title: Reduction of environmental temperature mitigates local anesthetic cytotoxicity in bovine articular chondrocytes.
abstract: The purpose of this study was to assess whether reducing environmental temperature will lead to increased chondrocyte viability following injury from a single-dose of local anesthetic treatment. Bovine articular chondrocytes from weight bearing portions of femoral condyles were harvested and cultured. 96-well plates were seeded with 15,000 chondrocytes per well. Chondrocytes were treated with one of the following conditions: ITS Media, 1x PBS, 2% lidocaine, 0.5% bupivacaine, or 0.5% ropivacaine. Each plate was then incubated at 37°C, 23°C, or 4°C for one hour and then returned to media at 37°C. Chondrocyte viability was assessed 24 hours after treatment. Chondrocyte viability is presented as a ratio of the fluorescence of the treatment group over the average of the media group at that temperature (ratio ± SEM). At 37°C, lidocaine (0.35 ± 0.04) and bupivacaine (0.30 ± 0.05) treated chondrocytes show low cell viability when compared to the media (1.00 ± 0.03) control group (p < 0.001). Lidocaine treated chondrocytes were significantly more viable at 23°C (0.84 ± 0.08) and 4°C (0.86±0.085) than at 37°C (p < 0.001). Bupivacaine treated chondrocytes were significantly more viable at 4°C (0.660 ± 0.073) than at 37°C or 23°C (0.330 ± 0.069) (p < 0.001 and p = 0.002 respectively). Reducing the temperature from 37°C to 23°C during treatment with lidocaine increases chondrocyte viability following injury. Chondrocytes treated with bupivacaine can be rescued by reducing the temperature to 4°C. Key pointsConfirm that local anesthetics, specifically bupivacaine and lidocaine, are toxic to chondrocytes in monolayerChondrocyte viability significantly improved for chondrocytes treated with bupivacaine when the environment was cooled to 23°C.Chondrocyte viability significantly improved for chondrocytes treated with bupivacaine or lidocaine when the environment was cooled to 4°CIt is the recommendation of the authors that physicians should be wary of the risks of injecting local anesthetics into the intra-articular space.Active cooling of the joint could potentially protect the articular cartilage from insult following treatment with local anesthetics.
authors.affiliation: San Francisco Veterans Affairs Medical Center, Department of Orthopaedic Surgery , San Francisco, CA, USA.
authors.forename: Tarik
authors.initials: T
authors.lastname: Onur
authors.affiliation: San Francisco Veterans Affairs Medical Center, Department of Orthopaedic Surgery , San Francisco, CA, USA.
authors.forename: Alexis
authors.initials: A
authors.lastname: Dang
keywords: Clinical hypothermia; articular cartilage; chondrolysis; local anesthetics; osteoarthritis