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Casing the Joint: The Material Development of Artificial Hips
- NYU Press
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7 Casing the Joint The Material Development of Artificial Hips Alex Faulkner INTRODUCTION Hundreds of thousands of people worldwide walk with the hidden aid of entirely artificial hips. Many have had artificial replacements installed for both of their hip joints. These devices, implanted by orthopedic surgeons in risky and expensive operations, restore locomotor function and reduce pain from arthritic or otherwise damaged joints. Indeed, artificial hips are perceived to be one of the success stories of modern technological surgery. Most people who function physically with these invisible aids, however, are unaware of their material composition , the process by which they have been manufactured, or even their brand name. For the user, their success is defined by their functionality : as long as it works and it reduces pain. Today, total hip prostheses, as orthopedic surgeons and manufacturers call them, are one of the major products of multinational companies that specialize in medical technology. In contemporary medicine, designs and materials frequently change as innovating surgeons and manufacturers seek improved performance, a broader range of potential implantees, and improved profitability for their devices. Innovation in materials and designs should thus be understood in the context of a commercial environment as well as one in which medical practitioners and patients seek technologies to alleviate pain and improve physical functioning. This essay discusses the various materials used in modern devices that replace the hip joint completely. By tracing the range of ma199 terials used as the prosthetic technology has evolved, the essay will outline the materials used in the different types of designs produced today. In medical terminology, the formation of an artificial joint between bones is known as arthroplasty. The hip joint is essentially a ball-andsocket joint, the “ball” being the rounded head of the thigh bone (femur), the socket being a cavity in the hip bone (acetabulum) itself. Human implant materials, to be successful, must exist in the tissue of the human body without causing adverse reaction, either to the tissue or to the materials. This means that the search for suitable materials is in part a search for “inert,” biologically compatible materials as well as materials that will withstand the forces exerted on joints by physical activity . As this essay will show, surgeons and engineers have experimented with a wide variety of materials—including metals, plastics, and ceramics—during the evolution of this type of implant. Some of the major developments in industrial engineering and materials science in the twentieth century, as one might expect, have contributed to the history of artificial hips. This essay divides its account of the development of artificial hips into four broad chronological stages: early history from the nineteenth century to the early 1940s; a “premodern” phase of accelerated activity from the mid-1940s to the mid-1950s; a “modern” phase from the mid1950s through the 1970s; and recent developments over the last twenty years. Since clinical developments in artificial hip replacement were taking place around the world simultaneously, this historical account is organized around developments that involve similar materials and similar surgical techniques. It is worth saying that any study of the development of artificial hip implants must contend with the fact that whatever historical record already exists has been compiled primarily by members of the profession responsible for developing and implanting these devices. Thus, largely orthopedic surgeons and designers have determined the existing literature. By contrast, only now is a view of these devices emerging from the perspective of those who have received implants, especially as a result of multidisciplinary research into the efficacy of health care technologies in the West. A leading commentator on the state of design and materials in hip implant technology at the end of the twentieth century has described the process of orthopedic innovation in hip prostheses as a “trial and error culture” (Huiskes, 1993). Thus, this chapter is concerned with the products of that culture, which is characterized by continual innovation 200 ALEX FAULKNER [34.236.152.203] Project MUSE (2024-03-19 09:34 GMT) and experimentation. It is easy to give the misleading impression that a technology has a clear, unilinear, predominantly technical and, with hindsight, predictable trajectory, in which one can discern the rational march of technological progress. And it is certainly the case, as noted above, that many perceive the artificial hip in its various forms to be a highly successful technology, the development of which is punctuated by heroic individuals and...