Siu Wing Sum, Qin Ling, Leung Kwok Sui
Musculoskeletal Research Laboratory, Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Shatin, Hong Kong.
J Bone Miner Metab. 2003;21(5):316-22. doi: 10.1007/s00774-003-0427-5.
Bone mineral density (BMD) is commonly used to predict osteoporotic fracture risk without considering the geometry of the bone. However, geometric parameters are also important in determination of bone strength. An index including both material and geometric properties may be therefore more relevant in prediction of fracture risk. We studied the correlation between parameters measured by noninvasive peripheral quantitative computed tomography (pQCT) and bone bending strength of the diaphysis of 45 fresh goat humeri and 27 femora. Multislice pQCT was used for measuring volumetric diaphyseal cortical BMD, total BMD, diaphyseal and cortical cross-sectional area (CSA), and cross-sectional moment of inertia (CSMI) and their derived bone strength indices (BSIs), including BSI(CSMI) (cortical BMD x CSMI) and BSI(CSA) (cortical BMD x cortical CSA). Conventional dual-energy absorptiometry (DXA) was also conducted to measure areal BMD of diaphysis for comparison. Ultimate fracture load was obtained via three-point bending test. Results showed that for femora, fracture load was correlated better with BSI(CSA) ( r = 0.697, P < 0.001) than cortical BMD ( r = 0.304, P > 0.05) and total BMD ( r = 0.387, P > 0.05) measured using pQCT and areal BMD ( r = 0.612, P < 0.001) measured using DXA. For humeri, fracture load was also correlated with BSI(CSA) ( r = 0.579, P < 0.001) but not with other pQCT parameters including cortical BMD and total BMD ( r = 0.282 and 0.305, respectively; P > 0.05, both). The best correlation was found with areal BMD measured by DXA ( r = 0.760, P < 0.001). In conclusion, pQCT noninvasive BSI(CSA) derived from cortical BMD (material) and its cortical CSA (bone geometry or distribution) may serve as an important noninvasive index for predicting long bone bending strength. The bending strength was also predicted by bone mass (areal BMD) measured by DXA, an integration of bone mineral and geometry. Further clinical studies are needed to validate the predictive value of BSI in long bone osteoporotic fracture.
骨密度（BMD）通常用于预测骨质疏松性骨折风险，而未考虑骨骼的几何形状。然而，几何参数在确定骨强度方面也很重要。因此，一个同时包含材料和几何特性的指标可能在预测骨折风险方面更具相关性。我们研究了通过无创外周定量计算机断层扫描（pQCT）测量的参数与45根新鲜山羊肱骨和27根股骨骨干的骨弯曲强度之间的相关性。使用多层pQCT测量骨干皮质骨体积骨密度、总骨密度、骨干和皮质骨横截面积（CSA）、截面惯性矩（CSMI）及其衍生的骨强度指数（BSIs），包括BSI(CSMI)（皮质骨密度×CSMI）和BSI(CSA)（皮质骨密度×皮质CSA）。还进行了传统双能X线吸收法（DXA）测量骨干的面积骨密度以作比较。通过三点弯曲试验获得极限骨折载荷。结果表明，对于股骨，骨折载荷与BSI(CSA)的相关性更好（r = 0.697，P < 0.001），优于使用pQCT测量的皮质骨密度（r = 0.304，P > 0.05）和总骨密度（r = 0.387，P > 0.05）以及使用DXA测量的面积骨密度（r = 0.612，P < 0.001）。对于肱骨，骨折载荷也与BSI(CSA)相关（r = 0.579，P < 0.001），但与其他pQCT参数（包括皮质骨密度和总骨密度，分别为r = 0.282和0.305；P均> 0.05）无关。与DXA测量的面积骨密度相关性最佳（r = 0.760，P < 0.001）。总之，由皮质骨密度（材料）及其皮质CSA（骨几何形状或分布）得出的pQCT无创BSI(CSA)可能是预测长骨弯曲强度的重要无创指标。骨量（面积骨密度）通过DXA测量，它综合了骨矿物质和几何形状，也可预测弯曲强度。需要进一步的临床研究来验证BSI在长骨骨质疏松性骨折中的预测价值。
