Department of Biology, School of Science, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA.
Bone. 2010 Aug;47(2):235-40. doi: 10.1016/j.bone.2010.05.015. Epub 2010 May 16.
This study was aimed to investigate the effects of Parathyroid hormone (PTH) and alendronate (ALN) on stress fracture repair. Stress fractures were induced in the ulnae of female adult rats. Animals were treated daily with vehicle, PTH (40 microg/kg) or alendronate (2 microg/kg), respectively. Bone mineral content (BMC) and bone mineral density (BMD) of bilateral ulnae were measured at two, four and eight weeks following induction of stress fracture. Histology at the ulna midshaft was undertaken at 2 and 4 weeks and mechanical testing was done at 8 weeks after stress fracture. PTH increased BMC significantly by 7% at 4 weeks and BMD and BMC significantly by 10% and 7% at 8 weeks compared to the control. Alendronate did not change BMD or BMC in comparison with the control. PTH significantly stimulated bone formation by 114% at 2 weeks, increased intracortical resorption area by 23% at 4 weeks, and enhanced the ultimate force of the affected ulnae by 15% at 8 weeks compared to the control. Alendronate significantly suppressed bone formation rate by 44% compared to the control at 4 weeks. These data indicate that PTH may accelerate intracortical bone remodeling induced by microdamage and alendronate may delay intracortical bone remodeling during stress fracture repair in rats. This study suggests that PTH may be used to facilitate stress fracture repair whereas bisphosphonates may delay tissue level repair of stress fractures.
本研究旨在探讨甲状旁腺激素（PTH）和阿仑膦酸钠（ALN）对应力性骨折修复的影响。在成年雌性大鼠的尺骨上诱导应力性骨折。动物分别每天用载体、PTH（40μg/kg）或阿仑膦酸钠（2μg/kg）治疗。在诱导应力性骨折后 2、4 和 8 周，分别测量双侧尺骨的骨矿物质含量（BMC）和骨矿物质密度（BMD）。在 2 和 4 周时对尺骨干进行组织学检查，在应力性骨折后 8 周进行力学测试。与对照组相比，PTH 在 4 周时 BMC 显著增加 7%，在 8 周时 BMD 和 BMC 分别显著增加 10%和 7%。与对照组相比，阿仑膦酸钠并未改变 BMD 或 BMC。与对照组相比，PTH 在 2 周时显著增加了 114%的骨形成率，在 4 周时增加了 23%的皮质内吸收面积，并在 8 周时增加了受影响尺骨的极限力 15%。与对照组相比，阿仑膦酸钠在 4 周时显著抑制了 44%的骨形成率。这些数据表明，PTH 可能加速微损伤引起的皮质内骨重塑，而阿仑膦酸钠可能在大鼠应力性骨折修复过程中延迟皮质内骨重塑。本研究表明，PTH 可用于促进应力性骨折修复，而双膦酸盐可能会延迟应力性骨折的组织水平修复。
