Biomechanics of human movement and its clinical applications.

All life forms on earth, including humans, are constantly subjected to the universal force of gravitation, and thus to forces from within and surrounding the body. Through the study of the interaction of these forces and their effects, the form, function and motion of our bodies can be examined and the resulting knowledge applied to promote quality of life. Under gravity and other loads, and controlled by the nervous system, human movement is achieved through a complex and highly coordinated mechanical interaction between bones, muscles, ligaments and joints within the musculoskeletal system. Any injury to, or lesion in, any of the individual elements of the musculoskeletal system will change the mechanical interaction and cause degradation, instability or disability of movement. On the other hand, proper modification, manipulation and control of the mechanical environment can help prevent injury, correct abnormality, and speed healing and rehabilitation. Therefore, understanding the biomechanics and loading of each element during movement using motion analysis is helpful for studying disease etiology, making decisions about treatment, and evaluating treatment effects. In this article, the history and methodology of human movement biomechanics, and the theoretical and experimental methods developed for the study of human movement, are reviewed. Examples of motion analysis of various patient groups, prostheses and orthoses, and sports and exercises, are used to demonstrate the use of biomechanical and stereophotogrammetry-based human motion analysis studies to address clinical issues. It is suggested that further study of the biomechanics of human movement and its clinical applications will benefit from the integration of existing engineering techniques and the continuing development of new technology.