Mechanical forces act at all levels in the biological system, from the organ level down to individual molecules. From observations and experiments, it has been found that these forces play a role in the health of the tissues. The question to ask is: How? By what mechanism are mechanical forces able to regulate tissue biology? The answer involves finding out how forces on the whole organ regulate gene expression in cells, or cause cells to change to a new cell type (i.e. differentiate). The relationship between mechanical forces and tissue biology has been investigated using computational modeling, and this paper begins with a review of that work. Next, an attempt is made to present a methodology for simulation of mechano-regulation. This requires the derivation of equations that relate the tissue state at time t _v to the tissue state at t > t ₀ when the mechanical loading is known. The final step is confirmation of these equations against observations made during specific processes known to be mechano-regulated; the two examples chosen are fracture healing and osteochondral defect healing. If computational tools capable of simulating tissue responses to stress can be derived, then it becomes possible to simulate the consequences of mechanical environment on growth, adaptation, and ageing.

1 Introduction

Mechanical forces constantly act on tissues and organs. Sometimes the consequences of mechanical forces are obvious, such as when a...