Motion capture is increasingly being used to assess the upper limb. The earliest study of the upper limb performed at Cardiff University was an investigative study using retro-reflective markers attached to the skin overlying the bony land marks of the thorax, clavicle, scapula, and humerus. Throughout the course of the current study this initial model and the experimental protocol have been revised. Particular attention was paid to accurate measurement of the kinematics of the scapula. The original model used markers placed directly over the bony land marks of the scapula to track its movement. In this study two alternative methods were assessed: a scapula locator, which is considered the "gold standard" in non invasive scapula tracking, but can only be used during static measurements and an acromion marker cluster, which can be used to assess dynamic movements of the shoulder. It was found that markers attached directly to the skin overlying the scapula bony landmarks can only be used to assess the level of glenohumeral elevation for arm elevations up to 80 during forward flexion. The acromion marker cluster was found to be suitable for tracking the movement of the scapula in most cases, except that it underestimated glenohumeral elevation during forward flexion due to a necessary design constraint. The first two applications of the model assessed the hypothesis that common activities of daily living can be performed without the capacity for full physiological range of motion of the scapulothoracic and glenohumeral articulations. It was found that there is an excess capacity of glenohumeral joint elevation not required for the majority of everyday tasks. However it was also found that there is no excess capacity in lateral rotation of the scapulothoracic articulation. Finally ethical approval was obtained to assess subjects with shoulder pathologies. Subjects were recruited from three different cohorts: mid-shaft clavicle fractures subjects with one or more previous glenohumeral dislocations and subjects with multi-directional instability. It was found that the method was able to distinguish between healthy subjects and patient cohorts, and also potentially between different patient cohorts. This study has served to develop the methods necessary to assess the kinematics of healthy and pathological shoulders and has provided preliminary results on the functionality of three patient cohorts
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