Fabrication and in vitro evaluation of a high-strength, flexible, and bioresorbable warp-knitted silk patch for tendon tissue repair.

Abstract

The global incidence of rotator-cuff injuries demands mechanically robust and bioresorbable patches to address the high failure rates of surgical repair. Here, we present a digitally fabricated, warp-knitted silk patch designed to meet this need. Through systematic modulation of key parameters (guide-bar configuration, needle pitch, and gauge), we engineered 17 distinct scaffolds from extra-coarse, degummed silk. Among them, the 4 × 1 tricot-stitch architecture (sample #14) emerged as the optimal candidate, exhibiting an balanced combination of high porosity (70.2 ± 0.1 %), high strength (Longitudinal tensile strength: 274 ± 8 N; Transverse tensile strength: 634 ± 33 N; Longitudinal tear strength: 270 ± 52 N; Transverse tear strength: 125 ± 14 N; Burst strength: 1 554 ± 33 N; Suture-pullout strength: > 46 N.), and controlled biodegradability (retaining 93 ± 3 % mass after 42 days). Critically, these properties not only exceed established mechanical benchmarks for tendon repair but are maintained under wet conditions simulating the in vivo environment. The patch further demonstrated good hemocompatibility (hemolysis rate 1.2 ± 0.1 %) and supported robust cell adhesion, spreading, and proliferation. Collectively, these data demonstrate that digital warp-knitting of coarse silk yarns enables single-step fabrication of lightweight, highly porous, and mechanically anisotropic patches that combine long-term strength retention with favorable biocompatibility-offering a promising off-the-shelf solution for tendon reconstruction. STATEMENT OF SIGNIFICANCE: Recurrent tears after rotator cuff repair remain a significant clinical challenge, often due to inadequate mechanical strength and poor tissue integration of existing patches. We address this by digitally warp-knitting a bioresorbable silk patch that uniquely combines high tensile and burst strength, exceeding native tendon requirements, with a high-porosity architecture conducive to cell infiltration. This patch provides durable mechanical support in a wet physiological environment while degrading controllably. It represents a clinically promising, off-the-shelf solution to enhance repair outcomes, bridging the critical gap between robust mechanical performance and effective biological integration for tendon reconstruction.