Histopathology in rabbit Achilles tendon after operative tenolysis (longitudinal fiber incisions)

The surgical treatment (tenolysis) of chronic Achilles tendinopathy is ofte n successful. However, little is known about the postoperative intratendino us changes after this procedure. The study group consisted of 21 rabbits. O perative tenolysis was done in each case on one Achilles tendon (AT). The A Ts of both legs were studied histologically and immunohistochemically using antibodies against collagen types I and III 2, 4 and 6 weeks postoperative ly. Nine rabbits without operation served as controls. A significant unifor m hypervascularization was noted in the entire operated tendon postoperativ ely, and this concurred with the contralateral nonoperated AT, but neither side showed changes in collagen fiber structure as judged by immunohistoche mistry. We conclude that the tenolysis procedure triggers neoangiogenesis a t the AT followed by increased blood flow and improved nutrition in the sam e. These changes could, at least partly, explain the often seen clinical su ccess in surgically treated tendinopathy.