[Wolff's law of transformation after 100 years].
In the introduction to the article the author briefly describes the history of the Wolff's invention that under the influence of the function the bone structure is restructuring. This functional adaptation however, has not been fully clarified until these days. At present the general scheme of the fundamental adaptation mechanism has been generally adopted according to which the bone responds to the inner strain by aposition of the new bone while inactivity results in resorption. The author's own experiment as well as modern experiments carried out by the Lanyon group have proved that the starting point for reaction is intermittent loading in which both pressure and tension have the same effect. The strain results in the deformation of the bone tissue which is by an unclear yet way perceived and signalled to the superficial osteoblasts. However, not all cases of the functional adaptation of the bone can be explained in this way, first of all the remodelling of deformities after fractures or the modelling of metaphysis and the lateral drift of diaphysis in the course of normal growth. In comparison to Currey and other authors who therefore share the view that there does not exist a uniform algorithm of the functional adaptation of bone the author explains the functional adaptation by a uniform even if complex algorithm comprising apart from the reaction of the bone to the inner strain another two mechanisms: 1. Modelling of the bone surface by the periosteum. The increase in pressure between periosteum and bone results in resorption, avulsion of periosteum to the aposition of the new bone. 2. In the course of the growth another factor participates in the functional adaptation, namely the physeal plate, responding to loading according to Hüter-Volkmann's law: "Overload results in reducing of the growth, while relief in its acceleration". In oblique loading the plate changes, due to asymmetric loading, the direction of the growth precisely in the direction of the pressure resultant. Only by the cooperation of the three given mechanisms all cases of the functional adaptation of the bone can be explained.(ABSTRACT TRUNCATED AT 400 WORDS)
Hert
J
J
D000818:Animals; D001696:Biomechanical Phenomena; D001842:Bone and Bones / Q000502:physiology*; D006801:Humans
Wolffův transformacní zákon po 100 letech.