Hamstring spasticity assessment: does the hip flexion angle impact outcomes?

PURPOSE: Hamstring spasticity is prevalent following neurological injury. The standardized assessment involves passive knee extension, in a position of 90° hip flexion. This creates passive insufficiency of the muscle and lacks ecological validity for walking, whereby the hip typically flexes to a maximum of 40° during swing phase, while the knee extends. This study compared assessment outcomes when completed in 40° and 90° hip flexion. METHODS: The Modified Ashworth Scale and Modified Tardieu Scale, were performed on 35 adults with a neurological condition. Each participant was assessed by three assessors, resulting in 105 trials at 40° and 90°. RESULTS: There was a significant increase in the proportion of trials rated as spastic using the Modified Ashworth Scale (p=.012, phi=.27), and Modified Tardieu Scale (p<.001, phi=.36), and the severity of spasticity using the Modified Ashworth Scale (p<.001, effect size (ES)=.50), and Modified Tardieu Scale (p<.001 ES=.47), at 90° hip flexion. The angle of reaction occurred 32° earlier at 90° hip flexion (p<.001, ES = 1.61). CONCLUSIONS: Completing hamstring assessments in 40° hip flexion may reduce the passive insufficiency and improve the ecological validity of assessment, for walking. This may assist in the selection of patients requiring intervention, when their goal relates to walking.

The position of the hip joint impacts hamstring spasticity assessment outcomes, regardless of the clinical outcome measure chosenThe application of bedside assessment methods in a manner reflective of functional tasks may assist in selecting individuals who require active spasticity interventionAs per international guidelines, the use of validated outcome measures in a goal directed and patient centered manner is required to maximize patient care.

Controlling modified Tardieu scale assessment speeds to match joint angular velocities during walking impacts spasticity assessment outcomes.

OBJECTIVE: To investigate whether tailoring the speed of the Modified Tardieu Scale to reflect an individual's joint angular velocity during walking influences spasticity assessment outcomes. DESIGN: Observational trial. SETTING: Inpatient and outpatient neurological hospital department. SUBJECTS: Ninety adults with lower-limb spasticity. INTERVENTIONS: N/A. MAIN MEASURES: The Modified Tardieu Scale was used to assess the gastrocnemius, soleus, hamstrings and quadriceps. The V1 (slow) and V3 (fast) movements were completed as per standardised testing. Two additional assessments were completed, reflecting joint angular velocities during walking based on (i) a healthy control database (controlled velocity) and (ii) the individual's real-time joint angular velocities during walking (matched velocity). The agreement was compared using Cohen's and Weighted Kappa statistics, sensitivity and specificity. RESULTS: There was poor agreement when rating trials as spastic or not spastic at the ankle joint (Cohen's Kappa = 0.01-0.17). Trials were classified as spastic during V3 and not spastic during the controlled conditions in 81.6-85.1% of trials when compared to stance phase dorsiflexion angular velocities and 48.0-56.4% when compared to swing phase dorsiflexion angular velocities. The severity of muscle reaction demonstrated poor agreement at the ankle (Weighted Kappa = 0.01-0.28). At the knee, there was a moderate-excellent agreement between the V3 and controlled conditions when rating a trial as spastic or not spastic (Cohen's Kappa = 0.66-0.84) and excellent agreement when comparing severity (Weighted Kappa = 0.73-0.94). CONCLUSION: The speed of assessment impacted spasticity outcomes. It is possible that the standardised protocol may overestimate the impact spasticity has on walking, especially at the ankle.

Does Femoroacetabular Impingement Syndrome Affect Self-Reported Burden in Football Players With Hip and Groin Pain?

