EXPERIMENTAL-DETERMINATION OF THE SUBCHONDRAL STRESS-REDUCING ROLE OF ARTICULAR-CARTILAGE UNDER STATIC AND DYNAMIC COMPRESSION

This paper describes a series of experiments investigating the ability of articular cartilage to act as a subchondral stress-reducing layer under both static and impact loading conditions. The cartilage was removed from its subchondral bone and rebonded to a rigid photoelastic substratum of known stress-optic properties. This allowed the shear stresses generated subchondrally by loads applied to the articular cartilage to be measured directly. The study demonstrated that while cartilage provides substantial subchondral protection under both statically and dynamically applied load, the protection under static loading is greater close to the cartilage-subchondral boundary than under the equivalent dynamic load. This behaviour is interpreted in terms of the contrasting deformation mechanisms operating in cartilage at low and high rates of loading.