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.
Clinical Relevance: Although bupivacaine is the most commonly used local anesthetic for intra-articular analgesia, the demonstrated toxicity to human articular chondrocytes is cause for concern. The present study demonstrated that ropivacaine is less chondrotoxic than bupivacaine and, therefore, may be safer for intra-articular analgesia.