Osteoporotic fractures are a very common bone disease that is difficult to completely cure. A large number of people worldwide suffer from pain caused by osteoporotic fractures every year, which can even cause disability and death. The compromised skeletal strength, lower density, trabecular microstructure, and bone-forming ability caused by osteoporotic fractures make them difficult to treat relative to normal fractures. An ideal scheme for osteoporotic fractures is to select internal fixation materials with matched mechanical and biological properties and carry anti-osteoporosis drugs on the plant to achieve bio-fixation and improve the condition of osteoporosis simultaneously. We designed a Mg-based MAO-MT-PLGA drug/ion delivery system (DDS) compatible with bone-like mechanical properties, degradation properties, and drug therapy. In this research, we evaluated the degradation behavior of Mg-based MAO-MT-PLGA DDS using immersion tests and electrochemical tests aided by SEM, EDS, XPS, XRD, and FT-IR. The DDS showed better corrosion resistance over Mg alloy and could release more Mg²⁺ due to the degradation of PLGA. According to cell viability and cell adhesion, the DDS showed better osteogenic characteristics over control group I (Mg alloy) and control group II (Mg-based MAO alloy), especially in the cells co-cultured with the leaching solution for 72 h, in which the DDS group increased to about 15% cell viability compared with group I (p < 0.05). The mRNA relative expressions, including ALP, collagen I, OCN, OPG, and Runx-2, as well as extracellular matrix calcium deposits of the DDS, are 1.5~2 times over control group I and control group II (p < 0.05), demonstrating a better ability to promote bone formation and inhibit bone resorption. After the DDS was implanted into the castrated rat model for one month, the trabeculae in the treatment group were significantly denser and stronger than those in the control group, with a difference of about 1.5 times in bone volume fraction, bone density, and the number of trabeculae, as well as the magnesium content in the bone tissue (p < 0.05). The above results demonstrated that the Mg-based MAO-MT-PLGA drug/ion delivery system is a potential treatment for osteoporotic fractures.

The Mg alloy vascular clip has biodegradability and good biocompatibility, which can improve the convenience and safety of clinical application. However, the Mg alloy vascular clip also has some disadvantages, such as an unreasonable structure design and a degradation rate which is too fast. In this study, the process of clamping blood vessels with a biodegradable Mg alloy (Mg-Zn-Nd-Zr and Mg-Zn-Nd) general V-type vascular clip was simulated by finite element simulation software (Abaqus). A new type of vascular clip, the P-type vascular clip, was analyzed and investigated through simulation. The differences between Mg alloy vascular clips of V-type and P-type were analyzed by finite element simulation. In addition, the effects of Zr element on the mechanical properties and corrosion resistance of P-type vascular clips were also investigated to improve the mechanical stability. The results show that during the V-type vascular clip closure of Mg-Zn-Nd-Zr alloy, this clip has some problems, such as uneven distribution of blood vessel stress, crevices in blood vessels and stress concentration. The improved P-type vascular clip has uniform closure, and there is no gap in the blood vessel, which can effectively avoid stress concentration. The improved P-type vascular clip is well closed and can effectively avoid stress concentration. The corrosion resistance of the Mg-Zn-Nd-Zr alloy P-type clip was better than that of the Mg-Zn-Nd alloy P-type clip (degradation rate of 2.02 mm/y and 2.61 mm/y on the 7th day, respectively). Mg-Zn-Nd-Zr alloy The P-type vascular clip remained closed even on the 7th day, which could meet the requirements of clinical application.