Assessment of a novel patient-specific 3D printed multi-material simulator for endoscopic sinus surgery

Background: Three-dimensional (3D) printing is an emerging tool in the creation of anatomical models for surgical training. Its use in endoscopic sinus surgery (ESS) has been limited because of the difficulty in replicating the anatomical details. Aim: To describe the development of a patient-specific 3D printed multi-material simulator for use in ESS, and to validate it as a training tool among a group of residents and experts in ear-nose-throat (ENT) surgery. Methods: Advanced material jetting 3D printing technology was used to produce both soft tissues and bony structures of the simulator to increase anatomical realism and tactile feedback of the model. A total of 3 ENT residents and 9 ENT specialists were recruited to perform both non-destructive tasks and ESS steps on the model. The anatomical fidelity and the usefulness of the simulator in ESS training were evaluated through specific questionnaires. Results: The tasks were accomplished by 100% of participants and the survey showed overall high scores both for anatomy fidelity and usefulness in training. Dacryocystorhinostomy, medial antrostomy, and turbinectomy were rated as accurately replicable on the simulator by 75% of participants. Positive scores were obtained also for ethmoidectomy and DRAF procedures, while the replication of sphenoidotomy received neutral ratings by half of the participants. Conclusion: This study demonstrates that a 3D printed multi-material model of the sino-nasal anatomy can be generated with a high level of anatomical accuracy and haptic response. This technology has the potential to be useful in surgical training as an alternative or complementary tool to cadaveric dissection

Applications of three-dimensional printing in ophthalmology

Three-dimensional (3D) printing is increasingly used to produce customised objects and is a promising alternative to traditional manufacturing methods in diverse fields, such as dentistry and orthopaedics. Already in use in other medical specialities, adoption in ophthalmology has been limited to date. This review aims to provide an overview of 3D printing technology with respect to current and potential applications in ophthalmic practice. Medline, Embase and internet search were performed with "3D printing", "ophthalmology", "dentistry", "orthopaedics" and their synonyms used as main search terms. In addition, search terms related to clinical applications such as "surgery" and "implant" were employed. 3D printing has multiple applications in ophthalmology, including in diagnosis, surgery, prosthetics, medications and medical education. Within the past decade, researchers have produced 3D printed models of objects such as implants, prostheses, anatomical models and surgical simulators. Further development is necessary to generate optimal biomaterials for various applications, and the quality and long-term performance of 3D models needs to be validated

