Fibrin Scaffold With Concentrated Growth Factor and Stromal Vascular Fraction: A Novel Approach for Repairing Chronic Rotator Cuff Tears in a Rabbit Model

Background: Rotator cuff tears (RCTs) represent a significant challenge in orthopaedic care, particularly in chronic cases where tendon healing is suboptimal. Novel biological therapies such as concentrated growth factor (CGF) and stromal vascular fraction (SVF) offer promising solutions for enhanced tendon repair. Hypothesis: This study hypothesized that a fibrin scaffold enriched with CGF and SVF would improve tendon healing by reducing fatty degeneration, increasing vascularization, and enhancing biomechanical properties in a chronic RCT rabbit model. Study Design: Controlled laboratory study. Methods: A chronic RCT model was developed in the subscapularis tendon of 28 male New Zealand rabbits. In the first phase (week 0), the chronic injury model was created surgically. At week 6, in addition to the transosseous repair technique, biological materials were applied into the bone tunnel in each group as follows: hydrogel (group 1), fibrin gel with CGF (group 2), CGF+SVF–enriched fibrin scaffold (group 3), and no repair (group 4). At week 12, animals were euthanized, and samples were collected for macroscopic, histological, immunohistochemical, and biomechanical analysis. Results: Group 3 demonstrated a superior result. Fatty degeneration was significantly lower in group 3 compared with group 1 (P = .045). Vascularization and cellularity scores were highest in group 3 (3.7 ± 0.5 and 3.6 ± 0.5, respectively), significantly greater than group 1 (1.4 ± 0.5 and 1.3 ± 0.5, respectively) (P = .024 and P = .004, respectively). Collagen fiber continuity and regularity scores were 3.7 ± 0.5 and 3.6 ± 0.5 in group 3, respectively, significantly better than group 1 (1.4 ± 0.5 and 1.3 ± 0.5, respectively) (P = .006 and P = .003, respectively). Biomechanical testing revealed the highest tensile strength in group 3 (116.14 ± 8.49 N; P < .001). Midsubstance tears, indicating robust healing, were observed in 85.7% of tendons in group 3 compared with 28.6% in group 1 (P = .002). Notably, group 3 also demonstrated superior outcomes compared with group 2, with significantly greater tensile strength (116.14 ± 8.49 N vs 100 ± 6.85 N; P < .001) and improved histological parameters including reduced fatty degeneration, and increased vascularization and collagen fiber regularity. Conclusion: The inclusion of CGF and SVF in fibrin scaffolds significantly enhances tendon healing in chronic RCTs, outperforming the use of CGF alone. This combined biological approach offers a promising therapeutic strategy to optimize tendon repair outcomes. Clinical Relevance: These findings support the clinical potential of CGF and SVF in improving repair outcomes in chronic RCT cases in sports medicine.