Special Issue "Failure Analysis of Biometals"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: 30 September 2018

Special Issue Editor

Guest Editor
Dr. Reza H Oskouei

College of Science and Engineering, Medical Device Research Institute, Flinders University, Adelaide, Australia
Website | E-Mail
Interests: Mechanical behaviour of biomaterials; Fretting wear and corrosion in biometals; Fatigue and Fracture; Failure Analysis

Special Issue Information

Dear Colleagues,

Metallic biomaterials (biometals) are widely used for the manufacture of medical implants, ranging from load-bearing orthopaedic prostheses to dental and cardiovascular implants, because of their favourable combination of properties including high strength, fracture toughness, biocompatibility, wear and corrosion resistance. Additionally, they can be fabricated using well-established techniques (such as casting and forging), and recently, additive manufacturing to produce complex and customised implants. Examples of metals and metal alloys that are used for the fabrication of implants include: Ti-based alloys (e.g., Ti6Al4V and Ti6Al7Nb), Co-based alloys (e.g., CoCrMo and CoNi), austenitic stainless steels (e.g., SS316L), Zr-Nb alloys, Ni-Ti Alloys, Mg alloys, porous tantalum foams, and precious metals and alloys.

Due to the significant consequences of implant material failure/degradation, in terms of both personal and financial burden, failure analysis of biometals (in vivo, in vitro and retrieval) has been always of paramount importance in order to understand the failure mechanisms and implement suitable solutions with the aim to improve the longevity of implants in the body. 

This Special Issue aims to present the latest developments and findings in the area of biometals failure. The scope includes (but is not limited to): New/advanced biometals, microstructural evaluation, mechanical properties, failure/degradation analysis, fracture, fatigue, wear, fretting wear, fretting corrosion, corrosion, in vitro and in vivo assessments, explant analysis, implant retrieval studies, biocompatibility assessments, porous biometals, surface modifications, simulations, and modelling.

Research articles, review articles, as well as communications, are invited.

Dr. Reza H Oskouei
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Biometals
  • Failure Analysis
  • In-vitro and In-vivo Assessments
  • Retrieval Studies
  • Microstructure
  • Fatigue and Fracture
  • Fretting Wear
  • Corrosion, Fretting Corrosion
  • Biotribology
  • Biocompatibility
  • Simulation and Modelling

Published Papers (4 papers)

