Yoshikawa T, Turner C H, Peacock M, Slemenda C W, Weaver C M, Teegarden D, Markwardt P, Burr D B
Department of Anatomy, Indiana University Medical Center, Indianapolis.
J Bone Miner Res. 1994 Jul;9(7):1053-64. doi: 10.1002/jbmr.5650090713.
An algorithm was developed to estimate the strength of the femoral neck from data generated by the dual-energy x-ray absorptiometry (DXA). This algorithm considers shape of the proximal femur as well as cross-sectional moment of inertia (CSMI) in the estimate. Proximal femora (10) from cadavers of white adults and an aluminum step wedge were scanned with the Lunar DPX to validate the calculation of CSMI. After scanning, each femoral neck was sectioned at its narrowest portion for direct measurement of CSMI. Three healthy young women were scanned five times each to evaluate the reproducibility of geometric measurements using DXA. There was a strong linear association between the CSMI measured directly and using DXA in both cadaver bones (r2 = 0.96) and the aluminum step wedge (r2 = 0.99). The coefficient of variation for CSMI from repeated measurements using DXA was less than 3%. This indicates that it is possible to estimate reproducibly the bending rigidity of bone from DXA measurements. The data from 306 normal subjects were analyzed to investigate geometric changes in the femoral neck with age. Although there was no strong correlation between CSMI and age in normal subjects of either sex, safety factor (SF, an index of strength of the femoral neck during walking) and fall index (FI, an index of the strength of the femoral neck during a fall) decrease with age in both sexes. We observed an alteration of the geometric structure of the femoral neck with age that may increase the stress on the femoral neck and decrease SF and FI.
开发了一种算法，用于根据双能X线吸收法（DXA）生成的数据估算股骨颈的强度。该算法在估算时考虑了股骨近端的形状以及截面惯性矩（CSMI）。使用Lunar DPX对白人成年人尸体的近端股骨（10根）和铝制阶梯楔形物进行扫描，以验证CSMI的计算。扫描后，将每个股骨颈在其最窄处切开，以直接测量CSMI。对三名健康年轻女性每人进行了五次扫描，以评估使用DXA进行几何测量的可重复性。在尸体骨骼（r2 = 0.96）和铝制阶梯楔形物（r2 = 0.99）中，直接测量的CSMI与使用DXA测量的CSMI之间均存在很强的线性关联。使用DXA重复测量得到的CSMI变异系数小于3%。这表明可以通过DXA测量可重复地估算骨骼的抗弯刚度。对306名正常受试者的数据进行分析，以研究股骨颈随年龄的几何变化。尽管在任何性别的正常受试者中，CSMI与年龄之间均无强相关性，但安全系数（SF，行走时股骨颈强度的指标）和跌倒指数（FI，跌倒时股骨颈强度的指标）在两性中均随年龄下降。我们观察到股骨颈的几何结构随年龄发生改变，这可能会增加股骨颈上的应力，并降低SF和FI。
