Recent Developments in Synovial Joint Biomechanics

Abstract

This review is concerned with the modern development of animal joint biomechanics. The understanding of the biomechanical function of synovial joints depends upon our ability to quantitatively measure and model the biorheological behavior of the major tissues of these joints (synovial fluid and articular cartilage), and their dynamic interactions during motion. Since synovial fluid is a macromolecular solution of the polyanionic hyaluronic acid and a dialysate of blood plasma, its rheological behavior is highly nonlinear and therefore most difficult to characterize quantitatively. And, since articular cartilage is composed of a permeable fiber-reinforced composite solid matrix swollen with water, its deformational behavior is also very difficult to characterize. As such, the dynamic interactions of these two biorheologically complex materials offer what are indeed challenging biomechanics problems. In this survey, we will discuss both the evolution, over the past 50 years or so, of our understanding of joint function and the difficult and unresolved problems arising from our attempts to quantitatively formulate and solve problems related to the characterization of normal and pathological joint function.