Introduction: Osteoarthritis is the most common type of arthritis and is one of the most common causes of pain and disability in adults. In the present study we investigated the level of inflammatory cytokines IL-1β and TNF-α and the amount of joint friction after non-traumatic model of knee osteoarthrosis in guinea pig.
Materials & Methods: Twenty-four matured albino male Dunkin-Hartley guinea pigs were assigned randomly into two groups; osteoarthrosis (OA) and control (n=12 in each group). The non-traumatic OA was induced by intra-articular injection of mono iodoacetate (MIA, 3 mg/kg) in the knee joint. Joint circumstance and weight of subjects were measured initially and after thirty days of MIA injection. After scarifying the animals on day 30, the level of IL-1β and TNF-α in synovial membrane and knee joint friction were measured. Control group received no intervention and all evaluations were performed on the normal knee joint.
Results: The induction of OA caused a significant increase in the joint circumstance compared to control group (P<0.05). 30 days after induced OA, the knee joint friction in flexion and extension movement was significantly increased compared to control group.  In OA group, the level of IL-1β and TNF-α showed a significant increase compared to control group (P<0.05). There was a positive correlation between IL-1β, TNF-α and knee joint friction (P<0.01).
Discussion: Non-traumatic osteoarthritis may increase the expression of inflammatory cytokines and joint friction, which in this condition the joint movement can aggravate cartilage damage.