双能X线吸收法在分析髋部骨折患者股骨颈结构强度中的应用

目的 利用双能X线吸收法(DXA)研究骨质疏松性股骨颈骨折患者和健康受试者髋关节的几何结构强度,探讨各强度参数与骨折发生危险性的关系.方法 在进行了100例健康者DXA双侧股骨颈骨密度(FN BMD)、骨结构参数[截面转动惯量(CSMI)、截面面积(CSA)、截面模量(SM)、皮质骨内径(ED)、皮质骨外径(OD)、皮质骨厚度(CT)、髋轴长度(HAL)、股骨颈干角(NSA)、髋关节强度指数(SI)]配对t检验比较的基础上,对59例股骨颈骨折患者与年龄匹配的健康组DXA髋部几何结构强度参数进行比较,并作为骨折危险因素变量带入条件logistic回归方程分析,计算各参数与骨折发生的相对危险性.结果 双侧髋部的DXA参数均呈高度正相关(r=0.847~0.998,P<0.05),部分参数存在较小但有统计学意义的差异.骨折组女性的FN BMD、CSMI、CSA、SM、CT和SI显著低于对照组女性.骨折组男性的FN BMD、CSMI、CSA、SM和SI显著低于对照组男性.经身高、体重和FN BMD 校正后,骨折组女性的CSMI、SM仍然显著低于对照组女性,骨折组男性的SM显著低于对照组男性.HAL为男、女性组入选股骨颈骨折模型的唯一因素,其OR值分别为1.385和1.269.结论 髋部几何结构参数差异可以解释骨折患者股骨近端骨强度的降低,DXA测量的HAL参数对于男、女性髋部骨折风险预测具有重要的临床意义.

The application of DXA-based strength analysis of the hip geometric structure in clinical femoral neck fracture

Objective Using dual energy X-ray absorptiometry (DXA) to study the differences of hip geometric structural strength between osteoporotic femoral neck fracture patients and healthy control subjects, thus to investigate the correlations between the structural parameters and fracture risk.Methods Paired t test was applied for comparison of bilateral femur DXA measurement parameters in 100 healthy subjects, including femoral neck bone mineral density (FN BMD) and bone geometric structure strength parameters (cross-sectional moment of inertia (CSMI), cross-sectional area (CSA), section modulus (SM), endocortical diameters (ED), outer diameter (OD), cortical thickness (CT), femoral neck-shaft angle (NSA), hip axis length (HAL) and hip strength index (SI)).The femoral DXA measurement parameters of 59 patients with femoral neck fracture were compared with those of age matched healthy controls.The DXA geometric parameters of hip were taken as the risk factors of femoral neck fracture and analyzed by conditional logistic regression.The relative risks of femoral neck fractures were calculated by these geometric strength parameters.Results There was high positive correlation (r=0.847~0.998, P<0.05) between the left and right DXA femoral measurement parameters.There was no significant difference in FN BMD, CSMI, CSA, NSA, or SI parameters between left and right hips in healthy controls, though there were small but significant differences in SM, OD, ED, CT, and HAL between left and right hips.In women with fractures, FN BMD, CSMI, CSA, SM, CT and SI were significantly lower than those in controls.In men with fractures, FN BMD, CSMI, CSA, SM and SI were significantly lower than those in controls.After adjusting for height, weight and FN BMD, the CSMI and SM in females with fracture were significantly lower than controls, as the SM in males with the fracture was significantly lower than controls.HAL was the only risk factor for femoral neck fracture in both males and females, with the OR values of 1.385 and 1.269, respectively.Conclusion Differences in hip geometric strength parameters between fractured and healthy controls can explain the reduction of proximal femoral bone strength in patients with femoral neck fractured.HAL obtained with DXA is the risk factor of hip fracture in both men and women.