Mobile inertial sensor based gait analysis: Validity and reliability of spatiotemporal gait characteristics in healthy seniors

Gait analysis is commonly used to identify gait changes and fall risk in clinical populations and seniors. Body-worn inertial sensor based gait analyses provide a feasible alternative to optometric and pressure based measurements of spatiotemporal gait characteristics. We assessed validity and relative and absolute reliability of a body-worn inertial sensor system (RehaGait^®) for measuring spatiotemporal gait characteristics compared to a standard stationary treadmill (Zebris^®). Spatiotemporal gait parameters (walking speed, stride length, cadence and stride time) were collected for 24 healthy seniors (age: 75.3 ± 6.7 years) tested on 2 days (1 week apart) simultaneously using the sensor based system and instrumented treadmill. Each participant completed walking tests (200 strides) at different walking speeds and slopes. The difference between the RehaGait^® system and the treadmill was trivial (Cohen’s d <0.2) except for speed and stride length at slow speed (Cohen’s d, 0.35 and 0.49, respectively). Intraclass correlation coefficients (ICC) were excellent for temporal gait characteristics (cadence and stride time; ICC: 0.99–1.00) and moderate for stride length (ICC: 0.73–0.89). Both devices had excellent day-to-day reliability for all gait parameters (ICC: 0.82–0.99) except for stride length at slow speed (ICC: 0.74). The RehaGait^® is a valid and reliable tool for assessing spatiotemporal gait parameters for treadmill walking at different speeds and slopes.     

The use of a single inertial sensor to identify stride,step, and stance durations of running gait

Current developments in inertial sensor technology could enable the measurement of running gait outside of the traditional laboratory environment. The purpose of this research was to determine the level of agreement between an inertial sensor and infrared camera based estimates of stride, step, and stance durations across a range of running speeds. An inertial sensor was placed on the sacrum of 10 elite national standard runners, and the stride, step, and stance of running gait were compared. A total of 504 samples were collected and the running velocities stratified into three equal groups of low (10–12 km/h), medium (13–15 km/h), and high (16–19 km/h). A single inertial sensor was found to be suitable for identifying stride duration with Bland–Altman limits of agreement of 95%. The stride data showed agreement at less than 0.02 s for most limits. Agreement for step showed five of the eight upper and lower limits below 0.02 s. The largest differences between both capture methods were for stance. An average bias of 0.0008 s was found and standard error ranged between 0.0004 s and 0.0009 s across all variables. The results from this research found that inertial sensors are suitable to measure stride, step, and stance duration, and provide the opportunity to measure running gait outside of the traditional laboratory.     

Three-dimensional lumbar segment movement characteristics during paediatric cerebral palsy gait

Kinematic analysis of the trunk during cerebral palsy (CP) gait has been well described. In contrast, movement of the lumbar spine is generally ignored. This is most likely due to the complex nature of the spine. As an alternative to using complex sensor protocols, this study modelled the lumbar region as a single segment and investigated characteristic patterns of movement during CP gait. In addition, the impact of functional level of impairment and the relationship with lower lumbar spinal loading were examined. Fifty-two children with CP (26 GMFCS I and 26 GMFCS II) and 26 controls were recruited. A full barefoot 3-dimensional kinematic and kinetic analysis were conducted. Lumbar segment movement demonstrated increased forward flexion for CP children. This movement became more pronounced according to GMFCS level with GMFCS II children demonstrating increases of up to 8°. In addition, a moderate correlation was present between lumbar flexion/extension and L5/S1 sagittal moments (r = 0.427 in the global frame and r = 0.448 with respect to the pelvis, p < 0.01). Children with CP demonstrated increased movement of the lumbar region compared to TD, with movement becoming more excessive as GMFCS level increased. Excessive forward flexion and loading at the lumbar spine were linked. However, the moderate correlation suggests other contributors to increased loading were present. In conclusion, this study is a first step at identifying how lumbar segment movement is altered during CP gait.     

