The influence of low bone mineral density on the fracture healing

所用动物为雌性日本白色家兔。将24只家兔分为实验组和对照组。实验组去势后喂含0.15%Ca的低钙饲料。对照组给予正常饲料。用双能X线骨密度仪（DEXA）测量了兔下颌骨的骨密度。发现实验组的骨矿物质密度比对照组小约20%。然后，将两组家兔的下颌骨取出后，使用电动机和骨凿制造人工骨折。骨折复位后用四孔微型钛板螺钉固定。分别于术后即刻、1周、2周处死动物。分别于术后4周、8周行X线片检查，比较两组骨愈合情况的差异。 关于我们 hy以及非脱矿切片的组织学检查。发现术后2周内所取标本的X线表现无显著差异。然而，在术后4周和8周采集的标本中，实验组的射线可透性较高。组织学检查显示，骨痂形成始于骨折线碎片末端，术后2至4周有明显的骨小梁形成。术后4周，在骨折线处观察到类骨质形成，呈现不规则的骨小梁图案。术后8周，骨愈合几乎完全，实验组中尽管表现出部分不规则模式，但几乎观察到正常层压。组织学检查显示，与对照组相比，实验组的骨形成活性略低。这些结果与射线可透性的差异一致。提示颌骨骨折后骨密度降低，可延缓骨折愈合。在临床上，当骨密度较低时，延长固定时间可能是必要的。少

The animals used were female japanease white rabbits. Twenty-four rabbits were divided into an experimental group and a control group. In the experimental group, after performing ovariectouiy, rabbits were fed a low-calcium diet containing 0.15% Ca. In the control gruop, rabbits were received a normal diet. Bone mineral dencity of the mandible of a rabbit was measured using DEXA (Dual Energy X-Ray Absorptiometry). It was found that the bone mineral density was smaller by about 20% in the experimental group than in the control group. Next, after the mandible of rabbits in both groups was exporsed, artificial fracture was created using an electric motor and a bone chisel. Then the fracture was reduced by manipulation and the fragments were fixed with titaniun microplates with four holes and screws. The animals were sacrificed immediately, 1 week, 2 weeks. 4 weeks and 8 weeks postoperatively, and the differences in the bone healing process between the two groups were examined by radiograp … More hy as well as by histological examination of nondemineralized sections.It was found that there were no significant differences in the radiographic findings of the specimens taken within 2 weeks after surgery. However, in specimens taken at 4 and 8 weeks after surgery, radiolucency was higher in the experimental group. Histological examination revealed that callus formation started at the end of the fragments in the fracture line, and that there was marked formation of bone trabeculae from 2 to 4 weeks after surgery. At 4 weeks after surgery, osteoid formation was noted in the fracture line presenting irregular patterns of trabeculae. At 8 weeks after surgery, the bony union was almost complete, and almost normal lamination was noted although exhibiting partly irregular patterns in the experimental group. Histological examination revealed that the activity of bone formation was slightly lower in the experimental group compared to the control group. These results were in agreement with the differences in radiolucency. It was suggested that the fracture healing of the jow bone may be delayed when the bone mineral density is decreased. In clinical practice, extention of the fixation period may be necessary when the bonemineral density is low. Less