Effectiveness of Client-Centered "Tune-Ups" on Community Reintegration, Mobility, and Quality of Life After Stroke: A Randomized Controlled Trial.

OBJECTIVE: To explore the effectiveness of a 2-week client-centered rehabilitation intervention (tune-up) delivered 6 months after inpatient discharge on community reintegration at 1 year in people with stroke. DESIGN: A multicenter randomized controlled trial with 2 groups: an intervention ("tune-up") group and a control group having the same exposure to assessment. SETTING: Three research laboratories. PARTICIPANTS: Participants (N=103) with hemiparetic stroke recruited from inpatient rehabilitation units at the time of discharge. INTERVENTIONS: Participants randomized to the tune-up group received 1-hour therapy sessions in their home 3times/wk for 2 weeks at 6 months postdischarge focusing on identified mobility-related goals. A second tune-up was provided at 12 months. MAIN OUTCOME MEASURES: Community reintegration measured by the Subjective Index of Physical and Social Outcome at 12 months and secondary outcomes included the Berg Balance Scale and measures of mobility and health-related quality of life up to 15 months. RESULTS: At 12 months, both groups showed significant improvement in community reintegration (P<.05), a trend evident at all time points, with no difference between groups (mean difference, -0.5; 95% confidence interval, -1.8 to 2.7; P=.68). Similarly, a main effect of time reflected improvement in mobility-related and quality of life outcomes for both groups (P≤.0.5), but no group differences (P≥.30). CONCLUSIONS: All participants in the tune-up group met or exceeded at least 1 mobility-related goal; however, the intervention did not differentially improve community reintegration. The improvements in mobility and quality of life over the 15-month postdischarge period may be secondary to high activity levels in both study groups and exposure to regular assessment.

Do Performance Measures of Strength, Balance, and Mobility Predict Quality of Life and Community Reintegration After Stroke?

OBJECTIVE: To investigate the extent to which physical performance measures of strength, balance, and mobility taken at discharge from inpatient stroke rehabilitation can predict health-related quality of life (HRQoL) and community reintegration after 6 months. DESIGN: Longitudinal study. SETTING: University laboratory. PARTICIPANTS: Adults (N=75) recruited within 1 month of discharge home from inpatient stroke rehabilitation. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: 36-Item Short Form Health Survey (SF-36) for HRQoL and Subjective Index of Physical and Social Outcome (SIPSO) for community reintegration. Physical performance measures were the 6-minute walk test, timed Up and Go (TUG) test, Berg Balance Scale, Community Balance and Mobility Scale, and isokinetic torque and power of hip, knee, and ankle on the paretic and nonparetic sides. Other prognostic variables included age, sex, stroke type and location, comorbidities, and motor FIM score. RESULTS: Separate stepwise linear regressions were performed using the SF-36 and SIPSO as dependent variables. The total paretic lower limb torque and 6-minute walk test predicted the SF-36 Physical Component Summary (adjusted R2=.30). The total paretic lower limb torque and TUG test predicted the SIPSO physical component (adjusted R2=.47). The total paretic lower limb torque significantly predicted the SF-36 Mental Component Summary, but the adjusted R2 was low (.06). Similarly, the TUG test significantly predicted the SIPSO social component, but again the adjusted R2 was low (.09). CONCLUSIONS: Measures of physical performance including muscle strength and mobility at discharge can partially predict HRQoL and community reintegration 6 months later. Further research is necessary for more accurate predictions.

Primary motor cortex underlies multi-joint integration for fast feedback control.

A basic difficulty for the nervous system is integrating locally ambiguous sensory information to form accurate perceptions about the outside world. This local-to-global problem is also fundamental to motor control of the arm, because complex mechanical interactions between shoulder and elbow allow a particular amount of motion at one joint to arise from an infinite combination of shoulder and elbow torques. Here we show, in humans and rhesus monkeys, that a transcortical pathway through primary motor cortex (M1) resolves this ambiguity during fast feedback control. We demonstrate that single M1 neurons of behaving monkeys can integrate shoulder and elbow motion information into motor commands that appropriately counter the underlying torque within about 50 milliseconds of a mechanical perturbation. Moreover, we reveal a causal link between M1 processing and multi-joint integration in humans by showing that shoulder muscle responses occurring ∼50 milliseconds after pure elbow displacement can be potentiated by transcranial magnetic stimulation. Taken together, our results show that transcortical processing through M1 permits feedback responses to express a level of sophistication that rivals voluntary control; this provides neurophysiological support for influential theories positing that voluntary movement is generated by the intelligent manipulation of sensory feedback.