The association between fear of falling and gait variability in both leg and trunk movements

The aim of this study was to explore whether FoF was associated with variability in both leg and trunk movements during gait in community-dwelling elderly. Ninety-three elderly people participated in this study. Each participant was categorized into either Fear or No-Fear group on the basis of having FoF. The participants walked 15 m at their preferred speed. The wireless motion recording sensor units were attached to L3 spinous process and right posterior surface of heel during gait. Gait velocity, stride time and stride length were calculated. Variability in lower limb movements was represented by coefficient of variation (CV) of stride time. Trunk variability was represented by autocorrelation coefficients (AC) in three directions (vertical: VT, mediolateral: ML and anteroposterior: AP), respectively. Gait parameters were compared between groups, and further analyses were performed using generalized linear regression models after adjustment of age, sex, fall experience, height, weight, and gait velocity. Although gait velocity, mean stride time and stride length did not differ significantly between groups, stride time CV and all ACs were significantly worse in the Fear group after adjustment for variables, even including gait velocity (stride time CV: p = 0.003, β = −0.793; AC-VT: p = 0.011, β = 0.053; AC-ML: p = 0.044, β = 0.075; AC-AP: p = 0.002, β = 0.078). Our results suggest that fear of falling is associated with variability in both leg and trunk movements during gait in community-dwelling elderly. Further studies are needed to prove a causal relationship.     

Direct comparison of PI-RADS version 2 and version 1 regarding interreader agreement and diagnostic accuracy for the detection of clinically significant prostate cancer

Purposeto simultaneously evaluate interreader agreement and diagnostic accuracy in the of PI-RADS v2 and compare it to v1.MethodsA total of 67 patients (median age 65.3 y, range 51.2–78.2 y; PSA 6.8 μg/L, 0.2–33 μg/L) undergoing MRI of the prostate and subsequent transperineal template biopsy within ≤6 months from MRI were included. Four readers from two institutions evaluated the likelihood of prostate cancer using PI-RADS v1 and v2 in two separate reading sessions ≥3 months apart. Interreader agreement was assessed for each pulse-sequence and for total PI-RADS scores using the intraclass correlation coefficient (ICC). Differences were considered significant for non-overlapping 95%-confidence intervals. Diagnostic accuracy was assessed with the area under the receiver operating characteristic curve (A_Z). A p-value <0.05 was considered statistically significant.ResultsInterreader agreement for DCE-scores was good in v2 (ICC₂ = 0.70; 95% CI: 0.66–0.74) and slightly lower in v1 (ICC₁ = 0.64, 0.59–0.69). Agreement for DWI scores (ICC₁ = 0.77, ICC₂ = 0.76) as well as final PI-RADS scores per quadrant were nearly identical (ICC₁ = ICC₂ = 0.71). Diagnostic accuracy showed no significant differences (p = 0.09–0.93) between v1 and v2 in any of the readers (range: A_Z = 0.78–0.88).ConclusionPI-RADS scores show similar interreader agreement in v2 and v1 at comparable diagnostic performance. The simplification of the DCE interpretation in v2 might slightly improve agreement while not negatively affecting diagnostic performance.     

Validity and test-retest reliability of the Stride Analyzer in people with knee osteoarthritis

