After reconstructing the anterior cruciate ligament (ACL), unsatisfactory bone tendon interface healing may often induce tunnel enlargement at the early healing stage. With good biological features and high formability, Magnesium-Zinc-Gadolinium (ZG21) wires are developed to bunch the tendon graft for matching the bone tunnel during transplantation. Microstructure, tensile strength, degradation, and cytotoxicity of ZG21 wire are evaluated. The rabbit model is used for assessing the biological effects of ZG21 wire by Micro-CT, histology, and mechanical test. The SEM/EDS, immunochemistry, and in vitro assessments are performed to investigate the underlying mechanism. Material tests demonstrate the high formability of ZG21 wire as surgical suture. Micro-CT shows ZG21 wire degradation accelerates tunnel bone formation, and histologically with earlier and more fibrocartilage regeneration at the healing interface. The mechanical test shows higher ultimate load in the ZG21 group. The SEM/EDS presents ZG21 wire degradation triggered calcium phosphate (Ca-P) deposition. IHC results demonstrate upregulation of Wnt3a, BMP2, and VEGF at the early phase and TGFβ3 and Type Ⅲ collagen at the late phase of healing. In vitro tests also confirmed the Ca-P in the metal extract could elevate the expression of Wnt3a, β catenin, ocn and opn to stimulate osteogenesis. Ex vivo tests of clinical samples indicated suturing with ZG21 wire did not weaken the ultimate loading of human tendon tissue. In conclusion, the ZG21 wire is feasible for tendon graft bunching. Its degradation products accelerated intra-tunnel endochondral ossification at the early healing stage and therefore enhanced bone-tendon interface healing in ACL reconstruction.

Mg-Nd-Zn-Zr (JDBM) alloy was studied as a candidate for biodegradable implant material because of its moderate mechanical properties, good biocompatibility, and favorable uniform degradation behavior. To verify whether JDBM alloy exhibits electroplasticity effect and then study the mechanism of electropulsing treatment on JDBM alloy, in this study, homogenized and pre-tensile deformed samples were treated by electropulsing. After the electropulsing treatment, the average grain size was refined due to recrystallization, micron-scale Mg₁₂Nd secondary phases precipitated slightly, while the morphology of nanoscale Zr particles changed from rodlike to ellipsoidal shape. The elongation to failure (EL) increased obviously for the homogenized and pre-tensile deformed JDBM alloy samples after electropulsing treatment, accompanying with no obvious sacrifice of the yield strength (YS) for the former and an evident decrease of YS for the latter, mainly due to the reduction of the dislocation density. The YS decrement and EL increment (77.57%) for the latter are more apparent attributed to the higher density of dislocations introduced by pre-tensile deformation. Therefore, the electropulsing treatment can obviously improve the mechanical properties of JDBM alloy, especially for the plasticity. The present work opens a new window for the fabrication of JDBM alloy profiles with high mechanical properties, especially for the plasticity, such as the cold drawing wires and tubes for biomedical applications. It also could provide theoretical references for other magnesium alloy processing.

Degradability of bone tissue engineering scaffold that matching the regeneration rate could allow a complete replacement of host tissue. However, the porous structure of biodegradable Mg scaffolds certainly generated high specific surface area, and the three-dimensional interconnected pores provided fast pervasive invasion entrance for the corrosive medium, rising concern of the structural integrity during the degradation. To clarify the structural evolution of the three-dimensional (3D) porous structure, semi-static immersion tests were carried out to evaluate the degradation performance in our previous study. Nevertheless, dynamic immersion tests mimicking the in vivo circulatory fluid through the interconnected porous structure have yet been investigated. Moreover, the effects of dynamic flow rates on the degradation deposition behavior of 3D porous Mg scaffolds were rarely reported. In this study, Mg scaffolds degraded at three flow rates exhibited different degradation rates and deposition process. A flow rate of 0.5 mL/min introduced maximum drop of porosity by accumulated deposition products. The deposition products provided limited protection against the degradation process at a flow rate of 1.0 mL/min. The three-dimensional interconnected porous structure of Mg scaffold degraded at 2.0 mL/min well retained after 14 days showing the best interconnectivity resistance to the degradation deposition process. The dynamic immersion tests disclosed the reason for the different degradation rates on account of flow rates, which may bring insight into understanding of varied in vivo degradation rates related to implantation sites.