BACKGROUND: It is unknown if football players with femoroacetabular impingement (FAI) syndrome report worse burden than those with other causes of hip/groin pain, and to what extent this is mediated by cartilage defects and labral tears. HYPOTHESIS: Football players with FAI syndrome would report worse burden than other symptomatic players, with the effect partially mediated by cartilage defects and/or labral tears. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 4. METHODS: Football (soccer and Australian football) players (n = 165; 35 women) with hip/groin pain (≥6 months and positive flexion-adduction-internal rotation test) were recruited. Participants completed 2 patient-reported outcome measures (PROMs; the International Hip Outcome Tool-33 [iHOT-33] and Copenhagen Hip and Groin Outcome Score [HAGOS]) and underwent hip radiographs and magnetic resonance imaging (MRI). FAI syndrome was determined to be present when cam and/or pincer morphology were present. Cartilage defects and labral tears were graded as present or absent using MRI. Linear regression models investigated relationships between FAI syndrome (dichotomous independent variable) and PROM scores (dependent variables). Mediation analyses investigated the effect of cartilage defects and labral tears on these relationships. RESULTS: FAI syndrome was not related to PROM scores (unadjusted b values ranged from -4.693 (P = 0.23) to 0.337 (P = 0.93)) and cartilage defects and/or labral tears did not mediate its effect (P = 0.22-0.97). CONCLUSION: Football players with FAI syndrome did not report worse burden than those with other causes of hip/groin pain. Cartilage defects and/or labral tears did not explain the effect of FAI syndrome on reported burden. CLINICAL RELEVANCE: FAI syndrome, cartilage defects, and labral tears were prevalent but unrelated to reported burden in symptomatic football players.

Assessment of upper limb abnormalities using the Kinect: Reliability, validity and detection accuracy in people living with acquired brain injury.

Upper limb kinematic abnormalities are prevalent in people with acquired brain injury (ABI). We examined if the Microsoft Kinect for Xbox One (Kinect) reliably (test-retest) and validly (concurrent) quantifies upper limb kinematics, and accurately classifies abnormalities (sensitivity/specificity), in an ABI cohort when compared to three-dimensional motion analysis (3DMA) and a subjective rating scale. We compared 42 adults with ABI to 36 healthy control (HC) participants. Walking trials were recorded by 3DMA and Kinect at self-selected (SSWS) and fast (FWS) walking speeds. When classifying abnormalities for 3DMA and Kinect, a 95% reference range (based on HC data) was calculated using the Kinematic Deviation Score worst axis (KDSw); values outside of this range were classified abnormal. Scores ≥ 2 in the subjective rating scale, based on International Classification of Functioning, Disability and Health Framework's Qualifiers Scale, were considered abnormal. Test-retest reliability and concurrent validity were determined using intra-class correlation coefficient (Absolute ICC2,1) and Pearson's or Spearman's correlation respectively. Fisher's Exact Test was conducted to determine sensitivity and specificity between each combination of the two methods. Strong test-retest reliability was observed for 3DMA (median(IQR) ICC:0.86(0.85-0.90)). Kinect showed overall strong SSWS test-retest reliability (ICC:0.87(0.84-0.91)) and moderate FWS test-retest reliability (ICC:0.61(0.56-0.65)). Concurrent validity between 3DMA and Kinect was overall moderate. Sensitivity and specificity between 3DMA, Kinect and subjective scores were overall modest. Our results suggest caution should be used if implementing Kinect as its validity is modest against criterion-reference 3DMA; however, given its reliability and similar sensitivity/specificity to 3DMA further responsiveness research is warranted.

Digital bathroom scales with open source software provide valid dynamic ground reaction force data for assessment and biofeedback.

BACKGROUND: Measuring dynamic vertical ground reaction force allows for assessment of important clinical and physical capacity factors such as weight bearing asymmetry, force distribution, and rate of force development. However, current technologies for accurately assessing ground reaction force are typically expensive. RESEARCH QUESTION: The aim of this study was to examine the validity and reliability of obtaining static and dynamic ground reaction force data from low-cost modified digital bathroom scales. METHODS: Four modified bathroom scales, two units each of two different brands, were examined. Repeated mechanical loading trials were performed with known loads ranging from 0.01 to 65 kg, with acquired data compared against the known loading to calculate accuracy, hysteresis, and non-linearity. Dynamic trials consisting of 5 times sit-to-stand and weight-shifting were performed by 32 adults. Absolute and relative agreement intraclass correlation coefficient, and Pearson's and Spearman's correlations were performed to determine validity and reliability for the mechanical tests. Bland-Altmann plots were created for each comparison. Mean absolute error (MAE) and unbiased cross-correlation were performed on the dynamic data, comparing the calibrated data to the known values from a Bertec force platform. RESULTS: Hysteresis and non-linearity were excellent (<0.2 % full-scale), and mechanical test results showed excellent reliability and validity. Cross-correlation results for the dynamic data were excellent, however MAE for the more rapid sit-to-stand task was higher than the slower weight-shifting test. This may have been due to the low default sampling rate for the lowest noise setting of the HX711 amplifier (10 Hz). SIGNIFICANCE: In summary, our results suggest that digital bathroom scales can be easily and inexpensively modified to obtain accurate vertical ground reaction force data, with sensitivity to detect changes of as little as 0.01 kg.

