Background: Intraarticular injections of corticosteroids combined with local anesthetics are commonly used for management of chronic pain symptoms associated with degenerative joint diseases and after arthroscopic procedures. Several studies suggest chondrotoxicity of local anesthetics whereas others report chondroprotective and cytotoxic effects of corticosteroids on cartilage. Given the frequency of use of these agents, it is important to know whether they are in fact toxic.
Questions/purposes: We asked whether (1) bupivacaine and triamcinolone acetonide, alone and combined, were chondrotoxic to chondrocytes in culture; (2) buffering of the reagents diminished toxicity of the bupivacaine and triamcinolone; and (3) the presence of the superficial layer of articular cartilage protects against toxicity.
Materials and methods: We obtained cartilage from three patients undergoing arthroplasty. To address triamcinolone acetonide, bupivacaine, and combinatorial toxicity to human chondrocytes, we set up monolayer chondrocyte cultures (n = 8 wells per condition). The question of buffering was addressed by performing the same assays as above, but the reagents were buffered. An MTT assay was used to assess chondrocyte survival in the monolayer. We harvested 21 articular plugs from each of three patients (total 63 plugs) and exposed them to the same reagents as above, including the buffered reagents. A Live/Dead assay was used to determine chondrocyte survival.
Results: Triamcinolone acetonide, bupivacaine, and their combination were toxic to human chondrocytes in the monolayer comparisons. The addition of buffering did not mitigate chondrocyte death. With the intact superficial layer in the plug group, bupivacaine was not toxic as compared with for the control group; all the other reagents (triamcinolone, combination bupivacaine/triamcinolone, buffered bupivacaine, buffered triamcinolone, and buffered combination) produced chondrotoxicity.
Conclusions: Triamcinolone induced chondrotoxicity in the articular plug and monolayer culture, whereas bupivacaine induced chondrotoxicity only in monolayer culture. The combined used of triamcinolone and bupivacaine did not show additive chondrocyte death in any arm. Buffering of bupivacaine increased its chondrotoxicity.
Clinical relevance: Although not necessarily reflecting in vivo conditions, our data suggest physicians should be cognizant of the potential in vitro chondrotoxicity of bupivacaine and triamcinolone when contemplating intraarticular administration.