Bioresorbable, amorphous magnesium-fiber reinforced bone cement with enhanced mechanical and biological properties

Abstract

In this study, we developed and characterized a fully biodegradable composite bone cement reinforced with short, randomly oriented amorphous magnesium fibers. Fibers of composition Mg₆₀Zn₃₅Ca₅ (in at.%) with 50 μm diameter and 2 mm length were produced by wire spinning and then mixed with a magnesium calcium phosphate cement using fiber volume fractions between 10 and 20 %. The interface strength between the fibers and cement was improved by treating the fibers with diammonium hydrogen phosphate. Compared to the reference cement without fibers, flexural strength was increased by 18 % for the composites with 13 and 18 vol% fibers, and the work of fracture was increased by over 1000× in all cases (p < 0.05, n = 6). Immersion in simulated body fluid for two and four weeks showed that the cement's struvite phase degrades first, and overall, the composite degrades slower. The degradation rate can be tailored to the application by changing the fiber percentage or the cement/fiber composition. Murine pre-osteoblastic cells (MC3T3) cultured in extracts of reference and composite cements had significantly higher cell viability, and composites with 13 vol% fibers also had a significantly higher number of cells compared to the control, indicating that the fibers can enhance and promote pre-osteoblastic cell growth. The results demonstrate that amorphous magnesium fibers enhance both the mechanical and biological properties of ceramic bone cement, expanding their prospects for clinical application.

Keywords: Amorphous metals; Biodegradable metals; Bone cement; Fiber reinforcement; Magnesium; Metallic glasses.