Clinical spasticity assessment using the Modified Tardieu Scale does not reflect joint angular velocity or range of motion during walking: Assessment tool implications.

OBJECTIVE: Spasticity assessment is often used to guide treatment decision-making. Assessment tool limitations may influence the conflicting evidence surrounding the relationship between spasticity and walking. This study investigated whether testing speeds and joint angles during a Modified Tardieu assessment matched lower-limb angular velocity and range of motion during walking. DESIGN: Observational study. SUBJECTS: Thirty-five adults with a neurological condition and 34 assessors. METHODS: The Modified Tardieu Scale was completed. Joint angles and peak testing speed during V3 (fast) trials were compared with these variables during walking in healthy people, at 0.400.59, 0.600.79 and 1.401.60 m/s. The proportion of trials in which the testing speed, start angle, and angle of muscle reaction matched the relevant joint angles and angular velocity during walking were analysed. RESULTS: The Modified Tardieu Scale was completed faster than the angular velocities seen during walking in 88.7% (0.400.59 m/s), 78.9% (0.600.79 m/s) and 56.2% (1.401.60 m/s) of trials. When compared with the normative dataset, 4.2%, 9.5% and 13.7% of the trials met all criteria for each respective walking speed. CONCLUSION: When applied according to the standardized procedure and compared with joint angular velocity during walking, clinicians performed the Modified Tardieu Scale too quickly.

The reproducibility and responsiveness of subjective assessment of upper limb associated reactions in people with acquired brain injury during walking.

OBJECTIVE: The aim of this study is to determine inter-rater, test-retest and intra-rater reproducibility and responsiveness of subjective assessment of upper limb associated reactions in people with acquired brain injury using (1) the 'Qualifiers Scale' of the International Classification of Functioning, Disability and Health Framework, and (2) visually estimated elbow flexion angle during walking. DESIGN: Observational study. SETTING: A brain injury rehabilitation centre, Melbourne, Australia. SUBJECTS: People with acquired brain injury and upper limb associated reactions and experienced neurological physiotherapists. MAIN MEASURES: The Qualifiers Scale applied to individual upper limb joints and global associated reaction on a 5-point scale (0-4), a summed upper limb severity score and visually estimated elbow flexion angle. RESULTS: A total of 42 people with acquired brain injury (mean age: 48.4 ± 16.5 years) were videoed walking at self-selected and fast speeds. A subset of 30 chronic brain injury participants (mean time post injury: 8.2 ± 9.3 years) were reassessed one week later for retest reproducibility. Three experienced neurological physiotherapists (mean experience: 22.7 ± 9.1 years) viewed these videos and subjectively rated the upper limb associated reactions. Strong-to-very strong test-retest, intra- and inter-rater reproducibility was found for elbow flexion angle (ICC > 0.86) and the Qualifiers Scale applied to global and individual upper limb joints (ICC > 0.60). Responsiveness of change from self-selected to fast walking speed (mean increase 0.46 m/s) was highest for elbow flexion angle (effect size = 0.83) and low-to-moderate for the Qualifiers Scale. CONCLUSION: Subjectively rated associated reactions during walking demonstrated strong reproducibility and moderate responsiveness to speed change. The Qualifiers Scale and elbow flexion angle can both subjectively quantify associated reactions during walking in a clinical setting.

Toward Accurate Clinical Spasticity Assessment: Validation of Movement Speed and Joint Angle Assessments Using Smartphones and Camera Tracking.

