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A 3D printed model of the female pelvis for practical education of gynecological pelvic examination
(2022)
Background
Pelvic palpation is a core component of every Gynecologic examination. It requires vigorous training, which is difficult due to its intimate nature, leading to a need of simulation. Up until now, there are mainly models available for mere palpation which do not offer adequate visualization of the concerning anatomical structures. In this study we present a 3D printed model of the female pelvis. It can improve both the practical teaching of gynecological pelvic examination for health care professionals and the spatial understanding of the relevant anatomy.
Methods
We developed a virtual, simplified model showing selected parts of the female pelvis. 3D printing was used to create a physical model.
Results
The life-size 3D printed model has the ability of being physically assembled step by step by its users. Consequently, it improves teaching especially when combining it with commercial phantoms, which are built solely for palpation training. This is achieved by correlating haptic and visual sensations with the resulting feedback received.
Conclusion
The presented 3D printed model of the female pelvis can be of aid for visualizing and teaching pelvic anatomy and examination to medical staff. 3D printing provides the possibility of creating, multiplying, adapting and sharing such data worldwide with little investment of resources. Thus, an important contribution to the international medical community can be made for training this challenging examination.
Purpose
Electrosurgery is the gold-standard procedure for the treatment of cervical dysplasia. The quality of the outcome depends on the accuracy of performance, which underlines the role of adequate training of surgeons, especially, as this procedure is often performed by novice surgeons. According to our knowledge, medical simulation has up until now lacked a model, which focuses on realistically simulating the treatment of cervical dysplasia with the concerning anatomy.
Methods and Result
In our work, we present a model created using 3D printing for holistically simulating diagnostic, as well as surgical interventions of the cervix, as realistically as possible.
Conclusion
This novel simulator is compared to an existing model and both are evaluated. By doing so, we aim to provide novice gynecologists with standardized and high-quality simulation models for practicing to improve their proficiency.
Background
Electrosurgical excisions are common procedures for treating cervical dysplasia and are often seen as minor surgeries. Yet, thorough training of this intervention is required, as there are considerable consequences of inadequate resections, e.g. preterm birth, the risk of recurrence, injuries and many more. Unfortunately, there is a lack of sufficiently validated possibilities of simulating electrosurgeries, which focus on high fidelity and patient safety.
Methods
A novel 3D printed simulator for examination and electrosurgical treatment of dysplastic areas of the cervix was compared with a conventional simulator. Sixty medical students experienced a seminar about cervical dysplasia. Group A underwent the seminar with the conventional and Group B with the novel simulator. After a theoretical introduction, the students were randomly assigned by picking a ticket from a box and went on to perform the hands-on training with their respective simulator. Each student first obtained colposcopic examination training. Then he or she performed five electrosurgical excisions (each). This was assessed with a validated score, to visualize their learning curve. Furthermore, adequate and inadequate resections and contacts between electrosurgical loop and vagina or speculum were counted. Both groups also assessed the seminar and their simulator with 18 questions (Likert-scales, 1–10, 1 = strongly agree / very good, 10 = strongly disagree / very bad). Group B additionally assessed the novel simulator with four questions (similar Likert-scales, 1–10).
Results
Nine of 18 questions showed statistically significant differences favoring Group B (p < 0.05). Group B also achieved more adequate R0-resections and less contacts between electrosurgical loop and vagina or speculum. The learning curves of the performed resections favored the novel simulator of Group B without statistically significant differences. The four questions focusing on certain aspects of the novel simulator indicate high appreciation of the students with a mean score of 1.6 points.
Conclusion
The presented novel simulator shows several advantages compared to the existing model. Thus, novice gynecologists can be supported with a higher quality of simulation to improve their training and thereby patient safety.
Evaluating the value of a 3D printed model for hands-on training of gynecological pelvic examination
(2022)
Background
Simulation in the field of gynecological pelvic examination with educational purposes holds great potential. In the current manuscript we evaluate a 3D printed model of the female pelvis, which improves practical teaching of the gynecological pelvic examination for medical staff.
