Architectural and geometric defects govern distinct load-transfer mechanisms in the meniscus.

Abstract

Mechanical disruption in fibrous tissues can arise either from geometric defects that introduce structural discontinuities or from architectural alterations that modify internal load-sharing networks. The mechanical distinction between these mechanisms remains poorly understood in the meniscus. Here, we combined experimental testing of fiber-reinforced biocomposite laminates with finite element (FE) modeling of the medial meniscus to investigate how fibers oriented perpendicular to the primary loading direction regulate deformation and load redistribution. Alginate-silk fibroin laminates with controlled transverse fiber depletion (FD) were tested under uniaxial tension, while complementary FE models incorporated region-specific depletion of radial fibers within the medial meniscus under compressive loading. In the laminates, transverse FD reduced tensile modulus and increased ultimate strain, while ultimate tensile strength remained largely unchanged, indicating preserved load-bearing capacity of tensile-aligned fibers despite reduced transverse reinforcement. Analysis of axial-transverse strain coupling revealed enhanced lateral deformation with increasing FD, consistent with reduced inter-fiber constraint. In contrast, notch introduction altered deformation pathways and fiber recruitment, resulting in apparent stiffening and reduced ultimate strain. FE simulations further showed that radial FD does not induce uniform mechanical weakening but instead produces region-dependent redistribution of strain, stress, and tibial contact pressure. Together, these findings demonstrate that architectural fiber disruption and geometric defects govern fundamentally different load-transfer mechanisms, establishing radial fibers as key regulators of deformation coupling rather than primary load-bearing elements. STATEMENT OF SIGNIFICANCE: Radial fibers are a defining structural feature of meniscal architecture and are increasingly recognized as mechanically important, yet their role in regulating deformation and load redistribution remains incompletely understood. By combining biomimetic composite experiments with finite element modeling of the meniscus, this study demonstrates that radial fibers function primarily as architectural coupling elements that regulate regional deformation and load transfer rather than acting as principal load-bearing components. Selective disruption of radial fiber continuity induces spatially localized redistribution of strain, stress, and tibial contact pressure without uniform mechanical weakening. These findings establish a mechanistic link between microscale fiber disruption and joint-level load redistribution, providing insight into early meniscal degeneration and informing both meniscal repair strategies and the design of biomimetic fibrous materials.