Interaction of locomotion and intraspinal lumbosacral organ in birds

Die Fähigkeit von Vögeln sich wendig und präzise in jedem bewohnbaren Lebensraum fortzubewegen, fasziniert Forscher seit über einem Jahrhundert. Es wird vermutet, dass die Beweglichkeit der Vögel durch ein mechanosensorisches Organ ermöglicht wird, welches direkt in die untere Wirbelsäule, im sog. Lumbosakralbereich, integriert ist. Diese Spezialisierung der Vögel im Lumbosakralbereich ist dabei einzigartig unter den Wirbeltieren. Obwohl die morphologischen Spezialisierungen bereits vor mehr als einem Jahrhundert entdeckt wurden, sind ihre funktionellen Merkmale nach wie vor unbekannt. Die unmittelbare Nähe dieses mechanosensorischen Organs zum Ischiasnerv und den damit ver- bundenen motorischen Schaltkreisen könnte erklären, wie Vögel die Grenzen der Nervenleitgeschwindigkeit umgehen, die neuronalen Schaltkreise verkürzen und so die Agilität und Tiefensensibilität (Propriozeption) auch bei hohen Geschwindigkeiten ermöglichen. Die lumbosakrale Region bzw. das "lumbosakrale Organ" (LSO) besteht aus einem sehr dichten Glykogenkörper, der zwischen den Ruckenmarkshälften eingekeilt ist und von einem Geflecht aus zahnförmigen Bändern gestützt wird. Aus den lateralen Seiten des Ruckenmarks ragen akzessorische Lappen in einen mit Flüssigkeit gefüllten, erweiterten Ruckenmarkskanal mit halbkreisförmigen, querverlaufenden Rillen auf der Dorsalseite. Diese akzessorischen Lappen könnten möglicherweise eine mechanosensorischer Funktion aufweisen. Die topographische Analyse der Anatomie dieser Lappen lässt auf zwei Anregungsmechanismen schließen, welche sich nicht zwangsläufig gegenseitig ausschließen. Zum einen könnte die enge Verbindung der akzessorischen Lappen mit dem das Rückenmark stützenden Ligamentum denticulare, einen dehnungsbasierten Mechanismus darstellen. Zum anderen deutet die Ausrichtung der Lappen hin zu den öffnungen der querliegenden Rillen, welche den Bogengängen eines Säugetierinnenohrs ähneln, auf einen Mechanismus hin, welcher über die Bewegung der Flüssigkeit induziert wird. In dieser Arbeit wurden existierende Hypothesen zur Funktionsweise des LSO und dessen Wahrnehmung von Strömungen, Druck oder Dehnung durch die Anwendung moderner Techniken erweitert. Im Gegensatz zu früheren Theorien wurden hier die Interaktion der lumbosakralen Spezialisierungen berücksichtigt. Die morphometrische 3D-Analyse von Daten, die per digitaler Dissektion erzeugt wurden, ermöglichen es den Flussigkeitsraum um das neurale Weichgewebe zu analysieren. Zusätzlich zeigt die klassische Dissektion zeigt feine Details des hängemattenartigen Netzwerks der dentikulären Bänder, die in unserer 3D-Karte nicht sichtbar sind. Durch die Kombination der Ergebnisse der digitalen und der klassischen Dissektion können wir die Verschiebung- und Verformungskapazität des Weichgewebes im vergrößerten und mit Flüssigkeit gefüllten lumbosakralen Wirbelsäulenkanal abschätzen. Die Ermittlung der morphologischen und biomechanischen Eigenschaften erlaubt uns die Hypothese eines sensorischen Mechanismus aufzustellen, der auf der Oszillation des lumbosakralen Weichgewebes durch externe Beschleunigung beruht und dessen Bewegung einem flussigkeitsgefullten Feder-Masse-Dämpfer-System ähnelt. Möglicherweise könnten Auslenkungen des neuralen Weichgewebes durch äußere physikalische Kräfte, über die mechanosensiblen, akzessorischen Lappen erfasst werden. Auf diese Weise könnte der LSO Beschleunigungskräfte unabhängig von dem im Kopf lokalisierten vestibulären Apparat wahrnehmen. Eventuell wird das viskoelastische Rückenmark durch den dichten Glykogenkörper belastet und dadurch verformt. Allerdings wurde bisher in keiner Studie untersucht, ob die Weichteile im Lumbosakralkanal von Vögeln beweglich sind. Die Identifizierung der Weichteilbewegungen in vivo innerhalb der stark pneumatisierten Knochen des fusionierten Synsakrums, die ebenfalls mit mehrschichtigem Weichgewebe bedeckt sind, ist mit den derzeit verfügbaren Techniken nur sehr schwierig zu analysieren. Aus diesem Grund haben wir eine Kombination aus digitaler in situ Dissektion und biophysikalischer Simulation zur Analyse herangezogen. Durch 3D-Scanns von Kadaver-LSO-Proben in verschiedenen Orientierungen konnten wir zeigen, dass die LSO-Weichgewebe im statischen Zustand eine geringe Positionsverschiebung aufweisen. Durch eine Abwandlung des traditionellen diceCT (Iod-kontrastverstärkende Computertomographie)-Protokolls konnten wir außerdem weitere Details der Topologie der Ligamenta denticularis sichtbar machen, welche sich auf die Mobilität des Weichgewebes auswirken könnten. Inspiriert von der LSO-Morphometrie entwickelten wir so ein konfigurierbares, biophysikalisches LSO-Modell, um die Auswirkungen einzelner Strukturen zu untersuchen. Die biophysikalische Simulation bestätigte unsere Annahme, dass das Netzwerk der dentikulären