Effects of local anesthetics on articular cartilage.

BACKGROUND: Recent basic science studies have demonstrated local anesthetic chondrotoxicity in vivo and in vitro in both human and animal cartilage. Clinically, chondrolysis associated with the use of intra-articular local anesthetic pain pumps has been described by several groups. This has raised concern regarding the clinical use of intra-articular local anesthetics.
METHODS: The authors undertook a review of the current orthopaedic literature on local anesthetic chondrotoxicity and its potential relationship to clinical chondrolysis.
RESULTS: Local anesthetics such as bupivacaine, lidocaine, and ropivacaine are chondotroxic to human articular cartilage in vitro, although ropivacaine is less so. The evidence suggests that there is a greater risk for chondrolysis with a longer exposure to a higher concentration of local anesthetic, such as with a pain pump, than with a single injection. However, late cellular and metabolic changes are seen after even a single injection of bupivacaine in animal models, and the loss of an intact cartilage matrix also leads to more extensive chondrocyte death. Some studies suggest that additives and the pH of the local anesthetic solution may also play a role in chondrotoxicity.
CONCLUSION: Intra-articular local anesthetics should be used with caution, especially continuous infusions of bupivacaine and lidocaine at high concentrations in joints with compromised cartilage. The consequences of a single intra-articular injection of local anesthetic remains unclear and requires further investigation. CLINICAL RELEVANCE: Intra-articular use of local anesthetics may have lasting detrimental effects on human articular cartilage and chondrocytes, although the clinical relationship between local anesthetic exposure and chondrolysis requires further study.