Ultrasound observation of GAG content of human hip joint cartilage in different old age groups

In this study, we observed the age-related changes of glycosaminoglycan (GAG) content of human hip joint cartilage based on ultrasound (US). Seventy human hip cartilage-bone samples were collected from hip-fracture patients (ages 51 to 96) and divided into 5 groups (10 years in an age group). They were firstly measured by ultrasound to obtain quantitative acoustic parameters, including the speed of sound (SOS), US amplitude attenuation coefficient (UAA) and normalized broadband US attenuation coefficient (nBUA). Then the samples were stained for GAG with toluidine blue. Results showed SOS, UAA, nBUA decreased by 5.49%, 36.67%, 25.57% from 50-80 age group (p<0.01), but increased by 0.34%, 1.19%, 5.23% in the 90 age group compared with the 80 age group, respectively. There were linear correlations between SOS and GAG optical density (r=0.825, p<0.01), as well as UAA and GAG optical density (r=0.708, p < 0.01). However, nBUA showed less significant linear correlation to GAG optical density (r=0.688, p < 0.07). In summary, GAG content of hip joint cartilage varied with aging in elderly people and conventional ultrasound can potentially be used to detect the age-related changes of acoustic prameters of human hip joint cartilage.