Histologic Analysis of Porcine Dermal Graft Augmentation in Treatment of Rotator Cuff Tears

Background: Biologic augmentation via extracellular matrix (ECM) scaffolds has been utilized to address rotator cuff tears with poor-quality tissue. Purpose: To evaluate the cellular changes in graft explants taken from patients treated with porcine dermal grafts for rotator cuff tears. Study Design: Case series; Level of evidence, 4 Methods: Four graft biopsy specimens were obtained from patients treated with porcine dermal grafts in an interposition technique for rotator cuff tears and compared with a nonimplanted graft and a normal rotator cuff specimen. Biopsy of the graft site was performed at 18 days, 3 months, 7 months, and 10.5 months after implantation. Hematoxylin and eosin staining was used to evaluate for cellular and vascular changes. Picrosirius red (PSR) stain with 90° polarized light was performed to evaluate collagen fibril size and orientation. All biopsy specimens were analyzed by a pathologist. Results: There was evidence of progressive remodeling of the porcine dermal grafts. The most mature grafts demonstrated vessel infiltration and extensive remodeling without evidence of inflammation, foreign body reaction, or tissue rejection. PSR demonstrated increased organization of collagen domains, resembling normal tendon by 10.5 months postoperatively. Conclusion: This series suggests that ECM grafts may serve as an effective scaffold for host cell infiltration, collagen reorganization, and vascularization as a result of histologic changes demonstrated with retrieval of specimens from patients with rotator cuff tears that were augmented with porcine dermal grafts.