Comparison of the effects of injectable platelet rich-fibrin (i-PRF) and concentrated growth factor (CGF) on bone and tendon healing in rabbit rotator cuff tear model

Purpose: The aim of this study is to investigate the effects of Injectable Platelet-Rich Fibrin (I-PRF) and Concentrated Growth Factor (CGF) on bone-tendon interface healing in a rabbit rotator cuff tear model and to evaluate the results comparatively. Materials and Methods: After ethics committee approval, a full-thickness tear model was created on both shoulders suprasupinatus tendons of 18 white New Zealand Albino rabbits. After the surgery, the rabbits were divided into three groups equally: 1st group was CGF, 2nd group was I-PRF and 3rd group was formed as control group. I-PRF and CGF were obtained by centrifugation of blood taken with a standard appropriate procedure. At the Rotator Cuff (RM) attachment site repaired surgically, CGF was applied to Group 1 and I-PRF was applied to Group 2 as the growth factor materials. After the sacrification procedure performed 6 weeks after the surgery, each surgical applied suprasupinatus tendon of the rabbits was removed together with the shoulder joint. Tissue samples from the left shoulder were taken for histological examination and samples from the right shoulder were used for biomechanical tensile testing. Damage load detection and elongation of the obtained Rotator cuff bone-tendon complex were measured by biomechanical tensile test using SHIMADZU brand EHF-EV200k2-040-0A model tensile device. Immunohistochemical staining was performed for histological analysis, and evaluations were made according to the Tendon-Bone junction scoring system that Nourissat et al. put forward in 2010. Results: In the biomechanical tensile test, the CGF group showed significant higher durability with 61.57N than the other groups (p=0.001). In the Elongation/Tension test, elongation was measured as 3.99mm in the CGF group, 3.14mm in the I-PRF group and 2.52mm in the control group, and a statistically significant difference in favor of CGF was found between the groups (p=0.030). While there was no statistically significant difference in the amount of cells in the tendon-bone junction (p=0.237) and Chondrocyte organization (p=0.327) in the tendon-bone junction scoring between the groups, statistically significant difference was found in favor of CGF in collagen type 2 amount (p=0.0001), gag score content (p=0.001) and collagen organization score (p=0.004). Conclusion: In this study, according to the results of mechanical and histological findings, it was shown that CGF was statistically significantly effective in healing of the bone-tendon junction compared to I-PRF. CGF application promoted protendon and cartilage formation in rabbit tenocytes, and the improvement in the histological appearance and mechanical properties of tendon repair were proven by tendon-bone junction score and biomechanical tensile tests. As a result, it has been shown in the direction of statistically significant results that supplementing the treatment with CGF in RM repair provides a more positive contribution to the healing of the bone-tendon interface than I-PRF. Keywords: Rotator Cuff tear, CGF, I-PRF, tendon-bone