Peri-tendinous injection of local anaesthetic, both alone and in combination with
corticosteroids, is commonly performed in the treatment of
tendinopathies. Previous studies have shown that local anaesthetics and
corticosteroids are chondrotoxic, but their effect on tenocytes remains unknown. We compared the effects of
lidocaine and
ropivacaine, alone or combined with
dexamethasone, on the viability of cultured bovine tenocytes. Tenocytes were exposed to ten different conditions: 1)
normal saline; 2) 1%
lidocaine; 3) 2%
lidocaine; 4) 0.2%
ropivacaine; 5) 0.5%
ropivacaine; 6)
dexamethasone (dex); 7) 1% lidocaine+dex; 8) 2% lidocaine+dex; 9) 0.2% ropivacaine+dex; and 10) 0.5% ropivacaine+dex, for 30 minutes. After a 24-hour recovery period, the viability of the tenocytes was quantified using the CellTiter-Glo viability assay and fluorescence-activated cell sorting (FACS) for live/dead cell counts. A 30-minute exposure to
lidocaine alone was significantly toxic to the tenocytes in a dose-dependent manner, but a 30-minute exposure to
ropivacaine or
dexamethasone alone was not significantly toxic.
Dexamethasone potentiated
ropivacaine tenocyte toxicity at higher doses of
ropivacaine, but did not potentiate
lidocaine tenocyte toxicity. As seen in other cell types,
lidocaine has a dose-dependent toxicity to tenocytes but
ropivacaine is not significantly toxic. Although
dexamethasone alone is not toxic, its combination with 0.5%
ropivacaine significantly increased its toxicity to tenocytes. These findings might be relevant to clinical practice and warrant further investigation.