Locomotor activity and histological changes observed in a mouse model of knee osteoarthritis

[Purpose] This study aimed to elucidate the changes in locomotor activity in a mouse model of knee osteoarthritis (OA). [Materials and Methods] Fourteen 20-week-old mice were divided into control and OA groups. Knee OA was surgically induced under anesthesia by destabilizing the meniscus. The OA group was reared normally for 8 weeks following surgery, during which OA was induced. Locomotor activity was measured every hour for 8 weeks using an infrared locomotor activity measurement device. Histological changes were evaluated according to the classification-system of Glasson. [Results] Locomotor activity in the OA group significantly decreased up to 2 weeks after surgery. Histological findings in the control group revealed an irregular cartilage surface in a portion of the tibia with no other abnormalities. Contrastingly, those in the OA group had eburnation of the medial femoral condyle, as well as fibrillation and fissures in the medial tibial plateau. Histological scores in the OA group were significantly higher than the control group. [Conclusion] Locomotor activity evaluations, in addition to histological scores and findings, are imperative for studies aiming to clarify the disease state and effect of interventions using mice models.