Abstract
Metal additive manufacturing (AM) technologies, commonly referred to as 3D printing, provide a good prospect for medical applications because complex geometries and customized parts can be fabricated to meet individual patient needs. Orthopedic implants are a group of medical parts with high relevance for AM. This paper discusses relevant AM technologies, several orthopedic applications, materials and material properties, mechanical surface finishing techniques, and measurement techniques from the literature. Today, most metal 3D printed implants are manufactured through metal powder bed fusion technology which includes direct metal laser sintering (DMLS), selective laser melting (SLM), and electron beam melting (EBM). Common materials include titanium alloys, cobalt chromium (CoCr) and stainless steel, chosen because of their biocompatibility and mechanical properties. Surface finishing is most often required for 3D printed implants due to the relatively poor surface quality to meet the desired surface texture for the application. Typically, postprocessing is done mechanically, including manual and automated grinding, sandblasting, polishing, or chemically, including electrochemical polishing. This review also covers an overview of surface quality characterization of AM metal implants which includes surface texture and topography. The surface parameters used to characterize the surface of the implants: surface roughness (Ra), differences between the peak and valley (Rz), waviness, and micro-finish.
3D-printed cobalt-chromium porous metal implants showed enhanced bone-implant interface and bone in-growth in a rabbit epiphyseal bone defect model
