Abstract: Objective To analyze the correlation of calcaneus quantitative ultrasound with dual-emission X-ray absorptiometry(DXA) in detecting bone mineral density(BMD) of elderly female patients with knee osteoarthritis. Methods One hundred and one elderly female patients with knee osteoarthritis were divided into 3 groups according to the age:<65,n=38;65-75,n=48;>75,n=15.The calcaneus quantitative ultrasound and DXA were performed in all the patients to detect BMD,the correlation between the results of calcaneus quantitative ultrasound and DXA was analyzed.Furthermore,with DXA T value as the standard,the diagnostic efficiency for osteoporosis and bone mineral density decreased of BUA,SOS,T-score and SI was analyzed. Results The DXA T of patients >75 was higher than that of patients <65 or 65-75,and the difference between groups had statistical significance(P<0.05).The BUA,T-score and SI of patients 65-75 were both lower than those of patients <65,and those of patients >75 were both lower than those of patients 65-75,and the difference between groups had statistical significance(P<0.05).BUA,T-score and SI were both had positive correlation with DXA T(R²=0.3154,0.3207,P<0.05),and both of them had good diagnostic performance for osteoporosis and BMD decrease.The best working point for osteoporosis was:BUA=55.205 dB/MHZ;T-score=-2.47;SI=65.635.The best working point for BMD decrease was:BUA=60.725 dB/MHZ;T-score=-1.605;SI=79.196. Conclusion BUA,T-score and SI by calcaneus quantitative ultrasound are closely related to BMD of women patients with knee osteoarthritis,which has prediction effect for osteoporosis,and is expected to become a clinical screening tool.