Comparison of intraarticular bupivacaine and levobupivacaine injection in rat synovial inflammation

Background/aim: Both bupivacaine and levobupivacaine are local anesthetics with strong analgesic efficacy that can be used intraarticularly. The aim of this study was to compare the effects of intraarticular bupivacaine and evobupivacaine injection on inflammation in articular cartilage and the synovium of the rat knee joint. Materials and methods: Twenty Sprague-Dawley rats were injected in the right knee joint with 0.2 mL of bupivacaine, while 0.2 mL of levobupivacaine was injected into the left knee joint. Groups of 5 were sacrificed on days 1, 7, 14, and 21 after bupivacaine and levobupivacaine administration and knee joints were examined for subintimal fibrosis, synovial hyperplasia, chronic inflammation, neutrophil infiltration, edema, and synovial and periarticular congestion by microscopy. Alterations in the articular cartilage structure were evaluated using Mankin scoring. Results: We found that both drugs have similar effects on synovial and articular cartilage resulting in mild to moderate congestion, edema, neutrophil infiltration, chronic inflammation, and synovial hyperplasia, which diminished gradually. However, increases in fibrosis were also seen to varying degrees. Thus, the use of these drugs intraarticularly can be recommended. Conclusion: Careful usage of bupivacaine and levobupivacaine is recommended in intraarticular applications since they cause inflammation shortly after injection and fibrosis at later time points.