[Quantitative evaluation of the degree of bone tissue deposition in sponge-like skeletal segments submitted to a...

In a 14-month old dog, injected twice with Alizarian red 27 and 7 days before sacrifice, both the distribution of the osteogenic areas and the rate of new bone tissue formation have been studied in the distal metaphysis of the right radius submitted to mechanical overloading by removing a piece of the ulnar shaft. The normally loaded left radius was used as a control. Following a four-month overloading, the bone tissue deposition rate appeared markedly reduced in the more peripherally located "tubular" spongiosa which underwent in parallel conspicuous structural changes. No alterations in the reconstruction rate and in the microscopical structure as compared to the control radius were observed instead in the deep-seated "laminar" spongiosa. The present, as well as previous findings, seem to support the view that (1) the two types of trabecular bone, i.e. the "tubular" and the "laminar" spongiosa, are subjected to quantitatively diverse loading, and (2) mechanical factors play a significant role in the control of the topographic distribution of bone tissue reconstruction.