Xing Xiao-ping, Xia Wei-bo, Meng Xun-wu, Zhou Xue-ying, Hu Ying-ying, Liu Huai-cheng
Department of Endocrinology, Peking Union Medical College Hospital, Union Medical College and Chinese Academy of Medical Sciences, Beijing 100730, China.
Zhonghua Yi Xue Za Zhi. 2003 May 10;83(9):791-5.
To evaluate the value of peripheral quantitative computed tomography (pQCT) in measuring bone architecture and biomechanic properties.
50 virgin female Wistar rats six months old were randomly divided into 4 groups: (1) 8 rats were killed as baseline group; (2) 8 rats underwent sham operation and then were killed 14 weeks after (sham operation group); (3) 16 rats underwent bilateral ovariectomy (OVX) without further intervention. Six and 14 weeks after the operation each 8 rats were killed (OVX group); and (4) 18 rats underwent OVX too. After the OVX 9 of the 18 rats were treated with 17beta-estradiol 20 micro g/kg/d IH and 9 rats were treated with estradiol valerate 800 micro g/kg/d po for 8 weeks respectively. Then the 18 rats were killed (OVX plus estrogen group, O + E group). The right tibiae of the rats were taken for histomorphometric analysis, and the right femora were prepared for pQCT scanning and bone biomechanical measurement with indentation test and three-point bending test.
Histomorphometric analysis showed that the trabecular volume of proximal tibia (Cn-BV/TV) in the OVX group was 8.1 +/- 1.4%, significantly lower than that in the sham operation group (19.5 +/- 1.5%, P < 0.01). pQCT scanning showed that the femoral trabecular bone mineral content (Trab BMC) in the OVX group was 1.7 +/- 0.3 mg/mm, significantly lower than that in the sham operation group (3.2 +/- 0.5 mg/mm, P < 0.01) and the femoral trabecular bone mineral density (Trab BMD) in the OVX group was 158 +/- 32 mg/mm(3), significantly lower than that in the sham operation group (320 +/- 39 mg/mm(3), P < 0.01). The cancellous maximal load (Can load) of the distal shaft of femur in the OVX group was 12.5 +/- 2.5 N, significantly lower than that in the sham operation group (45.9 +/- 3.2 N, P < 0.01). The cancellous stiffness (Can Stiff) of the distal shaft of femur in the OVX group was 226 +/- 48 N/mm, significantly lower than that in the sham operation group (396 +/- 72 N/mm, P < 0.01). The Can load of O + E group was 21.8 +/- 3.7 N, significantly higher than that in the OVX group (P < 0.05). The Can Stiff of the O + E group was 382 +/- 54 N/mm, significantly higher than that in the OVX group (P < 0.05). There were no significant differences in cortical bone determined by pQCT as well as biomechanic properties in measured by three point test after OVX and estrogen treatment. A significant positive correlation was shown between Trab BMD and Cn-TV/BV and between Trab BMD and Tb N (r = 0.88 and 0.73, both P < 0.01). Similarly, both Trab BMC and Trab BMD of the femur were significantly correlated with the Can load and Can Stiff determined by indentation test (r = 0.47 - 0.68, all P < 0.01). There was also a significant correlation of parameters measured by pQCT in cortical bone with the maximal load and stiffness for the femur midshaft, and the best correlation was found between the maximal load of femur midshaft and Crt BMC and Crt A (both r = 0.76 and P < 0.01).
The geometric, densitometric and mechanical properties in cortical and trabecular bones of rat can be well described by pQCT.
评估外周定量计算机断层扫描（pQCT）在测量骨结构和生物力学特性方面的价值。
将50只6月龄未交配的雌性Wistar大鼠随机分为4组：（1）8只大鼠处死后作为基线组；（2）8只大鼠接受假手术，术后14周处死（假手术组）；（3）16只大鼠接受双侧卵巢切除术（OVX），不进行进一步干预。术后6周和14周分别处死8只大鼠（OVX组）；（4）18只大鼠也接受OVX。18只大鼠中的9只在OVX后分别接受20μg/kg/d皮下注射17β-雌二醇和9只大鼠接受800μg/kg/d口服戊酸雌二醇治疗8周。然后处死这18只大鼠（OVX加雌激素组，O + E组）。取大鼠右侧胫骨进行组织形态计量学分析，取右侧股骨进行pQCT扫描，并通过压痕试验和三点弯曲试验进行骨生物力学测量。
组织形态计量学分析显示，OVX组近端胫骨的骨小梁体积（Cn-BV/TV）为8.1±1.4%，显著低于假手术组（19.5±1.5%，P<0.01）。pQCT扫描显示，OVX组股骨骨小梁骨矿物质含量（Trab BMC）为1.7±0.3mg/mm，显著低于假手术组（3.2±0.5mg/mm，P<0.01），且OVX组股骨骨小梁骨矿物质密度（Trab BMD）为158±32mg/mm³，显著低于假手术组（320±39mg/mm³，P<0.01）。OVX组股骨远端骨干的松质骨最大载荷（Can load）为12.5±2.5N，显著低于假手术组（45.9±3.②N，P<0.01）。OVX组股骨远端骨干的松质骨刚度（Can Stiff）为226±48N/mm，显著低于假手术组（396±72N/mm，P<0.01）。O + E组的Can load为21.8±3.7N，显著高于OVX组（P<0.05）。O + E组的Can Stiff为382±54N/mm，显著高于OVX组（P<0.05）。OVX和雌激素治疗后，pQCT测定的皮质骨以及三点试验测量的生物力学特性均无显著差异。Trab BMD与Cn-TV/BV以及Trab BMD与Tb N之间呈显著正相关（r = 0.88和0.73，均P<0.01）。同样，股骨的Trab BMC和Trab BMD均与压痕试验测定的Can load和Can Stiff显著相关（r = 0.47 - 0.68，均P<②01）。pQCT在皮质骨中测量的参数与股骨中段的最大载荷和刚度也存在显著相关性，并且在股骨中段最大载荷与Crt BMC和Crt A之间发现最佳相关性（两者r = 0.76且P<0.01）。
pQCT能够很好地描述大鼠皮质骨和松质骨的几何、密度和力学特性。