Noninvasive neurostimulation in chronic stroke: a double-blind randomized sham-controlled testing of clinical and corticomotor effects.

BACKGROUND: Repetitive peripheral magnetic stimulation (RPMS) is a painless and noninvasive method to produce afferents via the depolarization of the peripheral nervous system. A few studies tested RPMS after-effects on cerebral plasticity and motor recovery in stroke individuals, but evidences remain limited. OBJECTIVES: This study aimed to explore whether RPMS could mediate improvements in corticomotor and clinical outcomes associated with ankle impairments in chronic stroke. METHODS: Eighteen subjects with chronic stroke were randomly allocated to RPMS or sham group and compared to 14 healthy subjects. Stimulation was applied over the paretic tibialis anterior (TA). Ankle impairments on the paretic side and ipsilesional TA cortical motor representation were tested clinically and by transcranial magnetic stimulation (TMS), respectively. RESULTS: In the RPMS group, ankle dorsiflexion mobility and maximal isometric strength increased and resistance to plantar flexor stretch decreased. The magnitude of change seemed to be related to cortical and corticospinal integrity. Sham stimulation yielded no effect. Changes in TMS outcome and their relationships with clinical improvements were limited. CONCLUSIONS: RPMS improved ankle impairments in chronic stroke likely by a dynamic influence of sensory inputs on synaptic plasticity. The neurophysiological mechanisms potentially underlying the clinical effects are unclear. More studies are warranted to test the spinal and hemispheric changes responsible for the clinical improvements with emphasis on circuits spared by the lesion.

Kinematic and kinetic evaluation of the stance phase of stair ambulation in persons with stroke and healthy adults: a pilot study.

This study describes and contrasts the kinematics and kinetics of stair ambulation in people with chronic stroke and healthy control subjects. Three-dimensional motion data were collected from 10 persons with stroke (7 males) and 10 sex and age-matched older adults as they ascended and descended an instrumented staircase at self-selected speed with and without a handrail. Ankle, knee and hip joint angle and moment profiles were generated during stance and range of motion and peak moments were contrasted between groups, sides (stroke only) and condition. Cadence was lower in stroke than controls, although the kinematic profiles appeared similar during ascent and decent. Notable differences in joint kinetics were evident as the peak extensor moments were typically lower on the affected side in stroke compared with controls and the less affected side. These differences accounted for the lower magnitude net extensor support moment. The lower affected side hip abductor moments likely limited lateral stability. Handrail use tended to reduce the peak moments on the affected side only leading to more side-to-side differences than occurred without the handrail. The findings reveal differences in task performance between stroke and healthy groups that help inform rehabilitation practice.

Strength and aerobic requirements during stair ambulation in persons with chronic stroke and healthy adults.

OBJECTIVE: To estimate the cost of stair ascent and descent in relation to a measured standard of strength and metabolic (aerobic) capacities in persons with chronic stroke compared with healthy adults. DESIGN: Descriptive cross-sectional study. SETTING: Motion analysis laboratory. PARTICIPANTS: Persons with stroke (n=10) and sex- and age-matched older adults (n=10). INTERVENTION: Not applicable. MAIN OUTCOME MEASURES: Lower limb peak joint moments generated during stair walking, expressed as a percentage of the respective isokinetic peak torque, provided an estimate of the relative strength cost. The oxygen consumed during stair walking as a percentage of the maximum oxygen consumption estimated from a submaximal cycle ergometer test reflected the relative aerobic cost of stair ambulation. RESULTS: During ascent, plantarflexor strength cost was highest on the affected side (stroke) compared with the less affected side and control subjects. The costs associated with the knee extensors were highest in stroke (both sides) for both ascent and descent, and similarly the costs were highest for the less affected and affected plantarflexors during descent. No differences were detected between the affected and less affected sides. The oxygen consumed when ambulating 1 flight of stairs was comparable between groups, but the relative aerobic cost of stair ascent and descent was higher in stroke survivors because of their lower aerobic capacity. CONCLUSIONS: To our knowledge, this is the first study to compare the relative costs of stair ambulation in people with stroke and healthy controls. The higher strength and aerobic costs associated with stair negotiation in stroke resulting primarily from reduced strength and aerobic capacities, respectively, may limit mobility.

