Effect On The Healing Of Tiny Fracture Fragments Under Stress In Rabbits

Objective:Fracture healing is a highly complex regenerative process, by age, mechanical environment, endocrine, local blood supply, and many other factors, including stress is one of the main factors. Stress stimulation of fracture healing remains unclear, studies have shown that stimulation of bone stress good adaptability, bone cells have the feeling mechanical signals, but the detailed mechanism needs further study. The rapid development of biomechanics of fracture healing has opened up many new ideas and new areas, while increasing awareness of stress factors in the important role of fracture healing. All of the previous stress on the limbs are for the healing of long bone fractures, often encountered in the clinical setting of small joints avulsion fracture fragment of healing has not been reported. The purpose of this study is to establish a rabbit model of tiny fracture fragments, pieces of stress fracture healing of the small impact and how it affects whether the initial block of tiny fracture healing mechanism. Methods:20 rabbits, the first X-ray observation of the normal hind femur fractures without deformity and after the reunification of the greater trochanter of hind legs exposed incised with a homemade knife made up into small bone splitting greater trochanter avulsion fracture of the block, fracture block size is 0.5cm×0.3cm. The same left and right hind legs of rabbits fracture fragments were used to a small diameter of 2.0mm,2.0mm diameter Kirschner wire and a pull screws.2,4,6 weeks after the fracture line on X ray and CT examination contrast image changes, and killed five batches each time the original surgical incision in rabbits, their blood vessels around the fracture, soft tissue such as the general After observing signs along the original fracture site, take the best around and the space within the fracture callus specimens were retained, and a little from each of the same amount of callus 10% neutral formalin fixed, decalcified 5% nitric acid solution, paraffin embedded sections, HE staining for histological light microscope, all remaining callus-70℃refrigerator until the line of calcium and phosphorus content. Fixation compared between the two blocks on the small fracture healing. Results:We observed the experimental group rabbits 2 weeks after the fracture site edema, adhesions lighter than the control group; after 4 weeks and 6 weeks, the organization of the two groups at the fracture site was no significant difference. X-ray experimental callus growth rate faster than the control group, external callus volume, high intensity, short plastic callus. CT showed two weeks in the experimental group, compared with callus growth significantly, while the control group, less the amount of callus; 4 weeks experimental group are apparent inside and outside the callus, fracture line becomes blurred, but the control group, callus growth more, the growth of small fracture callus cross-section is very clear; 6 weeks, both groups are significant internal and external callus, fracture line disappeared in experimental group, the fracture shaping better fracture line fuzzy control group, but not disappeared, shaping the fracture poor. Callus tissue sections observed by light microscopy in both groups showed subchondral bone of the way, the experimental group hematoma disappearance of the faster machines, repair of the fibrous tissue of bone cartilage bone callus earlier was replaced by bone callus growth strong, ends earlier and faster healing callus, and callus bone ossification of cartilage, bone-like trabecular woven bone into early than in the control group, bone remodeling modeling better than the control group. Experimental group and control group fracture gap callus calcium and phosphorus levels were increased gradually after surgery to decrease after 6 weeks,4 weeks, indicators of calcium and phosphorus in the experimental group was significantly higher, P<0.01 there are significant statistically significant. Conclusion:The tiny fracture healing under way into the performance of the subchondral bone osteoblasts, suitable stress than non-stressed fixed-fixed micro fracture edema surrounding tissue block rapid inflammatory reaction, deposition of calcium and phosphorus in callus early, great content, fracture healing time is short.