Impact of platelet-rich plasma injection timing on healing of Achilles tendon injury in a rat model

Objective: The aim of this study was to evaluate the impact of the timing of platelet-rich plasma (PRP) application on the healing of Achilles tendon injury in a rat model. Methods: Fifty-four female Sprague-Dawley rats were divided into 4 groups: PRP preparation group (n=6); Achilles tendon tear and 150 mu L, of PRP received on the day following the injury (PRP day 0, group 1, n=16); Achilles tendon tear and 150 mu L of PRP received on the third day following injury (day 3, group 2, n=16); Achilles tendon tear and 150 mu L, of saline received on the day following injury (PRP day 0, group 3, n=16). Rats were sacrificed at 3 weeks. Consequently, biomechanical and histologic analyses were performed. Results: According to histological evaluation, inflammation, fibroblast density, epitenon thickness, and collagen fiber were significantly higher in group 1 than in group 2 (p<0.05). Biomechanical testing results of group 1 and group 2 were inferior to the control group, while the differences were not significant (p>0.05). Conclusion: Based on histological criteria, results of the present study suggest that immediate injection of PRP for tendon injury improves tendon healing in rats. Although the use of PRP is well recognized in orthopedic surgery, we aimed to highlight the importance of immediate application of PRP for acute tendon injury.