Bänder, sowie das Ausmaß der Beschleunigung, die Beweglichkeit der Weichteile beeinflussen. Durch Veränderung der Parameter des LSO-Modells konnten wir zeigen, dass fluiddynamische Effekte des lumbosakralen Wirbelkanals ebenfalls einen Einfluss auf die Zeit-und Frequenzantwort der Weichteile haben. Unsere Hypothese, dass das LSO einem Feder-Dämpfer-System ähnelt, wird durch das Glykogenkörper-Modell gestützt, welches als mechanischer Verstärker für Ruckenmarksschwingungen fungiert.Avian ability to agile and precise locomotion in every livable habitat has fascinated researchers for over a century. One explanation for birds' agility is a mechanosensory organ directly integrated into the lower spine in the lumbosacral region. The proximity of the potential mechanosensory organ to the sciatic nerve and its associated motor circuits could explain how birds circumvent the limits of nerve conduction velocity associated with proprioception by shortening neural circuits, thereby contributing to the agility of avian locomotion. Avian lumbosacral region's specializations are unique among vertebrates. The lumbosacral region, recently referred to as the lumbosacral organ (LSO), consists of a high-density glycogen body wedged between the spinal cord hemispheres, supported by a pronounced network of denticulate ligaments. From the lateral sides of the spinal cord, accessory lobes with potential mechanosensory function protrude into a fluid-filled expanded spinal canal with transverse semicircular grooves on the dorsal side. Although the LSO specializations were discovered more than a century ago, their functional features remain unknown. The topographic anatomy of the accessory lobes suggests two excitation mechanisms that are not necessarily mutually exclusive. Firstly, the intimal connection of the accessory lobes to the denticulate ligament network supporting the spinal cord offers a strain-based mechanism of accessory lobe excitation. Secondly, the accessory lobes' alignment with the opening of transverse grooves, which resemble the semicircular canals of the mammalian inner ear, indicates that the excitation mechanism could be associated with a fluid flow. In this thesis, by applying modern techniques to earlier hypotheses about the LSO’s perception of fluid flow, pressure, and strain - we developed a new mechanosensing hypothesis, which in contrast to previous theories, considers the interaction of the lumbosacral specializations. 3D morphometric analysis of data produced by digital dissection allows us to evaluate the fluid space around the neural soft tissue. Additionally, classical dissection shows fine details of the hammock-like network of denticulate ligaments not visible in our 3D map. We estimate potential soft tissue displacement and deformation capacity inside the enlarged and fluid-filled lumbosacral spinal canal by combining the digital and classical dissection results. Establishing morphological and biomechanical properties allows us to hypothesize a sensing mechanism based on lumbosacral soft tissue oscillation caused by external acceleration, with a motion similar to a fluid-filled spring-mass-damper system. Potentially the mechanosensitive accessory lobes encode signals about the internal state of the neural soft tissue, entrained by external physical forces. Hence, the LSO may sense acceleration forces independently from the vestibular apparatus localized in the head. A relatively dense glycogen body potentially loads the viscoelastic spinal cord, causing it to deform. However, no study has tested whether the soft tissues inside the lumbosacral canal of birds are movable. The state-of-the-art techniques show limits in identifying soft tissue movements in vivo inside highly pneumatized bones of a fused synsacrum covered with multilayered soft tissue. Therefore, we combined in situ digital dissection and biophysical simulation. 3D scanning of cadaver LSO samples in different orientations enabled us to reveal that the LSO soft tissues exhibit minor position displacement in a static state. Our modification of the traditional diceCT protocol allowed us to visualize previously undocumented details on the denticulate ligament topology, which potentially affects soft tissue mobility. Inspired by LSO morphometrics, we developed a reconfigurable biophysical LSO model to study the impact of individual lumbosacral anatomical structures. The biophysical simulation confirmed our assumption that the denticulate ligament network and the magnitude of acceleration affect soft tissue mobility. By altering the LSO model parameters, we also revealed the fluid dynamics effects of the lumbosacral spinal canal morphology on the soft tissues' time and frequency response. Our hypothesis that the LSO resembles a spring-damper system is supported by the glycogen body model acting as a mechanical amplifier for spinal cord oscillations

