Magnesium ion implantation enhances the osseointegration and vascularization of 3D-Printed CoCrMo alloy scaffolds for load-bearing orthopedic applications

Total knee arthroplasty (TKA) remains the gold-standard treatment for end-stage osteoarthritis, yet persistent challenges in prosthetic material performance limit its long-term clinical efficacy. CoCrMo alloy is commonly used material of femoral component in TKA due to its excellent mechanical durability. However, two critical limitations persist: (1) substantial elastic modulus mismatch inducing stress-shielding effects, and (2) bioinert surface impairing osseointegration. To address these dual challenges, we developed a synergistic surface engineering strategy combining 3D-printed porous architecture with Mg²⁺ functionalization <i>via</i> plasma immersion ion implantation (PIII). The porous structure significantly reduced the elastic modulus and achieve biomimetic mechanical compatibility. Mg²⁺-implanted scaffolds (CoCrMo-Mg) demonstrated multifunctional bioactivity through synergistic physicochemical interactions. Surface topography modification <i>via</i> 3D printing generated micro-scale features that enhanced osteoblast adhesion through mechanotransduction pathways, while the release of Mg²⁺ exerted immunomodulatory, pro-angiogenic and osteogenic effects. Mg²⁺-mediated downregulation of pro-inflammatory cytokines, established an anti-inflammatory microenvironment conducive to bone regeneration, while Mg²⁺ stimulation promoted substantial neovascularization - collectively creating an osteogenic niche favoring coupled angiogenesis-osteogenesis process. These findings were further validated <i>in vivo</i>, where the CoCrMo-Mg scaffolds showed improved anti-inflammation, neovascularization and bone ingrowth capacities, along with favorable biomechanical integration. Overall, this dual-modality approach combining structural optimization with bioactive ion engineering establishes a paradigm for developing mechanically compliant and biologically active orthopedic implants, with particular translational relevance for cementless TKA applications.