FILLING THE BONE DEFECT WITH OSTEOGENIC MATERIAL - AN EXPERIMENTAL-STUDY

in this experimental study with bone defects, we focussed on the one h and on external and internal osteogenic callus formation after filling the defect and on the other on the osteochondrogenic differentiation capacity of 4-day-old fibrous-like callus grafts and 12-day-old woven bone grafts in an osteogenic environment. A standard cortical bone def ect of the femur was created in 95 young rats. The defect was filled w ith a cortical bone graft and 4- and 12-day-old callus grafts. The gra fts were transplanted as such or in Nucleopore chambers. Follow-up was done at 1, 2, 3 and 6 weeks. The osteochondrogenic tissue formed was studied histologically and histomorphometrically. The results suggest that the filling of the bone defect had no influence on the primary ex ternal and internal osteogenic callus formation at 1 and 2 weeks. At 3 and 6 weeks in the chamber groups the persisting internal bridging wo ven bone was converted into more compact lamellar bone whereas periost eal callus remained at the edges of the defect. In the other groups at 3 and 6 weeks the normal shape of the cortex was reconstituting. Four -day-old fibrous-like callus formed bone in the Nucleopore chamber, in dicating that fibrous-like callus tissue at 4 days contains osteogenic cells, Twelve-day-old callus consisting of woven bone was partially d ifferentiated to cartilage, showing that woven bone contains cells cap able of chondrogenic differentiation.