A Systematic Review and Network Meta-Analysis of Biomedical Mg Alloy and Surface Coatings in Orthopedic Application

Bioactive MgO/MgCO3/Polycaprolactone Multi-gradient Fibers Facilitate Peripheral Nerve Regeneration by Regulating Schwann Cell Function and Activating Wingless/Integrase-1 Signaling

Peripheral nerve defects present complex orthopedic challenges with limited efficacy of clinical interventions. The inadequate proliferation and dysfunction of Schwann cells within the nerve scaffold impede the effectiveness of nerve repair. Our previous studies suggested the effectiveness of a magnesium-encapsulated bioactive hydrogel in repairing nerve defects. However, its rapid release of magnesium ions limited its efficacy to long-term nerve regeneration, and its molecular mechanism remains unclear. This study utilized electrospinning technology to fabricate a MgO/MgCO3/polycaprolactone (PCL) multi-gradient nanofiber membrane for peripheral nerve regeneration. Our findings indicated that by carefully adjusting the concentration or proportion of rapidly degradable MgO and slowly degradable MgCO3, as well as the number of electrospun layers, the multi-gradient scaffold effectively sustained the release of Mg2+ over a period of 6 weeks. Additionally, this study provided insight into the mechanism of Mg2+-induced nerve regeneration and confirmed that Mg2+ effectively promoted Schwann cell proliferation, migration, and transition to a repair phenotype. By employing transcriptome sequencing technology, the study identified the Wingless/integrase-1 (Wnt) signaling pathway as a crucial mechanism influencing Schwann cell function during nerve regeneration. After implantation in 10 mm critically sized nerve defects in rats, the MgO/MgCO3/PCL multi-gradient nanofiber combined with a 3D-engineered PCL nerve conduit showed enhanced axonal regeneration, remyelination, and reinnervation of muscle tissue 12 weeks post-surgery. In conclusion, this study successfully developed an innovative multi-gradient long-acting MgO/MgCO3/PCL nanofiber with a tunable Mg2+ release property, which underscored the molecular mechanism of magnesium-encapsulated biomaterials in treating nervous system diseases and established a robust theoretical foundation for future clinical translation.

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Duplex Fluorinated and Atomic Layer Deposition-Derived ZrO2 Coatings Improve the Corrosion Resistance and Mechanical Properties of Mg-2Zn-0.46Y-0.5Nd (wt.%) Alloy Plates and Screws

This study investigated the corrosion resistance and mechanical properties of Mg-2Zn-0.46Y-0.5Nd (wt.%) alloy plates and screws with fluorinated coatings and atomic layer deposition (ALD)-derived zirconia (ZrO2) coatings in vitro under physiological stress conditions. Synthetic polyurethane hemimandible replicas were split and fixed as the following three groups of magnesium alloy plates and screws: no additional surface coating treatment (Group A), with fluorinated coatings (Group B), and with duplex fluorinated and ALD-derived 100 nm ZrO2 coatings (Group C). A circulating stress of 1-10 N was applied to the distal bone segment, and a 4-week simulated body fluid immersion test was employed to study the remaining material volume and the mechanical properties of the different groups. Compared with Group A and Group B, the degradation rate of magnesium alloy plates and screws' head regions was significantly slowed down under the protection of duplex MgF2/ZrO2 coatings (p < 0.01). There was no significant difference in the degradation rate of the screw shaft region between groups (p = 0.077). In contrast to fluoride coatings, duplex MgF2/ZrO2 coatings maintained the mechanical strength of magnesium alloy plates and screws after a 14 day in vitro SBF immersion test. We conclude that duplex MgF2/ZrO2 coatings exhibited a certain protective effect on the Mg alloy plates and screws under physiological stress conditions.

Selective Laser Melting of the Porous Ta Scaffold with Mg-Doped Calcium Phosphate Coating for Orthopedic Applications

Addressing the repair of large-scale bone defects has become a hot research topic within the field of orthopedics. This study assessed the feasibility and effectiveness of using porous tantalum scaffolds to treat such defects. These scaffolds, manufactured using the selective laser melting (SLM) technology, possessed biomechanical properties compatible with natural bone tissue. To enhance the osteogenesis bioactivity of these porous Ta scaffolds, we applied calcium phosphate (CaP) and magnesium-doped calcium phosphate (Mg-CaP) coatings to the surface of SLM Ta scaffolds through a hydrothermal method. These degradable coatings released calcium and magnesium ions, demonstrating osteogenic bioactivity. Experimental results indicated that the Mg-CaP group exhibited biocompatibility comparable to that of the Ta group in vivo and in vitro. In terms of osteogenesis, both the CaP group and the Mg-CaP group showed improved outcomes compared to the control group, with the Mg-CaP group demonstrating superior performance. Therefore, both CaP and magnesium-CaP coatings can significantly enhance the osseointegration of three-dimensional-printed porous Ta, thereby increasing the surface bioactivity. Overall, the present study introduces an innovative approach for the biofunctionalization of SLM porous Ta, aiming to enhance its suitability as a bone implant material.

Self-Healing Micro Arc Oxidation and Dicalcium Phosphate Dihydrate Double-Passivated Coating on Magnesium Membrane for Enhanced Bone Integration Repair

Magnesium is a revolutionary biomaterial for orthopedic implants, owing to its eminent mechanical properties and biocompatibility. However, its uncontrolled degradation rate remains a severe challenge for its potential applications. In this study, we developed a self-healing micro arc oxidation (MAO) and dicalcium phosphate dihydrate (DCPD) double-passivated coating on a magnesium membrane (Mg-MAO/DCPD) and investigated its potential for bone-defect healing. The Mg-MAO/DCPD membrane possessed a feasible self-repairing ability and good cytocompatibility. In vitro degradation experiments showed that the Mg contents on the coating surface were 0.3, 3.8, 4.1, 6.1, and 7.9% when the degradation times were 0, 1, 2, 3, and 4 weeks, respectively, exhibiting available corrosion resistance. The slow and sustained release of Mg2+ during the degradation process activated extracellular matrix proteins for bone regeneration, accelerating osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs). The extract solutions of Mg-MAO/DCPD considerably promoted the activation of the Wnt and PI3K/AKT signaling pathways. Furthermore, the evaluation of the rat skull defect model manifested the outstanding bone-healing efficiency of the Mg-MAO/DCPD membrane. Taken together, the Mg-MAO/DCPD membrane demonstrates an optimized degradation rate and excellent bioactivity and is believed to have great application prospects in bone tissue engineering.