Validity of the Community Balance and Mobility Scale in community-dwelling persons after stroke.

OBJECTIVES: To examine the convergent validity, sensitivity to change, floor and ceiling effects of the Community Balance and Mobility Scale (CB&M) in community-dwelling stroke survivors. The secondary objective was to determine the correlations between the CB&M and lower-limb motor recovery and strength. DESIGN: Validity study. SETTING: Two university-based research centers. PARTICIPANTS: Community-dwelling persons after stroke (N=44; 24 men, 20 women; mean age, 62.6+/-12.6y). Baseline measures were taken 3 months after the onset of stroke (98.6+/-52.6d); participants were reassessed 8 months poststroke (246.8+/-57.2d). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: CB&M, Berg Balance Scale (BBS), Timed Up & Go (TUG), Chedoke McMaster Stroke Assessment (CMSA) Impairment Inventory for leg and foot, concentric bilateral isokinetic strength of the lower-limb flexor and extensor muscle groups using a dynamometer. The magnitude of the associations and the standardized response means (SRMs) among the CB&M, BBS, and TUG were used to examine the convergent validity and sensitivity to change, respectively. RESULTS: Moderate to high convergent validities (rho=.70 to .83, P<.001) were observed among the CB&M, BBS, and TUG. The CB&M was moderately correlated with the CMSA leg and foot scores (rho=.61 and .63, respectively, P<.001) and the paretic limb strength (rho=.67, P<.001). The CB&M demonstrated the greatest ability to detect change between the baseline and follow-up assessments (SRM=.83). CONCLUSIONS: The CB&M is valid and sensitive to change in assessing functional balance and mobility in ambulatory stroke survivors with moderate to mild neurologic impairments.

Gait changes following botulinum toxin A treatment in stroke.

PURPOSE: To characterize the effects of botulinum toxin A treatment of spastic plantar flexors in stroke on joint mobility and gait kinematics and kinetics. METHOD: Nine patients with hemiparetic stroke presenting with ankle hypertonicity participated in this exploratory open-label case series study. Comprehensive gait analysis provided bilateral kinematic and kinetic information for the ankle, knee, and hip joints throughout the stance phase. Data were obtained at baseline, 2 weeks, and 10 weeks post botulinum toxin injection of the spastic plantar flexors. RESULTS: Passive ankle range of motion increased post injection (p < .05). The amount of plantarflexion in late stance was significantly reduced (p < .05) while the maximum dorsiflexion increased in midstance at 10 weeks post treatment. The angular displacement profiles for the knee revealed that patients tended to display less hyperextension following treatment (p = .053). No significant changes in kinetic measures were found; however, case-by-case observations suggested that most patients experienced improvements in positive work production. CONCLUSIONS: The findings indicate that botulinum toxin treatment results in improved joint mobility and ankle kinematics and, in some patients, increases in positive work, suggesting better gait performance.

Test position and hip strength in healthy adults and people with chronic stroke.

