To evaluate the expression of senescence-related proteins according to the aging process and to determine the role of senescence-related proteins in the bone tissue and their effects on the process of bone union.

18 Sprague-Dawley rats (8 weeks old: 7, 32 weeks old: 6, and 70 weeks old: 5) were used in the experiment. A unilateral closed femur fracture was made, and the fracture callus was obtained 2 weeks after the fracture. The ossification process was observed in proliferative chondrocytes, the hypertrophic chondrocytes, and in the mesenchymal layer individually by immunohistochemistry, using p16, p21, c-fos and c-jun antibodies.

There was no significant differences in the manifestation of p-16, p-21, c-fos, c-jun gene according to the age. The positive ratio of p-16 was maximal in proliferative chondrocytes (54.93%) and decreased in the mesenchymal layer (46.48%), and in hypertrophic chondrocytes (10.85%), in order. The positive ratio of c-fos was maximal in proliferative chondrocytes (73.32%) and decreased in the mesenchymal layer (51.84%), and in hypertrophic chondrocytes (9.64%), in order.

We believe that senescent genes in the bone tissue participate in the differentiation of osteochondral cells and in the process of fracture callus ossification.