The effect of caffeic acid on tendon healing in rats with an Achilles tendon injury model

Objectives: This study aims to examine the effect of caffeic acid on tendon healing histopathologically and biomechanically in rats with an Achilles tendon injury model. Materials and methods: Twenty male Wistar-albino rats were used in this study. The rats were divided into two groups as the experimental group and control group. All rats underwent a bilateral achillotomy injury model and then surgical repair. Postoperatively, for four weeks, the experimental group was given intraperitoneal caffeic acid (100 mg/kg/day suspended in saline), while the control group was given only intraperitoneal saline. At the end of four weeks, after sacrificing each rat, right Achilles tendons were subjected to biomechanical analysis and the Achilles tendons were subjected to histopathological analysis. Bonar and Movin scores were used for histopathological analysis. In biomechanical analysis, tensile test was applied to Achilles tendons until rupture. For each tendon, failure load, displacement, cross-sectional area, maximum energy, total energy, length, stiffness, ultimate stress and strain parameters were recorded. Results: According to Bonar and Movin scoring, the experimental group had lower scoring values than the control group (p=0.002 and p=0.002, respectively). Bonar scoring parameters were analyzed separately. Vascularity, collagen, and ground substance scores were lower in the experimental group compared to the control group (p=0.001, p=0.003, and p=0.047, respectively). No significant difference was found for tenocyte (p=0.064). In biomechanical analysis, failure load, displacement, ultimate stress, strain, and stiffness values were found to be higher in the experimental group compared to the control group (p=0.049, p=0.005, p=0.028, p=0.021, and p=0.049, respectively). Conclusion: The caffeic acid contributed positively to tendon healing histopathologically and biomechanically in rats with an Achilles tendon injury model.