This article outlines the selection criteria for choosing an implant material for biomedical devices in orthopedic, dental, soft-tissue, and cardiovascular applications. It details the development of various implants, such as metallic, ceramic, and polymeric implants. The article discusses specific problems associated with implant manufacturing processes and the consequent compromises in the properties of functionally graded implants. It describes the manufacturing of the functionally-graded hip implant by using the LENS process. The article reviews four different types of tissue responses to the biomaterial. It discusses the testing methods of implant failure, such as in vitro and in vivo assessment of tissue compatibility.

This article discusses some of the additive manufacturing (AM) based fabrication of alloys and their respective mechanical, electrochemical, and in vivo performance. Firstly, it briefly discusses the three AM techniques that are most commonly used in the fabrication of metallic biomedical-based devices: binder jetting, powder-bed fusion, and directed-energy deposition. The article then characterizes the electrochemical properties of additive-manufactured/processed cobalt-chromium alloys. This is followed by sections providing an evaluation of the biological response to CoCr alloys in terms of the material and 3D printing fabrication. Discussion on the biological response as a function of direct cellular activity on the surface of CoCr alloys in static conditions (in vitro), in dynamic physiological conditions (in vivo), and in computer-simulated conditions (in silico) are further discussed in detail. Finally, the article provides information on the qualification and certification of AM-processed medical devices.

This article discusses the mechanisms of metal and alloy biocompatibility. It provides information on early testing and experience with metals in medical device applications. The article describes the response of implant and particulate materials to severe corrosion. It provides a description of metal binding and its effects on metabolic processes. Hypersensitive responses to metal ions are also reviewed. The article concludes with a discussion on the possible cancer-causing effects of metallic biomaterials.

In the field of medical device development and testing, the corrosion of metallic parts can lead to significant adverse effects on the biocompatibility of the device. This article describes the mechanisms of metal and alloy biocompatibility. It reviews the response of implant metals and particulate materials to corrosion. The effect of metal ions from an implanted device on the human body is also discussed. The article concludes with information on the possible cancer-causing effects of metallic biomaterials.

Titanium and its alloys have been used extensively in a wide variety of implant applications, such as artificial heart pumps, pacemaker cases, heart valve parts, and load-bearing bone or hip joint replacements or bone splints. This article discusses the properties of titanium and its alloys and presents a list of titanium-base biomaterials. Titanium components are produced in wrought, cast, and powder metallurgy (PM) form. The article describes forging, casting, and heat treating of titanium alloys for producing titanium components. Typical mechanical properties of titanium biomedical implant alloys are listed in a tabular form. The article presents an overview of the surface-modification methods for titanium and its alloys implants. It concludes with a section on biocompatibility and in vivo corrosion of titanium alloys.

Implant debris is known to cause local inflammation, local osteolysis, and, in some cases, local and systemic hypersensitivity. The debris can be stainless steel, cobalt alloy, and titanium alloy, and soluble debris obtained due to wear from all orthopedic implants. This article addresses the biologic aspects of implant debris, both locally and systemically. It describes debris-induced local effects, particle-induced proinflammatory responses, and debris-induced systemic effects. The article concludes with a discussion on the four systemic effects of implant debris, namely, neuropathic effects, hypersensitivity effects, carcinogenicity, and general toxicity.

Total joint replacement in orthopedic surgery can be achieved by excision, interposition, and replacement arthroplasty. This article details the most common materials used in total replacement synovial joints: metals, ceramics, and ultrahigh molecular weight polyethylene (UHMWPE). The principal physical properties and tribological characteristics of these materials are summarized. The article discusses pin-on-disk experiments and pin-on-plate experiments for determining friction and wear characteristics. It explains the use of various types of joint simulators, such as hip joint simulators and knee joint simulators, to evaluate the performance of engineering tribological components in machine simulators. The article concludes with a section on the in vivo assessment of total joint replacement performance.

Biomaterials are the man-made metallic, ceramic, and polymeric materials used for intracorporeal applications in the human body. This article primarily focuses on metallic materials. It provides information on basic metallurgy, biocompatibility, chemistry, and the orthopedic and dental applications of metallic biomaterials. A table compares the mechanical properties of some common implant materials with those of bone. The article also provides information on coatings, ceramics, polymers, composites, cements, and adhesives, especially where they interact with metallic materials.

