Integrated Strategies for Annulus Fibrosus Repair: Smart Biomaterials and Fabrication Technologies

Low back pain, linked to nucleus pulposus degeneration and annulus fibrosus (AF) defects, is a significant cause of global disability. The AF’s multilayered structure supports the spine, but its limited self-repair capacity makes treating AF injuries and herniation difficult. Traditional surgical interventions like discectomy often fail to restore AF integrity, resulting in high reherniation rates. In response, biomaterial-based strategies have emerged as promising alternatives, aiming to replicate AF structure, deliver bioactive factors, and promote tissue regeneration. This review evaluates the composition, biomechanics, and pathophysiology of the AF, emphasizing the fundamental properties of available biomaterials, integration with host tissues, mechanical properties, and biomimetic microenvironments in AF tissue remodeling and repair. We examine recent advances in AF repair biomaterials, including natural and synthetic hydrogels, decellularized extracellular matrix, electrospun scaffolds, and emerging technologies like three-dimensional bioprinting. These materials provide mechanical reinforcement, enhance cell adhesion, and modulate the degenerative microenvironment through controlled drug or growth factor release, offering a comprehensive approach to address the challenges of AF repair.