Coefficient of Start-Up Friction of Early Stage Osteoarthritic Cartilage Is Not Larger Than Normal Cartilage

It is well known that the disease of osteoarthritis (OA) deteriorates the lubrication properties of articular cartilage. Previous studies [1,2] have demonstrated that the coefficient of friction of rabbit knee cartilage increases significantly in OA models. The coefficient of start-up (static) friction in the normal canine knee joint has also been observed to increase with the duration of static loading [3], and further increases in the start-up friction of osteoarthritic cartilage were induced by surface abrasion and papain injection [4]. However, the change in the start-up friction due to OA disease induced by anterior cruciate ligament (ACL) transection (ACL transection model), has not been fully determined in previous studies, although such a model is considered to display symptoms similar to the clinical situation. Therefore, we investigated the effect of osteoarthritic deterioration on the start-up friction in the ACL transection OA model in the present study.