Histologic and biochemical analysis of osteogenic capacity of vascularized periosteum

We analyzed the osteogenic capacity of the vascularized periosteum histologically and biochemically using a new experimental model of the vascularized tibial periosteum-hydroxyapatite composite in rats. Bone formation was observed not only on the surface but also in the pores of the hydroxyapatite at 4 weeks. The alkaline phosphatase activity increased to a peak at 2 weeks, with half this activity maintained until 8 weeks. The bone-specific bone gla protein content increased constantly as time passed. On the other hand, in the vascularized fascia-hydroxyapatite composite group (control group), no bone formation was observed histologically, alkaline phospatase activity was low, and bone gla protein content was very low. These results indicate that (1) the vascularized periosteum has the most significant osteogenic capaacity at 2 weeks, with a constant level of the activity maintained thereafter, (2) it forms new bone soon after operation, and (3) the amount of bone increases as time passes.