Comparative Effects Of Platelet-Rich Plasma And Platelet-Rich Fibrin On Achilles Tendon Healing In Wistar Rats: A Randomized Experimental Study

Abstract

Background:
Achilles tendon healing is a complex and relatively slow biological process due to limited vascularization and the predominance of type I collagen, often resulting in suboptimal biomechanical recovery. Autologous platelet-based therapies such as platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) have been proposed to enhance tendon healing; however, comparative evidence remains limited.

Objective:
To compare the effects of PRP and PRF on Achilles tendon healing in a Wistar rat model using histopathological and biomechanical assessments after a one-month observation period.

Methods:
An experimental study was conducted using male Wistar rats divided into three groups: control (n = 10), PRP (n = 9), and PRF (n = 10). Tendon healing was evaluated by histopathological parameters, including cellular response (hypertrophy), inflammation and matrix quality, vascularization, cellular/collagen orientation, and vacuolization. Biomechanical properties were assessed using tensile strength testing and tendon length change during loading. Statistical analysis was performed using chi-square tests for categorical variables and independent t-tests or Mann–Whitney tests for numerical variables, with p < 0.05 considered statistically significant.

Results:
A total of 29 Achilles tendon specimens were analyzed. Histopathological evaluation showed no statistically significant differences among groups in cellular response (p = 0.386), inflammation and matrix quality (p = 0.104), or vascularization (p = 0.149). In contrast, significant differences were observed in cellular/collagen orientation (p < 0.001) and vacuolization (p < 0.001), with the PRF group demonstrating more favorable tissue organization. Biomechanical testing revealed no significant difference in tensile strength between the control and PRP groups (p = 0.619). The PRF group demonstrated significantly higher tensile strength compared with the control group (p < 0.001), while the difference between PRP and PRF did not reach statistical significance (p = 0.051). Tendon length change during tensile testing differed significantly between the control and PRF groups (p = 0.011), whereas no significant differences were observed between control and PRP (p = 0.211) or between PRP and PRF (p = 0.278).

Conclusion:
In this Wistar rat model, PRF was associated with superior collagen organization and improved biomechanical performance compared with PRP and control, particularly during the remodeling phase of Achilles tendon healing. These findings suggest that PRF may represent a more effective biological adjunct than PRP for enhancing tendon repair.