IntroductionSubjects with knee osteoarthritis walk differently compared to healthy subjects. Managing these gait alterations has been proven effective for reducing pain and increasing function. The Stride Analyzer is a low cost gait analysis tool but its clinimetric properties have not been investigated yet in subjects with symptomatic knee osteoarthritis. The aim of this study was to investigate the reliability and validity of the SA compared with the Gold standard (Vicon) in persons with knee OA.MethodsFifteen subjects with symptomatic knee osteoarthritis were instructed to walk at a self-selected speed in a gait laboratory. Temporospatial (TS) gait parameters were recorded simultaneously by the Stride Analyzer and by a 16-camera-infrared optoelectronic motion capturing system (Vicon). Validity and test-retest reliability of the Stride Analyzer were examined by Bland-Altman plots, intra-class correlation coefficients (ICC) and the standard error of measurement (SEM).ResultsTest-retest analyses showed good agreement for all TS parameters with ICC values ranging from 0.805 (single limb support right) to 0.949 (velocity) and SEM% values ranging from 0.78% (stance phase right (% of gait cycle)) to 4.52% (double limb support right (% of gait cycle)). Good agreement between Stride Analyzer and Vicon was found for the following TS parameters: velocity (z = 1.01), cadence (z = −0.85), stride length (z = 1.63) and gait cycle (z = 0.86). All other gait parameters showed lower ICC values (<0.689).InterpretationOur results suggest that the Stride Analyzer can be used in the clinical field to perform gait analysis in subjects with symptomatic knee osteoarthritis.     

Acute effects of anesthetic lumbar spine injections on temporal spatial parameters of gait in individuals with chronic low back pain: A pilot study

This study examined whether epidural injection-induced anesthesia acutely and positively affected temporal spatial parameters of gait in patients with chronic low back pain (LBP) due to lumbar spinal stenosis. Twenty-five patients (61.7 ± 13.6 years) who were obtaining lumbar epidural injections for stenosis-related LBP participated. Oswestry Disability Index (ODI) scores, Medical Outcomes Short Form (SF-36) scores, 11-point Numerical pain rating (NRS_pain) scores, and temporal spatial parameters of walking gait were obtained prior to, and 11-point Numerical pain rating (NRS_pain) scores, and temporal spatial parameters of walking gait were obtained after the injection. Gait parameters were measured using an instrumented gait mat. Patients received transforaminal epidural injections in the L1-S1 vertebral range (1% lidocaine, corticosteroid) under fluoroscopic guidance. Patients with post-injection NRS_pain ratings of “0” or values greater than “0” were stratified into two groups: 1) full pain relief, or 2) partial pain relief, respectively. Post-injection, 48% (N = 12) of patients reported full pain relief. ODI scores were higher in patients with full pain relief (55.3 ± 21.4 versus 33.7 12.8; p = 0.008). Post-injection, stride length and step length variability were significantly improved in the patients with full pain relief compared to those with partial pain relief. Effect sizes between full and partial pain relief for walking velocity, step length, swing time, stride and step length variability were medium to large (Cohen’s d > 0.50). Patients with LBP can gain immediate gait improvements from complete pain relief from transforaminal epidural anesthetic injections for LBP, which could translate to better stability and lower fall risk.     

In-depth analysis of interreader agreement and accuracy in categorical assessment of brown adipose tissue in (18)FDG-PET/CT

PurposeTo evaluate the interreader agreement of a three-tier craniocaudal grading system for brown fat activation and investigate the accuracy of the distinction between the three grades.Materials and methodsAfter IRB approval, 340 cases were retrospectively selected from patients undergoing (18)FDG-PET/CT between 2007 and 2015 at our institution, with 85 cases in each grade and 85 controls with no active brown fat. Three readers evaluated all cases independently. Furthermore standardized uptake values (SUV) measurements were performed by two readers in a subset of 53 cases. Agreement between the readers was assessed with Cohen's Kappa (k), the concordance correlation coefficient (CCC) and the intraclass correlation coefficient (ICC). Accuracy was assessed with Bland-Altman and receiver operating characteristics (ROC) analysis. A Bonferroni-corrected two-tailed p < 0.016 was considered statistically significant.ResultsAgreement for BAT grade was excellent by all three metrics with k = 0.83–0.89, CCC = 0.83–0.89 and ICC = 0.91–0.94. Bland-Altman analysis revealed only slight average over- or underestimation (−0.01−0.14) with the majority of disagreements within one grade. ROC analysis yielded slightly less accurate classification between higher vs. lower grades (Area under the ROC curves 0.78–0.84 vs. 0.88–0.92) but no significant differences between readers. Agreement was also excellent for the maximum SUV and the total brown fat volume (k = 0.90 and 0.94, CCC = 0.93 and 0.99, ICC = 0.96 and 0.99), but Bland-Altman plots revealed a tendency to underestimate activity by one of the readers.ConclusionGrading the activation of brown fat by assessment of the most caudally activated depots results in excellent interreader agreement, comparable to SUV measurements.     

