Abstract:

BACKGROUND: Stress stimulation can promote the healing of long bone fractures.
OBJECTIVE: To observe the effects of stress on the healing of micro fracture.
METHODS: Micro fracture models in bilateral greater trochanter of femur of rabbits were established. The micro fractures in one side fixed by Kirschner wire were taken as control and those in the other side fixed by lag screw were experimental group.
RESULTS AND CONCLUSION: X-ray showed that the growth of bone callus was quicker, external callus was more, gray value of callus was higher, and callus modeling time was shorter in the experimental group than in the control group. CT showed quicker growth of external callus and better fracture shaping of the experimental group compared with the control group. Light microscopy observation of callus tissue sections: the fracture healing way of the two groups was cartilaginous ossification; haematoma vanished , organization was quick, the recoverability fiber structure was replaced by bone callus in the early stage, the callus grew well, and healing at fracture was early and quick in the experimental group; ossification of cartilage bone callus and the transformation of trabecular bone into woven bone occurred more early, and the bone reconstruction was better of the experimental group compared with the control group. The calcium and phosphorus in callus of both groups were gradually increased before 6 weeks, and decreased at 6 weeks. The content of calcium and phosphorus at 4 weeks was obviously higher in the experimental group than that in the control group (P < 0.01). Healing way of the micro fracture is cartilaginous ossification. Appropriate compressive fixation is superior to fixation without compression because it can shorter the time of extinction of edema, deposition of calcium and phosphorus in bone callus and healing time, reduce the inflammatory response, increase the content of calcium and phosphorus in bone callus, and improve the quality of bone callus for quick shaping.