Kartogenin Enhances Collagen Organization and Mechanical Strength of the Repaired Enthesis in a Murine Model of Rotator Cuff Repair

Purpose: To investigate the use of kartogenin (KGN) in augmenting healing of the repaired enthesis after rotator cuff repair in a murine model. Methods: Seventy-two C57BL/6 wild-type mice underwent unilateral detachment and transosseous repair of the supraspinatus tendon augmented with either fibrin sealant (control group; n = 36) or fibrin sealant containing 100 μmol/L of KGN (experimental group; n = 36) applied at the repair site. Postoperatively, mice were allowed free cage activity without immobilization. Mice were humanely killed at 2 and 4 weeks postoperatively. Repair site integrity was evaluated histologically through fibrocartilage formation and collagen fiber organization and biomechanically through load-to-failure testing of the supraspinatus tendon–bone construct. Results: At 2 weeks, no differences were noted in percent area of fibrocartilage, collagen organization, or ultimate strength between groups. At 4 weeks, superior collagen fiber organization (based on collagen birefringence [17.3 ± 2.0 vs 7.0 ± 6.5 integrated density/μm²; P <.01]) and higher ultimate failure loads (3.5 ± 0.6 N vs 2.3 ± 1.1 N; P =.04) were seen in the KGN group. The percent area of fibrocartilage (13.2 ± 8.4% vs 4.4 ± 5.4%; P =.04) was higher in the control group compared with the KGN group. Conclusions: Rotator cuff repair augmentation with KGN improved the collagen fiber organization and biomechanical strength of the tendon–bone interface at 4 weeks in a murine model. Clinical Relevance: These findings have implications for improving the structural integrity of the repaired enthesis and potentially reducing the retear rate after rotator cuff repair, which can ultimately lead to improvements in clinical outcomes.