Effect of Aging on the Progression of Articular Cartilage Damage in a Rat Osteoarthritis Model

This study aimed to investigate and clarify the effect of aging on the progression of cartilage damage using a rat osteoarthritis model. In total, 12 rats, including three rats per age group, were assigned to the experimental group, and two rats (one 3 and 18 months old each) were assigned to the control group. In the experimental group, joint instability was induced using the destabilization of the medial meniscus model. After completion of the 4-week experimental period, the bilateral knee joints were harvested and the histological changes in the articular structures of the joints were observed using a light microscope. Medial dislocation of the medial meniscus, low staining of the cartilaginous substrate on the tibial side localized around the medial meniscus tip, and irregularities and fibrillation of the superficial layer of the cartilage on the tibial side were observed in all experimental age groups. No significant age-related differences were observed in the degree of observed findings and the score of cartilage degeneration. The results indicate that aging does not affect the early stages of progression of cartilage damage