OBJECTIVE: To determine if peak torques generated by the hip flexors and extensors are dependent on test position in healthy adults and in people with chronic stroke. DESIGN: Cross-sectional study. SETTING: Motor performance laboratory. PARTICIPANTS: Volunteers were 10 young (20.7+/-1.5y), 10 older adults (62.1+/-7y), and 10 stroke survivors (60.6+/-10y) who were an average of 5 years poststroke. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Isokinetic (60 degrees /s) peak concentric hip flexor and extensor torques (in Nm/kg) generated in supine and standing positions. RESULTS: Peak flexor torques measured in standing were generally higher than in supine (P=.018); a pattern evident in all groups, but significant only in stroke. An interaction between test position and group for hip extensor strength (P=.016) reflected 2 distinct patterns in which torques were highest in standing among the young subjects and highest in supine after stroke. CONCLUSIONS: Isokinetic hip flexor and extensor strength measured in standing and supine are comparable in young and older healthy people. In chronic stroke, the test position may over or underestimate maximum peak torque depending on the muscle group tested, particularly on the side ipsilateral to the lesion. These findings may have implications for predicting functional ability from strength measurements.

Short-term natural recovery of ankle sprains following discharge from emergency departments.

STUDY DESIGN: Prospective cohort study. OBJECTIVES: To examine the natural recovery from grade I and II ankle injuries over a 1-month period. BACKGROUND: There is a high rate of injury recurrence and persistence of symptoms following ankle sprains, suggesting that these injuries may not be adequately managed. However, little is known about the recovery process after discharge from emergency departments. METHODS AND MEASURES: Clinical assessment of ankle swelling, strength, and joint mobility and laboratory assessment of peak torque and joint range of motion (ROM) were performed 4 and 30 days following initial clinical assessment in the emergency department. Analyses for repeated measures determined change over time and differences between injured and noninjured ankles. Self-assessed ankle function was evaluated on day 4 and day 30, and its relationship to clinical and laboratory assessments determined. RESULTS: Forty-six subjects entered the study and complete datasets were obtained from 28. Significant swelling, weakness, and mobility restrictions were evident on initial assessment. Symptoms improved over time and, while clinical variables were normal by day 30, laboratory assessment indicated weakness of plantar flexors and limited active and passive ROM at 1 month. Swelling and reduced passive ROM were associated with overall function and limitations in sports and recreation activities, as well as quality of life 1 month postinjury. CONCLUSION: Clinically assessed strength and ankle dorsiflexion mobility suggested full recovery at 1 month post injury, yet more sensitive measures of ankle impairment and performance detected residual deficits. Persistent impairment and incomplete recovery of self-assessed function suggest the need for management beyond standard emergency department care. Associations between impairment measures and function may provide guidance for treatment intervention.

Changes in muscle group work associated with changes in gait speed of persons with stroke.

BACKGROUND: Knowledge of associations between changes in muscle work with changes in gait speed could assist gait training in persons with stroke. The purpose of the study was to determine changes in the work of major muscle groups during gait that were associated with increases in walking speed of persons with stroke following training. METHODS: The gait of 28 subjects (14 males, 14 females) with mean age of 64.2 (SD 11.7) years, at 4.8 (SD 6.9) years post stroke was studied using two-dimensional motion analysis before and after a strength training program. Outcome variables were changes in gait speed and changes in work associated with the hip flexors and extensors, knee flexors and extensors and ankle plantar flexors bilaterally. A stepwise linear regression analysis determined best positive work predictors of changes in gait speed. FINDINGS: Hip extension work in early stance and ankle plantarflexion work in late stance of the affected side accounted for 74.9% of the variance in change of gait speed; a second model showed that hip extension work in early stance of the affected and less-affected sides accounted for 74.3%, a similar amount of variance. INTERPRETATION: This work is the first to explore the changes in muscle work during gait that are associated with speed increases in persons with stroke. Augmenting hip extensor work in early stance on both sides, as well as ankle plantarflexion thrust on the affected side may be particularly beneficial in increasing the speed of walking of persons with stroke.

A randomized controlled trial of supervised versus unsupervised exercise programs for ambulatory stroke survivors.

