Assessment of Hydroxyproline Content in Rabbit Achilles Tendon Treated with Platelet Rich Fibrin (PRF)

Tendon is similar to rope and consists of strong, flexible, dense connective tissue. Tendon disorder healing is challenging as it is an avascular tissue. The repaired tissue appears scar-like, and its biomechanical properties never ultimately return to their pre-injury state. This study aimed to evaluate the effects of platelet-rich fibrin (PRF) on the hydroxyproline content of the Achilles tendon after injury. For this purpose, 24 adult rabbits weighing 1.5-2 kg were used in this study. The animals were divided into three groups of eight, including the advanced-PRF (A-PRF) group in which the tendon defect was treated with xenogeneic A-PRF, the leukocyte-PRF (L-PRF) group in which xenogeneic L-PRF was used for tendon defect treatment, and a control group which was treated with normal saline. Hydroxyproline concentration was measured 1 and 2 months after the operation. Clinically, lameness was improved in the A-PRF group, compared to the L-PRF and control groups at the end of the third week after the surgery. Hydroxyproline level was significantly increased in the A-PRF group (50.33±1.44), compared to the L-PRF (44.70±1.12) and control (35.97±1.05) groups 2 months after the surgery (P<0.05). Moreover, the L-PRF group showed an increase in hydroxyproline content, compared to the control at the same period. The results of the current study demonstrated that A-PRF could enhance the hydroxyproline content of rabbit Achilles tendon after injury. Xenogenic PRF can be used as an alternative biomaterial to accelerate and regenerate tendon tissue.