Early Detection of Tibial Cartilage Degradation and Cancellous Bone Loss in an Ovariectomized Rat Model

This study aimed to investigate degradation of the articular cartilage and loss of the cancellous bone in an ovariectomized (OVX) rat model simulating early human menopausal stage. Fourteen health female Sprague-Dawley rats were randomly divided into two groups (n = 7 per group): an OVX group that underwent bilateral ovariectomy to create an OVX model with low estrogen levels and a sham group in which only the periovarian fatty tissue was exteriorized. All the animals were sacrificed at 3 weeks after ovariectomy. The left tibiae were harvested. The articular cartilage at medial tibial plateau (MTP) and lateral tibial plateau (LTP) was assessed with quantitative high-frequency ultrasound. The cancellous bone was evaluated with micro-CT. The results indicated that, in comparison with the sham rats, the OVX rats exhibited significant alterations in acoustic parameters of the articular cartilage but insignificant changes in microarchitectural parameters of the cancellous bone in early stage of low estrogen levels. The results of this study suggest that cartilage degradation induced by estrogen reduction was detected earlier with quantitative ultrasound than that of the cancellous bone loss in 3 wk OVX rats.