BACKGROUND AND PURPOSE: Little is known about the relative efficacy of supervised versus unsupervised community exercise programs for stroke survivors. This study compared the effectiveness of a 10-week supervised strengthening and conditioning program (supervised) with a 1-week supervised instruction program followed by a 9-week unsupervised home program (unsupervised) and evaluated retention of changes at 6 months and 1 year after program completion. METHODS: Seventy-two subjects retained at baseline (27 women, 45 men; mean+/-SD age, 64.6+/-11.8 years) were randomly allocated to receive the supervised or unsupervised program. The primary outcome was walking speed over 6 minutes, and secondary outcome measures were Human Activity Profile, Medical Outcome Study 36-Item Short-Form survey (SF-36), Physiological Cost Index, and lower extremity muscle strength. RESULTS: The 6-minute walking speed increased significantly in both groups and remained significantly improved by 1 year. The Human Activity Profile demonstrated an increasing trend only in the supervised group that was significant by 1 year. The SF-36 Physical Component summary score increased significantly in the supervised group and remained improved by 1 year; the unsupervised group showed significant improvement at 1 year. Women made greater gains in supervised programs, but men made greater gains in unsupervised programs. CONCLUSIONS: Supervised exercise programs and unsupervised programs after initial supervised instruction were both associated with physical benefits that were retained for 1 year, although supervised programs showed trends to greater improvements in self-reported gains. Gender differences require further research.

Use of Rasch Analysis to Evaluate and Refine the Community Balance and Mobility Scale for Use in Ambulatory Community-Dwelling Adults Following Stroke.

BACKGROUND: The Community Balance and Mobility Scale (CB&M) is increasingly used to evaluate walking balance following stroke. OBJECTIVE: This study applied Rasch analysis to evaluate and refine the CB&M for use in ambulatory community-dwelling adults following stroke. METHODS: The CB&M content was linked to task demands and motor skill classifications. Rasch analysis was used to evaluate internal construct validity (structural validity) and refine the CB&M for use with ambulatory community-dwelling adults following stroke. The CB&M data were collected at 3 time points: at discharge from inpatient rehabilitation and at 6 and 12 months postdischarge (N=238). Rasch analysis evaluated scale dimensionality, item and person fit, item response bias, scoring hierarchy, and targeting. Disordered scoring hierarchy was resolved by collapsing scoring categories. Highly correlated and "misfitting" items were removed. Sensitivity to change was evaluated with standardized response means (SRMs) and one-way repeated-measures analysis of variance. RESULTS: The CB&M was primarily linked to closed body transport task demands. Significant item-trait interaction, disordered scoring hierarchies, and multidimensionality were found. Scoring categories were collapsed in 15/19 items, and 5 misfitting items were removed. The resulting stroke-specific 14-item unidimensional CB&M (CB&MStroke) fit Rasch model expectations, with no item response bias, acceptable targeting (13% floor effects and 0% ceiling effects), and moderate-to-strong sensitivity to change at 6 months postdischarge (SRM=0.63; 95% confidence interval=-1.523, -0.142) and 12 months postdischarge (SRM=0.73; 95% confidence interval=-2.318, -0.760). LIMITATIONS: Findings are limited to a modest-sized sample of individuals with mild-to-moderate balance impairment following stroke. CONCLUSIONS: The CB&MStroke shows promise as a clinical scale for measuring change in walking balance in ambulatory community-dwelling adults poststroke. Future studies are recommended in a larger sample to validate and further refine the scale for use in this clinical population.

Effect of early supervised physiotherapy on recovery from acute ankle sprain: randomised controlled trial.