Reproducibility of gait variability measures in people with Alzheimer's disease

Gait variability may be especially important to measure in people with Alzheimer's disease (AD) as it is related to risk of falling and may reflect the cognitive demand of walking. Its usefulness as an outcome measure in people with AD is currently limited by the lack of published evaluation of its reproducibility. Therefore measures of temporal and spatial gait variability were recorded using an instrumented mat on two occasions, one week apart in 16 community-dwelling people with mild to moderate probable AD. Data were combined in three ways for analysis: all available strides; all available strides from walks with mean velocity within 10 cm/s of each other; and the first 12 strides from the second method. Measures of velocity, stride length and cadence variability were all found to have good reliability using an average of 64 strides from velocity-matched walks (ICC_3,1 0.77–0.90) however only stride length variability reached acceptable reliability for a clinical test (ICC_3,1 0.9). Estimates of the number of strides required to reach an ICC of 0.9 for velocity, cadence and stride width variability were between 169 and 212. Poor to moderate reliability of gait variability measures was obtained using 12 strides. Minimal detectable change values, calculated to reflect absolute agreement, appear to be feasible and may assist with evaluation of interventions to improve gait. Further research should examine the effects on reproducibility of gait variability measures, of systematic cueing aimed at producing consistent, optimal walking in larger groups with a range of dementia type and severity.     

Analysis of stroke patient walking dynamics using a tri-axial accelerometer

The purpose of this study was to describe the characteristics of stroke patient gait using the acceleration signals which were obtained during walking. Sixty-three stroke hemiplegic patients and 21 age-matched healthy elderly individuals took part in this study. A wireless tri-axial accelerometer, fixed to a belt at the level of the L3 spinous process, was used to measure trunk acceleration. Subjects were instructed to walk at a self-selected, comfortable walking speed. The acceleration signal was sampled at the rate of 200 Hz. Gait parameters and functional recovery tests were also evaluated. We analyzed the correlation between the gait parameters, functional recovery and acceleration. Acceleration was utilized as the root mean square (RMS), normalized RMS by velocity and average step length, as a measure of gait smoothness, and autocorrelation (AC) as a measure of stride similarity and regularity. The raw RMS and AC values of the stroke were significantly lower than the matched healthy elderly (p < 0.01) in all axes. In contrast, the stroke patients’ normalized RMS values were higher than the controls (p < 0.05) in all axes. These results suggest that accelerometry gait parameters can discriminate between the stroke patients and the control group. The values of normalized RMS correlated with the smoothness or dynamics of the walking pattern, which reflects motor recovery and gait abilities. This study suggests that normalized RMS of accelerometer recordings from the trunk is valid in objectively measuring walking movements as an index of treatment outcome for patients in rehabilitation.     

Position of the major curve influences asymmetrical trunk kinematics during gait in adolescent idiopathic scoliosis

Background and purposeAdolescent idiopathic scoliosis (AIS) is a structural, lateral curvature with rotation of the spine that develops around puberty. The influence of this spinal deformity on three-dimensional trunk movements during gait has not yet been elucidated. The aim of this study was to determine the influence of spinal curve pattern (single thoracic curve vs. single lumbar curve) on trunk kinematics during gait.MethodsTwenty-two patients with a single thoracic curve (Lenke type 1) and 17 patients with a single lumbar curve (Lenke type 5) were included in this study. Trunk symmetry in the sagittal, coronal, and transverse planes during gait was evaluated using an optoelectronic motion capture system.ResultsIn the type 1 group, the trunk was significantly rotated towards the concave side in the transverse plane during gait (mean difference of transverse rotation angle between concave side load and the convex side load, 8.8 ± 0.6°, p < 0.01). In the type 5 group, the trunk was significantly rotated towards the convex side in the coronal plane throughout the stance phase of gait (mean difference of coronal inclination angle, 1.9 ± 0.3°, p < 0.05).ConclusionsThe AIS patients with a single thoracic curve showed asymmetrical trunk movement in the transverse plane, and patients with a single lumbar curve showed asymmetrical trunk movement in the coronal plane. These results indicate that the spinal curve pattern influenced trunk kinematics, and suggest that the global postural control strategy of patients with AIS differs according to the curve pattern.     

