Additive manufacturing for biomedical bone implants: Shaping the future of bones

Perpetual innovation in technology, materials and processes has ushered in a new era of significant advancements in biomedical implants, which are critical for reestablishing functional capacity for patients affected with skeletal injuries or diseases. Traditional manufacturing methodologies are constrained by lack of customization, suboptimal biocompatibility, and mechanical incompatibility; however, additive manufacturing (AM) or 3D printing, is revolutionizing biomedical bone implants by addressing these critical challenges. This article provides a historical perspective on AM, an in-depth analysis of its various technologies and evaluates their suitability for producing different types of bone implants, including orthopedic, dental, craniofacial, spinal, joint, and maxillofacial implants. Material selection is a crucial aspect of implant fabrication, encompassing considerations from both the additive manufacturing processes and biocompatibility perspectives, so the use of metals, polymers, ceramics, composites and bioinks in AM is discussed, emphasizing their biocompatibility and mechanical properties. Moreover, this review examines the intricate design considerations for custom implants, including topological optimization, biomimetic designs and the crucial role of CAD and 3D modeling in crafting implants with desired porosity, surface roughness, and mechanical properties followed by surface modification strategies, including the deployment of bioactive coatings and advanced treatment modalities, engineered to augment osseointegration and modulate biological responses for improved implant integration. Furthermore, this review also examines the multifaceted challenges currently impeding the advancement of Additive Manufacturing in bone implant production, including substantial cost implications, pressing demands for novel material development, and the imperative for vigilant process optimization. On top of that, the potential integration of Artificial Intelligence (AI) and Machine Learning (ML) is presented as a promising avenue for enhancing design processes, optimizing manufacturing parameters, and improving quality control. In conclusion, this paper highlights the significant advancements that Additive Manufacturing brings to the field of biomedical bone implants. By enabling the creation of customized, high-performance implants tailored to the specific needs of individual patients, AM promises to transform orthopedic care and related medical disciplines.