Electronic Thesis and Dissertation Repository


Doctor of Philosophy




Tom Jenkyn


The purpose of this collection of studies was to further develop the knowledge of shoulder motion in order to better understand joint function through direct measurement of 3D scapulohumeral joint kinematics using a technique of high accuracy. Markerless, bi-planar fluoroscopic radiostereometric analysis using a generic shoulder model was developed in this thesis, reducing the amount of radiation exposure to subjects. The studies compared kinematic data of the scapulohumeral joint in six degrees of freedom with a precise, in-vivo measuring technique. Data were collected on young and older healthy individuals, individuals with a torn supraspinatus and post-surgical intervention.

Although this generic model method has higher error than other biplanar fluoroscopic techniques, it is still more accurate than skin-based motion capture techniques. Younger and older healthy groups have similar scapulohumeral motion patterns for abduction, forward flexion and a more complex motion of arm across the chest. Major differences were noted during humeral abduction when comparing an age-matched controlled group to groups with injured supraspinatus muscles and post-surgical repair of the supraspinatus muscles. In the injured group, there is significantly higher scapulohumeral rhythm which is significantly lowered post-surgery.

These are the first studies of this nature using generic models to analyze scapulohumeral kinematics. Future research could include the evaluation of muscle function before and after repair in tandem with kinematic results and comparisons of the scapulohumeral kinematics between different surgical repair techniques. This information will allow clinicians to make more informed treatment plans based on the needs of each individual patient.