Pre-stress in articular cartilage due to internal swelling pressure

The triphasic theory has been used to calculate the pre-stress in spherical and cylindrical layer models of articular cartilage. In the present study, cartilage was assumed to be homogeneous with a uniform fixed charge density. The tissue is attached to subchondral bone of a given radius of curvature. It has been determined that: 1) the maximum radial elastic stress occurs at the cartilage-bone junction and the maximum circumferential elastic stress occurs at the cartilage surface; 2) radial elastic stress is generally larger than the tangential elastic stress; 3) the maximum elastic stress increases with decreasing radius of curvature for cartilage layers of fixed thickness. The existence of pre-stresses may serve to reduce collagen tension resulting from joint loading, and may also be an important factor in determining the collagen ultrastructure within the cartilage solid matrix.