Effects of plasma rich in growth factors (PRGF) on biomechanical properties of Achilles tendon repair

Purpose To assess the biomechanical effects of intra‐tendinous injections of PRGF on the healing Achilles tendon after repair in a sheep model. Methods Thirty sheep were randomly assigned into one of the six groups depending on the type of treatment received (PRGF or placebo) and survival time (2, 4 and 8 weeks). The Achilles tendon injury was repaired by suturing the tendinous edges employing a three‐loop pulley pattern. A trans‐articular external fixation system was then used for immobilization. The PRGF or placebo was administered on a weekly basis completing a maximum of three infiltrations. The force, section and tension values were compared between the operated and healthy Achilles tendons across all groups. Results The PRGF‐treated tendons had higher force at 8 weeks compared with the placebo group ( p = 0.007). Between 2 and 4 weeks, a significant increase in force in both the PRGF‐treated tendon ( p = 0.0027) and placebo group ( p = 0.0095) occurred. No significant differences were found for section ratio between PRGF‐treated tendons and the placebo group for any of the time periods evaluated. At 2 weeks, PRGF‐treated tendons had higher tension ratio compared with placebo group tendons ( p = 0.0143). Both PRGF and placebo treatments significantly improved the force ( p < 0.001 and p = 0.0095, respectively) and tension ( p = 0.009 and p = 0.0039, respectively) ratios at 8 weeks compared with 2 weeks. Conclusion The application of PRGF increases Achilles tendon repair strength at 8 weeks compared with the use of placebo. The use of PRGF does not modify section and tension ratios compared with placebo at 8 weeks. The tension ratio progressively increases between 2 and 8 weeks compared with the placebo.