The effect of intra-articular ketamine injection on cartilage and synovial tissue in rats

Aim: One of the most important causes of delayed discharge from hospital and rehabilitation in patients undergone arthroscopy is postoperative pain. Intraarticular analgesic injection is a new technique for pain control in such patients and is a good alternative because of its limited systemic effects. This brings up the question of whether these injections have unwanted effects on the synovial tissue. The beneficial and side effects of intra-articular ketamine injection after arthroscopy will be investigated in this study. Methods: Twenty rats were included in the study. Ketamine was injected at doses of 10 mg/kg (0,2 ml) to their right knee intra-articularly and same amount of isotonic NaCl was injected into the their left knee as control group. They were then sacrificed on days 1, 7, 14 and 21. The joints were labeled according to the day and direction. Samples were examined in Hematoxylin- Eosin and Masson-Trichrome dye by light microscopy. Intra-articular, peri-articular and synovial inflammations were investigated in the knee joint. Results: Although inflammation was high for the group sacrificed the 1st day after ketamine injection, we did not find a significant difference between rats injected with saline and ketamine. There was no significant difference in the number of synovial membrane-forming cells and subintimal fibrosis. Conclusion: Patients with circulatory failure-disorders, advanced age, and comorbidity may not have the same reaction to intra-articular ketamine, as did the animals in our study. It should be investigated by further in vitro and wider studies