OBJECTIVE: To investigate whether a three-dimensional (3-D) camera (Microsoft Kinect) and a smartphone can be used to accurately quantify the joint angular velocity and range of motion (ROM) compared to a criterion-standard 3-D motion analysis system during a lower limb spasticity assessment. DESIGN: Observational, criterion-standard comparison study. SETTING: Large rehabilitation center. PARTICIPANTS: A convenience sample of 35 controls, 35 patients with a neurologic condition, and 34 rehabilitation professionals (physiotherapists and rehabilitation doctors) participated (N=104). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The Modified Tardieu Scale was used to assess spasticity of the quadriceps, hamstrings, soleus, and gastrocnemius. Data for each trial were collected concurrently using the criterion-standard Optitrack 3-D motion analysis (3DMA) system, Microsoft Kinect, and a smartphone. Each healthy control participant was assessed by 1 health professional and each patient with a neurological condition was assessed by 3 health professionals. Spearman correlation coefficient and intraclass correlation coefficient with 95% confidence intervals were used to report the strength of the relationships investigated. RESULTS: The smartphone and Microsoft Kinect demonstrated excellent concurrent validity with the 3DMA system. Overall, 74.8% of the relationships investigated demonstrated a very strong (≥0.80) correlation across all of the testing parameters. The Microsoft Kinect was superior to the smartphone for measuring joint start and end angle, the smartphone was superior for measuring joint angular velocity, and the 2 systems were comparable for measuring total joint ROM. CONCLUSIONS: These findings provide preliminary evidence that user-friendly, low-cost technologies can be used to facilitate accurate measurements of joint angular velocity and angles during a lower limb spasticity assessment in a clinical setting.

Three-dimensional cameras and skeleton pose tracking for physical function assessment: A review of uses, validity, current developments and Kinect alternatives.

BACKGROUND: Three-dimensional camera systems that integrate depth assessment with traditional two-dimensional images, such as the Microsoft Kinect, Intel Realsense, StereoLabs Zed and Orbecc, hold great promise as physical function assessment tools. When combined with point cloud and skeleton pose tracking software they can be used to assess many different aspects of physical function and anatomy. These assessments have received great interest over the past decade, and will likely receive further study as the integration of depth sensing and augmented reality smartphone cameras occurs more in everyday life. RESEARCH QUESTION: The aim of this review is to discuss how these devices work, what options are available, the best methods for performing assessments and how they can be used in the future. METHODS: Firstly, a review of the Microsoft Kinect devices and associated artificial intelligence, automated skeleton tracking algorithms is provided. This includes a narrative critique of the validity and clinical utility of these devices for assessing different aspects of physical function including spatiotemporal, kinematic and inverse dynamics data derived from gait and balance trials, and anatomical assessments performed using the depth sensor information. Methods for improving the accuracy of data are examined, including multiple-camera systems and sensor fusion with inertial monitoring units, model fitting, and marker tracking. Secondly, alternative hardware, including other structured light and time of flight methods, stereoscopic cameras and augmented reality leveraging smartphone and tablet cameras to perform measurements in three-dimensional space are summarised. Software options related to depth sensing cameras are then discussed, focussing on recent advances such as OpenPose and web-based methods such as PoseNet. RESULTS AND SIGNIFICANCE: The clinical and non-laboratory utility of these devices holds great promise for physical function assessment, and recent developments could strengthen their ability to provide important and impactful health-related data.

Assessment of isometric muscle strength and rate of torque development with hand-held dynamometry: Test-retest reliability and relationship with gait velocity after stroke.

Isometric rate of torque development examines how quickly force can be exerted and may resemble everyday task demands more closely than isometric strength. Rate of torque development may provide further insight into the relationship between muscle function and gait following stroke. Aims of this study were to examine the test-retest reliability of hand-held dynamometry to measure isometric rate of torque development following stroke, to examine associations between strength and rate of torque development, and to compare the relationships of strength and rate of torque development to gait velocity. Sixty-three post-stroke adults participated (60 years, 34 male). Gait velocity was assessed using the fast-paced 10 m walk test. Isometric strength and rate of torque development of seven lower-limb muscle groups were assessed with hand-held dynamometry. Intraclass correlation coefficients were calculated for reliability and Spearman's rho correlations were calculated for associations. Regression analyses using partial F-tests were used to compare strength and rate of torque development in their relationship with gait velocity. Good to excellent reliability was shown for strength and rate of torque development (0.82-0.97). Strong associations were found between strength and rate of torque development (0.71-0.94). Despite high correlations between strength and rate of torque development, rate of torque development failed to provide significant value to regression models that already contained strength. Assessment of isometric rate of torque development with hand-held dynamometry is reliable following stroke, however isometric strength demonstrated greater relationships with gait velocity. Further research should examine the relationship between dynamic measures of muscle strength/torque and gait after stroke.

Three-dimensional assessment of squats and drop jumps using the Microsoft Xbox One Kinect: Reliability and validity.

