Aim: The aim of this study was to evaluate histopathologically the therapeutic effects of platelet-rich plasma (PRP) and MPA (methylprednisolone acetate) injections in rabbits achill tendinopathies induced by collagenase (Collagenase Type I)

Materials and Methods: Achilles tendinopathy was formed with intrathendinous injections of type I collagenase into the proximal and distal regions of the right and left achilles tendons of 23 rabbits. PRP was injected distal to the right Achilles tendons and MPA to the distal of the left Achilles tendons. A 0,9% saline solution was also injected into the proximal parts of all achilles tendons. Rabbits were euthanized 3, 6, and 8 weeks after the therapeutic injections. The degree of histopathological degeneration of the tendons was made according to the Modified Movin scoring.

Results: Statistically significant differences were detected between the treatment groups and the 0.9% saline injected group (p<0.05). In the histopathological evaluations performed at the end of the 6th week no statistically significant difference was detected between the treatment groups (p>0.05) without tenocyte nuclei (p<0.05). At the end of the 8 weeks vascularization and tenocyte nuclei (p<0.05) parameters was observed better in the Achilles tendons of the rabbits undergoing PRP injection compared to rabbits with MPA application.

Conclusion: In conclusion, we consider that PRP injections tend to provide an earlier improvement in the treatment of tendinopathy compared to MPA injection.