Anin vitroandin vivocharacterization of fineWE43Bmagnesium wire with varied thermomechanical processing conditions

Abstract

Absorbable implants made of magnesium alloys may revolutionize surgical intervention, and fine magnesium wire will be critical to many applications. Functionally, the wires must have sufficient mechanical properties to withstand implantation and in-service loading, have excellent tissue tolerance, and exhibit an appropriate degradation rate for the application. Alloy chemistry and thermomechanical processing conditions will significantly impact the material's functional performance, but the exact translation of these parameters to implant performance is unclear. With this in mind, fine (127 µm) WE43B magnesium alloy wires in five thermomechanical process (TMP) conditions (90% cold work [CW], and 250, 375, 400, and 450°C heat treatments) were investigated for their effect on mechanical and corrosion behavior. The TMP conditions gave clear metallurgical differences: transverse grain dimensions ranged from 200 nm (CW) to 3 µm (450°C), UTS varied from 324 MPa (450°C) to 608 MPa (250°C), and surgical knotting showed some were suitable (CW, 400°C, 450°C) while others were not (250°C, 350°C). In vitro and in vivo corrosion testing yielded interesting and in some cases conflicting results. After 1 month immersion in cell culture medium, wire corrosion was extensive, and TMP conditions altered the macrocorrosion morphology but not the rate or total release of magnesium ions. After 1 month subdermal implantation in mice, all wires were well tolerated and showed very little corrosion (per µCT and histology), but differences in localized corrosion were detected between conditions. This study indicates that WE43B wires treated at 450°C may be most suitable for surgical knotting procedures. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1987-1997, 2018.

Biodegradable Metallic Wires in Dental and Orthopedic Applications: A Review

“…Due to imparting of a huge cold working happened during the drawing process, production of thin metallic wire with considerable strength is potentially achievable [2]. Equation (1) represents the percentage of cold work that could be achieved by single-pass wire drawing process [3]:…”

“…Moreover, different intermediate and/or post heat treatments coinciding with precise die(s) design and manufacturing could lead to the fabrication of the fine wire with acceptable ductility for different applications [3].…”

Building towards a standardised approach to biocorrosion studies: a review of factors influencing Mg corrosion in vitro pertinent to in vivo corrosion

“…This encapsulation was suggested as the reason the corrosion rate of the fast corroding AZ91 samples was substantially decreased (by a factor of 10) in vivo. Fibrous encapsulation was also present during the subcutaneous implantation of fine WE43B wires in adult female mice [130], and was also suggested as the reason for the slower in vivo corrosion rates. This type of soft tissue reaction is also present in the exposed parts of orthopaedic implants.…”

The mechanical property and corrosion resistance of Mg-Zn-Nd alloy fine wires in vitro and in vivo

“…Fig. 3 shows mechanical property of ZN20 alloy wires in this study and some typical Mg alloy wires in recent studies [ [25] , [26] , [27] , [28] , [29] ]. These magnesium alloy wires exhibit two characteristics: high strength with lower ductility or good ductility with lower strength.…”