中老年女性腰椎椎后肌群退变与腰椎骨密度的关系研究

A clinical study on the relationship between lumbar vertebrae posterior muscle group degeneration and lumbar bone mineral density in middle-aged and elderly females

目的:研究中老年女性腰椎椎后肌群退变与腰椎骨密度的关系。方法:以一项前瞻性中国城乡流行病学研究项目招募的社区健康志愿者中的中老年女性作为研究对象,共115例。45岁≤年龄<60岁者62例(中年组),年龄≥60岁者53例(老年组)。使用定量CT分别测量其腰椎骨密度,并测量L3椎体中部层面椎后肌群的肌肉面积及脂肪面积,计算腰椎椎后肌群内的肌肉脂肪浸润程度(muscle fat infiltration,MFI)[MFI=脂肪面积/(肌肉面积+脂肪面积)×100%]。采用直线相关分析和多元线性回归分析探讨腰椎骨密度与腰椎椎后肌群退变的关系。结果:中年组的腰椎骨密度、椎后肌群肌肉面积均高于老年组[(132.74±35.74)mg·cm^(-3),(91.43±28.40)mg·cm^(-3),t=6.779,P=0.000;(40.68±6.62)cm^2,(38.01±6.41)cm^2,t=2.182,P=0.031],椎后肌群脂肪面积、MFI均低于老年组[(1.89±0.99)cm^2,(2.34±1.45)cm^2,t=-1.997,P=0.048;(4.48±2.11)%,(5.85±3.44)%,t=-2.604,P=0.010];2组的体质量指数比较,组间差异无统计学意义[(23.96±3.22)kg·m^(-2),(24.08±3.06)kg·m-2,t=-0.190,P=0.850]。中年组、老年组及总体研究对象的腰椎骨密度均与年龄呈负相关(r=-0.552,P=0.000;r=-0.599,P=0.000;r=-0.690,P=0.000)。中年组腰椎骨密度与椎后肌群脂肪面积及MFI均呈负相关(r=-0.267,P=0.037;r=-0.304,P=0.017),与椎后肌群肌肉面积不存在直线相关关系(r=0.081,P=0.581);老年组腰椎骨密度与椎后肌群脂肪面积及MFI均呈负相关(r=-0.331,P=0.017;r=-0.371,P=0.007),与椎后肌群肌肉面积不存在直线相关关系(r=0.235,P=0.094);总体研究对象的腰椎骨密度与椎后肌群脂肪面积及MFI均呈负相关(r=-0.191,P=0.042;r=-0.214,P=0.023),与椎后肌群肌肉面积不存在直线相关关系(r=0.132,P=0.163)。以腰椎骨密度为因变量,以年龄、体质量指数、腰椎椎后肌群肌肉面积和脂肪面积作为自变量,进行多元线性回归分析,得到的回归方程分别为,腰椎骨密度(中年组)=379.695-3.929×年龄-7.609×腰椎椎后肌群脂肪面积、腰椎骨密度(老年组)=146.419-1.190×年龄-6.350×腰椎椎后肌群脂肪面积、腰椎骨密度(总体研究对象)=269.577-2.962×年龄-5.307×腰椎椎后肌群脂肪面积。结论:中老年女性腰椎椎后肌群脂肪含量的增加可能会导致腰椎骨密度的下降,是骨质疏松的重要危险因素。

Objective:To study the relationship between lumbar vertebrae posterior muscle group degeneration and lumbar bone mineral density(BMD)in middle-aged and elderly females.Methods:One hundred and fifteen middle-aged and elderly females were selected as the subjects from community healthy volunteers that were recruited for a prospective urban and rural epidemiologic study in China.Sixty-two females ranged in age from 45 to 60 years(middle-aged group),and 53 females were≥60 years old(elder group).Their lumbar BMD were measured by using quantitative computerized tomography(CT),and muscle area and fat area of posterior vertebral muscle group were measured at the level of middle-layer of L 3 vertebrae.The degree of muscle fat infiltration(MFI)(MFI=fat area/(muscle area+fat area)×100%)of lumbar vertebrae posterior muscle group was calculated.The relationship between lumbar BMD and lumbar vertebrae posterior muscle group degeneration were analyzed by using linear correlation analysis and multiple linear regression(MLR)analysis.Results:The lumbar BMD and the muscle area of posterior vertebral muscle group were higher(132.74+/-35.74 vs 91.43+/-28.40 mg/cm(3),t=6.779,P=0.000;40.68+/-6.62 vs 38.01+/-6.41 cm(2),t=2.182,P=0.031),and the fat area of posterior vertebral muscle group and the MFI were lower(1.89+/-0.99 vs 2.34+/-1.45 cm(2),t=-1.997,P=0.048;4.48+/-2.11 vs 5.85+/-3.44%,t=-2.604,P=0.010)in middle-aged group compared to elder group.There was no statistical difference in body mass index(BMI)between the 2 groups(23.96+/-3.22 vs 24.08+/-3.06 kg/m(2),t=-0.190,P=0.850).The lumbar BMD was negatively correlated with the age of research objects in middle-aged group and elder group and of general research objects(r=-0.552,P=0.000;r=-0.599,P=0.000;r=-0.690,P=0.000).The lumbar BMD was negatively correlated with the fat area of posterior vertebral muscle group and the MFI(r=-0.267,P=0.037;r=-0.304,P=0.017)and there was no linear correlation between lumbar BMD and muscle area of posterior vertebral muscle group(r=0.081,P=0.581)in middle-aged group.The lumbar BMD was negatively correlated with the fat area of posterior vertebral muscle group and the MFI(r=-0.331,P=0.017;r=-0.371,P=0.007)and there was no linear correlation between lumbar BMD and muscle area of posterior vertebral muscle group(r=0.235,P=0.094)in elder group.The lumbar BMD of general research objects was negatively correlated with the fat area of posterior vertebral muscle group and the MFI(r=-0.191,P=0.042;r=-0.214,P=0.023),and there was no linear correlation between lumbar BMD and muscle area of posterior vertebral muscle group(r=0.132,P=0.163).The lumbar BMD(Y)was chosen as the dependent variable and age(X1),BMI(X2)and muscle area(X3)and fat area(X4)of lumbar vertebrae posterior muscle group were chosen as the independent variable to make a MLR analysis,and then the linear regression equations(middle-aged group:Y=379.695-3.929×X1-7.609×X4;elder group:Y=146.419-1.190×X1-6.350×X4;general research objects:Y=269.577-2.962×X1-5.307×X4)were established.Conclusion:The increase in fat content of lumbar vertebrae posterior muscle group may lead to the decrease in lumbar BMD in middle-aged and elderly females,and it may be an important risk factor for osteoporosis.