Smoothness of gait detects early alterations of walking in persons with multiple sclerosis without disability

In people with Multiple Sclerosis (pwMS) with little or no signs of disability, early detection of walking impairments represents a challenging issue, as simple gait metrics (e.g. speed, cadence, stride length, etc.) may not significantly differ from those of healthy individuals. In this study, we aimed to assess the existence of possible differences in spatial-temporal parameters and smoothness of gait measures (assessed through Harmonic Ratio, HR) obtained from trunk accelerations between 50 pwMS without disability (Expanded Disability Status Scale score =1) and 50 age-matched healthy controls. The results show no differences in terms of gait velocity, stride length, stance/swing and double support phases duration, while HR in the direction of motion was significantly lower in pwMS (2.92 vs. 3.67, p < 0.001), thus indicating a less smooth gait. The study of trunk accelerations through calculation of HR represents a fast, non-intrusive technique that allows early identification of anomalies in gait patterns of pwMS in absence of disability.     

Decreased skin temperature of the foot increases gait variability in healthy young adults

We investigated the effects of reduction in plantar skin temperature on gait. Thirty-four healthy subjects (20 men and 14 women; mean age 22.2 ± 2.5 years; mean height 166.8 ± 8.3 cm) walked 16 m under two different conditions – normal conditions (NC) with the skin at a basal temperature, and cold conditions (CC) after cooling of the plantar skin to about 15 °C. Wireless motion-recording sensor units were placed on the back at the level of L3 and on both heels to measure acceleration and angular velocity. Gait velocity and mean stride, stance and swing times were calculated. The variability of lower limb movement was represented by the coefficients of variation (CVs) of stride, stance and swing times, and that of trunk movement was represented by autocorrelation coefficients (ACs) in three directions (vertical: VT; mediolateral: ML; and anteroposterior: AP). Gait velocity was significantly lower under CC conditions than under NC (p < 0.0001). None of the temporal parameters were changed by plantar cooling. However, all parameters of gait variability were significantly worse under CC, and AC-VT, AC-ML, and AC-AP were significantly lower under CC than under NC, even after adjusting for gait velocity (p = 0.0005, 0.0071, and 0.0126, respectively). Our results suggest that reducing plantar skin temperature induces gait variability among healthy young adults. Further studies are now needed to explore the relationship between plantar skin temperature and gait in the elderly.     

Cognitive motor interference during dual-task gait in essential tremor

BackgroundFunctional ambulation requires concurrent performance of motor and cognitive tasks, which may create interference (degraded performance) in either or both tasks. People with essential tremor (ET) demonstrate impairments in gait and cognitive function. In this study we examined the extent of interference between gait and cognition in people with ET and controls during dual-task gait.MethodsWe tested 62 controls and 151 ET participants (age range: 72–102). ET participants were divided into two groups based on median score on the modified Mini Mental State Examination. Participants walked at their preferred speed, and performed a verbal fluency task while walking. We analyzed gait velocity, cadence, stride length, double support time, stride time, step width, step time difference, coefficient of variation (CV) of stride time and stride length.ResultsVerbal fluency performance during gait was similar across groups (p = 0.68). Velocity, cadence and stride length were lowest whereas step time difference (p = 0.003), double support time (p = 0.009), stride time (p = 0.002) and stride time CV (p = 0.007) were highest for ET participants with lower cognitive scores (ETp-LCS), compared with ET participants with higher cognitive scores (ETp-HCS) and controls. ETp-LCS demonstrated greatest interference for double support time (p = 0.005), step time difference (p = 0.013) and stride time coefficient of variation (p = 0.03).ConclusionsETp-LCS demonstrated high levels of cognitive motor interference. Gait impairments during complex tasks may increase risk for falls for this subgroup and underscore the importance of clinical assessment of gait under simple and dual-task conditions.     

