Augat P, Iida H, Jiang Y, Diao E, Genant H K
Osteoporosis and Arthritis Research Group, Department of Radiology, University of California, San Francisco, USA.
J Orthop Res. 1998 Sep;16(5):629-35. doi: 10.1002/jor.1100160517.
The strength of the radius depends on the mechanical properties of cancellous and cortical bone. By assessing both compartments quantitatively with bone densitometry, we tried to identify the specificity of each in predicting the load at which the distal radius will fracture. Twenty human cadaver forearms were scanned for bone mineral and geometric properties with quantitative computed tomography and dual x-ray absorptiometry. In both a neutral loading situation and one in which the wrist was extended 45 degrees, the load distribution was determined with pressure-sensitive films, and a fracture simulating a fall on the hand was produced with a material testing machine. Fractures that occur with the wrist in extension were produced by a central impact of the scaphoid onto the radiocarpal joint, and those that occur under neutral loading conditions were produced by a more commonly distributed loading pattern. The load at fracture was most specifically predicted (r2=0.74) by bone mineral and geometric measures of the cortex at the shaft of the radius. Bone mineral density measures of trabecular (r2=0.64) and total (r2=0.66) bone were less successful in predicting the fracture load. After adjustment for bone size, the geometric and density measures revealed similar specificity. Cortical bone, therefore, contributes significantly to the strength of the distal radius and may play an important role in the prediction of osteoporotic wrist fractures.
桡骨的强度取决于松质骨和皮质骨的力学性能。通过使用骨密度测定法对这两个部分进行定量评估，我们试图确定它们各自在预测桡骨远端骨折负荷方面的特异性。使用定量计算机断层扫描和双能X线吸收法对20具人类尸体的前臂进行骨矿物质和几何特性扫描。在中立加载情况和手腕伸展45度的情况下，使用压敏膜确定负荷分布，并使用材料试验机模拟手部着地跌倒导致的骨折。手腕伸展时发生的骨折是由舟骨对桡腕关节的中央撞击引起的，而在中立加载条件下发生的骨折是由更常见的分布加载模式引起的。骨折负荷最具特异性的预测指标（r2 = 0.74）是桡骨干皮质的骨矿物质和几何测量值。小梁骨（r2 = 0.64）和总体骨（r2 = 0.66）的骨矿物质密度测量值在预测骨折负荷方面效果较差。在对骨大小进行调整后，几何和密度测量显示出相似的特异性。因此，皮质骨对桡骨远端的强度有显著贡献，并且可能在骨质疏松性腕部骨折的预测中起重要作用。
