Abstract
ABSTRACT The intra-subject, the inter-operator, and the inter-laboratory variabilities are the main sources of uncertainties in gait analysis, and their effects have been partially described in the literature for adult populations. This study aimed to extend the repeatability and reproducibility analysis to a pediatric population, accounting for the effects induced by the intra-subject variations, the measurement setup, the marker set configuration, and the involved operators in placing markers and EMG electrodes. We evaluated kinematic, kinetic and EMG outputs collected from gait analyses performed on two healthy children in two laboratories, by two operators, and with two marker placement protocols. The two involved centers previously defined a common acquisition procedure based on their routine pipelines. The similarity of kinematic, kinetic, and EMG curves were evaluated by means of the coefficients of the Linear Fit Method, and the Mean Absolute Variability with and without the offset among curves. The inter-operator variability was found to be the main contribution to the overall reproducibility of kinematic and kinetic gait data. On the contrary, the main contribution to the variability of the EMG signals was the intra-subject repeatability that is due to the physiological stride to stride muscle activation variability.
Highlights
Three-dimensional gait analysis is a common exam performed in motion capture laboratories to quantify movement dysfunctions (Cappozzo et al 2005), and it may provide information on the development of the neuromuscular system (Hausdorff et al 1999)
Considering the differences in gait pattern between adults and children (Hausdorff et al 1999), and the widespread use of gait analysis in the pediatric population, this study aims to quantify the mentioned sources of uncertainty, in order to assess if the main contribution to the variability of pediatric gait data is related to the variability of the subject, the laboratory, or the operator according to two different biomechanical models
The average Mean Absolute Variability (MAV) was 5°, while the maximum difference between MAV, and the offset-corrected MAVOC was less than 1.5°, indicating that most of the intrasubject variability was due to variation in the shape of the curve, rather than offset
Summary
Three-dimensional gait analysis is a common exam performed in motion capture laboratories to quantify movement dysfunctions (Cappozzo et al 2005), and it may provide information on the development of the neuromuscular system (Hausdorff et al 1999). Gorton et al (Gorton et al 2009) evaluated the variability in kinematic data among 12 laboratories and 24 operators studying numerous trials conducted on one healthy adult. They found that variability in marker placement among examiners was the largest quantifiable source of uncertainty when considering gait performed in different centers. They concluded that by introducing a standardized protocol the variability could decrease by 20%.
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