Therapeutic effect of functional electrical stimulation-triggered gait training corresponding gait cycle for stroke

The purpose of this study was to determine the therapeutic effects of functional electrical stimulation (FES) applied to the gluteus medius and tibialis anterior muscles during the gait cycle in individuals with hemiparetic stroke. Eighteen patients who had suffered a stroke were enrolled in this study. The participants were divided into either the gluteus medius and tibialis anterior (GM + TA) training group (n = 9) or the control group (n = 9). The GM + TA group received FES-triggered gait training to the gluteus medius (GM) in the stance phase and the tibialis anterior (TA) in the swing phase for 30 min, 5 session a week over a 6-week period, and control group who received only gait training without FES-triggered for the same duration of time. A foot-switch sensor was used to trigger the device in the stance (GM) and swing (TA) phases of the gait cycle reciprocally. This study measured three types of outcome measures, including spatiotemporal gait parameters, muscles activities, and balance function. After 6 weeks training, there was a significant improvement in gait velocity, cadence, stride length, and gait symmetry in the GM + TA training group compared to the control group. Dynamic balance function was significantly improved in the GM + TA training group compared to the control group. The mean changeable values of the GM was significantly greater strength in the GM + TA training group than the control group. These findings suggest that FES-triggered gait training of the GM in the stance phase and TA in the swing phase may improve the spatiotemporal parameters of gait in persons with hemiparetic stroke.     

Estimation of foot trajectory during human walking by a wearable inertial measurement unit mounted to the foot

To establish a supportive technology for reducing the risk of falling in older people, it is essential to clarify gait characteristics in elderly individuals that are possibly linked to the risk of falling during actual daily activities. In this study, we developed a system to monitor human gait in an outdoor environment using an inertial measurement unit consisting of a tri-axial accelerometer and tri-axial gyroscope. Step-by-step foot trajectories were estimated from the sensor unit attached to the dorsum of the foot. Specifically, stride length and foot clearance were calculated by integrating the gravity-compensated translational acceleration over time during the swing phase. Zero vertical velocity and displacement corrections were applied to obtain the final trajectory, assuming the slope of the walking surface is negligible. Short, normal, and long stride-length walking of 10 healthy participants was simultaneously measured using the proposed system and a conventional motion capture system to evaluate the accuracy of the estimated foot trajectory. Mean accuracy and precision were approximately 20 ± 50 mm, for stride length, and 2 ± 7 mm for foot clearance, indicating that the swing phase trajectory of the sensor unit attached to the foot was reconstructed more accurately and precisely using the proposed system than with previously published methods owing to the flat floor assumption. Although some methodological limitations certainly apply, this system will serve as a useful tool to monitor human walking during daily activities.     

Effectiveness of an innovative hip energy storage walking orthosis for improving paraplegic walking: A pilot randomized controlled study

