The effects of bone turnover rate on subchondral trabecular bone structure and cartilage damage in the osteoarthritis rat model

The effects of bone turnover rate on subchondral trabecular changes and cartilage destruction were evaluated in an iodoacetate-induced osteoarthritis rat model. Thirty female rats were randomly divided into three groups as the ovariectomized group, the no-treatment group and the bisphosphonate medication group. Arthritis was induced by a single intra-articular iodoacetate injection into the right tibiofemoral joint. Eight weeks after this injection, tibiofemoral joints on both sides were scanned with a micro-CT. Subchondral trabecular indices were measured on both sides of the tibial lateral condyle epiphysis. In the ovariectomized group, the percentage of bone volume, trabecular thickness and trabecular bone pattern factor of the arthritic sides were lower than those of the control sides, while trabecular separation and structure model index of the arthritic sides were higher than those of the control sides (p < 0.05). In the no-treatment group, only trabecular thickness of the arthritic sides was lower than in the control sides (p < 0.05). In the bisphosphonate medication group, trabecular indices were no different between the arthritic and control sides. Articular cartilage destruction and severity of arthritis increased significantly in the order: ovariectomized group < no-treatment group < bisphosphonate medication group (p < 0.05). After osteoarthritis development, severities of subchondral trabecular changes appeared to be strongly affected by bone turnover rate. Furthermore, a correlation was found between cartilage destruction severity and subchondral trabecular change in the intra-articular iodoacetate-injected osteoarthritis rat model.