3D printing for clinical application in otorhinolaryngology

The Creation of an Average 3D Model of the Human Cartilaginous Nasal Septum and Its Biomimetic Applications

The cartilaginous nasal septum is integral to the overall structure of the nose. Developing our an-atomic understanding of the septum will improve the planning and techniques of septal surgeries. While the basic dimensions of the septum have previously been described, the average shape in the sagittal plane has yet to be established. Furthermore, determining the average shape allows for the creation of a mean three-dimensional (3D) septum model. To better understand the average septal shape, we dissected septums from 40 fresh human cadavers. Thickness was measured across pre-defined points on each specimen. Image processing in Photoshop was used to superimpose lateral photographs of the septums to determine the average shape. The average shape was then combined with thickness data to develop a 3D model. This model may be utilized in finite elemental analyses, creating theoretical results about septal properties that are more translatable to real-world clinical practice. Our 3D septum also has numerous applications for 3D printing. Realistic models can be created for educational or surgical planning purposes. In the future, our model could also serve as the basis for 3D-printed scaffolds to aid in tissue regeneration to reconstruct septal defects. The model can be viewed at the NIH 3D model repository (3DPX ID: 020598, Title: 3D Nasal Septum).

Cost-effective 3D scanning and printing technologies for outer ear reconstruction: current status

Current 3D scanning and printing technologies offer not only state-of-the-art developments in the field of medical imaging and bio-engineering, but also cost and time effective solutions for surgical reconstruction procedures. Besides tissue engineering, where living cells are used, bio-compatible polymers or synthetic resin can be applied. The combination of 3D handheld scanning devices or volumetric imaging, (open-source) image processing packages, and 3D printers form a complete workflow chain that is capable of effective rapid prototyping of outer ear replicas. This paper reviews current possibilities and latest use cases for 3D-scanning, data processing and printing of outer ear replicas with a focus on low-cost solutions for rehabilitation engineering.

3D Printed Larynx as a Novel Simulation Tool for Window Elaboration in Medialization Laryngoplasty

OBJECTIVE

Surgical simulation training in residents has declined due to the limited exposure to cadaveric specimens. Three-dimensional (3D)-printing technology is rapidly taking an important role in different medical areas, especially in surgical specialties. It provides an alternative for resident simulation practices and for developing surgical skills before exposure to real settings. The elaboration of the thyroid window in the medialization laryngoplasty procedure requires high technical precision and experience for better outcomes.

METHODS

The computer-based 3D reconstruction model was created using computed tomograph scan images from a standard larynx. The final model was created using a deposition modeling 3D printing technique with polylactic acid filament. The model was tested for surgical simulation practice in three otolaryngology residency programs in Bogotá, Colombia.

RESULTS

The model had similar anatomic detail and it was considered very useful, safe, and relevant for surgical simulation.

CONCLUSIONS

3D printed models are a cost-effective alternative for resident training.

3D-printing a cost-effective model for mastoidectomy training

BACKGROUND

3D-printed temporal bone models can potentially provide a cost-effective alternative to cadaver surgery that can be manufactured locally at the training department. The objective of this study was to create a cost-effective 3D-printed model suitable for mastoidectomy training using entry level and commercially available print technologies, enabling individuals, without prior experience on 3D-printing, to manufacture their own models for basic temporal bone training.

METHODS

Expert technical professionals and an experienced otosurgeon identified the best material for replicating the temporal bone and created a cost-effective printing routine for the model using entry-level print technologies. Eleven participants at a temporal bone dissection course evaluated the model using a questionnaire.

RESULTS

The 3D-printed temporal bone model was printed using a material extrusion 3D-printer with a heat resistant filament, reducing melting during drilling. After printing, a few simple post-processing steps were designed to replicate the dura, sigmoid sinus and facial nerve. Modifying the 3D-printer by installing a direct-drive and ruby nozzle resulted in more successful prints and less need for maintenance. Upon evaluation by otorhinolaryngology trainees, unanimous feedback was that the model provided a good introduction to the mastoidectomy procedure, and supplementing practice to cadaveric temporal bones.

CONCLUSION

In-house production of a cost-effective 3D-printed model for temporal bone training is feasible and enables training institutions to manufacture their own models. Further, this work demonstrates the feasibility of creating new temporal bone models with anatomical variation to provide ample training opportunity.

