Szulc Pawel, Munoz Françoise, Duboeuf François, Marchand François, Delmas Pierre D
INSERM 403 Research Unit, Hôpital Edouard Herriot, 69437 Lyon, France.
Bone. 2006 Apr;38(4):595-602. doi: 10.1016/j.bone.2005.09.004. Epub 2005 Oct 24.
The risk of fragility fractures in elderly men is only partly explained by areal bone mineral density (aBMD) measured by dual X-ray absorptiometry (DXA). Several studies suggest the importance of bone morphology for the risk of fracture. The aim of this study was to assess the value of bone size and estimated structural parameters for the prediction of incident fractures in a large cohort of men. This study was made in 759 men aged 50-85 from the MINOS cohort. During a 90-month follow-up, 74 men sustained incident vertebral and peripheral fractures. Areal BMD was measured by DXA at femoral neck, distal radius and distal ulna. Estimates of structural bone parameters and volumetric BMD (vBMD) were derived from aBMD measured by DXA. Given the limited number of fractures, the predictive value of investigated parameters was assessed for peripheral and vertebral fractures jointly by using logistic regression. Men who sustained the fractures had, at baseline, lower aBMD (3.5-6.5%), lower bone mineral content (BMC 5.4-8.7%) and lower cortical thickness (3.5-6.9%) compared with the men without fracture. At all the three skeletal sites, aBMD, BMC, width, cortical area and thickness, cross-sectional moment of inertia (CSMI), and section modulus predicted incident fractures (O.R. = 1.28-1.92 per 1 SD decrease, P < 0.05-0.0001). Fracture risk was weakly associated with vBMD for ulna (O.R. = 1.25 per 1 SD decrease, P < 0.05) but not for femoral neck or radius. After adjustment for aBMD, bone width remained a significant predictor of fractures (O.R. = 1.37-1.48 per 1 SD decrease, P < 0.02-0.01). Men with osteopenia (BMD T score < -1) and low bone width (T score < -1) had the fracture incidence similar to that observed in men with BMD T score < -2. Bone width and aBMD of the femoral neck and radius were predictive of fractures in 49 men with the incident peripheral fractures, whereas their O.R. did not attain the level of statistical significance in 25 men with the incident vertebral fractures. Men, who had both low aBMD and low CSMI ( both T scores < -1), had the fracture risk 3.8 to 4.2 higher than the reference group (both T scores >or= -1). Men, who had both low aBMD and low section modulus (both T scores < -1), had the fracture risk 2.1 to 4.1 higher than the reference group (both T scores >or= -1). In conclusion, men who sustained a fragility fracture during a 90-month follow-up had, at baseline, lower BMC because they had narrower bones but not necessarily less dense. In elderly men, small bone width, low BMC and poor resistance to bending may increase bone fragility. Low bone width seems to be associated with an increased fracture risk in elderly men regardless of aBMD.
老年男性脆性骨折的风险仅部分可由双能X线吸收法（DXA）测量的面积骨密度（aBMD）来解释。多项研究表明骨形态对于骨折风险具有重要意义。本研究的目的是评估在一大群男性中，骨大小和估计的结构参数对于预测新发骨折的价值。本研究纳入了来自MINOS队列的759名年龄在50 - 85岁的男性。在为期90个月的随访期间，74名男性发生了新发椎体和外周骨折。通过DXA测量股骨颈、桡骨远端和尺骨远端的aBMD。结构骨参数和体积骨密度（vBMD）的估计值由DXA测量的aBMD得出。鉴于骨折数量有限，通过逻辑回归联合评估所研究参数对外周骨折和椎体骨折的预测价值。与未发生骨折的男性相比，发生骨折的男性在基线时aBMD较低（低3.5 - 6.5%）、骨矿物质含量（BMC低5.4 - 8.7%）以及皮质厚度较低（低3.5 - 6.9%）。在所有三个骨骼部位，aBMD、BMC、宽度、皮质面积和厚度、截面惯性矩（CSMI）以及截面模量均能预测新发骨折（每降低1个标准差，优势比（O.R.） = 1.28 - 1.92，P < 0.05 - 0.0001）。尺骨的骨折风险与vBMD弱相关（每降低1个标准差，O.R. = 1.25，P < 0.05），但股骨颈或桡骨并非如此。在调整aBMD后，骨宽度仍然是骨折的显著预测因素（每降低1个标准差，O.R. = 1.37 - 1.48，P < 0.02 - 0.01）。骨量减少（BMD T评分 < -1）且骨宽度低（T评分 < -1）的男性骨折发生率与BMD T评分 < -2的男性相似。股骨颈和桡骨的骨宽度及aBMD可预测49例发生外周骨折男性的骨折情况，而在25例发生椎体骨折的男性中其O.R.未达到统计学显著水平。aBMD和CSMI均低（T评分均 < -1）的男性骨折风险比参照组（T评分均≥ -1）高3.8至4.2倍。aBMD和截面模量均低（T评分均 < -1）的男性骨折风险比参照组（T评分均≥ -1）高2.1至4.1倍。总之，在90个月随访期间发生脆性骨折的男性在基线时BMC较低，因为他们的骨骼更窄，但不一定密度更低。在老年男性中，小的骨宽度、低BMC以及抗弯曲能力差可能会增加骨脆性。无论aBMD如何，低骨宽度似乎都与老年男性骨折风险增加相关。
