A biomimetic bilayer fibrous scaffold for repair of massive rotator cuff tear via minimally invasive delivery

• A clinical treatment strategy integrating customizable biomimetic structural scaffold with a novel minimally invasive delivery technique is proposed. • A novel minimally invasive delivery system facilitates precise implantation of large 3D-printing scaffold through small incision. • Biomimetic bilayer scaffold with aligned and crimped fibers enhances tendon stem cell adhesion and directional alignment. Therapeutic arthroscopy is a common minimally invasive procedure, yet repairing massive rotator cuff tears remains challenging due to difficulties in delivering patches and replicating the complex tendon–bone interface. Herein, a clinical treatment strategy integrating customizable biomimetic structural scaffold with a novel minimally invasive delivery technique is proposed. First, inspired by the collagen fiber network of rotator cuff, a biomimetic bilayer heterogeneous fibrous scaffold was designed and fabricated. The tendon layer combines aligned and crimped fibers to replicate natural tendon collagen and guide tendon cell migration, while the bone repair layer features randomly-oriented crimped fibers to provide osteogenic topological cues. Results demonstrated that crimped (36.17 % porosity, 30-μm pore diameter) and parallel-fibered (50-μm spacing) scaffolds enhanced tendon stem cell adhesion and directional alignment compared to control groups. Second, a specialized minimally invasive delivery system was pioneered to transport a 50 × 30 mm scaffold to the intra-articular target site through a minimal incision (≤10 mm), while preserving structural integrity and spatial orientation. Finally, arthroscopic simulations and implantation experiments validated the efficacy of this minimally invasive delivery strategy. This integrated solution for rotator cuff repair combines structural biomimetics, functional compatibility, and clinical feasibility, demonstrating strong translational potential.