## 4 Discussion  
The acetabular fractures treatment aims at the obtainment of an anatomical reduction, in order to minimize the risk of post-traumatic osteoarthritis, and of a stable fixation, able to maintain this reduction during the healing process. In transverse and T-shaped fractures, the entire medial portion of the acetabulum is detached from the upper portion so there are no bone structures capable of preventing medial subluxation of the femoral head. For this reason, traditionally, systems capable of fixing both columns are used in these fracture patterns. With this aim, plates that allow fixation of both columns and the quadrilateral plate through the anterior intrapelvic access have been developed. However, literature on the biomechanical stability guaranteed by these plates is limited. The aim of this study was to compare, from a biomechanical point of view, the supraprecineal plate (SQBP) and the traditional reconstruction plate (SPP) in the treatment of transverse and T-shaped fractures of the acetabulum. Observing the generated plate geometries, their property of following the articulate shapes of the hip stands out. The possibility to deform a 3D CAD plate design on the patient geometry, which immediately could fit on the patient's pelvic bone, would allow the surgeon to further minimize operation times and risks related to blood loss during surgical intervention with respect to the standard plane plates. Although rapid manufacturing techniques are emerging in the orthopedic devices production, the diffusion of these methodologies is still limited, especially in the field of load bearing plates [42]. Therefore, if the direct production of this patient specific plate through standard manufacturing technologies would comport realizability difficulties, an alternative approach could be implemented: thanks to the generation of a mold CAD model on the basis of the patient-adapted 3D CAD design, obtained in accordance with the procedure described in this work, the surgeon can model the plate on the physical mold manufactured in plastic materials through a low-cost 3D printing [43] thus obtaining a patient-adapted plate. This preoperative planning procedure, above all, would abolish any in-situ bending, reducing intervention time and preserving the patient from surgical risks as bleeding and infections [43]. Our plates comparison should be discussed in details. Focusing on the stress distribution, the models with the most solicited bone-plate contact zones are the ones with highest stress detected on the plate: the SPP plate showed the highest stresses manifestation. Furthermore, the SPP plate showed a more flexible behavior with respect to the SQBP plate because of its ability to adapt to the bone shape and thus it transfers more easily the load to the bone. The SQBP C2 configuration would result conversely stiffer and with lower strains present in the supraprecineal portion than the others, decreeing lower induced stresses to the bone. Even with equal screws configuration, the SQBP plate allows the reduction of stresses on the bone. Taking into account the results of the IFM, the intraprecineal portion of the SBQP plate, although without screws, brings improvements in the shear strain reduction (four times less than the standard plate: 65% vs. 16%). The same results have not been noticed on the axial compressions: on this axis, the two plates seem to similarly behave. The SQBP plate with the screw configuration C1 achieves the best results in transverse fracture: it imposes an axial compression to the fracture gap (although the optimal range is only reached in 31% of points couples) and at the same time it minimizes the shear strain (which is within the acceptable range in 82% of the measurements). The same behavior was not demonstrated in T shaped fractures: although the SQBP plate with the screw configuration C1 produces an optimal axial compression in 45.5% of the occurrences, shear strains are generated, reaching up the 77% of the average fracture gap wideness.