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Research

Open AccessFeature PaperArticle Failure Analysis of PHILOS Plate Construct Used for Pantalar Arthrodesis Paper II—Screws and FEM Simulations
Metals 2018, 8(4), 279; https://doi.org/10.3390/met8040279
Received: 19 March 2018 / Revised: 16 April 2018 / Accepted: 16 April 2018 / Published: 18 April 2018
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Abstract
A fractured stainless steel 3.5 mm proximal humerus internal locking system (PHILOS) plate and screws were investigated in this paper. This plate was used for ankle arthrodesis of a 68-year-old female with a right ankle deformity. Both the plate and screws were considered
[...] Read more.
A fractured stainless steel 3.5 mm proximal humerus internal locking system (PHILOS) plate and screws were investigated in this paper. This plate was used for ankle arthrodesis of a 68-year-old female with a right ankle deformity. Both the plate and screws were considered in this investigation. Optical and scanning electron microscopes (SEM) were used to document fracture surface characteristics, such as extensive scratching, plastic deformation, rubbed surfaces, discoloration, and pitting, along with cleavage, secondary cracking, deposits of debris, striations, and dimples. Indications of these features show that the plate failed by corrosion fatigue, however, overloading separated the screw(s) in two parts. Radiographic evidence shows that the screws failed ahead of the plate from the proximal end. Three-dimensional models of the plate and the screws: cortical, locking, and cannulated, were constructed using Solidworks and imported in ANSYS Workbench 16.2 to simulate the loading conditions and regions of stress development. Statistical analysis was conducted to understand the impact of different factors on the maximum von Mises stresses of the locking compression plate. These factors were the load, screw design pattern, coefficient of friction between the plate and screws, and cortical screw displacement. In summary, the finite element simulation of the plate validates the fractographic examination results. The following observations were made: (a) as the angle between the screws and the plates increased, the von Mises stresses increased in the cortical screws; and (b) the stress in the locking screws was lower than that of the cortical screws, which may be due to locking the screws with fixed angles onto the plate. Finally, fractographic examination of the cortical and locking screws supports the mechanism of corrosion-fatigue fracture from crack initiation sites, pits, due to the presence of inclusion bodies for this material (ASTM standards F138-03 and F139-03) documented for the plate in Paper I. Full article
(This article belongs to the Special Issue Failure Analysis of Biometals)
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Open AccessArticle Failure Analysis of PHILOS Plate Construct Used for Pantalar Arthrodesis Paper I—Analysis of the Plate
Metals 2018, 8(3), 180; https://doi.org/10.3390/met8030180
Received: 21 December 2017 / Revised: 5 March 2018 / Accepted: 8 March 2018 / Published: 13 March 2018
Cited by 1 | PDF Full-text (14289 KB) | HTML Full-text | XML Full-text
Abstract
The failure of a proximal humerus internal locking system (PHILOS) used in a pantalar arthrodesis was investigated in this paper. PHILOS constructs are hybrids using locking and non-locking screws. Both the plate and the screws used in the fusion were obtained for analysis.
[...] Read more.
The failure of a proximal humerus internal locking system (PHILOS) used in a pantalar arthrodesis was investigated in this paper. PHILOS constructs are hybrids using locking and non-locking screws. Both the plate and the screws used in the fusion were obtained for analysis. However, only the plate failure analysis is reported in this paper. The implant had failed in several pieces. Optical and scanning electron microscopic analyses were performed to characterize the failure mode(s) and fracture surface. The chemical composition and mechanical properties of the plate were determined and compared to controlling specifications to manufacture the devices. We found that equivalent tensile strength exceeded at the locations of high stress, axial, and angular displacement and matched the specification at the regions of lower stress/displacement. Such a region-wise change in mechanical properties with in vivo utilization has not been reported in the literature. Evidence of inclusions was qualitatively determined for the stainless steel 316L plate failing the specifications. Pitting corrosion, scratches, discoloration and debris were present on the plate. Fracture surface showed (1) multi-site corrosion damage within the screw holes forming a 45° maximum shear force line for crack-linking, and (2) crack propagation perpendicular to the crack forming origin that may have formed due to the presence of inclusions. Fracture features such as beach marks and striations indicating that corrosion may have initiated the crack(s), which grew by fatigue over a period of time. In conclusion, the most likely mechanism of failure for the device was due to corrosion fatigue and lack of bony in-growth on the screws that may have caused loosening of the device causing deformity and pre-mature failure. Full article
(This article belongs to the Special Issue Failure Analysis of Biometals)
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Open AccessArticle In Vitro Corrosion Assessment of Additively Manufactured Porous NiTi Structures for Bone Fixation Applications
Metals 2018, 8(3), 164; https://doi.org/10.3390/met8030164
Received: 14 January 2018 / Revised: 1 March 2018 / Accepted: 6 March 2018 / Published: 8 March 2018
Cited by 2 | PDF Full-text (5658 KB) | HTML Full-text | XML Full-text
Abstract
NiTi alloys possess distinct functional properties (i.e., shape memory effect and superelasticity) and biocompatibility, making them appealing for bone fixation applications. Additive manufacturing offers an alternative method for fabricating NiTi parts, which are known to be very difficult to machine using conventional manufacturing
[...] Read more.
NiTi alloys possess distinct functional properties (i.e., shape memory effect and superelasticity) and biocompatibility, making them appealing for bone fixation applications. Additive manufacturing offers an alternative method for fabricating NiTi parts, which are known to be very difficult to machine using conventional manufacturing methods. However, poor surface quality, and the presence of impurities and defects, are some of the major concerns associated with NiTi structures manufactured using additive manufacturing. The aim of this study is to assess the in vitro corrosion properties of additively manufactured NiTi structures. NiTi samples (bulk and porous) were produced using selective laser melting (SLM), and their electrochemical corrosion characteristics and Ni ion release levels were measured and compared with conventionally fabricated NiTi parts. The additively manufactured NiTi structures were found to have electrochemical corrosion characteristics similar to those found for the conventionally fabricated NiTi alloy samples. The highest Ni ion release level was found in the case of 50% porous structures, which can be attributed to their significantly higher exposed surface area. However, the Ni ion release levels reported in this work for all the fabricated structures remain within the range of most of values for conventionally fabricated NiTi alloys reported in the literature. The results of this study suggest that the proposed SLM fabrication process does not result in a significant deterioration in the corrosion resistance of NiTi parts, making them suitable for bone fixation applications. Full article
(This article belongs to the Special Issue Failure Analysis of Biometals)
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Open AccessArticle Failure Analysis and Reliability of Ni–Ti-Based Dental Rotary Files Subjected to Cyclic Fatigue
Metals 2018, 8(1), 36; https://doi.org/10.3390/met8010036
Received: 12 November 2017 / Revised: 29 December 2017 / Accepted: 3 January 2018 / Published: 6 January 2018
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Abstract
The cyclic fatigue resistance of ProTaper Universal (PTU), ProTaper Gold (PTG), and ProTaper Next (PTN) nickel titanium (NiTi) rotary files was evaluated. Fifteen instruments of each type were selected, totaling 195 files. The instruments were rotated until fracture in an artificial canal with
[...] Read more.
The cyclic fatigue resistance of ProTaper Universal (PTU), ProTaper Gold (PTG), and ProTaper Next (PTN) nickel titanium (NiTi) rotary files was evaluated. Fifteen instruments of each type were selected, totaling 195 files. The instruments were rotated until fracture in an artificial canal with dimensions corresponding to the dimensions of each instrument tested: +0.1 mm in width and 0.2 mm in depth, an angle of curvature of 45°, a radius of curvature of 5 mm, and a center of curvature 5 mm from the instrument tip. The fracture surfaces of three representative samples of each subgroup were examined using scanning electron microscopy (SEM). Time to fracture was analyzed via analysis of variance and Tukey’s tests (P < 0.05). PTG F1 and F2 had significantly higher resistance than PTU F1 and PTN X2, and PTU F2 and PTN X3, respectively. PTN X2 showed a significantly higher resistance than PTU F1. The PTG series demonstrated superior cyclic fatigue (CF) behavior compared with that of the PTU and PTN series. Full article
(This article belongs to the Special Issue Failure Analysis of Biometals)
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