BackgroundThe high energy cost of paraplegic walking using a reciprocating gait orthosis (RGO) is attributed to limited hip motion and excessive upper limb loading for support. To address the limitation, we designed the hip energy storage walking orthosis (HESWO) which uses a spring assembly on the pelvic shell to store energy from the movements of the healthy upper limbs and flexion-extension of the lumbar spine and hip and returns this energy to lift the pelvis and lower limb to assist with the swing and stance components of a stride. Our aim was to evaluate gait and energy cost indices for the HESWO compared to the RGO in patients with paraplegia.MethodsThe cross-over design was used in the pilot study. Twelve patients with a complete T4-L5 chronic spinal cord injury underwent gait training using the HESWO and RGO. Gait performance (continuous walking distance, as well as the maximum and comfortable walking speeds) and energy expenditure (at a walking speed of 3.3 m/min on a treadmill) were measured at the end of the 4-week training session.ResultsCompared to the RGO, the HESWO increased continuous walking distance by 24.7% (P < 0.05), maximum walking speed by 20.4% (P < 0.05) and the comfortable walking speed by 15.3% (P < 0.05), as well as decreasing energy expenditure by 13.9% (P < 0.05).ConclusionOur preliminary results provide support for the use of the HESWO as an alternative support for paraplegic walking.     

Reliability and minimum detectable change of the gait profile score for post-stroke patients

The objectives of this work were (i) to determine Gait Profile Score (GPS) for hemiparetic stroke patients, (ii) to evaluate its reliability within and between sessions, and (iii) to establish its minimal detectable change (MDC). Seventeen hemiparetic patients (mean age 54.9 ± 10.5 years; 9 men and 8 women; 6 hemiparetic on the left side and 11 on the right side; mean time after stroke 6.1 ± 3.5 months) participated in 2 gait assessment sessions within an interval of 2–7 days. Intra-session reliability was obtained from the intraclass correlation coefficient (ICC) between the three strides of each session. Inter-session reliability was estimated by the ICC from the averages of that three strides. GPS value of non paretic lower limb (NPLL) (13.9 ± 2.4°) was greater than that of paretic lower limb (PLL) (12.0 ± 2.8°) and overall GPS (GPS_O) was 13.7 ± 2.5°. The Gait Variable Scores (GVS), GPS and GPS_O exhibited intra-session ICC values between 0.70 and 0.99, suggesting high intra-day stability. Most of GVS exhibited excellent inter-session reliability (ICC between 0.81 and 0.93). Only hip rotation, hip abduction of PLL exhibited moderate reliability with ICC/MDC values of 0.57/10.0° and 0.71/3.1°, respectively. ICC/MDC values of GPS were 0.92/2.3° and 0.93/1.9° for PLL and NPLL, respectively. GPS_O exhibited excellent test-retest reliability (ICC = 0.95) and MDC of 1.7°. Given its reliability, the GPS has proven to be a suitable tool for therapeutic assessment of hemiparetic patients after stroke.     

Validity and repeatability of three in-shoe pressure measurement systems

In-shoe pressure measurement devices are used in research and clinic to quantify plantar foot pressures. Various devices are available, differing in size, sensor number and type; therefore accuracy and repeatability. Three devices (Medilogic, Tekscan and Pedar) were examined in a 2 day × 3 trial design, quantifying insole response to regional and whole insole loading. The whole insole protocol applied an even pressure (50–600 kPa) to the insole surface for 0–30 s in the Novel TruBlue™ device. The regional protocol utilised cylinders with contact surfaces of 3.14 and 15.9 cm² to apply pressures of 50 and 200 kPa. The validity (% difference and Root Mean Square Error: RMSE) and repeatability (Intra-Class Correlation Coefficient: ICC) of the applied pressures (whole insole) and contact area (regional) were outcome variables. Validity of the Pedar system was highest (RMSE 2.6 kPa; difference 3.9%), with the Medilogic (RMSE 27.0 kPa; difference 13.4%) and Tekscan (RMSE 27.0 kPa; difference 5.9%) systems displaying reduced validity. The average and peak pressures demonstrated high between-day repeatability for all three systems and each insole size (ICC ≥ 0.859). The regional contact area % difference ranged from −97 to +249%, but the ICC demonstrated medium to high between-day repeatability (ICC ≥ 0.797). Due to the varying responses of the systems, the choice of an appropriate pressure measurement device must be based on the loading characteristics and the outcome variables sought. Medilogic and Tekscan were most effective between 200 and 300 kPa; Pedar performed well across all pressures. Contact area was less precise, but relatively repeatable for all systems.