Functional osteology. Algorithms of fatigue injury elimination

Aim: to determine the role of osteoclast-osteoblast remodeling (OOR) as a mechanism responsible for morphofunctional skeletal stability and fatigue injury elimination from functional osteology point of view. Based on the data of literature and their own findings the authors have revealed two mechanisms of fatigue micro-injury elimination. The first mechanism begins with resorption of the involved area and subsequent deposition of new bone tissue (OOR), the second one is responsible for filling the gap space with mineralized bone tissue without cement line formation and preliminary resorption. It is suggested that the initiation of the mechanisms of fatigue micro-injury elimination is regulated by feedback principle: the higher is the level of cyclic deformities, the more active is the process of filling without preliminary resorption, and, vice versa, the less is the level of deformity, the more intense is resorption activation with delayed deposition of bone tissue within the space of resorption lacuna. In its essence OOR is a local regulator of the degree of bone structure deformability, because, according to the laws of material science, resorption cavities while decreasing the modulus of elasticity of any material, increase its deformability. The greater is porosity, the higher is deformity level, and vice versa. As a result, optimization of the level of cyclic deformities is provided, initiating the convectional fluid flow along the lacunar-andcanalicular system and delivery of nutritious substances, regulators, etc. to osteocytes, as well as withdrawal of residues from them.