In vitro assessment of human chondrocyte viability after treatment with local anaesthetic, magnesium sulphate or normal saline

Purpose Local anaesthetic agents are often used as an intra-articular analgesic following arthroscopic procedures. However, there is increasing evidence of a potential toxic effect to chondrocytes within the articular cartilage. The aim of this study was to compare the effect on human chondrocyte viability of treatment with bupivacaine, levobupivacaine and ropivacaine. The second aim was to compare the effect on chondrocyte viability of the local anaesthetics with magnesium, a potential alternative analgesic agent. Methods Chondrocytes were exposed to one of the local anaesthetic agents (levobupivacaine 0.13, 0.25, 0.5%; bupivacaine 0.13, 0.25, 0.5%; ropivacaine 0.19, 0.38, 0.75%), normal saline or 10% magnesium sulphate for 15 min. Cells exposed to cell culture media served as controls. Twenty-four hours after exposure, cell viability was assessed using the CellTiter 96 AQueous One Solution Cell Proliferation Assay. Results There was no significant difference in chondrocyte viability after treatment with either normal saline or magnesium sulphate. With the exception of 0.13% levobupivacine, all local anaesthetic treatment showed significantly greater toxic effects than either normal saline or magnesium sulphate. Statistically significant dose-dependent responses of decreasing cell viability were found with increasing local anaesthetic concentration. Conclusions A dose-dependent reduction in chondrocyte viability after treatment with common local anaesthetic agents was confirmed. Local anaesthetic agents had a greater deleterious effect on chondrocytes than did 10% magnesium sulphate. These findings suggest the need for continuing caution with the use of intra-articular local anaesthetic. Magnesium sulphate is a potential alternative intra-articular analgesic agent.