Methods
We evaluated the benefit of a 3D printed model of the female pelvis (Pelvisio®) as part of a seminar (“skills training”) for teaching gynecological examination to medical students. Each student was randomly assigned to Group A or B by picking a ticket from a box. Group A underwent the skills training without the 3D printed model. Group B experienced the same seminar with integration of the model. Both groups evaluated the seminar by answering five questions on Likert scales (1–10, 1 = “very little” or “very poor”, 10 equals “very much” or “very good”). Additionally, both groups answered three multiple-choice questions concerning pelvic anatomy (Question 6 to 8). Finally, Group B evaluated the 3D printed model with ten questions (Question 9 to 18, Likert scales, 1–10).
Results
Two of five questions concerning the students’ satisfaction with the seminar and their gained knowledge showed statistically significant better ratings in Group B (6.7 vs. 8.2 points and 8.1 vs. 8.9 points (p < 0.001 and p < 0.009). The other three questions showed no statistically significant differences between the traditional teaching setting vs. the 3D printed model (p < 0.411, p < 0.344 and p < 0.215, respectively). The overall mean score of Question 1 to 5 showed 8.4 points for Group B and 7.8 points for Group A (p < 0.001). All three multiple-choice questions, asking about female pelvic anatomy, were answered more often correctly by Group B (p < 0.001, p < 0.008 and p < 0.001, respectively). The mean score from the answers to Questions 9 to 18, only answered by Group B, showed a mean of 8.6 points, indicating, that the students approved of the model.
Conclusion
The presented 3D printed model Pelvisio® improves the education of female pelvic anatomy and examination for medical students. Hence, training this pivotal examination can be supported by a custom designed anatomical model tailored for interactive and explorative learning.
Melt electrowriting, a high‐resolution additive manufacturing technology, has so far been developed with vertical stacking of fiber layers, with a printing trajectory that is constant for each layer. In this work, microscale layer shifting is introduced through deliberately offsetting the printing trajectory for each printed layer. Inaccuracies during the printing of sinusoidal walls are corrected via layer shifting, resulting in accurate control of their geometry and mechanical properties. Furthermore, more substantial layer shifting allows stacking of fiber layers in a horizontal manner, overcoming the electrostatic autofocusing effect that favors vertical layer stacking. Novel nonlinear geometries, such as overhangs, wall texturing and branching, and smooth and abrupt changes in printing trajectory are presented, demonstrating the flexibility of the layer shifting approach beyond the state‐of‐the‐art. The practice of microscale layer shifting for melt electrowriting enables more complex geometries that promise to have a profound impact on the development of products in a broad range of applications.
Background: The clinical management of teeth with complex dens invaginatus (DI) malformations and apical periodontitis may be challenging due to the lack of routine. The aim of this case report is to describe the endodontic treatment of an immature tooth with DI and to discuss strategies for preclinical training for teeth with such malformations. Case report: A 9-year-old male presented with an immature maxillary incisor with DI (Oehlers Type II) and apical periodontitis which was diagnosed by cone beam computed tomography (CBCT). Revitalization was initially attempted but then abandoned after failure to generate a stable blood clot. Nevertheless, considerable increase in both root length and thickness could be detected after medication with calcium hydroxide followed by root canal filling with MTA as an apical plug. Conclusions: The endodontic management of teeth with DI requires thorough treatment planning. In immature teeth, under certain conditions, root maturation may occur even with conventional apexification procedures. From an educational perspective, different strategies including CBCT and 3D-printed transparent tooth models for visualization of the complex internal morphology and redesigned 3D-printed replica with various degrees of difficulty for endodontic training, can be used to overcome the challenges associated with endodontic treatment of such teeth.
