[The healing of bone fractures in rats during the readaptation after a 14-day head-down suspension]

Histological, histochemical and histomorphometric methods have been used to study an effect of a 14-day head-down suspension on healing the fractured fibular diaphysis in the rats traumatized immediately after suspension. The study of the fibulae on Days 11 and 17 following an operative fracture indicated that both in control and experimental rats the ends of fractured bones were tightly interconnected by the calluses. A comparative study of the calluses and their structural components as well as detailed investigation of histological structure of calluses on the 11th and 17th post-traumatic days did not reveal significant differences between control and experimental animals. Furthermore, the rate of cartilage replacement by spongy bone tissue in calluses of experimental animals was even somewhat higher than that in control rats. Thus the data obtained give ground to believe that in a readaptation period after 14-day suspension resulting in the osteoporotic changes of weight-bearing bones a repair process in the bones is rapidly normalized and in some parameters exceeds it in control animals.