[The effect of stress-relaxation plate fixation on the remodeling of the cortex under plate].

OBJECTIVE: To explore the influence of stress-relaxation plate(SRP) fixation on the remodeling of cortex under plate. METHODS: Twenty-eight New Zealand rabbits were used in this study, the bilateral tibia were osteotomized in the middle and fixed with SRP (experimental group) and rigid plate (control group) respectively. The scanning electron microscopy was used to observe the bone remodeling process from 2 to 48 weeks after operation. RESULTS: There was cortex osteoporosis beneath plate in different degree in both experimental and control groups before 8 weeks, it showed as the disorganization of collagen fiber structure and formation of resorption cavities. In comparison, the osteoporosis degree in experimental group showed milder than that of the control group. After 12 weeks, the resorption cavities became smaller, and the structure of collagen fibers became regular with the alignment parallel to the long axis of cortex. In contrast to the experimental group, the bone osteoporosis under plate of control group exacerbated continuously. CONCLUSION: Without removal of the bone plate, SRP fixation not only reduce the degree of plated bone osteoporosis, but also make the osteoporosic bone return to normal.