Allogenic platelet`s growth factors increased achilles tendon callus strength in rats

The study was conducted on 64 adult male Wistar rats. The experimental group consisted of 32 animals with experimental cut of the Achilles tendon and local injection of allogenic platelet rich plasma. The control group comprised 32 rats with cut of the tendon and saline local injection. The animals were euthanized after 7, 14, 21, and 42 d. The mechanical testing of the tensile strength of the tendons was performed on an universal testing machine. Biomechanical testing was performed at 7, 14, 21, and 42 d after cutting the Achilles tendons. The maximal breaking force (Fmax), force at the end of proportional range (Fs), and stiffness of the tendons (H) were evaluated. At 7 d postoperative, there were no significant differences in Fmax (P=0.53) and Fs (P=0.48) of the Achilles tendons among the groups. Significant differences between the examined and control groups in the H (P=0.021) were found at day 7 of the experiment. Mechanical testing results in the mean Fmax, Fs, and H values were significantly higher in experimental group in comparison to controls at 14, 21, and 42 d (all P<0.05). Growth factors from allogenic platelet rich plasma administered locally increased significantly the tensile strength of rats’ Achilles tendon callus after experimental cut at 14, 21, and 42 d.