定量CT中老年腰腹肌群退变与腰椎骨密度相关性的研究

Quantitative CT study on the correlation between the degeneration of the lumbar-abdominal muscle group and the lumbar vertebral bone mineral density in the middle-aged and the elderly

目的研究中老年人群腰腹肌群肌肉退变与腰椎骨密度的关系。方法使用定量CT(quantitative computerized tomography,QCT)测定187名40~69岁受试者腰椎骨密度(bone mineral density,BMD),根据BMD值分为骨量正常组及骨量减少组,将腰腹肌群分为腹壁肌群、腹直肌、椎旁肌群、椎后肌群及腰大肌5组,在腰3椎体中部层面测定各组肌群肌肉面积并计算肌指数(skeletal muscle mass index,SMI),同时测定血清性激素水平。使用独立样本t检验及Mann-Whitney U检验比较两组间各组肌群SMI的差异,使用线性相关分析研究各组肌群SMI与腰椎BMD之间的关系,绘制受试者工作特征曲线(receiver operating characteristic curve,ROC)评价各组肌群SMI诊断低骨量的效能。结果骨量减少组各组肌群SMI均低于骨量正常组,其中男性腹直肌及椎旁肌群SMI两组间差异有统计学意义(P<0.05),腹直肌SMI与BMD呈弱正相关(r=0.270,P=0.018;校正年龄因素后r=0.251,P=0.029);女性腹壁肌群及腹直肌SMI两组间差异有统计学意义(P<0.05),除腰大肌外,其余各组肌群SMI均与BMD呈弱正相关,其中腹直肌相关性最高(r=0.415,P<0.001;校正年龄因素后r=0.301,P=0.001)。男性两组间睾酮差异无统计学意义,BMD及各组肌群SMI与睾酮均无明显相关性;女性骨量减少组雌二醇水平远低于骨量正常组(P<0.001),BMD与雌二醇呈中度正相关(r=0.452,P<0.001),腹直肌、腹壁肌群SMI与雌二醇呈弱正相关(r=0.227,P=0.017;r=0.213,P=0.023)。男性腹直肌SMI曲线下面积(area under curve,AUC)为0.679,女性腹直肌与腹壁肌群SMI的AUC分别为0.669及0.655。结论中老年人群腰腹肌群肌肉退变与腰椎骨密度存在一定相关性,其中腹直肌相关性最佳。

Objective To investigate the relationship between lumbar and abdominal muscle degeneration andlumbar vertebral bone mineral density(BMD)in middle-aged and elderly people.Methods The BMD of 187 subjects aged 40-69 years were measured by quantitative CT(QCT),and then according to the BMD,all subjects were divided into the normal group and the low bone mass group.Lumbar and abdominal muscle were divided into five groups:abdominal wall muscles,rectus abdominis muscle,paravertebral muscles,posterior vertebral muscles and psoas major muscle.The area of each muscle group was measured by QCT at the level of middle-layer of L3 vertebrae,and using skeletal muscle mass index(SMI)as measurement index.Besides,the serum hormone level of all subjects were determined.The differences of each muscle SMI between the two groups were analyzed by the independent sample t test and Mann-whitney U test,the relationship between each muscleSMI and vertebral BMD were analyzed by the linear correlation analysis,and the receiver operating characteristic curve(ROC)was plotted to evaluate the efficacy of each muscle SMI in diagnosing low bone mass.Results Each muscle SMI in the low bone mass group was lower than that in the normal group,and the difference between the two groups of rectus abdominis and paravertebral muscle SMI was statistically significant(P<0.05)in males.The rectus abdominis SMI was weakly positively correlated with BMD(r=0.270,P=0.018,adjusted for age,r=0.251,P=0.029).The abdominal wall muscle and rectus abdominis SMI between the two groups were statistically significant(P<0.05)in females.Except psoas maximus,SMI of all the other muscle groups showed a weak positive correlation with BMD,among which,rectus abdominis had the highest correlation(r=0.415,P<0.001,adjusted for age r=0.301,P=0.001).There was no statistically significant difference in testosterone between the two groups in males,and there was no significant correlation between each muscle group SMI or BMD and testosterone.In female,the estradiol level in the low bone mass group was far lower than that in the normal group(P<0.001).There was a moderately positive correlation between BMD and estradiol(r=0.452,P<0.001),and weakly positive correlation between rectus abdominis and abdominal wall muscle group SMI and estradiol(r=0.227,P=0.017 and r=0.213,P=0.023,respectively).The area under the curve(AUC)of the rectus abdominis SMI in males was 0.679,and the AUC of the rectus abdominis and abdominal wall muscles SMI in females were 0.669 and 0.655,respectively.Conclusion There is a certain correlation between lumbar abdominal muscle degeneration and lumbar vertebral BMD in middle-aged and elderly people,which indicates that rectus abdominis muscle has the best correlation with BMD.