# 3D Printing Applications in Orthopaedic Surgery: Clinical Experience and Opportunities
## 4 Discussion  
3D-printing technology is innovative and revolutionary in many fields. In orthopaedic surgery, the premises are very interesting, but the application's perspectives are not yet completely well known. Our experience reports some of the possible advantages of this new technology in orthopaedic surgery. Our results in trauma surgery offer a modern proposal to surgeons for the rational planning of open reduction and internal fixation (ORIF) of complex fractures [16]. The lower number of intraoperative radiographic controls, the reduction of the procedure time, and the advanced patient compliance allow the reduction of X-ray exposure for patients and healthcare professionals and optimise surgical outcomes. In addition, the introduction of this method during residency in the orthopaedic surgical area could practically involve the trainees and improve training satisfaction and quality of learning [17]. The development and feasibility of this method, however, depends on the cost and effectiveness analysis. A 3D printing model adds to the already-required costs of a CT, X-ray, or MRI exam. The dimensions of the models, the material used for printing, and the details of the prototypes directly influence the final cost. To date, our experience shows that the major charge for a custom-made prosthesis paid by the public health service can offer a better chance for a new life to a patient who will be able to return autonomously, without burdening additional state subsidies for disability or an inability to work. At the same time, the 15% reduction in surgical time for proximal humeral fractures leads us to conclude that the savings obtained on less use of the active operating room was about 300 euros per  
Figure 7: X-ray of the hip at 3, 6, and 12 months’ follow-up, showing a stable fixation of the implant over the time. operation [18; 19], but we are still not able to provide a suitable follow-up of these patients to certify even better clinical outcomes. One of the limitations of this method, however, is that the procedures for printing the 3D model, in our experience, have proved to be long and complex. The accuracy of 3D printing depends primarily on the quality of the CT scan, which, for fractures, should be able to create cuts within 0.5 mm, and also on the technical capabilities of the printer. We did not encounter problems in print accuracy due to limited resolution and/or bone segmentation in each slice of the CT. For practical reasons (to optimise printing time and not to print exceeding and quite useless parts of the humerus bone diaphysis) the print layers were on planes spatially rotated with respect to the CT images planes. The \"3D model with oriented surfaces creation\" during phase three creates a continuous and interpolated surface between the CT sections. As a direct consequence, there is no loss of resolution due to the spatial rotation of the bone's 3D model and the following definition of the printing layers. The loss of parallelism between CT planes and printing planes does not affect the accuracy level of the final 3D-printed object. Contemporary 3D printers have an extruded filament thickness of approximately 0.1 mm. In practice, due to the vibrations originating from the movement of the printer itself, the spatial resolution that can be obtained rarely reaches this limit, and is usually about 0.5 mm. Another purely surgical limitation is that the 3D-printed fracture simulation was performed without soft tissues so that the implants could be oriented in the most optimal position, but, certainly, this is not totally reproducible in reality. On the other hand, the management of pelvis bone loss in revision hip prosthetic surgery is often a real challenge for the orthopaedic surgeon [20]. In the past, reconstruction often seemed impossible, with a strong negative impact on the patient's quality of life and with a high negative economic and social impact. Nowadays, the 3D printing technology application to prosthetic surgery has made it possible to overcome these limits.