| [ Summary ] |
Harold Frost hypothesized the mechanostat, which is the controlling mechanism for bone behavior concerning loading generated by tissue gravity. This integrats three physiological functions of bone tissue ; modeling, the remodeling conservation mode, and the remodeling disuse mode. Modeling, activity to cause the drift of bone tissue, increases the bone volume and strengthens the inner structure. The remodeling conservation mode works to repair micro-injuryies at the tissue level, preserving the structure and volume of bone tissue. The remodeling disuse mode weakens the inner structure of the bone by increasing bone resorption, leading to osteoporosis. These three functions are regulated by the respective optimum ranges of the strain threshold in bone tissue. Under micro-gravity conditions the reduction of load on bone activates the remodeling disuse mode, consequently increasing strain levels on the tissue. At this point, the decrease in bone mass and mechanical property stops when the strain value reaches the threshold of the remodeling conservation mode. The mechanostat hypothesis presents a standard, which illuminates the research on bone regulation in relation to load. |