The stiffness of normal articular cartilage and the predominant acting stress levels: implications for the aetiology of osteoarthrosis.

A survey was conducted of compressive stiffness of normal articular cartilage over the entire surfaces of 13 knees and 10 ankle joints, using an indentation technique. Contoured maps of the stiffness of these joints was obtained. A direct relationship found between the stiffness and the predominant level of stress to which the cartilage was subjected, suggests a process of cartilage adaptation to stress. This finding, together with further evidence of osteoarthrotic damage in areas where infrequent but excessive levels of stress occur, supports a hypothesis which implicates a particular pattern of mechanical stress as being an important aetiological factor in osteoarthrosis.