Tailoring Mg-0.5B and Mg-0.5B-5Sn alloys for hallux valgus implants: Cytocompatibility, inflammatory response, antimicrobial, and mechanical durability

• Improved Properties with Tin : Mg-0.5B-5Sn showed better antibacterial, corrosion, and wear resistance than Mg-0.5B due to tin addition. • Biocompatibility vs Strength : Mg-0.5B had higher strength and anti-inflammatory effect; Mg-0.5B-5Sn had slightly higher cytotoxicity but targeted inflammation better. • Promising for HV Implants : Mg-0.5B-5Sn offers a good balance of bioactivity, strength, and durability for use in HV correction implants. Hallux valgus (HV) is a common orthopedic condition characterized by a deformity of the first toe, and it is more prevalent in women. It results from progressive valgus subluxation of the metatarsophalangeal (MTP) joint and varus deviation of the first metatarsal, leading to pain, discomfort, and increased fracture risk. Surgical correction often requires implants with optimal mechanical, corrosion, and biological properties. This study evaluates two novel magnesium alloys, Mg-0.5B and Mg-0.5B-5Sn, for HV treatment. Boron enhances strength and bioactivity, whereas tin improves corrosion resistance and Antimicrobial properties. Biological tests revealed moderate cytotoxicity in Mg-0.5B, while Mg-0.5B-5Sn showed concentration-dependent cytotoxicity typical of Mg alloys, with acceptable viability at physiologically relevant extract levels but improved Antimicrobial activity. Anti-inflammatory evaluation showed that Mg-0.5B strongly suppressed TNF-α expression, while Mg-0.5B-5Sn additionally inhibited COX-II and LOX enzymatic pathways. Corrosion analysis revealed rapid degradation of Mg-0.5B, while Mg-0.5B-5Sn formed a protective surface layer, enhancing durability. Corrosion behavior was quantified using potentiodynamic polarization, Potentiodynamic analysis revealed an extremely high corrosion rate for Mg-0.5B (468.1 mm/year), whereas Mg-0.5B-5Sn showed a drastically reduced rate of 7.47 mm/year due to Sn-induced suppression of anodic dissolution and stabilization of the surface film. Mechanical tests showed higher compressive strength for Mg-0.5B, but immersion tests revealed increased strain in Mg-0.5B-5Sn over 14 days as a result of material softening. Wear testing under walking and jogging conditions demonstrated superior wear resistance in Mg-0.5B-5Sn, attributed to its refined microstructure and intermetallic phases. Overall, Mg-0.5B-5Sn shows strong potential as a biodegradable orthopedic implant material for HV correction, effectively balancing biocompatibility, mechanical integrity, and corrosion and wear resistance.