Orthopaedic coatings

The success of total joint surgery can be traced back to the introduction of cemented devices in the hip during the 1960s. Since then, joint replacement operations have been carried out in increasing numbers. Originally, surgery focused on replacement of the hip joint however, this early success has extended to include a similar number of knee joint replacement operations. Ankle, elbow, wrist and shoulder replacements are also carried out but in much smaller numbers. The 'in service' demands on joint replacement devices have changed with the increase in the average life expectancy of the population and the pressure from younger, more active patients for earlier surgical intervention. The main approach to improving the longevity of replacement parts has focused on enhancing the interface between the metal components and the adjacent bone. This has been achieved by the introduction of various types of coating -most commonly applied using plasma spray processes. This chapter reviews the history of joint replacement, the characteristics of various types of orthopaedic coatings and their clinical use. The focus is on total hip replacement, as the hip is the main joint on which much of the pioneering work was carried out and, as such, it continues to be at the forefront of developments in design, technology and surgical approach.