Implantable microdevice for the treatment of hydrocephalus

We present a novel microdevice for the treatment of hydrocephalus. Hydrocephalus is a pathological condition in which excessive cerebrospinal fluid (CSF) is accumulated within the subarachnoid space of the brain due to deficient arachnoid granulations, resulting in the brain damage or death. Current treatment for hydrocephalus is to surgically implant a shunt device to drain the excessive fluid from the ventricles to peritoneal cavity or other parts of the body. This method has over 50% failure rate due to occlusions and mechanical failures of shunt components. The proposed microfabricated device can mimic the function of normalarachnoid granulations and thus can replace the deficient arachnoid granulations. The microfabricated arachnoid granulations (MAG) consist of arrays of microvalves and microneedles.The microvalves are made of a PDMS/Parylene composite layer and have a 3-D dome petal shape. Such geometry enables the microvalve to rectify fluid flow in the forward and backward direction due to pressure differentials like normal arachnoid granulation. Microvalve design was optimized using 3-D numerical simulation. The microvalves were fabricated using three main microfabrication techniques: diffuser lithography for dome-shaped SU-8 mold fabrication, thin polymer film deposition and reflow for PDMS/Parylene membrane formation, and excimer laser machining for valve opening. The pressure drop vs. flow rate characteristics of the fabricated microvalve was investigated through in-vitro flow tests using a bench-top CSF simulator. The results showed that a 10x10 microvalve array with combined opening shape is optimal for our application.The microneedle array is to surgically pierce the dura mater membrane after being assembled with the microvalve. The microneedles were fabricated using three main techniques: diffraction photolithography for tapered SU-8 needle fabrication, RIE etching for needle sharpening, and excimer laser machining for through-hole creation. Puncture tests were conducted using pig’s dura mater and the microneedles coated with a Ti layer showed promising results (16 out of 100 needles pierced dura and the needles were not deformed). Blood adhesion tests were also carried out using human blood simulating the CSF dynamics and no significant platelet adhesion was observed at the microneedles. The MAG presented in this dissertation demonstrates a great potential for the treatment of hydrocephalus.Ph.D., Mechanical Engineering and Mechanics -- Drexel University, 201

Organic Light-Emitting Transistors in a Smart-Integrated System for Plasmonic-Based Sensing

AbstractThe smart integration of multiple devices in a single functional unit is boosting the advent of compact optical sensors for on‐site analysis. Nevertheless, the development of miniaturized and cost‐effective plasmonic sensors is hampered by the strict angular constraints of the detection scheme, which are fulfilled through bulky optical components. Here, an ultracompact system for plasmonic‐sensing is demonstrated by the smart integration of an organic light‐emitting transistor (OLET), an organic photodiode (OPD), and a nanostructured plasmonic grating (NPG). The potential of OLETs, as planar multielectrode devices with inherent micrometer‐wide emission areas, offers the pioneer incorporation of an OPD onto the source electrode to obtain a monolithic photonic module endowed with light‐emitting and light‐detection characteristics at unprecedented lateral proximity of them. This approach enables the exploitation of the angle‐dependent sensing of the NPG in a miniaturized system based on low‐cost components, in which a reflective detection is enabled by the elegant fabrication of the NPG onto the encapsulation glass of the photonic module. The most effective layout of integration is unraveled by an advanced simulation tool, which allows obtaining an optics‐less plasmonic system able to perform a quantitative detection up to 10−2 RIU at a sensor size as low as 0.1 cm3

Radiological Society of North America (RSNA) 3D printing Special Interest Group (SIG): Guidelines for medical 3D printing and appropriateness for clinical scenarios

