Biomechanics of human movement and its clinical applications

Abstract

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.

Figure 1

Determining the nonmeasurable force (Δf) in the spring from the measured deformation of the spring (Δx) using Hooke's law.

Figure 2

Traditional gait output of (A) joint angles and (B) joint moments at the hip, knee and ankle of the right limb (black, solid line) and left limb (black, dotted line) in a typical patient with spastic diplegia cerebral palsy and in that of the healthy controls (gray, solid line) during level walking. BW: body weight; LL: leg length.

Figure 3

Reconstruction of a 3D geometric computer model of (A) the pelvis and (B) the locomotor system from computed tomography.

Figure 4

Instrumented massive proximal femoral prosthesis that enables the measurement of femoral axial forces in vivo.

Figure 5

Perspective projection model of the fluoroscopy system. X‐ and Y‐axes define the image plane. Rays of the point source X‐ray passing through the CT volume are projected onto the image plane to form a DRR.

Figure 6

A volumetric model‐based 2D to 3D registration method with a new similarity measure, called the weighted edge‐matching score (WEMS), for measuring natural knee kinematics with single‐plane fluoroscopy. (A) Lateral view and (B) oblique view.