Biointegrative bone screws: materials, architected structures and intelligent design strategies for next-generation orthopedic fixation
TL;DR
This review synthesizes materials- and structure-based strategies for transforming conventional screws from inert mechanical fasteners into biointegrative and functionally programmable implants and provides a Frontiers in Materials-oriented framework for the rational design and translational assessment of next-generation biointegrative bone screws.
Abstract
Bone screws are essential load-bearing fixation devices in spinal, dental, trauma and reconstructive orthopedic surgery, yet their long-term reliability remains limited by loosening, stress shielding, fatigue damage, infection risk and incomplete osseointegration. This review synthesizes materials- and structure-based strategies for transforming conventional screws from inert mechanical fasteners into biointegrative and functionally programmable implants. We first compare permanent metallic systems, including titanium, stainless steel and cobalt–chromium alloys, with biodegradable magnesium-, iron- and zinc-based systems, highlighting the competing requirements of strength, elastic modulus, degradation or corrosion behavior, and biological safety. We then examine how external geometry, thread configuration, surface curvature, roughness, micro/nanotopography and functional coatings regulate insertion stability, protein adsorption, macrophage response, osteogenic differentiation and bone–implant contact. Particular emphasis is placed on architected porous and mechanical-metamaterial designs, including triply periodic minimal surface (TPMS) structures, auxetic lattices, stochastic trabecular-like networks and graded porosity, because these architectures can simultaneously tune apparent stiffness, provide space for vascularized bone ingrowth and modify pull-out, torsional and fatigue behavior. Finally, topology optimization, finite element analysis and data-driven artificial intelligence are discussed as enabling tools for patient-specific and function-driven screw design. The available evidence indicates that no single material, surface treatment or lattice architecture can satisfy all clinical demands. Future bone screws are likely to coordinated optimization of material chemistry, macrogeometry, surface biology, internal architecture, additive-manufacturing quality control and validation strategy. This review provides a Frontiers in Materials-oriented framework for the rational design and translational assessment of next-generation biointegrative bone screws.