Este número da revista Cadernos de Estudos Sociais estava em organização quando fomos colhidos pela morte do sociólogo Ernesto Laclau. Seu falecimento em 13 de abril de 2014 surpreendeu a todos, e particularmente ao editor Joanildo Burity, que foi seu orientando de doutorado na University of Essex, Inglaterra, e que recentemente o trouxe à Fundação Joaquim Nabuco para uma palestra, permitindo que muitos pudessem dialogar com um dos grandes intelectuais latinoamericanos contemporâneos. Assim, buscamos fazer uma homenagem ao sociólogo argentino publicando uma entrevista inédita concedida durante a sua passagem pelo Recife, em 2013, encerrando essa revista com uma sessão especial sobre a sua trajetória

Tissue mimicking materials for imaging and therapy phantoms: a review

Tissue mimicking materials (TMMs), typically contained within phantoms, have been used for many decades in both imaging and therapeutic applications. This review investigates the specifications that are typically being used in development of the latest TMMs. The imaging modalities that have been investigated focus around CT, mammography, SPECT, PET, MRI and ultrasound. Therapeutic applications discussed within the review include radiotherapy, thermal therapy and surgical applications. A number of modalities were not reviewed including optical spectroscopy, optical imaging and planar x-rays. The emergence of image guided interventions and multimodality imaging have placed an increasing demand on the number of specifications on the latest TMMs. Material specification standards are available in some imaging areas such as ultrasound. It is recommended that this should be replicated for other imaging and therapeutic modalities. Materials used within phantoms have been reviewed for a series of imaging and therapeutic applications with the potential to become a testbed for cross-fertilization of materials across modalities. Deformation, texture, multimodality imaging and perfusion are common themes that are currently under development

Ceramic coatings for Cervical Total Disc Replacement

Surgical interventions for the treatment of chronic neck pain, which affects 330 million people globally, include fusion and cervical total disc replacement (CTDR). Most of the currently clinically available CTDRs designs include a metal-on-polymer (MoP) bearing. Numerous studies suggest that MoP CTDRs are associated with issues similar to those affecting other MoP joint replacement devices, including excessive wear and wear particle-related inflammation and osteolysis. The aim of this study was to investigate the biotribology of a novel metal-on-metal (MoM) design of cervical total disc replacement device in its pristine form and coated with chromium nitride or silicon nitride, in order to understand the influence of loading conditions upon the tribological performance of the implant, and to investigate biological effects of the wear debris produced by the implants. To achieve this, a series of studies were carried out. Chromium nitride and silicon nitride coatings have been characterised for their mechanical properties, chemical composition and surface finish. Whilst some of the experiments showed minor differences between the mechanical properties and adhesion of the coatings, there was no indication of significant differences between the chromium nitride and silicon nitride coated samples. Functional testing in the six-station spine wear simulator showed that MoM CTDRs produced wear volumes significantly lower than those of the commercially available MoP devices. The wear volumes were reduced further by three-fold, following testing under altered ISO-18192-1:2011 kinematics, whereby, reduced ranges of motions were applied. Whilst the silicon nitride coated CTDRs failed catastrophically early in the test, chromium nitride coated CTDRs produced an eight-fold reduction in wear volumes, when compared to the pristine devices tested under the same conditions. Investigation of potential biological effects of the particles generated in wear testing showed that that high concentrations (5-50µm3 per cell) of CoCrMo particles resulted in significant reduction of cell viability of the L929 fibroblast cells, but not the dural fibroblasts, which were used in this study. No ceramic coating particles, at any concentrations, caused significant reduction of cell viability. In summary, results presented in this thesis showed that whilst the MoM CTDR device exhibited significantly lower wear rates than those of the commercially available MoP devices, the cytotoxic wear particles could potentially lead to adverse biological reactions, particularly in patients with metal hypersensitivity, and lead to devastating consequences similar to those of failed MoM THRs. Currently, the consequences of similar failure, leading to metalosis or pseudotumour formation in the vicinity of the spinal cord are unknown. During the investigation of the ceramic coatings, it was also found that chromium nitride ceramic coating could not only lower wear rates further, but it also has the potential to reduce the cytotoxic potential of the wear particles