Browsing by Author "Cockcroft, John"

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    Kinematics and temporospatial parameters during gait from inertial motion capture in adults with and without HIV : a validity and reliability study
    (BMC (part of Springer Nature), 2020-07-24) Berner, Karina; Cockcroft, John; Louw, Quinette
    Background: Inertial measurement unit (IMU)-based motion capture systems are gaining popularity for gait analysis outside laboratories. It is important to determine the performance of such systems in specific patient populations. We aimed to validate and determine within-day reliability of an IMU system for measuring lower limb gait kinematics and temporal–spatial parameters (TSP) in people with and without HIV. Methods: Gait was recorded in eight adults with HIV (PLHIV) and eight HIV-seronegative participants (SNP), using IMUs and optical motion capture (OMC) simultaneously. Participants performed six gait trials. Fifteen TSP and 28 kinematic angles were extracted. Intraclass correlations (ICC), root-mean-square error (RMSE), mean absolute percentage error and Bland–Altman analyses were used to assess concurrent validity of the IMU system (relative to OMC) separately in PLHIV and SNP. IMU reliability was assessed during within-session retest of trials. ICCs were used to assess relative reliability. Standard error of measurement (SEM) and percentage SEM were used to assess absolute reliability. Results: Between-system TSP differences demonstrated acceptable-to-excellent ICCs (0.71–0.99), except for double support time and temporophasic parameters (< 0.60). All TSP demonstrated good mean absolute percentage errors (≤7.40%). For kinematics, ICCs were acceptable to excellent (0.75–1.00) for all but three range of motion (ROM) and four discrete angles. RMSE and bias were 0.0°–4.7° for all but two ROM and 10 discrete angles. In both groups, TSP reliability was acceptable to excellent for relative (ICC 0.75–0.99) (except for one temporal and two temporophasic parameters) and absolute (%SEM 1.58–15.23) values. Reliability trends of IMU-measured kinematics were similar between groups and demonstrated acceptable-to-excellent relative reliability (ICC 0.76–0.99) and clinically acceptable absolute reliability (SEM 0.7°–4.4°) for all but two and three discrete angles, respectively. Both systems demonstrated similar magnitude and directional trends for differences when comparing the gait of PLHIV with that of SNP. Conclusions: IMU-based gait analysis is valid and reliable when applied in PLHIV; demonstrating a sufficiently low precision error to be used for clinical interpretation (< 5° for most kinematics; < 20% for TSP). IMU-based gait analysis is sensitive to subtle gait deviations that may occur in PLHIV.
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    The postural stability of children with foetal alcohol spectrum disorders during one-leg stance : a feasibility study
    (AOSIS, 2018) Brink, Yolandi; Cockcroft, John; Seedat, Soraya; May, Philip; Kalberg, Wendy; Louw, Quinette
    Background: Postural control may be impaired in children with foetal alcohol spectrum disorders (FASD). The study assessed the protocol feasibility in terms of (1) recruiting children with FASD in a rural, small town; (2) using the measurement instruments in a real-life setting; (3) the one-leg standing (OLS) task and (4) presenting preliminary results on postural stability of children with and without FASD. Methods: Nine-year-old children diagnosed with and without FASD were invited to participate. Twenty-eight children performed OLS. Feasibility outcomes included recruitment, measurement instrument use and task instruction. Postural stability outcomes included standing duration, centre of pressure (COP) and body segment acceleration. Results: Participants recruitment was feasible in terms of the (1) ability to sample a reasonable participant number in a rural town setting and the capacity to increase the sample size if more schools are included in the sampling frame and (2) use of assent and consent forms that were appropriate for this population. The measurement instruments were user-friendly, cost-effective and time-efficient. Instructions for the task require amendment to address foot placement of the non-weight–bearing leg. There was a significant difference between cases and controls on mean COP velocity (p = 0.001) and the pelvis segment acceleration in the mediolateral direction (p = 0.01) and the anteroposterior direction (p= 0.027). The control children took longer to achieve postural control. The girls demonstrated a significant difference for the COP anteroposterior displacement (p = 0.008) and velocity (p = 0.049). Conclusions: The recruitment of children with and without FASD in a rural, small town and the administration of measurement instruments in a real-life, school-based setting was feasible. However, the verbal instructions for the task require revision. The male control group took longer to achieve postural control because the task was performed differently between the two groups. However, the case girls were slower to achieve postural control than control girls though performing the task similarly.