Background: It has been shown that bupivacaine, the most commonly used local anesthetic for postoperative intra-articular use, is cytotoxic to bovine articular chondrocytes in vitro. Ropivacaine is as effective as bupivacaine for intra-articular analgesia and has less systemic toxicity. We compared the in vitro viability of human articular chondrocytes after exposure to bupivacaine, ropivacaine, and saline solution control.
Methods: Macroscopically normal human articular cartilage was harvested from the femoral head or tibial plateau of five patients. Full-thickness cartilage explants and cultured chondrocytes isolated from these patients were treated with 0.9% normal saline solution, 0.5% ropivacaine, or 0.5% bupivacaine for thirty minutes. Twenty-four hours after treatment, chondrocyte viability was measured with use of the LIVE/DEAD Viability/Cytotoxicity Kit for cartilage explants and with use of the CellTiter-Glo Luminescent Cell Viability Assay for cultured chondrocytes.
Results: Chondrocyte viability in cartilage explants was significantly greater after treatment with ropivacaine as compared with bupivacaine (94.4% +/- 9.0% compared with 78% +/- 12.6%; p = 0.0004). There was no difference in viability after treatment with ropivacaine as compared with saline solution (94.4% +/- 9.0% compared with 95.8% +/- 5.7%; p = 0.6). The viability of cultured chondrocytes was significantly greater after treatment with ropivacaine as compared with bupivacaine (63.9% +/- 19% as compared with 37.4% +/- 12% of the value in the saline solution group; p < 0.0001).
Conclusions: In vitro, 0.5% ropivacaine is significantly less toxic than 0.5% bupivacaine in both intact human articular cartilage and chondrocyte culture.