ICSBB Invited Speech: Influence of Loading Conditions on the Structure and Mechanical Properties of Articular Cartilage.

The aim of this session is to discuss how loading conditions that a joint is exposed to influence both the structure and mechanical properties of the underlying articular cartilage. This is important as cartilage degeneration, as occurs during osteoarthritis, involves changes to structure and properties. Different joints across the body are exposed to different movements and, thus, loading. For example, the loads and stresses experienced by the hip are different to those experienced by the knee during walking or running. Different joints also experience different rates of cartilage degeneration. The ankle, while exposed to higher stress experiences little cartilage degeneration unlike the hip or knee. Variation in structure and mechanical properties occur across different joints, within a joint and within a joint component. The knee is a good example of this. The medial and lateral components of the knee are exposed to different types of loading. During walking, the lateral femoral condyle of the knee rotates unlike the more static medial condyle. However, most compressive loads pass through the medial knee. The patella, menisci and ligaments all affect loading distribution across the knee. Thus, the knee joint is used as an example of how cartilage properties and structure vary within a joint, and differences in the boundary conditions that cartilage is exposed to. The session includes: - background to the knee, its anatomy and biomechanics; - discussion of the different loading conditions knee cartilage is exposed to in vivo; - description of the differences in cartilage structure (including collagen orientation and arrangement); - detail of the mechanical properties typically measured (including different testing regimes) and how these vary across the knee. Finally the question is asked, whether trends between cartilage boundary conditions and structure/properties can be determined? Experiments are currently taking place in our laboratory to answer this question. These build on our previous knee mechanics and cartilage micro-structural studies. [ABSTRACT FROM AUTHOR]