This study aims to identify kinematic differences between children with Ponseti treated clubfoot and age-mat- ched healthy controls during gait, using the Oxford Foot Model. This pilot is part of a large project comparing gait kinematics between children with Ponseti treated clubfoot with and without relapse and healthy controls. Final results could identify relevant gait parameters which will allow for early detection of a relapse clubfoot.
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A clubfoot is characterized by a three-dimensional deformity with an equinus, varus, cavus and adduction component. Nowadays the Ponseti method is the preferred treatment for clubfeet, aiming to achieve a normal appearing, functional and painless foot. The reoccurrence of clubfoot components in treated clubfeet, a relapse, is a known problem in clubfoot patients. 3Dgait analysis can be used in assessment of foot function and residual deviations in gait or possible relapses. Gait analysis is frequently used to analyse differences in gait between clubfoot and healthy controls. However, the usage of multisegment foot models is, although of importance considering the characteristics of the clubfoot, rare. In order to capture the full multi-planar and multi-joint nature of a clubfoot, it is highly important to implement multi-segment foot models in gait analysis. In order to improve treatment of individual relapse clubfoot kinematics differences in clinical relevant functional outcomes should be known.
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In wheelchair sports, the use of Inertial Measurement Units (IMUs) has proven to be one of the most accessible ways for ambulatory measurement of wheelchair kinematics. A three-IMU configuration, with one IMU attached to the wheelchair frame and two IMUs on each wheel axle, has previously shown accurate results and is considered optimal for accuracy. Configurations with fewer sensors reduce costs and could enhance usability, but may be less accurate. The aim of this study was to quantify the decline in accuracy for measuring wheelchair kinematics with a stepwise sensor reduction. Ten differently skilled participants performed a series of wheelchair sport specific tests while their performance was simultaneously measured with IMUs and an optical motion capture system which served as reference. Subsequently, both a one-IMU and a two-IMU configuration were validated and the accuracy of the two approaches was compared for linear and angular wheelchair velocity. Results revealed that the one-IMU approach show a mean absolute error (MAE) of 0.10 m/s for absolute linear velocity and a MAE of 8.1◦/s for wheelchair angular velocity when compared with the reference system. The twoIMU approach showed similar differences for absolute linear wheelchair velocity (MAE 0.10 m/s), and smaller differences for angular velocity (MAE 3.0◦/s). Overall, a lower number of IMUs used in the configuration resulted in a lower accuracy of wheelchair kinematics. Based on the results of this study, choices regarding the number of IMUs can be made depending on the aim, required accuracy and resources available.
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