Hydrophilic (AB)\(_{n}\) Segmented Copolymers for Melt Extrusion‐Based Additive Manufacturing
(2021)
Several manufacturing technologies beneficially involve processing from the melt, including extrusion‐based printing, electrospinning, and electrohydrodynamic jetting. In this study, (AB)\(_{n}\) segmented copolymers are tailored for melt‐processing to form physically crosslinked hydrogels after swelling. The copolymers are composed of hydrophilic poly(ethylene glycol)‐based segments and hydrophobic bisurea segments, which form physical crosslinks via hydrogen bonds. The degree of polymerization was adjusted to match the melt viscosity to the different melt‐processing techniques. Using extrusion‐based printing, a width of approximately 260 µm is printed into 3D constructs, with excellent interlayer bonding at fiber junctions, due to hydrogen bonding between the layers. For melt electrospinning, much thinner fibers in the range of about 1–15 µm are obtained and produced in a typical nonwoven morphology. With melt electrowriting, fibers are deposited in a controlled way to well‐defined 3D constructs. In this case, multiple fiber layers fuse together enabling constructs with line width in the range of 70 to 160 µm. If exposed to water the printed constructs swell and form physically crosslinked hydrogels that slowly disintegrate, which is a feature for soluble inks within biofabrication strategies. In this context, cytotoxicity tests confirm the viability of cells and thus demonstrating biocompatibility of this class of copolymers.
Melt electrowriting (MEW) is a high-resolution additive manufacturing technology that balances multiple parametric variables to arrive at a stable fabrication process. The better understanding of this balance is underscored here using high-resolution camera vision of jet stability profiles in different electrical fields. Complementing this visual information are fiber-diameter measurements obtained at precise points, allowing the correlation to electrified jet properties. Two process signatures—the jet angle and for the first time, the Taylor cone area—are monitored and analyzed with a machine vision system, while SEM imaging for diameter measurement correlates real-time information. This information, in turn, allows the detection and correction of fiber pulsing for accurate jet placement on the collector, and the in-process assessment of the fiber diameter. Improved process control is used to successfully fabricate collapsible MEW tubes; structures that require exceptional accuracy and printing stability. Using a precise winding angle of 60° and 300 layers, the resulting 12 mm-thick tubular structures have elastic snap-through instabilities associated with mechanical metamaterials. This study provides a detailed analysis of the fiber pulsing occurrence in MEW and highlights the importance of real-time monitoring of the Taylor cone volume to better understand, control, and predict printing instabilities.
There is a specialized niche for the electrohydrodynamic jetting of melts, from biomedical products to filtration and soft matter applications. The next frontier includes optics, microfluidics, flexible electronic devices, and soft network composites in biomaterial science and soft robotics. The recent emphasis on reproducibly direct‐writing continual molten jets has enabled a spectrum of contemporary microscale 3D objects to be fabricated. One strong suit of melt processing is the capacity for the jet to solidify rapidly into a fiber, thus fixing a particular structure into position. The ability to direct‐write complex and multiscaled architectures and structures has greatly contributed to a large number of recent studies, explicitly, toward fiber–hydrogel composites and fugitive inks, and has expanded into several biomedical applications such as cartilage, skin, periosteum, and cardiovascular tissue engineering. Following the footsteps of a publication that summarized melt electrowriting literature up to 2015, the most recent literature from then until now is reviewed to provide a continuous and comprehensive timeline that demonstrates the latest advances as well as new perspectives for this emerging technology.
The aim of the work was the development of thiol-ene cross-linked hydrogels based on functionalized poly(glycidol)s (PG) and hyaluronic acid (HA) for extrusion based 3D bioprinting. Additionally, the functionalization of the synthesized PG with peptides and the suitability of these polymers for physically cross-linked gels were investigated, in a proof of principle study in order to demonstrate the versatile use of PG polymers in hydrogel development.
First, the precursor polymers of the different hydrogel systems were synthesized. For thiol-ene cross-linked hydogels, linear allyl-functionalized PG (P(AGE-co-G)) and three different thiol-(SH-)functionalized polymers, ester-containing PG-SH (PG SHec), ester-free PG-SH (PG-SHef) and HA-SH were synthesized and analysed, The degree of functionalization of these polymers was adjustable.