OBJECTIVE:  To assess the efficacy of a programme of supervised physiotherapy on the recovery of simple grade 1 and 2 ankle sprains. DESIGN:  A randomised controlled trial of 503 participants followed for six months. SETTING:  Participants were recruited from two tertiary acute care settings in Kingston, ON, Canada. PARTICIPANTS:  The broad inclusion criteria were patients aged ≥16 presenting for acute medical assessment and treatment of a simple grade 1 or 2 ankle sprain. Exclusions were patients with multiple injuries, other conditions limiting mobility, and ankle injuries that required immobilisation and those unable to accommodate the time intensive study protocol. INTERVENTION:  Participants received either usual care, consisting of written instructions regarding protection, rest, cryotherapy, compression, elevation, and graduated weight bearing activities, or usual care enhanced with a supervised programme of physiotherapy. MAIN OUTCOME MEASURES:  The primary outcome of efficacy was the proportion of participants reporting excellent recovery assessed with the foot and ankle outcome score (FAOS). Excellent recovery was defined as a score ≥450/500 at three months. A difference of at least 15% increase in the absolute proportion of participants with excellent recovery was deemed clinically important. Secondary analyses included the assessment of excellent recovery at one and six months; change from baseline using continuous scores at one, three, and six months; and clinical and biomechanical measures of ankle function, assessed at one, three, and six months. RESULTS:  The absolute proportion of patients achieving excellent recovery at three months was not significantly different between the physiotherapy (98/229, 43%) and usual care (79/214, 37%) arms (absolute difference 6%, 95% confidence interval -3% to 15%). The observed trend towards benefit with physiotherapy did not increase in the per protocol analysis and was in the opposite direction by six months. These trends remained similar and were never statistically or clinically important when the FAOS was analysed as a continuous change score. CONCLUSIONS:  In a general population of patients seeking hospital based acute care for simple ankle sprains, there is no evidence to support a clinically important improvement in outcome with the addition of supervised physiotherapy to usual care, as provided in this protocol.Trial registration ISRCTN 74033088 (www.isrctn.com/ISRCTN74033088).

Activity classification in persons with stroke based on frequency features.

Recent advances in the use of inertial measurement units (IMUs) for motion analysis suggest the possibility of using this technology for the monitoring of daily activities of individuals during rehabilitation post-stroke. Previous studies have utilized features extracted from accelerometer and gyroscope signals to develop classification models capable of identifying activities performed within large datasets. In this study, nine k-nearest neighbor cross-validated classifiers were developed using frequency-features derived from shank-mounted IMUs on the less-affected and affected limbs of subjects with stroke. These classifiers were evaluated for two separate datasets of post-stroke gait; the first a classification of three separate gait activities (overground walking, stair ascent, and stair descent), and the second a classification of five gait activities, overground walking, stair ascent, and descent with a distinction between stepping pattern used while negotiating stairs (step-over-step (SOS) and step-by-step (SBS)). The comparison showed the highest classification accuracy, 100% for the three-activities and 94% for the five-activities, was obtained using a classifier composed of features derived from accelerometer and gyroscope measurements from both IMUs on less-affected and affected limbs.

Energy flow analysis of the lower extremity during gait in persons with chronic stroke.

BACKGROUND: A decline in walking capacity and high energy cost can limit mobility following stroke. Mechanical energy exchange between lower limb and trunk segments can reflect gait inefficiencies, but reveals little about active energy flow between adjacent segments through muscle actions. This study evaluated mechanical energy expenditures (MEEs) during walking in stroke and healthy groups to understand movement control and explore the impact of walking speed on mechanical energy exchanges. METHODS: Thirteen adults with hemiparesis and six healthy controls walked at self-selected speed. Power curves for each lower limb joint were segmented into concentric and eccentric sources of muscle power and transfer/no-transfer modes to calculate MEEs during stance. FINDINGS: MEEs were lower in the stroke group on the affected side compared to the less affected side and compared to controls. Specifically, the affected plantarflexors transferred less energy distally via concentric action in late stance compared to the less affected side. However, the stroke group generated greater energy at the ankle in the absence of transfer compared to controls. Less concentrically transferred energy through midstance and absorbed in late stance was evident by the knee extensors bilaterally in stroke. At the hip, the total energy (no transfer) was reduced on the affected side. Classifying stroke subjects by walking speed (<.6m/s, >.6m/s) revealed disruptions in harnessing energy through motion and transfer energy across segments in the slower group. INTERPRETATION: The limited ability of those with stroke to exploit intersegmental energy transfer to optimize efficiency may limit endurance and functional independence.

Reducing fear of falling in seniors through education and activity programs: a randomized trial.