The Microsoft Xbox One Kinect™ (Kinect V2) contains a depth camera that can be used to manually identify anatomical landmark positions in three-dimensions independent of the standard skeletal tracking, and therefore has potential for low-cost, time-efficient three-dimensional movement analysis (3DMA). This study examined inter-session reliability and concurrent validity of the Kinect V2 for the assessment of coronal and sagittal plane kinematics for the trunk, hip and knee during single leg squats (SLS) and drop vertical jumps (DVJ). Thirty young, healthy participants (age = 23 ± 5yrs, male/female = 15/15) performed a SLS and DVJ protocol that was recorded concurrently by the Kinect V2 and 3DMA during two sessions, one week apart. The Kinect V2 demonstrated good to excellent reliability for all SLS and DVJ variables (ICC ≥ 0.73). Concurrent validity ranged from poor to excellent (ICC = 0.02 to 0.98) during the SLS task, although trunk, hip and knee flexion and two-dimensional measures of knee abduction and frontal plane projection angle all demonstrated good to excellent validity (ICC ≥ 0.80). Concurrent validity for the DVJ task was typically worse, with only two variables exceeding ICC = 0.75 (trunk and hip flexion). These findings indicate that the Kinect V2 may have potential for large-scale screening for ACL injury risk, however future prospective research is required.

Reliability and validity of the Wii Balance Board for assessment of standing balance: A systematic review.

The use of force platform technologies to assess standing balance is common across a range of clinical areas. Numerous researchers have evaluated the low-cost Wii Balance Board (WBB) for its utility in assessing balance, with variable findings. This review aimed to systematically evaluate the reliability and concurrent validity of the WBB for assessment of static standing balance. Articles were retrieved from six databases (Medline, SCOPUS, EMBASE, CINAHL, Web of Science, Inspec) from 2007 to 2017. After independent screening by two reviewers, 25 articles were included. Two reviewers performed the data extraction and quality assessment. Test-retest reliability was investigated in 12 studies, with intraclass correlation coefficients or Pearson's correlation values showing a range from poor to excellent reliability (range: 0.27 to 0.99). Concurrent validity (i.e. comparison with another force platform) was examined in 21 studies, and was generally found to be excellent in studies examining the association between the same outcome measures collected on both devices. For studies reporting predominantly poor to moderate validity, potentially influential factors included the choice of 1) criterion reference (e.g. not a common force platform), 2) test duration (e.g. <30 s for double leg), 3) outcome measure (e.g. comparing a centre of pressure variable from the WBB with a summary score from the force platform), 4) data acquisition platform (studies using Apple iOS reported predominantly moderate validity), and 5) low sample size. In conclusion, evidence suggests that the WBB can be used as a reliable and valid tool for assessing standing balance. Protocol registration number: PROSPERO 2017: CRD42017058122.

Assessment of Lower Limb Muscle Strength and Power Using Hand-Held and Fixed Dynamometry: A Reliability and Validity Study.

INTRODUCTION: Hand-held dynamometry (HHD) has never previously been used to examine isometric muscle power. Rate of force development (RFD) is often used for muscle power assessment, however no consensus currently exists on the most appropriate method of calculation. The aim of this study was to examine the reliability of different algorithms for RFD calculation and to examine the intra-rater, inter-rater, and inter-device reliability of HHD as well as the concurrent validity of HHD for the assessment of isometric lower limb muscle strength and power. METHODS: 30 healthy young adults (age: 23±5 yrs, male: 15) were assessed on two sessions. Isometric muscle strength and power were measured using peak force and RFD respectively using two HHDs (Lafayette Model-01165 and Hoggan microFET2) and a criterion-reference KinCom dynamometer. Statistical analysis of reliability and validity comprised intraclass correlation coefficients (ICC), Pearson correlations, concordance correlations, standard error of measurement, and minimal detectable change. RESULTS: Comparison of RFD methods revealed that a peak 200 ms moving window algorithm provided optimal reliability results. Intra-rater, inter-rater, and inter-device reliability analysis of peak force and RFD revealed mostly good to excellent reliability (coefficients ≥ 0.70) for all muscle groups. Concurrent validity analysis showed moderate to excellent relationships between HHD and fixed dynamometry for the hip and knee (ICCs ≥ 0.70) for both peak force and RFD, with mostly poor to good results shown for the ankle muscles (ICCs = 0.31-0.79). CONCLUSIONS: Hand-held dynamometry has good to excellent reliability and validity for most measures of isometric lower limb strength and power in a healthy population, particularly for proximal muscle groups. To aid implementation we have created freely available software to extract these variables from data stored on the Lafayette device. Future research should examine the reliability and validity of these variables in clinical populations.

