Porous coatings are used in the field of joint replacement, particularly in cementless total hip/knee arthroplasty. This article reviews the offerings and biomaterial properties in orthopedic surgery for the contemporary class of highly porous metals. It describes the traditional porous metals/coatings having an open-cell structure, high porosity, and a microstructure resembling that of the cancellous bone. The traditional porous metal/coating includes fiber-metal mesh, cobalt-chromium (CoCr) beads, cancellous-structured titanium, and plasma spray. The article discusses other porous metals/coatings that have been developed due to the limitations of traditional porous metals for numerous open-cell-structured metals, such as titanium-base foams and trabecular metals.

Metallography plays a significant role in the quality control of metals and alloys used in the manufacture of implantable surgical devices. This article provides information and data on metallographic techniques along with images showing the microstructure of biomedical orthopedic alloys, including stainless steels, cobalt-base alloys, titanium and titanium alloys, porous coatings, and emerging materials.

Physically, tantalum is a dark, blue-gray, lusterless metal that exists in two crystalline forms: an alpha-phase with a body-centered cubic structure, and a brittle beta-phase with a tetragonal orientation. This article tabulates the physical and material properties of tantalum. It discusses the use of tantalum in medical electronics and the advantage of tantalum over stainless steel. The article describes the manufacturing and medical applications of tantalum foam.

Additive manufacturing (AM), or three-dimensional (3D) printing, has been widely used for biomedical devices due to its higher freedom of design and its capability for mass customization. Additive manufacturing can be broadly classified into seven categories: binder jetting, directed energy deposition (DED), material extrusion, material jetting, powder-bed fusion (PBF), sheet lamination, and vat photopolymerization. Due to their capability for manufacturing high-quality parts that are fully dense, PBF and DED are the most widely used groups of AM techniques in processing metals directly. In this article, the processing of titanium and its alloys by PBF and DED is described, with a specific focus on their use in biomedical devices. The article then covers the density and mechanical properties of both commercially pure titanium and titanium-aluminum-vanadium alloy. Lastly, the challenges and potential of using new titanium-base materials are discussed.

Tantalum is one of the most versatile corrosion-resistant metals known. The outstanding corrosion resistance and inertness of tantalum are attributed to a very thin, impervious, protective oxide film that forms on exposure of the metal to slightly anodic or oxidizing conditions. This article provides a discussion on the mechanism of corrosion resistance and on the behavior of tantalum in different corrosive environments, namely, acids; salts; organic compounds; reagents, foods, and pharmaceuticals; body fluids and tissues; and gases. It contains several tables that summarize the effects of acids, salts, and miscellaneous corrosive reagents on tantalum and applications for tantalum equipment in chemical, pharmaceutical, and other industries. Finally, the article presents a discussion on hydrogen embrittlement, the galvanic effects, and cathodic protection of tantalum and describes the corrosion resistance of different types of tantalum-base alloys.

Stereolithographic (STL) additive manufacturing (AM) can be used to fabricate practical components. This article discusses the processes involved in STL-AM of biological scaffolds, providing information on bioscaffold processing, cavity arrangements, and microlattice distributions. Within the last topic, the sub-topic of scaffold modulation is discussed.

Cellular or foam structures can be described by means of two broader cases: foams in which the pores are all connected to each other and with the environment (open-pore foams) and foams in which every single pore is completely enclosed by the matrix (closed-pore foams). This article describes the four process groups for the production of open- and closed-pore metal foams. It discusses the principles of the foaminal process with the description of various foaming agents, solidified metal foam, and geometries and derived structures of metal foams. The use of syntactic metal foam in various fields is included. The article reviews the mechanical properties of closed-pore metal foams, details the machining and joining procedures of the metal foams, and presents the applications of the metal foam.

This article provides an overview of additive manufacturing (AM) methods, the three-dimensional (3D)-AM-related market, and the medical additive manufactured applications. It focuses on the current scenario and future developments related to metal AM for medical applications. The discussion covers the benefits of using 3D-AM technology in the medical field, provides specific examples of medical devices fabricated by AM, reviews trends in metal implant development using AM, and presents future prospects for the development of novel high-performance medical devices via metal 3D-additive manufacturing.

This article describes manufacturing procedures that produce aluminum foams and have since become industrially important and successful. It discusses the foaming of melts by blowing agents and foaming of melts by gas injection. The article focuses on aluminum foams based on the Foaminal technology, because those foams dominate the technical applications of aluminum foams. It also discusses the mechanical properties of metal foams, such as general compression behavior, elastic behavior, strain-rate sensitivity, tensile behavior, ductility, fatigue, and mechanical damping. The article concludes with information on the applications of highly porous metal structures.

Powder-bed fusion (PBF) is a group of additive manufacturing (AM) processes that includes selective laser sintering, selective laser melting, and electron beam melting. This article explains the processes and parameters of PBF systems that are used for biomedical applications. It also presents the desirable properties of biomedical devices and the advantages of using PBF systems for biomedical applications.

Additive manufacturing, or three-dimensional printing technologies, for biomedical applications is rather different from other engineering components, particularly for biomedical implants that are intended to be used within the human body. This article contains two sections: "Design and Manufacturing Considerations of 3D-Printed, Commercially Pure Titanium and Titanium Alloy-Based Orthopedic Implants" and "Device Testing Considerations Following FDA Guidance" for additive-manufactured medical devices. These are further subdivided into five major focus areas: materials; design, printing, printing characteristics and parameters as well as postprinting validation; removal of the many manufacturing material residues and sterilization; physical, chemical, and mechanical assessments of the final devices; and biological considerations of all the final devices including biocompatibility.

Additive manufacturing (AM), or three-dimensional printing, has ushered in an era of mass customization in the many different industries in which it is used. The use of the personalized surgical instrument (PSI) is no exception. Initially, PSIs were not a result of the use of AM; rather, what occurred is an improvement in their methods of manufacturing. This article discusses the fundamentals, benefits, manufacturing, and other application examples beyond orthopedics of PSIs. In addition, an outlook of AM in biomedical applications is also covered.

This article focuses on different aspects of wear particle analysis. It discusses the different wear regimes in the wear rate versus time (bathtub) curve. The article explains the essence of condition monitoring and how to properly sample lubricants for condition monitoring. It also discusses in-service lubricant analysis for condition monitoring, focusing on the spectrometric oil analysis program. The article describes the characteristics of wear particles and analytical techniques for characterizing them. It also describes the characteristics of different types of wear particles and the mechanisms by which they are generated. The article concludes with a summary of the major applications of wear particle analysis.

Three-dimensional microscopy can be used to reveal the shape, distribution, and connectivity of three-dimensional (3D) features that lie buried within an opaque material. This article discusses several experimental techniques that can be used to generate 3D images. These include serial sectioning, focused ion beam tomography, atom probe tomography, and X-ray microtomography. Nine case studies are presented that represent the work of the various research groups currently working on 3D microscopy using serial sectioning and illustrate the variants of the basic experimental techniques. The article also discusses the techniques for reconstruction and visualization of 3D microstructures with advanced computer software and hardware.

Hydroxyapatite (HA) is one of the most popular materials in tissue scaffold engineering due to its similarity to the nature of human bone; it accounts for more than half of the total weight of the latter. Selective laser sintering (SLS) is an additive manufacturing method that is used in producing tissue engineering parts from HA feedstocks. This article provides a brief overview of the process itself, along with a detailed review of HA-based tissue engineering applications using SLS. Discussion on the various polymer composites is presented. A detailed overview of selected publications on HA-based SLS studies is listed, which provides insight regarding technical aspects of processing HA powder feedstocks.