Effect of pirfenidone on tendon healing

Background: The most critical issues in tendon healing include tendon adhesions and a loss of tendon strength. Adhesions result from fibrotic tissues developing in both surrounding tissues and tendons. Materials and Methods: Twenty-four rats were divided into two groups. Their Achilles tendons were cut 4 mm proximal to the calcaneal insertion and sutured with 6 / 0 monofilament nonabsorbable sutures. In the control group, saline solution was applied to the surgical field. In the experimental group, pirfenidone was applied to the surgical field locally and given orally for each rat to provide both local and systemic effects for 14 days following surgery. After a gait analysis, rats were sacrificed during the 4th postoperative week, and macroscopical, histopathological, and biomechanical analyses were performed. Results were compared with the statistical analyses. Results: The macroscopic scores of the experimental group were significantly higher than the control group (P = 0.007). The Achilles functional index scores were not significantly different between the two groups (P = 0.55). Histopathological scores were substantially closer to healthy tendons in the experimental group (P = 0.004). Biomechanically, the force required to rupture the tendons and tendon stiffness was significantly greater in the experimental group than in the control group (P = 0.028 for both). Conclusion: This study shows that tendons healed better with pirfenidone treatment.