Abstract

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. Methods: Monolayer human chondrocytes and intact cartilage samples were cultured for one 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 to 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 three hours with a single dose of 1% lidocaine exhibited significantly more cell death (7.9%) compared to control media (2.9%; p<0.001). No significant difference in cell death was observed in chondrocytes treated for six hours with 0.25% bupivacaine (2.7%) versus controls (2.8%; p=0.856) or cells treated for 12 hours in 0.5% ropivacaine (2.9%) versus controls (2.4%; p=0.084). There was no significant difference in GAG expression (p=0.627) or DNA-normalized GAG expression (p=0.065) 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). Conclusions: 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. These results suggest that the intra-articular administration of 1% lidocaine, even in a single dose, should be used with caution.