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.

Stainless steels are used for medical implants and surgical tools due to the excellent combination of properties, such as cost, strength, corrosion resistance, and ease of cleaning. This article describes the classifications of stainless steels, such as austenitic stainless steels, martensitic stainless steels, ferritic stainless steels, precipitation-hardening stainless steels, and duplex stainless steels. It contains a table that lists common medical device applications for stainless steels. The article discusses the physical metallurgy and physical and mechanical properties of stainless steels. Medical device considerations for stainless steels, such as fatigue strength, corrosion resistance, and passivation techniques, are reviewed. The article explains the process features of implant-grade stainless steels, including type 316L, type 316LVM, nitrogen-strengthened, ASTM F1314, ASTM F1586, ASTM F2229, and ASTM F2581 stainless steels.

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.

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.

This article provides highlights of the general process and workflow of creating a 3D-printed model from a medical image and discusses the applications of additively manufactured materials. It provides a brief background on Food and Drug Administration (FDA) classification and regulation of medical devices, with an emphasis on 3D-printed devices. Then, the article discusses two broad applications of 3D printing in craniofacial surgery: surgery and education. Next, it discusses, with respect to surgical applications, preoperative planning, use in the operating room, surgical guides, and implants. The article includes sections on education that focus on the use of 3D-printed surgical simulators and other tools to teach medical students and residents. It briefly touches on the FDA regulations associated with the respective application of 3D printing in medicine. Lastly, the article briefly discusses the state of medical billing and reimbursement for this service.

Additive manufacturing (AM), or three-dimensional (3D) printing, is a class of manufacturing processes that create the desired geometries of an object, or an assembly of objects, layer by layer or volumetrically. AM has been used extensively for manufacturing medical devices, due to its versatility to satisfy the specific needs of an intended medical field for the product/device. This article provides a comprehensive review of AM in medical devices by the medical specialty panels of the Food and Drug Administration (FDA) Code of Federal Regulations, Parts 862 to 892, including anesthesiology, ear and nose, general hospital, ophthalmic, plastic surgery, radiology, cardiovascular, orthopedic, dental, neurology, gynecology, obstetrics, physical medicine, urology, toxicology, and pathology. It is classified under these panels, and critical reviews and future outlooks are provided. The application of AM to fabricate medical devices in each panel is reviewed; lastly, a comparison is provided to reveal relevant gaps in each medical field.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of cobalt alloys (cast Vitallium and cast ASTM F75 alloys) and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the fatigue fracture, microcrack, and stair-step fracture surface of these alloys.

This article commences with a discussion on the qualitative and quantitative criteria for metal injection molding (MIM), including production quantities, shape complexity, material performance, and cost. It discusses geometric factors, such as surface finish, component size, and mass range, which help to identify a component for MIM. The article describes certain part features, including holes, undercuts, and flat faces. It concludes with a discussion on the common materials used in MIM; tensile properties of 17-4 PH stainless steel MIM, cast and wrought products; and attributes of the MIM process.

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.

Metal injection molding (MIM) is a metalworking technology that has its origins as a commercial technology only dating back to the early 1970s. This article explores why the MIM is the preferred solution for many fabricated components. It illustrates the MIM components required for different end-use markets such as electronics and telecommunications, medical, automotive, power hand tools, industries, and firearms.

Bridging the gap between education and medical practice, centralized hospital-based 3D printing, or what is termed point-of-care (POC) manufacturing, has been rapidly growing in the United States as well as internationally. This article provides insights into the considerations and the current workflow of creating 3D-printed anatomical models at the POC. Case studies are introduced to show the complex range of anatomical models that can be produced while also exploring how patient care benefits. It describes the advanced form of communication in medicine. The advantages as well as pitfalls of using the patient-specific 3D-printed models at the POC are addressed, demonstrating the fundamental knowledge needed to create 3D-printed anatomical models through POC manufacturing.

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.