Radiographic evaluation of the effect of nitric oxide on bone healing: an experimental study

Abstract

Methods:Twenty adult Sprague-Dawley rats were used in a critical-size, segmental femoral defect model. A standard 5 mm segmental defect, approximately twice the diameter of the diaphysis, was created in the middle of the shaft. A polyethylene plate (23x3x4 mm) and L3-size postdental screws (1.2 mm in diameter) were used for rigid fixation. The defect was grafted using demineralized rat-bone (femur and tibia) matrix (DBM) in the control group, and DBM treated with nitrosoalbumin (an active NO congener) in the study group. Serial radiographs were obtained at 1, 3, 5, 6, and 10 weeks postoperatively. Bone formation and union were scored by three independent observers. Results: The interobserver reliability study for radiographic scoring yielded an intraclass correlation coefficient of r=0.97. At the end of the 10th postoperative week none of the rats in the control group had 100% callus formation and union, whereas nearly 100% callus formation and union were observed in two and six study animals, respectively. Similarly, the calculated median values for the defect area occupied by new bone were 43% and 83% in the control and study groups, respectively. Analysis of data on bone formation showed a statistically significant difference between the two groups (Kruskal-Wallis H test, p=0.022). Conclusion: Significant difference in radiologic results suggest that NO may promote healing and new bone formation when given in the early phase of bone healing.