The effect of local anesthetic and corticosteroid combinations on chondrocyte viability.

PURPOSE: Local anesthetic and corticosteroid combination injections are often used in clinical practice, however research investigating the chondrotoxic properties of these combinations is minimal. The goal of this study was to evaluate the effect of single injection doses of 1% lidocaine or 0.25% bupivacaine in combination with single injection doses of dexamethasone sodium phosphate (Decadron), methylprednisolone acetate (Depo-Medrol), betamethasone sodium phosphate and betamethasone acetate (Celestone Soluspan), or triamcinolone acetonide (Kenalog) on human chondrocyte viability.

METHODS: All treatment conditions were delivered to human chondrocytes in vitro for the medication's respective average duration of action using a bioreactor containing a continuous infusion pump constructed to mimic joint fluid metabolism. A two-color fluorescence assay was used to evaluate cell viability. A mixed-effects regression model was used to evaluate the mean differences in cell viability between treatment groups.

RESULTS: At 14 days, a single injection dose of 1% lidocaine or 0.25% bupivacaine in combination with betamethasone sodium phosphate and betamethasone acetate solution illustrated significant chondrotoxicity when compared with the local anesthetics alone (P < 0.01). Methylprednisolone acetate and Triamcinolone acetonide both showed significant evidence of chondrotoxicity (P = 0.013; P = 0.016, respectively) when used in combination with 1% lidocaine compared with lidocaine alone, but showed no significant chondrotoxicity in combination with 0.25% bupivacaine (P's = n.s.).

CONCLUSIONS: Clinicians should use caution when injecting 1% lidocaine or 0.25% bupivacaine in conjunction with betamethasone sodium phosphate and betamethasone acetate solution due to its pronounced chondrotoxic effect in this study. 1% lidocaine used in combination with methylprednisolone acetate or triamcinolone acetonide also led to significant chondrotoxicity.