Osmotic Pressure, Solid Stress, and the Diffuse Double Layer

Abstract

Osmotic pressure is often mentioned as being fundamental to developing an understanding of articular cartilage. And indeed, we have mentioned osmotic pressure on several occasions as being responsible for the swelling pressure of articular cartilage. For cartilage in the unloaded state is pre-stressed. The tensile stress in the collagen network is balanced by the osmotic swelling pressure of the aggrecan molecules, bound within the collagen network. And when cartilage is loaded and consolidates, the aggrecan is compressed and the osmotic swelling pressure increases and provides resistance to the loads applied on the surface of articular cartilage. So osmotic pressure is fundamental to understanding the mechanical behavior of articular cartilage, and so worthy of close examination.