For physically cross-linked hydrogels, peptide-functionalized PG (P(peptide-co-G)), was synthesized through polymer analogue thiol-ene modification of P(AGE-co-G).
Subsequently, thiol-ene cross-linked hydrogels were prepared with the synthesized thiol- and allyl-functionalized polymers. Depending on the origin of the used polymers, two different systems were obtained: on the one hand synthetic hydrogels consisting of PG-SHec/ef and P(AGE-co-G) and on the other hand hybrid gels, consisting of HA-SH and P(AGE-co-G). In synthetic gels, the degradability of the gels was determined by the applied PG-SH. The use of PG-SHec resulted in hydrolytically degradable hydrogels, whereas the cross-linking with PG-SHef resulted in non-degradable gels.
The physical properties of these different hydrogel systems were determined by swelling, mechanical and diffusion studies and subsequently compared among each other. In swelling studies the differences of degradable and non-degradable synthetic hydrogels as well as the differences of synthetic compared to hybrid hydrogels were demonstrated.
Next, the stiffness and the swelling ratios (SR) of the established hydrogel systems were examined in dependency of different parameters, such as incubation time, polymer concentration and UV irradiation. In general, these measurements revealed the same trends for synthetic and hybrid hydrogels: an increased polymer concentration as well as prolonged UV irradiation led to an increased network density. Moreover, it was demonstrated that the incorporation of additional non-bound HMW HA hampered the hydrogel cross-linking resulting in gels with decreased stiffness and increased SR. This effect was strongly dependent on the amount of additional HMW HA.
The diffusion of different molecular weight fluorescein isothiocyanate-dextran (FITC-dextran) through hybrid hydrogels (with/without HMW HA) gave information about the mesh size of these gels. The smallest FITC-dextran (4 kDa) completely diffused through both hydrogel systems within the first week, whereas only 55 % of 40 kDa and 5-10 % HMW FITC-dextrans (500 kDa and 2 MDa) could diffuse through the networks.
The applicability of synthetic and hybrid hydrogels for cartilage regeneration purpose was investigated through by biological examinations. It was proven that both gels support the survival of embedded human mesenchymal stromal cells (hMSCs) (21/28 d in vitro culture), however, the chondrogenic differentiation was significantly improved in hybrid hydrogels compared to synthetic gels. The addition of non-bound HMW HA resulted in a slightly less distinct chondrogenesis.
Lastly the printability of the established hydrogel systems was examined. Therefore, the viscoelastic properties of the hydrogel solutions were adjusted by incorporation of non-bound HMW HA. Both systems could be successfully printed with high resolution and high shape fidelity.
The introduction of the double printing approach with reinforcing PCL allowed printing of hydrogel solutions with lower viscosities. As a consequence, the amount of additional HMW HA necessary for printing could be reduced allowing successful printing of hybrid hydrogel solutions with embedded cells. It was demonstrated that the integrated cells survived the printing process with high viability measured after 21 d. Moreover, by this reinforcing technique, robust hydrogel-containing constructs were fabricated.
In addition to thiol-ene cross-linked hydrogels, hydrogel cross-linking via ionic interactions was investigated with a hybrid hydrogel based on HMW HA and peptide-functionalized PG. Rheological measurements revealed an increase in the viscosity of a 2 wt.% HMW HA solution by the addition of peptide-functionalized PG. The increase in viscosity could be attributed to the ionic interactions between the positively charge PG and the negatively charge HMW HA.
In conclusion, throughout this thesis thiol-ene chemistry and PG were introduced as promising cross-linking reaction and polymer precursor for the field of biofabrication. Furthermore, the differences of hybrid and synthetic hydrogels as well as chemically and physically cross-linked hydrogels were demonstrated.
Moreover, the double printing approach was demonstrated to be a promising tool for the fabrication of robust hydrogel-containing constructs. It opens the possibility of printing hydrogels that were not printable yet, due to too low viscosities.