3D Printing in Otolaryngology Surgery: Descriptive Review of Literature to Define the State of the Art

BACKGROUND

Three-dimensional (3D) printing has allowed great progression in the medical field. In otolaryngology practice, 3D printing can be used for planning in case of malformation/complex surgery, for surgeon training, and for recreating missing tissues. This systematic review aimed to summarize the current benefits and the possible future application of 3D technologies in the otolaryngology field.

METHODS

A systematic review of articles that discuss the use of 3D printing in the otolaryngology field was performed. All publications without the restriction of time and that were published by December 2021 in the English language were included. Searches were performed in the PubMed, MEDLINE, Scopus, and Embase databases. Keywords used were: "3D printing", "bioprinting", "three-dimensional printing", "tissue engineering" in combination with the terms: "head and neck surgery", "head and neck reconstruction", "otology", "rhinology", "laryngology", and "otolaryngology".

RESULTS

Ninety-one articles were included in this systematic review. The articles describe the clinical application of 3D printing in different fields of otolaryngology, from otology to pediatric otolaryngology. The main uses of 3D printing technology discussed in the articles included in the review were surgical planning in temporal bone malformation, the reconstruction of missing body parts after oncologic surgery, allowing for medical training, and providing better information to patients.

CONCLUSION

The use of 3D printing in otolaryngology practice is constantly growing. However, available evidence is still limited, and further studies are needed to better evaluate the benefits of this technology.

A 3D Printed Human Ear Model for Standardized Testing of Hearing Protection Devices to Blast Exposure

Hypothesis

A 3D printed human temporal bone (TB) that is anatomically accurate would cost-effectively reproduce the responses observed in blast testing of human cadaveric TBs with and without passive hearing protection devices (HPDs).

Background

HPDs have become critical personal protection equipment against auditory damage for service members. Acoustic test fixtures and human TBs have been used to test and develop HPDs; however, the lack of a cost-effective, standardized model impedes the improvement of HPDs.

Methods

In this study, the 3D printed TB model was printed with flexible and rigid polymers and consisted of the ear canal, tympanic membrane (TM), ossicular chain, middle ear suspensory ligaments/muscle tendons, and middle ear cavity. The TM movement under acoustic stimulation was measured with laser Doppler vibrometry. The TB model was then exposed to blasts with or without HPDs and pressures at the ear canal entrance (P0) and near the TM in the ear canal (P1) were recorded. All results were compared with that measured in human TBs.

Results

Results indicated that in the 3D printed TB, the attenuated peak pressures at P1 induced by HPDs ranged from 0.92 to 1.06 psi (170-171 dB) with blast peak pressures of 5.62-6.54 psi (186-187 dB) at P0, and measured results were within the mean and SD of published data. Vibrometry measurements also followed a similar trend as the published results.

Conclusions

The 3D printed TB model accurately evaluated passive HPDs' protective function during blast and the potential for use as a model for acoustic transmission was investigated.

The cutting edge of customized surgery: 3D-printed models for patient-specific interventions in otology and auricular management-a systematic review

PURPOSE

3D-printing (three-dimensional printing) is an emerging technology with promising applications for patient-specific interventions. Nonetheless, knowledge on the clinical applicability of 3D-printing in otology and research on its use remains scattered. Understanding these new treatment options is a prerequisite for clinical implementation, which could improve patient outcomes. This review aims to explore current applications of 3D-printed patient-specific otologic interventions, including state of the evidence, strengths, limitations, and future possibilities.

METHODS

Following the PRISMA statement, relevant studies were identified through Pubmed, EMBASE, the Cochrane Library, and Web of Science. Data on the manufacturing process and interventions were extracted by two reviewers. Study quality was assessed using Joanna Briggs Institute's critical appraisal tools.

RESULTS

Screening yielded 590 studies; 63 were found eligible and included for analysis. 3D-printed models were used as guides, templates, implants, and devices. Outer ear interventions comprised 73% of the studies. Overall, optimistic sentiments on 3D-printed models were reported, including increased surgical precision/confidence, faster manufacturing/operation time, and reduced costs/complications. Nevertheless, study quality was low as most studies failed to use relevant objective outcomes, compare new interventions with conventional treatment, and sufficiently describe manufacturing.

