This study evaluated the biomechanical and histologic characteristics of the rotator cuff tendon and muscle tissue with rat models with diabetes mellitus (DM) (group 1) and 30 male rats without DM (group 2). We conducted a time zero study without any additional procedures or external variables at 9 weeks after induction of the diabetic rat model. Thereafter, quantitative evaluation of advanced glycation end products (AGEs) was accomplished via enzyme-linked immunosorbent assay and immunohistochemistry (IHC). Fatty infiltration was investigated with Oil Red O staining, and the peroxisome proliferator activated receptor-gamma (PPAR-gamma) value was studied with IHC. Grossly, the supraspinatus tendons of the group 1 rats were more friable and discolored (yellowish) than those of group 2. In the biomechanical analysis, group 1 rats showed significantly inferior ultimate failure load ( P =.001) and ultimate stress ( P =.02). Group 1 was significantly inferior to group 2 in terms of total histologic scoring ( P <.001). Mean AGE levels were significantly higher in group 1 ( P <.001), as determined by IHC. In evaluating fatty infiltration, the degree of Oil Red O staining was significantly higher in group 1 ( P <.001), but there was no significant difference in PPAR-gamma value between the 2 groups ( P =.14). The intact rotator cuffs of rats with DM were associated with inferior biomechanics in association with AGE accumulation and increased fatty infiltration, as confirmed by histologic examination The hyperglycemic state caused by DM is associated with rotator cuff tendon degeneration. [ Orthopedics . 2022;45(3):e154–e161.]

Background: The healing failure rate after rotator cuff repair is considerably high. Purpose: To evaluate the effect of a porous suture containing transforming growth factor beta 1 (TGF-β1) on the sustained release of TGF-β1 and rotator cuff healing in a rat model. Study Design: Controlled laboratory study. Methods: A porous suture was developed, and its tensile strength was measured. TGF-β1 was delivered using the porous suture, and a TGF-β1 release test and human fibroblast proliferation assay were performed. For the animal experiment, 30 rats were randomly allocated into 3 groups (n = 10 each). A bilateral supraspinatus tendon tear was made in all the rats, and repair was performed. Group 1 received repair only; group 2, repair and a single injection of TGF-β1; and group 3, repair using the porous suture containing TGF-β1. Eight weeks after repair, biomechanical and histological analyses were performed. Results: The porous suture was successfully developed with mechanical properties compatible with the conventional suture, and the sustained release of TGF-β1 from the porous suture was confirmed. In addition, the cell proliferation assay confirmed the biological safety of the porous suture. In the animal experiment, group 3 biomechanically exhibited the largest cross-sectional area and the highest ultimate failure load and ultimate stress (all P < .05). Histological examination revealed that group 3 showed significantly better collagen fiber density and tendon-to-bone maturation than did groups 1 and 2 (all P < .05). Conclusion: The porous suture containing TGF-β1 could sustainedly and safely release TGF-β1, and its use during rotator cuff repair could improve rotator cuff healing, as assessed on the basis of the biomechanical and histological changes in the rat model in this study. Considering the effectiveness, safety, and convenience of the porous suture without extra effort in surgery, the findings of the present study will have a far-reaching effect on the treatment of rotator cuff tears. Clinical Relevance: The porous suture containing TGF-β1 might improve healing after rotator cuff repair.