Appendix Mathematical models of the knee

Abstract

Mathematical models make it possible to calculate the values of quantities which are difficult or impossible to measure and provide insights which are not obtained from experiment alone. They are a necessary adjunct to the experimental method, but are not a common feature of biological or clinical research. A model is based on a series of assumptions or hypotheses about the way a physical system works. It is validated by comparing its predictions with independent experimental measurement. Reasonable validation then gives confidence in the assumptions on which the model is based and in the predictions of quantities which cannot be measured. The purpose in presenting our models here is to explain the differences between unloaded and loaded motion described in Chapter 3.