In vitro antibacterial activity and biocompatibility of a porous scaffold containing magnesium / 中国组织工程研究

BACKGROUND: The three-dimensional organic/inorganic scaffold materials using polymer/bioceramic composites can endow the necessary physical and chemical properties and enhance the mechanical properties of the materials. However, most bone substitution materials cannot prevent infection at the defect site. It has been found that the degradation of magnesium can produce local alkaline environment, so that magnesium has certain antibacterial activity. OBJECTIVE: To investigate the in vitro antibacterial activity and cytocompatibility of magnesium-containing scaffolds. METHODS: Polylactic acid/β-tricalcium phosphate/magnesium porous scaffolds were prepared by low-temperature rapid prototyping technology. The PTM (2:1) and PTM (1:2) groups referred to two mixing mass ratios (β-tricalcium phosphate:magnesium = 2:1 and 1:2), respectively. Two scaffolds of polylactic acid (P group) and polylactic acid/β-tricalcium phosphate (PT group) were also prepared by low-temperature rapid prototyping technology. The surface morphology, pore size, porosity and compression modulus of the scaffolds were measured. Staphylococcus aureus (ATCC 35923) was seeded on the scaffolds of each group for 24 hours. The antibacterial activity of the scaffolds was observed through spread plate method and confocal laser scanning microscopy. Mouse preosteoblasts MC3T3-E1 were co-cultured with the scaffolds of each group. The cell attachment and proliferation were evaluated by cell counting kit-8 assay. RESULTS AND CONCLUSION: (1) A relatively uniform porous structure was found on the scaffold surfaces in each group. There were no significant differences in the pore size and porosity among groups (P > 0.05). (2) The compression modulus in the PTM (2:1) and PTM (1:2) groups were significantly higher than those in the P and PT groups (P 0.05). (4) After 6 hours of culture, the number of attached cells in the PT, PTM (2:1) and PTM (1:2) groups was greater than that in the P group (P 0.05). (5) At 1 day of culture, the cell proliferation in the PT group was superior to that in the P group (P 0.05). (6) These results indicate that the polylactic acid/β-tricalcium phosphate/magnesium scaffold not only possesses good antibacterial activity, but also exhibits excellent cytocompatibility and certain anti-compressive ability.

Biomodelo para la docencia de grado y postgrado en pediatría / Biomodel for teaching undergraduate and graduate in pediatrics

Introducción: La incorporación de la Clínica y la Imagenología permiten una mejor comprensión de la Anatomía. El objetivo de este trabajo es desarrollar un prototipo rápido en material sintético que replique detalles anatómicos para ser utilizado en la docencia de grado y postgrado en Pediatría. Material y Método: Caso 1: Niña de 1 año de edad con síndrome de dificultad respiratoria a causa de una malformación vascular. Caso 2: recién nacido con malformación torácica. Con la finalidad de analizar una conducta adecuada, se solicitó la confección de un prototipo rápido a escala 1:1 que simulara una condición idéntica a la topografía torácica del paciente, utilizando imágenes virtuales 3D almacenadas en formato DICOM.Técnica de generación de prototipo rápido: Se obtuvouna malla digital tridimensional y se generó el código “g”que se utilizó para controlar el hardware de producción. Se efectuó simulación digital y producción en material plástico (ABS) con técnica de deposición y fusión (MDF).Se validó el prototipo comparándo lo con las mediciones testigos del modelo virtual en 3 D.Resultados y Discusión: El modelo replicó exactamente los defectos hallados en la tomografía y endoscopía, confirmando la presencia de la malformación vascular y su repercusión sobre el aparato respiratorio. El prototipo rápido muestra las estructuras internas y externas del cuerpo humano con máxima precisión permitiendo una visión topográfica de situaciones “normales o patológicas” que facilitaría la docencia y el entrenamiento del equipo quirúrgico para proponer un plan de tratamiento adecuado. Hay numerosas áreas de la medicina que sebeneficiarían con este modelo que podría ser construído con diversos tipos de materiales de diferente flexibilidad y consistencia. Conclusiones: El prototipo rápido le da estado físico a las imágenes virtuales 3D, permitiendo la docencia y entrenamiento del equipo quirúrgico.

Introduction: The incorporation of the clinic and the imaging allow a better understanding of anatomy. Theaim of this work is to develop a rapid prototype in synthetic material that replicates anatomical details to be used inteaching and surgical training in Pediatrics. Material and method: Case 1: one year old female with respiratory distress syndrome because of vascular malformation. Case 2: newborn patient with thoracic malformation. In order to discuss appropriate conduct, the making of rapid prototyping in scale 1:1 was requested to simulate an identical condition of the thoracic topography of the patients, using virtual 3D images stored in the DICOM format. Rapid prototype technique: code "g" was generated, which was used to control the hardware of production and a three-dimensional digital grid was obtained. Digital simulation and production in plastic (ABS) with deposition and fusion technique (MDF) was performed. The prototype was validated by comparing measurements with witnesses of the virtual model in 3 D. Results and discussion: the model replied exactly the defects found in the scan and endoscopy, confirming the presence of vascular malformation and its impact on the respiratory system. Rapid prototype shows the internal and external structures of the human body with maximum precision allowing a topographic view of "normal or pathological" situations that would facilitate the teaching and training of the surgical team to propose an appropriate treatment plan. There are many areas of medicine that would benefit from this model that couldbe built with different types of materials with different flexibility and consistency. Conclusions: Rapid prototype gives form to virtual 3D images, allowing teaching and training of the surgical team.