OBJECTIVES: To determine the relative effect of education and activity programs on fear of falling, balance, strength, and health status. DESIGN: A randomized intervention trial with two groups (education and activity); evaluators were blind to group allocation. SETTING: Motor performance laboratory at Queen's University. PARTICIPANTS: Thirty-eight community-dwelling seniors who reported a fear of falling and activity restriction but were free of neurological and mobility-limiting orthopedic conditions. INTERVENTIONS: Programs designed to reduce fear of falling were delivered weekly to groups of three to five seniors for 8 weeks, each session lasting 1 hour. The activity program included low-resistance exercises and weight-shifting activities. Education focused on identifying and reducing risk factors for falls. MEASUREMENTS: Balance confidence, activity level, limits of stability (LOS), isokinetic strength, and health status were measured twice preintervention (baseline), postintervention, and 6 weeks later. RESULTS: Both programs reduced fear of falling (P <.006) as ascertained from the balance confidence scores. Differential effects were observed in LOS (P <.05); activity improved balance, whereas education led to modest declines. Gains in perception of health status were limited to physical health for the activity group and mental health for the education group. Benefits were generally sustained at follow-up. CONCLUSION: Improved balance confidence is not intervention-specific, but associated changes in physical ability and health status are a function of the composition of the intervention program.

Measurement of lower limb joint kinematics using inertial sensors during stair ascent and descent in healthy older adults and stroke survivors.

This study validated the feasibility of inertial sensors in estimating lower limb joint kinematics during stair ambulation in healthy older adults and stroke survivors. Three dimensional motion data were collected using an inertial sensor-based system from 9 persons with stroke and 9 healthy older adults as they ascended and descended a staircase at a self-selected pace. The measured joint angles were compared with a laboratory-based motion capture system by computing differences in range of motion (RoM), grand mean error, standard deviation, and coefficients of multiple correlations. For stroke survivors, differences in RoM measurements between these two systems were determined to be 3.3 ± 8.1°, while the highest correlations were found in the estimation of sagittal plane joint angles after offset correction. Results suggest that the inertial sensor system is suitable for estimating major joint angles in healthy older adults as well as the RoM for stroke survivors. New calibration procedures are necessary for applying the technology to a stroke population.

Concurrent validation of Xsens MVN measurement of lower limb joint angular kinematics.

This study aims to validate a commercially available inertial sensor based motion capture system, Xsens MVN BIOMECH using its native protocols, against a camera-based motion capture system for the measurement of joint angular kinematics. Performance was evaluated by comparing waveform similarity using range of motion, mean error and a new formulation of the coefficient of multiple correlation (CMC). Three dimensional joint angles of the lower limbs were determined for ten healthy subjects while they performed three daily activities: level walking, stair ascent, and stair descent. Under all three walking conditions, the Xsens system most accurately determined the flexion/extension joint angle (CMC > 0.96) for all joints. The joint angle measurements associated with the other two joint axes had lower correlation including complex CMC values. The poor correlation in the other two joint axes is most likely due to differences in the anatomical frame definition of limb segments used by the Xsens and Optotrak systems. Implementation of a protocol to align these two systems is necessary when comparing joint angle waveforms measured by the Xsens and other motion capture systems.

Estimation of spatio-temporal parameters for post-stroke hemiparetic gait using inertial sensors.

This paper represents the first step in developing an inertial sensor system that is capable of assessing post-stroke gait in terms of walking speed and temporal gait symmetry. Two inertial sensors were attached at the midpoint of each shank to measure the accelerations and angular velocity during walking. Despite the abnormalities in hemiparetic gait, the angular velocity of most of the testing subjects (12 out of 13) exhibited similar characteristics as those from a healthy population, enabling walking speed estimation and gait event detection based on the pendulum walking model. The results from a standardized 10-meter walk test demonstrated that the IMU-based method has an excellent agreement with the clinically used stopwatch method. The gait symmetry results were comparable with previous studies. The gait segmentation failed when the angular velocity deviates significantly from the healthy groups' profile. With further development and concurrent validations, the inertial sensor-based system may eventually become a useful tool for continually monitoring spatio-temporal gait parameters post stroke in a natural environment.