This article commences with a description of the prosthetic devices and implants used for internal fixation. It describes the complications related to implants and provides a list of major standards for orthopedic implant materials. The article illustrates the body environment and its interactions with implants. The considerations for designing internal fixation devices are also described. The article analyzes failed internal fixation devices by explaining the failures of implants and prosthetic devices due to implant deficiencies, mechanical or biomechanical conditions, and degradation. Finally, the article discusses the fatigue properties of implant materials and the fractures of total hip joint prostheses.

This article focuses on the analysis of materials and mechanical- (or biomechanical-) based medical device failures. It reviews the failure analysis practices, including evidence receipt, cleaning, nondestructive examination, destructive examination, exemplars analysis, and device redesign. The article examines the common failure modes, such as overload, fatigue, corrosion, hydrogen embrittlement, and fretting, of medical devices. The failure analysis of orthopedic implants, such as permanent prostheses and internal fixation devices, is described. The article reviews the failure mechanisms in some of the more common medical device materials, namely, stainless steels, titanium alloys, cobalt-base alloys, and nitinol. It presents case histories with examples for failure analysis.

Bearing in mind the three-legged stool approach of device design/manufacturing, patient factors, and surgical technique, this article aims to inform the failure analyst of the metallurgical and materials engineering aspects of a medical device failure investigation. It focuses on the device "failures" that include fracture, wear, and corrosion. The article first discusses failure modes of long-term orthopedic and cardiovascular implants. The article then focuses on short-term implants, typically bone screws and plates. Lastly, failure modes of surgical tools are discussed. The conclusion of this article presents several case studies illustrating the various failure modes discussed throughout.

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.

This article reviews the concepts considered important for an understanding of the processes used for preparing cobalt-chromium alloy implants, the microstructures resulting from this processing, and the resulting material properties. The review includes solidification of alloys, diffusionless (martensitic) phase transformation as occurs with face-centered cubic to hexagonal close-packed transformation in cobalt-chromium alloys, and stacking faults and twins and their role in this transformation. It also discusses the strengthening mechanisms that are responsible for the mechanical properties of cast and wrought cobalt alloys. The article contains tables that list the commonly used cobalt alloys and their biomedical applications and chemical compositions. It discusses the mechanical and corrosion properties of cobalt alloys, and provides a description of the microstructure of cobalt alloys.

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 (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.

This article discusses the physical metallurgy of cast cobalt alloys with an emphasis on the crystallography, compositions, phases and microstructure, and properties. Cobalt alloys are cast by several different foundry methods. The article describes the argon-oxygen decarburization and continuous casting process. It provides information on castability and quality of the casted alloys. The article details the postcasting treatment, including heat treatment, hot isostatic pressing, and coatings. It summarizes the applications of cast cobalt alloys.

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.

Metallic alloys that are typically used for medical purposes include stainless steels, Ti-6Al-4V, and Co-Cr-Mo. This article discusses the relative merits of each of these alloys. The utilization of stainless steels in the biomedical industry, especially in relation to the additive manufacturing (AM) process, is the main focus of this article. The characteristics of various stainless steels are described subsequently, and the categories that are of relevance to the biomedical industry are identified. The types of stainless steels covered are austenitic, ferritic, martensitic, duplex, and precipitation-hardened stainless steels. The article discusses the potential benefits of AM for biomedical devices. It describes the types of AM processes for stainless steels, namely binder jet, directed-energy deposition, and laser powder-bed fusion. The article reviews the AM of austenitic, martensitic, and PH stainless steels for biomedical applications. In addition, the challenges and obstacles to the clinical use of AM parts are covered.

The biocompatibility of a material relates to its immunological response, toxicity profile, and ability to integrate with surrounding tissue without undesirable local or systemic effects on a patient. This article underscores the transformation of the medical device design ecosystem engaged as an integral part of the device ecosystem. It discusses the applications of biomaterials, including orthopedic, cardiovascular, ophthalmic, and dental applications. The article describes four major categories of biomaterials such as metals, polymers, glass and ceramics, and composites. A discussion on natural materials, nanomaterials, and stem cells is also provided. The article concludes with examples of biomaterials applications, such as endovascular devices, knee implants, and neurostimulation.