Evidence of Muscle Co-Contraction: In Vivo Pressure Measurement and Force Estimation

The human hip joint has been extensively studied both analytically and through experiment. The joint is essentially spherical, a ball and socket, and therefore simpler mechanically than many other joints in human body. In the United States alone major hip surgery is conducted several hundred thousand times each year. Detailed knowledge about the loading of the natural hip joint or alternatively, of an instrumented hip prosthesis can contribute to further improvement in prosthesis design and/or mechanical testing of hip implants, bone stress calculations and computer simulation of bone remodelling. Data on hip loading can also refine surgical procedures and recommend changes in traditional patient management and rehabilitation protocols. Measured joint load data can also revise extant mathematical models of the human lower extremity musculo-skeletal system by incorporating the total muscle force applied and thereby produce better estimates of the magnitude and time course of activity in muscles about the hip joint during movement.