Human Chondrocyte Viability After Treatment With Local Anesthetic and/or Magnesium: Results From an In Vitro Study

PURPOSE: We aimed to assess the effect on chondrocyte viability of adding magnesium to a variety of commonly available local anesthetic agents. METHODS: Human chondrocytes were grown under standard culture conditions. Cells were exposed to a local anesthetic agent with the addition of magnesium (10%, 20%, or 50%). Cells were also exposed to the varying concentrations of magnesium and 0.9% saline solution. Untreated cells served as controls. The CellTiter 96 AQueous One Solution Cell Proliferation Assay was used to assess for cell viability 24 hours after exposure. One-way analysis of variance was used to test for statistical significance. RESULTS: Magnesium sulfate alone was no more toxic than normal saline solution (P > .3) compared with untreated cells. The addition of magnesium to the local anesthetic agents resulted in greater cell viability than when cells were treated with a local anesthetic alone (lidocaine [P = .033], levobupivacaine [P = .007], bupivacaine [P < .001], and ropivacaine [P < .001]). CONCLUSIONS: Our findings support the use of magnesium either alone or in combination with a local anesthetic rather than a local anesthetic alone, and this represents a potential strategy for the reduction of chondrocyte toxicity associated with intra-articular local anesthetic administration after arthroscopy. CLINICAL RELEVANCE: The addition of magnesium to a local anesthetic results in a reduced toxic effect to the articular chondrocyte. This may represent a potential approach to intra-articular analgesia.