• Intra-articular injection of cobalt chloride solution successfully induced knee osteoarthritis in New Zealand rabbits, with severity increasing with concentration and time.
• Higher cobalt chloride concentrations led to more severe cartilage degeneration, including involvement of deep cartilage and subchondral bone.
• Histological and immunohistochemical analyses confirmed progressive cartilage degradation, with increased OARSI scores and elevated IL-1 and TNF-α expression.
• The model provides a reliable chemical-induced osteoarthritis animal model for studying disease mechanisms and therapeutic interventions.