Deleterious effects of local corticosteroid injections on the Achilles tendon of rats

The purpose of this study was to examine the pathological changes in the Ac hilles tendon and its paratenon after intratendinous corticosteroid injecti ons and to reveal the effects of this drug on healthy tendon. We also sough t for the effects of these injections compared with compression with a clam p on the Achilles tendons of the rats. Fifty-two Achilles tendons in 26 mal e Wistar rats were included in the study. Betamethasone injections were app lied to the left tendons at different intervals, while the right tendons se rved for compression with mosquito clamps for varied periods. At the end of 30 days, all of the tendons were excised and examined histopathologically according to a semiquantitative scoring system. Histopathologic evaluation demonstrated some degree of degeneration in both groups. Statistical analys is showed no significant difference among the two groups, but in macroscopi c evaluation, the tendons in the betamethasone group demonstrated enlargeme nt and strong adhesion to the subcutaneous tissue. We conclude that intrate ndinous betamethasone injections are as harmful as compression with a clamp and can be used as a degeneration-producing model in further studies. Enla rgement of the tendon mass and strong adhesion to the subcutaneous tissue c an be due to injection of the betamethasone partly outside the tendon.