Design and Additive Manufacturing of Bone Implants: A Review of Recent Technological Advancements

Abstract Bone implants have transformed the field of orthopedics by offering an effective approach to bone repair and replacement. In this review, recent development of designing and manufacturing technologies, materials, bone implant structural architectures, and drug delivery systems are addressed. Additive manufacturing, especially 3D printing, is essential for making customizable bone implants with intricate geometry. The success of a bone implant depends on the selection of appropriate materials. Because of the high resistance to corrosion, the properties of being nontoxic and highly lightweight yet highly strong, the titanium alloy (Ti6Al4V) is vastly used. In addition, the bio-active ceramics hydroxyapatite is commonly used due to the property of the ceramics to enhance the osteeconductivity of the implant. However, the implant in the form of a solid implant can cause a difference in mechanical properties, ensuing in stress shielding. The realization of the designs in the form of porous structures in bone implants is of major importance in vascularization and bone ingrowth. The key approach of the designs is the variability of the sizes and the patterns of the pores, which enhance bone ingrowth and implant function; the bone implants represent the progress in bone regeneration. In the aspect of the localized and continuous release of the therapeutic medications from bone implants, there is major innovation. The approach of the technologies, which involve polymer-drug encapsulation, and the drug reservoir within the implant, highlights the methodologies being pursued. The recent advances in the manufacture of bone implants have been fueled by the integration of state-of-the-art technologies, optimized porosity structures, and efficient drug delivery technologies that have uncovered a new innovative pathway.