Toward a mechanically biocompatible intervertebral disc: Engineering of combined biomimetic annulus fibrosus and nucleus pulposus analogs

Abstract

Intervertebral disc (IVD) degeneration and accompanying lower back pain impose global medical and societal challenges, affecting over 600 million people worldwide. The IVD complex fibrocartilaginous structure is responsible for the spine biomechanical function. The nucleus pulposus (NP), composed of swellable glycosaminoglycan (GAG), transfers compressive loads to the surrounding fiber‐reinforced annulus fibrosus (AF) lamellae, which stretches under tension. Together, these substructures allow the IVD to withstand extremely high and complex loads. Key to mimic the complete disc must consider the properties of its substructures. This study presents three novel substructures–a biomimetic silk‐reinforced composite lamella for the AF, a GAG analog for the NP, and a novel biomimetic combined AF‐NP construct. The biomimetic AF demonstrates nonlinear, hyperelastic, and anisotropic behavior similar to the native human AF, while the NP analog demonstrates mechanical behavior similar to the human NP. The synergized biomimetic AF‐NP demonstrates similar behavior to the unconfined NP, with significantly increased deformations indicating improved performance. Validation of the AF‐NP construct mechanics using a finite element model yields results compatible with native human IVD under various physiological loadings. The ability of our AF‐NP construct to mimic the native IVD offers a revolutionary concept for the potential development of a fully functional IVD.

Plant Biomimetic Principles of Multifunctional Soft Composite Development: A Synergistic Approach Enabling Shape Morphing and Mechanical Robustness

“…The biocomposites are fabricated as previously described. , Silk fibers are manually wrapped around thin 3D-printed frames to create a unidirectional and organized array of fibers. The fiber thickness on each frame is measured using a digital micrometer at ten locations at least.…”

From hyperglycemia to intervertebral disc damage: exploring diabetic-induced disc degeneration

“…The nutrition of the NP is mainly supplied by the vertebral body-cartilage endplate ( 84 ). During spinal movement, the NP rolls like a bearing to support the vertebral body and assists other parts of the spine to complete physiological activities ( 91 ). When the NP bears an external force, the force is uniformly transferred to the surrounding AF, which can balance the stress ( 86 , 92 ).…”

Predictive Refined Computational Modeling of ACL Tear Injury Patterns

“…The truss elements were constructed manually by connecting pairs of corresponding nodes of the ACL matrix elements along the path of the ligament, starting from the tibia and ending at the femoral insertion site, creating 27 strings from the 824 truss elements attached between the solid elements' nodes (Figure 1B). Thus, each two-node truss element shared common nodes with the corresponding solid elements, allowing translation-only load transfer between the matrix and fiber constituents, as previously described [26,[28][29][30]. To verify our method for ACL partial tears, we established a sensitivity test to examine the correlation between the geometrical tear size to the ligament cross-section and the percentage of torn fibers required, using nine different tear sizes implemented by deleting elements in the lateral direction of the ligament.…”