Mg-Ca-Zn Soft Tissue Fixation Alloy for Controlled Biodegradation

The patent uses a ternary Mg-Ca-Zn alloy composite material that combines magnesium with calcium and zinc elements. This composite structure achieves both biocompatibility (from magnesium base) and improved ductility (from alloying elements), resolving the contradiction between reliability and strength. The specific composition range (Ca: 0.1-1.0 wt%, Zn: 0.1-1.0 wt%) creates a synergistic effect where the alloying elements enhance ductility without compromising biodegradability.

The patent applies parameter changes by controlling the crystal grain size within a specific range (1-10 μm) through hot extrusion processing. This parameter control transforms the microstructure to achieve optimal balance between strength and ductility. The grain size refinement through hot extrusion at controlled temperatures (200-400°C) and ratios (10-100 mm/min) enables the material to maintain both structural integrity and deformability.

The patent extracts and eliminates rare earth elements (RE) from the alloy composition, replacing them with conventional Zn and Ca elements. This extraction removes the source of high cost while maintaining the core functionality. The patent achieves this by defining a specific composition range that excludes RE elements (Zn: 0.1-1.0 wt%, Ca: 0.1-1.0 wt%) while still achieving the desired balance of strength and deformability through controlled crystal grain structure.

The patent changes the microstructural parameters by controlling crystal grain size (1-10 μm) through hot extrusion, replacing the long-period stacking structure approach with a grain refinement approach. This parameter change enables the material to achieve both strength and deformability without requiring rare earth elements. The hot extrusion process parameters (temperature 200-400°C, ratio 10-100 mm/min) are specifically controlled to achieve the target grain size and microstructure.

The patent applies parameter changes by precisely controlling the alloy composition within narrow ranges (Ca: 0.1-1.0 wt%, Zn: 0.1-1.0 wt%) and crystal grain size (1-10 μm). These parameter controls regulate the degradation rate to match tissue healing time (2-8 weeks) while maintaining cost-effectiveness by using inexpensive Ca and Zn elements instead of rare earth metals. The controlled composition prevents rapid degradation and associated toxicity.

The patent creates a dynamic balance between degradation rate and tissue healing rate by controlling the alloy composition and microstructure. The degradation is designed to occur at a controlled pace (complete degradation within one year, with 50-92% residual ratio at 4 weeks) that matches the biological healing process. This dynamic control prevents both rapid degradation (toxicity) and slow degradation (permanent foreign body).

The patent changes the material composition parameters by replacing titanium with a magnesium-based alloy system. This fundamental parameter change eliminates the high density and high X-ray absorption characteristics of titanium that cause metal artifacts. The Mg-Ca-Zn alloy maintains sufficient strength for tissue fixation while being radiolucent, allowing clear MRI and X-ray imaging without artifact interference.

The patent uses a magnesium-based composite alloy (Mg-Ca-Zn ternary alloy) that combines the advantages of biodegradability with adequate mechanical strength. This composite material replaces the non-biodegradable titanium while providing both necessary structural support and imaging compatibility. The specific alloy composition and microstructure control ensure the material provides sufficient strength for surgical clips and staples while being transparent to imaging modalities.