Histological and Biomechanical Effects of Local Anesthetics and Steroids on Rat's Achilles Tendon

Local anesthetics peri-tendinous injection, alone or in combination with corticosteroids, is widely used in the treatment of tendonitis. Reduction of patient pain and prevent the loss of motion is provided in this way. As a result of such injections to the tendinopathies around shoulder, elbow, wrist, hip and ankle, positive results were shown in patients. The aim of this study was to show the histological and biomechanical differences occured in peri-tendinous sheath of rat achilles tendon following injection of both different concentrations of local anesthetics and steroids alone and different combinations of them. Hundred adult female Wistar albino rats were divided into ten groups of 10 rats each. After inflammation was created, injections were perfomed in tendons according to groups. As a local anesthetic, lidocaine and bupivacaine injections with different concentrations and combinations of dexamethasone were used. After one week follow-up, rats were sacrificed. Obtained tendon sections were examined biomechanically and histologically. As a result, the most toxic effect on tendon was seen in dexamethasone injection group. This group, in terms of toxicity, was followed by group with dexamethasone in combination with low and high dose lidocaine. The groups with low or high dose bupivacaine combined dexamethasone, were found as the least toxic group. In clinical practice, the application of dexamethasone alone may increase the tendon complications in patients. Therefore, before the injection, dexamethasone should be combined with a local anesthetic, especially bupivacaine instead of lidocaine, so risk of complications might be reduced.