Stürmer Ewa K, Seidlová-Wuttke Dana, Sehmisch Stephan, Rack Thomas, Wille Joern, Frosch Karl H, Wuttke Wolfgang, Stürmer Klaus M
Department of Trauma and Reconstructive Surgery, Georg-August-University of Göttingen, Göttingen, Germany.
J Bone Miner Res. 2006 Jan;21(1):89-96. doi: 10.1359/JBMR.050913. Epub 2005 Sep 26.
The fracture of bone plays a key role in osteoporosis. BMD measurement, however, is only an indirect parameter of this phenomenon. We therefore developed a highly sensitive three-point bending test for the metaphyseal tibias in rats to evaluate stiffness and strength. This was validated in a right-left comparison and a bioassay with soy-free food, estradiol, raloxifene, and testosterone in orchidectomized rats.
Osteoporosis becomes manifest predominantly in the metaphyseal rat tibia. The anti-osteoporotic character of substances should, therefore, be tested (mechanically) in this bone area.
We evaluated a new three-point bending test for the metaphyseal tibia in rats in a right-left trial. In an animal experiment, we studied the change of bone quality under estradiol (E)-, raloxifene (R)-, and testosterone (T)-supplemented food and compared it with trabecular BMD (qCT).
In the right-left comparison, the mean difference between the metaphyseal loads of both tibias in 37 rats was 8.43% for the maximum load (Fmax) and 6.46% for the failure load (fL). These results show the high reproducibility of the test, because they are close to the usual intraindividual difference of the two extremities. In a second experiment, four groups of 11 3-month-old male orchidectomized rats were fed with soy-free food only (C) or with the additives E, T, or R for 12 weeks. E and R were similar for Fmax and fL. There were significant differences in the stiffness (E = 406.92 N/mm versus R = 332.08 N/mm), the yield load (yL; E = 99.17 N versus R = 83.33 N), and the ratio between yL and Fmax (E = 86.33% versus R = 76.37%). T was similar to the controls concerning F(max), fL, and stiffness. There were significant differences in yL (T = 49.00N versus C = 39.5N) and the ratio between yL and Fmax (T = 64.28% versus C = 51.28%).
Estradiol is superior to raloxifene concerning stiffness and yield load, and both are superior to testosterone. We conclude that the described three-point bending test for the metaphyseal tibia is a highly sensitive method to study hormones and substances with regard to their osteoprotective character. The precision and the low SD of the presented results are superior to the data from qCT and the calculated index of stiffness (SSI).
骨骨折在骨质疏松症中起关键作用。然而，骨密度测量只是这一现象的间接参数。因此，我们开发了一种用于大鼠胫骨近端干骺端的高灵敏度三点弯曲试验，以评估其刚度和强度。通过左右对比以及在去势大鼠中使用无大豆食物、雌二醇、雷洛昔芬和睾酮进行生物测定对该试验进行了验证。
骨质疏松症主要在大鼠胫骨近端干骺端表现出来。因此，物质的抗骨质疏松特性应在该骨区域进行（机械）测试。
我们在左右试验中评估了一种用于大鼠胫骨近端干骺端的新三点弯曲试验。在一项动物实验中，我们研究了补充雌二醇（E）、雷洛昔芬（R）和睾酮（T）的食物对骨质量的影响，并将其与小梁骨密度（定量计算机断层扫描）进行比较。
在左右对比中，37只大鼠双侧胫骨近端干骺端负荷的平均差异，最大负荷（Fmax）为8.43%，破坏负荷（fL）为6.46%。这些结果表明该试验具有很高的可重复性，因为它们接近两个肢体通常的个体内差异。在第二项实验中，四组11只3个月大的去势雄性大鼠分别仅喂食无大豆食物（C）或添加E、T或R的食物12周。E组和R组在Fmax和fL方面相似。在刚度（E = 406.92N/mm对R = 332.08N/mm）、屈服负荷（yL；E = 99.17N对R = 83.33N）以及yL与Fmax的比值（E = 86.33%对R = 76.37%）方面存在显著差异。T组在F(max)、fL和刚度方面与对照组相似。在yL（T = 49.00N对C = 39.5N）以及yL与Fmax的比值（T = 64.28%对C = 51.28%）方面存在显著差异。
在刚度和屈服负荷方面，雌二醇优于雷洛昔芬，且两者均优于睾酮。我们得出结论，所描述的胫骨近端干骺端三点弯曲试验是一种研究激素和物质骨保护特性的高灵敏度方法。所呈现结果的精度和低标准差优于定量计算机断层扫描数据和计算出的刚度指数（SSI）。
