Degradation behaviour of LAE442-based plate–screw-systems in an in vitro bone model

Lee

et al. 2018

Sci Rep

A polymer coating as polycaprolactone (PCL) is applied to improve the initial corrosion resistance of biodegradable magnesium. In addition, plasma electrolytic oxidation (PEO) is performed to increase adhesion between the polymer and the metal. However, when a complex-shaped material such as a screw is implanted in a bone, the surface coatings are locally damaged, and the protective role of the coating is not sufficiently maintained. In this study, the optimal conditions for producing a polymer coating on a screw were determined by varying the concentration of the PCL and the coating cycles, and were examined in vitro and in vivo. Among various the PCL coating conditions of 2∼6 cycles with 5∼7 wt.% concentrations, the 6 wt.% + 4 cycles group was applied uniformly to the screw thread. In the case of the non-uniform PCL layers, oxides and gases were present between the Mg and the PCL layer because internal magnesium corrosion and the layer peel off. The 6 wt.% + 4 cycles group had a high corrosion resistance due to the low wear on the thread. Denser and thicker bone formed around the PCL-coated screw in rat femur. This difference was due to the high corrosion resistance, which provided sufficient time for bone healing and promoting new bone growth.

Section: Discussionmentioning

confidence: 73%

Improvement of osteogenesis by a uniform PCL coating on a magnesium screw for biodegradable applications

Lee

et al. 2018

Sci Rep

J Biomedical Materials Res

“…For orthotopic implant locations, the rat is superior, due to its size and consequent applicability of implant material in bony structures. When more complex, patient adapted implants, like plate screw systems, interlocked intramedullary nailing systems or intranasal stents, are the focus of interest, a larger animal model can be necessary, as production engineering and applicability might be limited in miniaturized devices, and the geometry will be more comparable to the later target application, which is predominately in humans. Another advantage of large animal models like the sheep and pig is their lower metabolism compared to mice and rats, which is also more comparable to humans.…”

Section: In Vivo Testing Of Magnesium Alloysmentioning

confidence: 99%

Magnesium alloys: A stony pathway from intensive research to clinical reality. Different test methods and approval‐related considerations

Willbold

Weizbauer

Loos³

et al. 2016

Self Cite

The first degradable implant made of a magnesium alloy, a compression screw, was launched to the clinical market in March 2013. Many different complex considerations are required for the marketing authorization of degradable implant materials. This review gives an overview of existing and proposed standards for implant testing for marketing approval. Furthermore, different common in vitro and in vivo testing methods are discussed. In some cases, animal tests are inevitable to investigate the biological safety of a novel medical material. The choice of an appropriate animal model is as important as subsequent histological examination. Furthermore, this review focuses on the results of various mechanical tests to investigate the stability of implants for temporary use. All the above aspects are examined in the context of development and testing of magnesium-based biomaterials and their progress them from bench to bedside. A brief history of the first market launch of a magnesium-based degradable implant is given. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 329-347, 2017.

Adv Healthcare Materials

“…[ 146,199 ] The accelerated corrosion behavior of Mg and its alloys, in accordance with an early loss of integrity and a high hydrogen evolution rate, has been proven in various in vivo studies. [ 21,35,[200][201][202] A lower and upper limit for the corrosion rate of degradable suture implants is currently not defi ned. Surface treatments, especially coatings, are currently under extensive investigation to delay corrosion and to provide an increased implant endurance.…”

Section: Reviewmentioning

confidence: 99%

“…Surface treatments, especially coatings, are currently under extensive investigation to delay corrosion and to provide an increased implant endurance. [165][166][167]202 ] In the case of degradable metallic sutures, coatings might play an important role in optimizing suture corrosion rate and rate variation at different stages of degradation. Sutures naturally possess a large surface to volume ratio, which usually promotes an increased loss in mass and integrity.…”

Section: Reviewmentioning

confidence: 99%

Recent Advances in Biodegradable Metals for Medical Sutures: A Critical Review

Seitz

Ďurišin

Goldman

et al. 2015

Self Cite

215

158

Sutures that biodegrade and dissolve over a period of several weeks are in great demand to stitch wounds and surgical incisions. These new materials are receiving increased acceptance across surgical procedures whenever permanent sutures and long-term care are not needed. Unfortunately, both inflammatory responses and adverse local tissue reactions in the close-to-stitching environment are often reported for biodegradable polymeric sutures currently used by the medical community. While bioabsorbable metals are predominantly investigated and tested for vascular stent or osteosynthesis applications, they also appear to possess adequate bio-compatibility, mechanical properties, and corrosion stability to replace biodegradable polymeric sutures. In this Review, biodegradable alloys made of iron, magnesium, and zinc are critically evaluated as potential materials for the manufacturing of soft and hard tissue sutures. In the case of soft tissue closing and stitching, these metals have to compete against currently available degradable polymers. In the case of hard tissue closing and stitching, biodegradable sternal wires could replace the permanent sutures made of stainless steel or titanium alloys. This Review discusses the specific materials and degradation properties required by all suture materials, summarizes current suture testing protocols and provides a well-grounded direction for the potential future development of biodegradable metal based sutures.