Impact of Lidocaine and Bupivacaine on Chondrocyte Activity in Cartilage

Researcher(s)

  • Naod Asres, Human Physiology, University of Delaware

Faculty Mentor(s)

  • Xin Lu, Mechanical Engineering, University of Delaware

Abstract

Intra-articular injection of local anesthetics, such as lidocaine and bupivacaine, are commonly used during clinical procedures and to reduce postoperative pain. The purpose of this study was to evaluate the effects of lidocaine and bupivacaine on chondrocyte activity in cartilage. Cartilage samples were harvested from juvenile bovine knees or human healthy and osteoarthritic (OA) cartilage. Samples were submerged in media, phosphate buffered saline as vehicle control, or 1% lidocaine or 0.25% bupivacaine for their half lives, 90 and 160 minutes, respectively. Twenty-four hours after exposure, chondrocyte viability, calcium signaling, and ECM synthesis were assessed. Seven to ten days after exposure, chondrocyte viability and ECM degradation were assessed. ECM synthesis and degradation was evaluated using a click chemistry method. In bovine cartilage 24 hours after exposure, both lidocaine and bupivacaine reduced chondrocyte viability in the top zone by ~30%, but had no effect in the middle zone. In the middle zone, chondrocyte calcium signaling responsive rate increased in lidocaine treated samples, and time to reach the 1st calcium peak and time to relax 50% increased. Lidocaine exposed cartilage samples also had reduced ECM synthesis, but bupivacaine exposed samples did not. After 1 week, viability was reduced by lidocaine in the top zone and bupivacaine in the middle zone. After 10 days, neither lidocaine or bupivacaine exposure induced loss of GAG from the cartilage. In human cartilage, submersion in full strength lidocaine or bupivacaine killed virtually all chondrocytes in the healthy and OA samples. OA samples were then submerged in several dilutions of lidocaine. A dose-dependent effect was elicited, as chondrotoxicity decreased with decreasing concentrations of lidocaine. 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.