An algorithm for bone mechanoresponsiveness: implementation to study the effect of patient-specific cell mechanosensitivity on trabecular bone loss

The rate of bone loss is subject to considerable variation between individuals. With the 'mechanostat' model of Frost, genetic variations in bone mechanoresponsiveness are modelled by different mechanostat 'setpoints'--which may also change with age or disease. In this paper, the following setpoints are used: epsilonmin (strain below which resorption is triggered); epsilonmax (strain above which deposition occurs); omegacrit (microdamage-level above which damage-stimulated resorption occurs). To simulate decreased mechanosensitivity, epsilonmax is increased. Analyses carried out on a simplified model of a trabecula show that epsilonmax is a critical parameter: if it is higher in an individual (genetics) or increases (with age) the mass deficit each remodelling cycle increases. Furthermore, there is a value of epsilonmax above which trabecular perforation occurs, leading to rapid loss of bone mass. Maintaining bone cell mechanosensitivity could therefore be a therapeutic target for the prevention of osteoporosis.