3D Printing, Histological, and Radiological Analysis of Nanosilicate-Polysaccharide Composite Hydrogel as a Tissue-Equivalent Material for Complex Biological Bone Phantom.

Nanosilicate-polysaccharide composite hydrogels are a well-studied class of materials in regenerative medicine that combine good 3D printability, staining, and biological properties, making them an excellent candidate material for complex bone scaffolds. The aim of this study was to develop a hydrogel suitable for 3D printing that has biological and radiological properties similar to those of the natural bone and to develop protocols for their histological and radiological analysis. We synthesized a hydrogel based on alginate, methylcellulose, and laponite, then 3D printed it into a series of complex bioscaffolds. The scaffolds were scanned with CT and CBCT scanners and exported as DICOM datasets, then cut into histological slides and stained using standard histological protocols. From the DICOM datasets, the average value of the voxels in Hounsfield Units (HU) was calculated and compared with natural trabecular bone. In the histological sections, we tested the effect of standard histological stains on the hydrogel matrix in the context of future cytological and histological analysis. The results confirmed that an alginate/methylcellulose/laponite-based composite hydrogel can be used for 3D printing of complex high fidelity three-dimensional scaffolds. This opens an avenue for the development of dynamic biological physical phantoms for bone tissue engineering and the development of new CT-based imaging algorithms for the needs of radiology and radiation therapy.

Management of Complex Acetabular Fractures by Using 3D Printed Models.

Background and Objectives: Using 3D printed models in orthopaedics and traumatology contributes to a better understanding of injury patterns regarding surgical approaches, reduction techniques, and fracture fixation methods. The aim of this study is to evaluate the effectiveness of a novel technique implementing 3D printed models to facilitate the optimal preoperative planning of the surgical treatment of complex acetabular fractures. Materials and Methods: Patients with complex acetabular fractures were assigned to two groups: (1) conventional group (n = 12) and (2) 3D printed group (n = 10). Both groups included participants with either a posterior column plus posterior wall fracture, a transverse plus posterior wall fracture, or a both-column acetabular fracture. Datasets from CT scanning were segmented and converted to STL format, with separated bones and fragments for 3D printing in different colors. Comparison between the two groups was performed in terms of quality of fracture reduction (good: equal to, or less than 2 mm displacement, and fair: larger than 2 mm displacement), functional assessment, operative time, blood loss, and number of intraoperative x-rays. Results: A significant decrease in operative time, blood loss, and number of intraoperative x-rays was registered in the 3D printed group versus the conventional one (p < 0.01), with 80% of the patients in the former having good fracture reduction and 20% having fair reduction. In contrast, 50% of the patients in the conventional group had good reduction and 50% had fair reduction. The functional score at 18-month follow-up was better for patients in the 3D printed group. Conclusions: The 3D printing technique can be considered a highly efficient and patient-specific approach for management of complex acetabular fractures, helping to restore patient's individual anatomy after surgery.

The Human Vomeronasal (Jacobson's) Organ: A Short Review of Current Conceptions, With an English Translation of Potiquet's Original Text.

The vomeronasal organ (VNO) is a structure located in the anteroinferior portion of the nasal septum and is part of the accessory olfactory system. The VNO, together with its associated structures, has been shown to play a role in the formation of social and sexual behavior in animals, thanks to its pheromone receptor cells and the stimulating effect on the secretion of gonadotropin-releasing hormone. The VNO was first described as a structure by the Dutch botanist and anatomist Frederik Ruysch in 1703 while dissecting a young male cadaver. This finding, however, is widely contradicted due to no elaborate descriptions being made by the Ruysch. The description of the VNO is more widely attributed to the Danish surgeon Ludwig Jacobson, with whom the VNO has been synonymized, as in 1803 he described the structure in a variety of mammals. Whilst Jacobson extensively studied prior reports of the VNO, he publicly denied its existence in humans. Following these discoveries and some contradictory statements in 1891, M. Potiquet published one of the more influential reviews on the topic. To this day, despite the first report of the organ's existence being made in a human and many articles stating its presence and supporting its function, the presence of a VNO in humans is still widely debated upon.