Impact of Lidocaine and Bupivacaine on Chondrocyte Viability and Metabolic Activity on Cartilage Explants

• Naod Asres, Human Physiology, University of Delaware

• Xin Lu, Mechanical Engineering, University of Delaware

Intra-articular injection of local anesthetics such as lidocaine and bupivacaine are commonly used by clinicians to relieve their patients of postoperative pain. While there is extensive literature regarding the cytotoxic effects of lidocaine and bupivacaine, there is insufficient evidence to suggest whether or not they have a significant impact on the chondrocyte viability and metabolic activity in cartilage explants. The purpose of this study was to evaluate the effects of lidocaine and bupivacaine on healthy chondrocytes. Articular cartilage explants were harvested from the femoral condyle and patellar groove of bovine joints. Samples were then cultured in chondrogenic medium, and control samples were exposed to either chondrogenic medium or phosphate buffered saline (PBS) while treated samples were exposed to either lidocaine or bupivacaine. Chondrocyte viability of the top and middle zones was assessed either 24 hours or 1 week after treatment. Impact on metabolic activity was assessed by determining glycosaminoglycan (GAG) synthesis, collagen synthesis, and GAG loss using a click-chemistry based method. After 24 hours, both lidocaine and bupivacaine were found to have significantly reduced chondrocyte viability. After 1 week, significant difference in chondrocyte viability was only found between the middle and top zones of samples in the control and lidocaine groups. Samples treated with lidocaine were found to have significantly lower GAG synthesis in comparison to both control groups and bupivacaine, as well as significantly lower collagen synthesis in comparison to samples in the PBS control group. Neither samples treated with lidocaine or bupivacaine were found to have differences in GAG Loss. These findings present insight into the chondrotoxic effect of lidocaine and bupivacaine that will better inform clinicians of the true effects of these local anesthetics, as well as providing a basis of knowledge to further build upon in future experiments regarding their impact on articular cartilage.