Predicting Dynamic Foot Function From Static Foot Posture: Comparison Between Visual Assessment, Motion Analysis, and a Commercially Available Depth Camera.

UNLABELLED: STUDY DESIGN :Controlled laboratory study. OBJECTIVE: To evaluate the ability of 3 methods to assess static foot posture to predict rearfoot and midfoot kinematics during gait. BACKGROUND: Static foot posture is commonly used clinically to infer dynamic function. Limitations of static clinical assessments may be overcome through advances in technologies, including commercially available depth cameras. METHODS: The Foot Posture Index (FPI) of 31 males (average age, 22.5 years) was assessed using visual observation, a 3-D motion-analysis system, and a depth camera. Pearson correlations were used to evaluate relationships between FPI items and rearfoot and midfoot kinematics during walking. The ability of the static variables to predict dynamic function was assessed using multiple linear regression. RESULTS: Most FPI items (85%) were not correlated with foot kinematics, regardless of assessment method. There were 6 fair to moderate correlations between visual FPI items and total rearfoot (r = -0.36 to -0.39, P<.05) and midfoot (r = 0.37 to 0.61, P<.05) motion, 2 fair correlations between 3-D motion-analysis FPI items and total midfoot (r = -0.43, P = .02) and peak rearfoot (r = -0.40, P = .03) motion, and 2 fair correlations between the depth-camera FPI items and average rearfoot (r = -0.38 to 0.44, P<.05) motion. Visual assessment of the FPI provided the best prediction model, explaining 37% of the variance in total midfoot inversion/eversion. CONCLUSION: Static measures of foot posture are weakly correlated with rearfoot or midfoot kinematics, and have limited dynamic prediction ability. Our findings suggest that the FPI may not be an accurate representation of rearfoot or midfoot movement during walking, regardless of the measurement technique employed.

Gait assessment using the Microsoft Xbox One Kinect: Concurrent validity and inter-day reliability of spatiotemporal and kinematic variables.

The revised Xbox One Kinect, also known as the Microsoft Kinect V2 for Windows, includes enhanced hardware which may improve its utility as a gait assessment tool. This study examined the concurrent validity and inter-day reliability of spatiotemporal and kinematic gait parameters estimated using the Kinect V2 automated body tracking system and a criterion reference three-dimensional motion analysis (3DMA) marker-based camera system. Thirty healthy adults performed two testing sessions consisting of comfortable and fast paced walking trials. Spatiotemporal outcome measures related to gait speed, speed variability, step length, width and time, foot swing velocity and medial-lateral and vertical pelvis displacement were examined. Kinematic outcome measures including ankle flexion, knee flexion and adduction and hip flexion were examined. To assess the agreement between Kinect and 3DMA systems, Bland-Altman plots, relative agreement (Pearson's correlation) and overall agreement (concordance correlation coefficients) were determined. Reliability was assessed using intraclass correlation coefficients, Cronbach's alpha and standard error of measurement. The spatiotemporal measurements had consistently excellent (r≥0.75) concurrent validity, with the exception of modest validity for medial-lateral pelvis sway (r=0.45-0.46) and fast paced gait speed variability (r=0.73). In contrast kinematic validity was consistently poor to modest, with all associations between the systems weak (r<0.50). In those measures with acceptable validity, the inter-day reliability was similar between systems. In conclusion, while the Kinect V2 body tracking may not accurately obtain lower body kinematic data, it shows great potential as a tool for measuring spatiotemporal aspects of gait.

Reliability and concurrent validity of the Microsoft Xbox One Kinect for assessment of standing balance and postural control.

