective in persons with PD.

Benefits of implanted peroneal functional electrical stimulation for continual gait adaptations in people with 'drop foot' due to chronic stroke.

BACKGROUND: Benefits of peroneal functional electrical stimulation in people with post-stroke drop foot may particularly emerge in environments that require continual gait adaptation. Such adaption is known to increase the attentional demands of gait. RESEARCH QUESTIONS: Is performance of a target stepping task more accurate and less attention demanding with electrical stimulation ON compared to OFF in people with post-stroke drop foot? METHODS: Thirteen people with an implanted electrical stimulation system participated in this observational study. Participants performed a walking task with irregularly spaced targets on a self-paced treadmill, both as a single task and combined with an auditory Stroop task. Participants performed each task with electrical stimulation ON and OFF. In the OFF condition participants were allowed to use their own ankle-foot orthosis. The effects of Device (ON, OFF) and interaction of Device*Task (single, dual) on stepping performance in mediolateral and anteroposterior direction were tested based on the total error of foot placement relative to the targets, using repeated measurements ANOVA. Differences between electrical stimulation ON and OFF on auditory Stroop task accuracy were assessed using a non-parametric Wilcoxon signed-rank test. Non-parametric correlations were calculated to associate changes in stepping performance with paretic leg motor function (Fugl-Meyer Assessment - leg score). RESULTS: Data of 12 participants were used for analysis. Mediolateral total error was smaller with peroneal functional electrical stimulation ON compared to OFF (Δ = 1.0 cm, p = 0.011). In the anteroposterior direction, no significant effects of Device were found. There were no significant interaction effects of Device*Task in either direction. Changes in total error (ON vs OFF) were not significantly associated with leg motor function. Stroop task accuracy was not statistically different between ON and OFF. SIGNIFICANCE: Implanted electrical stimulation may have benefits with regard to mediolateral accuracy of a continual target stepping task, although the effect size is relatively small. This benefit seems to be independent of the performance of a concurrent attention-demanding task and may reflect better gait stability in the mediolateral direction, which is known to be a problem in people with stroke.