Robotic-assisted plate osteosynthesis of the anterior pelvic ring and acetabulum: an anatomical feasibility study.

Pelvic ring injuries or acetabular fractures present a challenge to trauma surgeons. Recently, endoscopic dissection techniques for visualization of the anterior pelvic ring and acetabulum have been presented. Robotic-assisted surgical systems offer advantages in terms of improved visualization and easier instrument handling. The aim of this pilot anatomic study was to verify the feasibility of robotic-assisted plate osteosynthesis on the anterior pelvic ring and acetabulum. The experiment was performed on a human whole body specimen. The DaVinci system with standard instruments as used in RARP was used. After docking the system, the anterior pelvic ring was first prepared as previously described for the endoscopic techniques. This was followed by dissection of both acetabula analogous to pelvic lymphadenectomy as performed during RARP. After the dissection was performed along the pelvic brim up to the iliosacral joint, the complete anterior column of the acetabulum including quadrilateral surface and incisura ischiadica major could be visualized. Finally, robotic-assisted endoscopic plate osteosynthesis was performed on the symphysis and anterior acetabular column as previously described in the endoscopic techniques. Robotic-assisted plate osteosynthesis of the anterior pelvic ring and acetabulum is feasible with the available robotic-assisted systems. Due to the excellent freedom of movement of the robotic arms, combined with the magnifying 3D visualization of the system, highly accurate preparation of the situs in preparation for plate osteosynthesis can be performed. The question of reduction of dislocated fractures remains open and is the subject of further investigation. Compared with conventional laparoscopy, robotic-assisted preparation nevertheless appears to offer an advantage in view of the complexity of the operation.

Process Window for Highly Efficient Laser-Based Powder Bed Fusion of AlSi10Mg with Reduced Pore Formation.

The process window for highly efficient laser-based powder bed fusion (LPBF), ensuring the production of parts with low porosity, was determined by analyzing cross-sections of samples that were generated with laser powers varying between 10.8 W and 1754 W, laser beam diameters varying between 35 µm and 200 µm, and velocities of the moving laser beam ranging between 0.7 m/s and 1.3 m/s. With these parameters, the process alters between different modes that are referred to as simple heating, heat conduction melting (HCM), key-bowl melting (KBM), and deep-penetration melting (DPM). It was found that the optimum process window for a highly efficient LPBF process, generating AlSi10Mg parts with low porosity, is determined by the ratio PL/db of the incident laser power PL and the beam diameter db of the beam on the surface of the bead, and ranges between PL/db = 2000 W/mm and PL/db = 5200 W/mm, showing process efficiencies of about 7-8%. This optimum process window is centered around the range PL/db = 3000-3500 W/mm, in which the process is characterized by KBM, which is an intermediate process mode between HCM and DPM. Processes with PL/db < 2000 W/mm partially failed, and lead to balling and a lack of fusion, whereas processes with PL/db > 5200 W/mm showed a process efficiency below 5% and pore ratios exceeding 10%.