The Microsoft Kinect V2 for Windows, also known as the Xbox One Kinect, includes new and potentially far improved depth and image sensors which may increase its accuracy for assessing postural control and balance. The aim of this study was to assess the concurrent validity and reliability of kinematic data recorded using a marker-based three dimensional motion analysis (3DMA) system and the Kinect V2 during a variety of static and dynamic balance assessments. Thirty healthy adults performed two sessions, separated by one week, consisting of static standing balance tests under different visual (eyes open vs. closed) and supportive (single limb vs. double limb) conditions, and dynamic balance tests consisting of forward and lateral reach and an assessment of limits of stability. Marker coordinate and joint angle data were concurrently recorded using the Kinect V2 skeletal tracking algorithm and the 3DMA system. Task-specific outcome measures from each system on Day 1 and 2 were compared. Concurrent validity of trunk angle data during the dynamic tasks and anterior-posterior range and path length in the static balance tasks was excellent (Pearson's r>0.75). In contrast, concurrent validity for medial-lateral range and path length was poor to modest for all trials except single leg eyes closed balance. Within device test-retest reliability was variable; however, the results were generally comparable between devices. In conclusion, the Kinect V2 has the potential to be used as a reliable and valid tool for the assessment of some aspects of balance performance.

Instrumenting gait assessment using the Kinect in people living with stroke: reliability and association with balance tests.

BACKGROUND: The Microsoft Kinect has been used previously to assess spatiotemporal aspects of gait; however the reliability of this system for the assessment of people following stroke has not been established. This study examined the reliability and additional information that the Kinect provides when instrumenting a gait assessment in people living with stroke. METHODS: The spatiotemporal variables of step length, step length asymmetry, foot swing velocity, foot swing velocity asymmetry, peak and mean gait speed and the percentage difference between the peak and mean gait speed were assessed during gait trials in 30 outpatients more than three months post-stroke and able to stand unsupported. Additional clinical assessments of functional reach (FR), step test (ST), 10 m walk test (10MWT) and the timed up and go (TUG) were performed, along with force platform instrumented assessments of center of pressure path length velocity during double-legged standing balance with eyes closed (DLEC), weight bearing asymmetry (WBA) and dynamic medial-lateral weight-shifting ability (MLWS). These tests were performed on two separate occasions, seven days apart for reliability assessment. Separate adjusted multiple regressions models for predicting scores on the clinical and force platform assessments were created using 1) the easily assessed clinically-derived gait variables 10MWT time and total number of steps; and 2) the Kinect-derived variables which were found to be reliable (ICC > 0.75) and not strongly correlated (Spearman's ρ < 0.80) with each other (i.e. non-redundant). RESULTS: Kinect-derived variables were found to be highly reliable (all ICCs > 0.80), but many were redundant. The final regression model using Kinect-derived variables consisted of the asymmetry scores, mean gait velocity, affected limb foot swing velocity and the difference between peak and mean gait velocity. In comparison with the clinically-derived regression model, the Kinect-derived model accounted for >15% more variance on the MLWS, ST and FR tests and scored similarly on all other measures. CONCLUSIONS: In conclusion, instrumenting gait using the Kinect is reliable and provides insight into the dynamic balance capacity of people living with stroke. This system provides a minimally intrusive method of examining potentially important gait characteristics in people living with stroke.

Concurrent validity of the Microsoft Kinect for assessment of spatiotemporal gait variables.

Spatiotemporal characteristics of gait such as step time and length are often associated with overall physical function in clinical populations, but can be difficult, time consuming and obtrusive to measure. This study assessed the concurrent validity of overground walking spatiotemporal data recorded using a criterion reference - a marker-based three-dimensional motion analysis (3DMA) system - and a low-cost, markerless alternative, the automated skeleton tracking output from the Microsoft Kinect™ (Kinect). Twenty-one healthy adults performed normal walking trials while being monitored using both systems. The outcome measures of gait speed, step length and time, stride length and time and peak foot swing velocity were derived using supervised automated analysis. To assess the agreement between the Kinect and 3DMA devices, Bland-Altman 95% bias and limits of agreement, percentage error, relative agreement (Pearson's correlation coefficients: r) overall agreement (concordance correlation coefficients: rc) and landmark location linearity as a function of distance from the sensor were determined. Gait speed, step length and stride length from the two devices possessed excellent agreement (r and rc values >0.90). Foot swing velocity possessed excellent relative (r=0.93) but only modest overall (rc=0.54) agreement. Step time (r=0.82 and rc=0.23) and stride time (r=0.69 and rc=0.14) possessed excellent and modest relative agreement respectively but poor overall agreement. Landmark location linearity was excellent (R(2)=0.991). This widely available, low-cost and portable system could provide clinicians with significant advantages for assessing some spatiotemporal gait parameters. However, caution must be taken when choosing outcome variables as some commonly reported variables cannot be accurately measured.