The In Vitro Chondrotoxicity of Single-Dose Local Anesthetics

Background: The administration of amide-type local anesthetics to cartilaginous tissues has revealed potential chondrotoxicity. Purpose: This study evaluated whether administration of single doses of 1% lidocaine, 0.25% bupivacaine, and 0.5% ropivacaine resulted in decreased chondrocyte viability or cartilage matrix degradation in vitro. Study Design: Controlled laboratory study. Methods: Monolayer human chondrocytes and intact cartilage samples were cultured for 1 week in media. Each drug was delivered in a custom bioreactor over its clinical duration of action. A Live/Dead Viability/Cytotoxicity Assay was used to determine the ratio of dead to live cells for monolayer chondrocyte cultures compared with controls. Damage to the cartilage extracellular matrix (ECM) in en bloc cartilage samples was evaluated by analysis of DNA, glycosaminoglycan (GAG), and collagen content. Results: Chondrocytes treated for 3 hours with a single dose of 1% lidocaine exhibited significantly more cell death (7.9%) compared with control media (2.9%; P < .001). No significant difference in cell death was observed in chondrocytes treated for 6 hours with 0.25% bupivacaine (2.7%) versus controls (2.8%; P = .856) or cells treated for 12 hours in 0.5% ropivacaine (2.9%) versus controls (2.4%; P = .084). There was no significant difference in GAG expression (P = .627) or DNA-normalized GAG expression (P = .065) between the intact cartilage treatment groups; however, the DNA-normalized GAG expression was markedly lower in cartilage cultures treated with 1% lidocaine (3.36 +/- 1.15) compared with those in control media (7.61 +/- 3.83). Conclusion: The results of this in vitro study indicate that a single-dose administration of 1% lidocaine resulted in a significant decrease in chondrocyte viability when compared with control cultures. Clinical Relevance: Single-dose injections of 1% lidocaine may be significantly chondrotoxic, and further investigation regarding in vivo chondrotoxicity appears warranted.