## 4 Additive Manufacturing--3D Printing and 3D Printers
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Category** & **Advantages** & **Disadvantages** & **References** \\ \hline \multirow{2}{*}{Mechanical Properties} & Lightweight, mimicking the strength of & May have weaker load-bearing properties & \\  & human bone and reducing stress shielding. & compared to traditional metals like titanium. & [4,67] \\ \hline \multirow{2}{*}{Biocompatibility} & Minimal inflammatory, enhances & Risk of poor integration or delamination & \\  & tissue integration. & over time in some cases. & [50,86] \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Table showing advantages and disadvantages of 3D printing of PAEK implants. Figure 3: Schematic diagram showing FF process of PAEK composite. Advancements in AM are paving the way to produce more complex, patient-specific implant designs, while also improving cost-efficiency. One notable development is the emergence of new 3D printer designs, such as those from the New Dimension 3D printing company, which offer enhanced capabilities for producing intricate, personalized implants [92]. These advancements enable more precise control over the material properties, allowing for the creation of implants tailored to a patient's unique anatomical requirements. In addition to these technological improvements, the cost-benefit analysis conducted by [PERSON] et al. highlights the economic advantages of AM in healthcare settings, particularly for cranial implants [93]. Despite the higher initial cost of 3D printing, another study found that the overall cost was reduced due to factors such as shorter surgical times, fewer postoperative complications, and quicker recovery periods [93]. Specifically, the use of AM reduced the average cost per patient by 15%, considering the savings in operating room time, anesthesia use, and hospital stays [93]. These findings suggest that while the upfront investment in AM technology may be higher, the long-term savings from reduced healthcare resource use make it a cost-effective solution for patient-specific implants. To accommodate the rapid evolution of 3D-printed implants, while ensuring both safety and innovation, the regulatory standards must evolve to address the unique challenges and opportunities presented by this technology. For high-risk devices, such as orthopedic implants classified as Class III under the EU Medical Device Regulation (MDR), compliance typically requires extensive technical documentation and clinical trials reviewed by a notified body, which can take years [94]. However, customized or patient-specific devices produced via 3D printing often fall under more flexible frameworks, such as annex XIII of the MDR [94]. These frameworks allow for deviations from the standard safety and performance requirements when sufficient justification is provided, enabling the development of bespoke implants for individual patients without compromising the regulations [94]. Globally recognized standards such as ISO 13485 Medical Devices (ISO--International Organization for Standardization, n.d.; ISO--ISO 13485-Medical Devices, n.d.), which outline requirements for quality management systems in the design and manufacture of medical devices, play a critical role in ensuring consistency and safety in 3D-printed implants [95]. For example, ISO 13485 certification ensures that every step of the manufacturing process from material selection and design considerations to risk analysis and labelling adheres to strict quality control protocols [95; 96]. Incorporating these standards, particularly in point-of-care manufacturing, is essential to maintain traceability, minimize the contamination risk, and uphold device quality. In the United States, the FDA regulates 3D-printed devices under its Quality System Regulation (QSR), which is aligned with the ISO 13485 principles [95; 96]. The FDA has issued specific guidance on submissions for 3D-printed devices, emphasizing material traceability, design optimization, and adherence