Determining upper limb kinematics and dynamics during everyday tasks
In planning orthopaedic procedures or designing joint replacements for the upper limb, detailed knowledge on the kinematic and dynamic behaviour of the shoulder, elbow and wrist joints during the performance of everyday tasks is essential. Previous studies have included kinematic analyses of everyday activities involved in feeding and personal hygiene though none have included both the kinematic and dynamic analyses of these tasks. This study has involved the development, validation and application of experimental methods and analysis techniques, enabling the measurement and modelling of upper limb kinematics and dynamics. A four camera video-based motion analysis system was used to track reflective spheres attached at specific locations on the upper limb and trunk. Novel methods for the definition of the embedded trunk frame and glenohumeral rotation centre were incorporated. Joint attitudes, cadences, angular velocities and angular accelerations were calculated prior to the determination of external forces and moments through the dynamic modelling of the upper limb. The procedures developed have been validated against known measurements and the results of previous studies. These have been applied to obtain kinematic and dynamic data from unimpaired subjects and subjects with shoulder impairment during performance of ten everyday tasks involved in feeding, personal hygiene and the use of everyday objects. Elbow and shoulder flexion were found to be the primary components for the successful completion of the selected tasks. Reaching to the opposite side of the neck was identified as being the most complex of the activities tested in terms of rotation at the shoulder and elbow. Characteristic patterns of motion at the joints of the upper limb were identified during anterior targeted lifting. Differences in performance between the unimpaired and impaired subjects were identified, particularly in the results for cadence and the individual joint velocities and accelerations.