Kinematic modeling of the shoulder complex in tetraplegia

In comparison to other joints in the human body, the shoulder complex is particularly reliant on the coordination of active muscle forces to generate both movement and stability during activities using the upper extremities. The resultant imbalance of muscle forces across the shoulder, coupled with the increased reliance on the shoulder for functional mobility, puts the individual with tetraplegia at great risk for developing shoulder pathology. The ability to quantify the movement of the shoulder, and in particular the sequence of shoulder complex movement components within functional tasks, can provide information to better inform clinical and surgical decision making. In this article, we will discuss the impact of tetraplegia on shoulder biomechanics and function, provide an overview of general principles and current status of kinematic modeling of the shoulder complex, and describe emerging applications of quantitative motion analysis of the shoulder complex.