Application of 3D Surface Scanners in Forensic Science and Medicine ( I ): Digital Storage of Human Skeletons and Development of Appraisal Methods for Incident Scenes / 대한법의학회지

The aim of this project was to use 3D scanning data collected at incident scenes and various evidence to 1) develop surveying methods based on 3D data consisting of overall and detailed scene evidence, captured by long-range and micros-canner, which can be shared by personnel working in different fields such as forensic medicine, video analysis, physical analysis, traffic engineering, and fire investigation; 2) create digital storage for human skeletons and set the foundation for virtual anthropology; and 3) improve the credibility of 3D evidence by virtual remodeling and simulation of incident scenes and evidence to provide a basis for advanced and high-tech scientific investigation. Two complete skeletons of male and female were scanned using 3D micro-scanner. Each bone was successfully reproduced and assembled in virtual space. In addition, recreating evidence scheduled for invasive examination by creating RP (rapid prototype) was possible. These outcomes could play an important role in setting up the new field of virtual anthropology. Case-specific surveying methods were developed through analysis of 3D scanning data collected by long-range surface scanners at the scenes of vehicular accidents, falls, shootings, and violent crimes. A technique and recording method was also developed for detecting forged seals by micro-scanning the pressure exerted on the seal. Appraisal methods developed in this project could be utilized to secure 3D data of human skeletal remains and incident scenes, create a standard for application, and increase objectivity, reproducibility, and accuracy of scanning methods. We plan to develop case-specific 3D data analysis techniques to improve the credibility of analysis at the NFS and to establish a 3D data collection and analysis team.

Accuracy of simulation surgery of Le Fort I osteotomy using optoelectronic tracking navigation system

INTRODUCTION: The aim of this study was to demonstrate that the simulation surgery on rapid prototype (RP) model, which is based on the 3-dimensional computed tomography (3D CT) data taken before surgery, has the same accuracy as traditional orthograthic surgery with an intermediate splint, using an optoelectronic tracking navigation system. MATERIALS AND METHODS: Simulation surgery with the same treatment plan as the Le Fort I osteotomy on the patient was done on a RP model based on the 3D CT data of 12 patients who had undergone a Le Fort I osteotomy in the department of oral and maxillofacial surgery, Seoul National University Dental Hospital. The 12 distances between 4 points on the skull, such as both infraorbital foramen and both supraorbital foramen, and 3 points on maxilla, such as the contact point of both maxillary central incisors and mesiobuccal cuspal tip of both maxillary first molars, were tracked using an optoelectronic tracking navigation system. The distances before surgery were compared to evaluate the accuracy of the RP model and the distance changes of 3D CT image after surgery were compared with those of the RP model after simulation surgery. RESULTS: A paired t-test revealed a significant difference between the distances in the 3D CT image and RP model before surgery.(P<0.0001) On the other hand, Pearson's correlation coefficient, 0.995, revealed a significant positive correlation between the distances.(P<0.0001) There was a significant difference between the change in the distance of the 3D CT image and RP model in before and after surgery.(P<0.05) The Pearson's correlation coefficient was 0.13844, indicating positive correlation.(P<0.1) CONCLUSION: Theses results suggest that the simulation surgery of a Le Fort I osteotomy using an optoelectronic tracking navigation system is relatively accurate in comparing the pre-, and post-operative 3D CT data. Furthermore, the application of an optoelectronic tracking navigation system may be a predictable and efficient method in Le Fort I orthognathic surgery.

Surgical Simulation for Placement of Isometric Point of Anterior Cruciate Ligament: A System using Three-dimensional Computer Models and Rapid Prototyping Models / 대한정형외과학회잡지

PURPOSE: This research aims at developing a simulation system for training of the correct placement of isometric points in arthroscopic reconstruction of anterior cruciate ligaments, using personal computer-based software and rapid prototyping knee models. MATERIALS AND METHODS: CT scan images of the knee joints of thirteen patients were used. Simulation software was developed on V-works(Clinic3D Inc.), a three-dimensional medical imaging system. Rapid prototyping models were made of hardened starch with a 0.178 mm slice thickness. RESULTS: In the first phase, trainee surgeons can study the positions of the bony attachments of healthy anterior cruciate ligaments, and compare their multiplanar reformatting images and a three-dimensional computer model of the bones. In the second phase, trainee sur-geons can place isometric points on the three-dimensional computer models and compare the results with the points set by a supervis-ing surgeon. Finally, rapid prototyping models, which are almost identical to the actual bones, are produced to allow the trainees to observe the isometric points marked on the models. CONCLUSION: Our system can provide a patient-specific simulation environment for beginners at arthroscopic anterior cruciate ligament reconstruction. It can be used as an educational and training tool for locating the isometric point of the anterior cruciate ligament during an operation.

A Patient-Specific Surgical Simulation System for Spinal Screw Insertion Composed of Virtual Roentgenogram, Virtual C-Arm, and Rapid Prototyping / 대한정형외과학회잡지

PURPOSE: This research aims at developing a PC-based spinal screw insertion simulation program and rapid prototyping spine models for correct placement of spinal screws. MATERIALS AND METHODS: We developed a surgical simulator on top of a 3-D medical imaging system V-worksTM (Cybermed, Inc.) and used Z-402 (Z Corporation) models made of hardened starch. RESULTS: The first phase is training surgeons using the simulation software. The trainees could simulate the insertion of spinal screws using the PC-based software. The second phase is a planning software to determine the ideal entry point and insertion angle using the multiplanar reconstruction images of spine CT. Finally, a rapid prototyping model of which the size is identical to the actual bone is produced for simulation surgery prior to the actual one. CONCLUSION: The system provides a tool for educating and training the beginners of spinal screw insertion, and also a pre-surgical simulation environment for planning the actual insertion surgery.