Considerations for coordinate system definitions for imaging-based kinematic measures at the shoulder joint

Imaging-based approaches for quantifying joint kinematics and arthrokinematics of joint movement have become more commonplace in the research environment. Both static and dynamic approaches are being utilized to quantify rotation and translation of the shoulder joint complex in global and anatomically-defined coordinate systems. International Society of Biomechanics (ISB) standard approaches have been defined for many of the joints in the body including the shoulder. However, these standards pertain to more traditional, experimental surface-marker based approaches in which assumptions are made about the relationship between the skin overlying bony landmarks and the actual bony movement. Imaging-based approaches allow for direct visualization of the underlying bony morphology (and landmarks) making highly-accurate coordinate system definition possible for both joint kinematics and arthrokinematics of the shoulder. Standards for such approaches are lacking. Considerations for standardization of protocols that define imaging-based coordinate systems for the shoulder will be discussed.