Abstract
Introduction
Local anaesthetic has been reported to have a detrimental effect on human chondrocytes both in vitro and in vivo. Magnesium, an NMDA-receptor antagonist, may be an alternative intra-articular analgesic agent following arthroscopy. We aimed to report the dose response effect of commonly used local anaesthteitc on chondrocyte viability and also report on the effect of adding magnesium to local anaesthetic.
Methods
Human chondrocytes were grown under standard conditions. Cells were exposed to either lignocaine (0.5, 1, 2%), levobupivacaine (0.125, 0.25, 0.5%), bupivacaine (0.125, −.25, 0.5%) or ropivacaine (0.1875, 0.375, 0.75%) for 15 minutes. Cells were also exposed to a local anesthetic agent with the addition of magnesium (10, 20, or 50%). Cells exposed to media or saline served as controls. The MTS assay was used to assess cell viability 24-hours after exposure.
Results
One-way ANOVA showed an expected dose response in all local anaesthetic groups with the exception of lignocaine. Magnesium alone was no more toxic than normal saline (P>0.3). 50% magnesium showed similar effect on cell viability to the least toxic local anaesthetic (lignocaine 1%, P=0.31). The addition of magnesium to the local anesthetic agents resulted in greater cell viability than when cells were treated with the respective local anaesthetic alone (lignocaine (P=0.033), levobupivacaine (P=0.007), bupivacaine (P<0.001), ropivacaine (P<0.001)).
Conclusion
We have shown that cell viability is greater in the presence of magnesium than selected local anaesthetics and also with the addition of magnesium to local anaesthetic compared to the local anesthetic agent alone. We believe that these findings offer support to an alternative intra-articular analgesia following arthroscopy.
