Question

Equation 5.44 states a relationship between remodeling variables and the damage burden (Do) waiting to be repaired in an equilibrium state: Do = (kD sq RL ) I (n R~ lao Fs). If the loading increases, an increase in the damage burden can be avoided by increasing either the activation frequency or the diameter of the osteons, or both. Does one of these options have any advantages over the other? Think about the differences in the porosity increase that would occur during and after the remodeling, the metabolic energy required to support the cells doing the remodeling, and the effects of the altered osteonal structure on fatigue damage resistance. What are the limitations on increasing ReI How about lao?

Answer 1

In the context of bone remodeling, increasing the activation frequency or osteonal diameter can help maintain the damage burden in an equilibrium state when loading is increased. Each route has its pros and cons involving changes in porosity, metabolic energy, and resistance to fatigue damage, with inherent limitations based on biological and mechanical factors.

Step-by-step explanation:

The question relates to the equilibrium state of bone remodeling, where the damage burden maintained in a bone system in the presence of changes in mechanical variables like loading is analyzed. The equation provided, although not fully detailed in the question, refers to parameters that control bone remodeling such as remodeling activation frequency and osteonal diameter. When loading on the bone increases, to avoid an increase in the damage burden, either the activation frequency (Fs) or the diameter of the osteons (d), or both, can be increased.

Increasing the activation frequency enhances the rate of bone turnover without significantly increasing porosity, but it may increase the metabolic energy required for the process, as more cellular cycles of bone remodeling are initiated. On the other hand, increasing the diameter of the osteons would lead to fewer overall cycles needed for remodeling a given volume of bone, potentially saving metabolic energy but might result in increased bone porosity, potentially reducing resistance to fatigue damage.

There are limitations to how much these variables can be altered. For increasing osteonal diameter, a balance must be struck so as not to overly increase the porosity of the bone, which can compromise its structural integrity. Regarding activation frequency, the body's metabolic resources and the need for synchronized cycles of bone deposition and resorption could limit an increase in frequency.