Biodegradable Iron and Porous Iron: Mechanical Properties, Degradation Behaviour, Manufacturing Routes and Biomedical Applications

Abstract

Biodegradable metals have been extensively studied due to their potential use as temporary biomedical devices, on non-load bearing applications. These types of implants are requested to function for the healing period, and should degrade after the tissue heals. A balance between mechanical properties requested at the initial stage of implantation and the degradation rate is required. The use of temporary biodegradable implants avoids a second surgery for the removal of the device, which brings high benefits to the patients and avoids high societal costs. Among the biodegradable metals, iron as a biodegradable metal has increased attention over the last few years, especially with the incorporation of additive manufacturing processes to obtain tailored geometries of porous structures, which give rise to higher corrosion rates. Withal by mimic natural bone hierarchical porosity, the mechanical properties of obtained structures tend to equalize that of human bone. This review article presents some of the most important works in the field of iron and porous iron. Fabrication techniques for porous iron are tackled, including conventional and new methods highlighting the unparalleled opportunities given by additive manufacturing. A comparison among the several methods is taken. The effects of the design and the alloying elements on the mechanical properties are also revised. Iron alloys with antibacterial properties are analyzed, as well as the biodegradation behavior and biocompatibility of iron. Although is necessary for further in vivo research, iron is presenting satisfactory results for upcoming biomedical applications, as orthopaedic temporary scaffolds and coronary stents.

Biocompatibility and Biological Performance of Additive-Manufactured Bioabsorbable Iron-Based Porous Interference Screws in a Rabbit Model: A 1-Year Observational Study

“…Our initial implant centerline average roughness (Ra) was 25 μm and the porosity rate was 15.4%, as degradation progressed, roughness and porosity rate increased gradually. These findings were compatible with previous literature [ 3 , 12 , 26 ].…”

“…Inert metallic biomaterials have long been used in medical applications owing to their satisfactory mechanical properties, excellent corrosion resistance, and ease of production [ 1 , 2 ]. These devices are designed for load-bearing and permanent implantation within the body, unless they require interventional removal [ 3 , 4 ]. However, when used for mechanical support, permanent inert materials can cause several complications over time; these may include hypersensitivity reactions, foreign body sensation, implanted tissue weakening due to stress shielding over time, diagnostic image interferences, and even secondary surgery for implant removal [ 2 , 3 , 4 , 5 ].…”

“…These devices are designed for load-bearing and permanent implantation within the body, unless they require interventional removal [ 3 , 4 ]. However, when used for mechanical support, permanent inert materials can cause several complications over time; these may include hypersensitivity reactions, foreign body sensation, implanted tissue weakening due to stress shielding over time, diagnostic image interferences, and even secondary surgery for implant removal [ 2 , 3 , 4 , 5 ]. Therefore, a perfect strategy to avoid these complications may include the use of clinically safe and effective, self-degradable metallic implants; they can be used for initial support and then for gradually transferring load toward the healing tissues until complete recovery.…”

“…Thus far, most studies on the clinical biocompatibility of iron-based bioabsorbable implants have been in vivo [ 25 ]. Studies have reported that iron from implants is typically metabolized safely within a host body [ 3 , 12 , 13 , 14 , 25 ]. Similarly, we previously reported no detectable adverse metabolic responses in our animal study on short-term (3-month) biocompatibility of iron-based bioabsorbable implants [ 26 ].…”

Construction of Vascularized Tissue Engineered Bone with nHA-Coated BCP Bioceramics Loaded with Peripheral Blood-Derived MSC and EPC to Repair Large Segmental Femoral Bone Defect

“…Therefore, the development of biodegradable and osteoinductive biomaterials is needed. Biodegradable metals are the focus of current research, but their biodegradation behavior and biocompatibility still require further research. , Traditionally, the ceramic materials are not suitable for repairing segmental bone defects due to their inherent brittleness and poor mechanical properties . However, in recent years, a growing number of studies proved that the bioceramics only need to meet the initial stability; their mechanical strength will be improved with the ingrowth of new bone tissue after implantation. , Meanwhile, most bioceramics will degrade slowly and finally achieve the regenerative repair of segmental bone defects.…”