Objective        To establish a mouse model of stable tibial fracture and observe the procedure of fracture healing.       Methods       A total of 24 C57BL/6J mice at an age of 6 to 8 weeks and weighing 18 to 25 g were randomly divided into sham-operation group

and 3 groups of tibial fracture for 7

14 and 21 d(n=6). After all mice were anesthetized with 10% sodium pentobarbital at 1 mL/kg

and cut an incision of 0.5 cm

the mice from the later 3 groups had their tibial shaft cut and then fixed with intramedullary nail. X-ray radiology and micro-CT scanning were used to observe the healing in 7

14 and 21 d after the operation. Histological analysis was also used to observe the morphological changes of the healing.       Results       A mouse model of stable tibial fracture was established. At day 7 after fracture

there were few cartilage calluses at the fracture site

which were mainly composed of undifferentiated mesenchymal cells. At day 14 after fracture

cartilage callus was mainly composed with hypertrophy chondrocytes and began to calcify. At day 21 after fracture

the cartilage had disappeared and new bone formed

which contained a lot of osteoblasts and osteocytes.       Conclusion        A mouse model of stable tibial fracture is established successfully

whose healing process is similar to the process of clinical fracture healing. This model may be more suitable to study fracture healing.