CONCLUSION

Several clinical interventions using patient-specific 3D-printing in otology are considered promising. However, it remains unclear whether these interventions actually improve patient outcomes due to lack of comparison with conventional methods and low levels of evidence. Further, the reproducibility of the 3D-printed interventions is compromised by insufficient reporting. Future efforts should focus on objective, comparative outcomes evaluated in large-scale studies.

Bringing hydrogel-based craniofacial therapies to the clinic

This review explores the evolution of the use of hydrogels for craniofacial soft tissue engineering, ranging in complexity from acellular injectable fillers to fabricated, cell-laden constructs with complex compositions and architectures. Addressing both in situ and ex vivo approaches, tissue restoration secondary to trauma or tumor resection is discussed. Beginning with relatively simple epithelia of oral mucosa and gingiva, then moving to more functional units like vocal cords or soft tissues with multilayer branched structures, such as salivary glands, various approaches are presented toward the design of function-driven architectures, inspired by native tissue organization. Multiple tissue replacement paradigms are presented here, including the application of hydrogels as structural materials and as delivery platforms for cells and/or therapeutics. A practical hierarchy is proposed for hydrogel systems in craniofacial applications, based on their material and cellular complexity, spatial order, and biological cargo(s). This hierarchy reflects the regulatory complexity dictated by the Food and Drug Administration (FDA) in the United States prior to commercialization of these systems for use in humans. The wide array of available biofabrication methods, ranging from simple syringe extrusion of a biomaterial to light-based spatial patterning for complex architectures, is considered within the history of FDA-approved commercial therapies. Lastly, the review assesses the impact of these regulatory pathways on the translational potential of promising pre-clinical technologies for craniofacial applications. STATEMENT OF SIGNIFICANCE: While many commercially available hydrogel-based products are in use for the craniofacial region, most are simple formulations that either are applied topically or injected into tissue for aesthetic purposes. The academic literature previews many exciting applications that harness the versatility of hydrogels for craniofacial soft tissue engineering. One of the most exciting developments in the field is the emergence of advanced biofabrication methods to design complex hydrogel systems that can promote the functional or structural repair of tissues. To date, no clinically available hydrogel-based therapy takes full advantage of current pre-clinical advances. This review surveys the increasing complexity of the current landscape of available clinical therapies and presents a framework for future expanded use of hydrogels with an eye toward translatability and U.S. regulatory approval for craniofacial applications.

A simple and convenient 3D printed temporal bone model for drilling simulating surgery

BACKGROUND

It is still far away from most of us in that it requires complex 3D modeling.

AIMS/OBJECTIVES

To investigate a more precision, simple, convenient and economical three-dimensional (3D) printed temporal bone model printed by a commercial desktop 3D printer, which can be widely promoted and applied in the training of beginners in otology.

MATERIAL AND METHODS

The CT data of the temporal bone were imported into Mimics to construct a 3D digital model of the temporal bone. After loaded into a high-precision 3D printer, a high-precision temporal bone model was printed at a scale of 1:1. Then, the model was evaluated by 5 senior attending physicians, including its morphological accuracy, simulation about surgery, advantages and educational value, using the 7-point Likert scale.

RESULTS

A life-like temporal bone model was successfully printed out. Five senior attending physicians all thought that the printed model was similar to the natural temporal bone in physical properties and the haptic sensation of bone drilling, and was accurate, simple, convenient and effective. In addition, the model was considered to be of high application value in the teaching of temporal bone anatomy and surgery simulation, which had a material cost of only 3 dollars.

CONCLUSIONS

The high-precision 3D printed temporal bone model is highly similar to the natural temporal bone, and can be conveniently and effectively used in the training of simulating temporal bone surgery for beginners in otology. Its production is simple and economical, so it can be popularized on a large scale.

Procedure Increasing the Accuracy of Modelling and the Manufacturing of Surgical Templates with the Use of 3D Printing Techniques, Applied in Planning the Procedures of Reconstruction of the Mandible

The application of anatomical models and surgical templates in maxillofacial surgery allows, among other benefits, the increase of precision and the shortening of the operation time. Insufficiently precise anastomosis of the broken parts of the mandible may adversely affect the functioning of this organ. Applying the modern mechanical engineering methods, including computer-aided design methods (CAD), reverse engineering (RE), and rapid prototyping (RP), a procedure used to shorten the data processing time and increase the accuracy of modelling anatomical structures and the surgical templates with the use of 3D printing techniques was developed. The basis for developing and testing this procedure was the medical imaging data DICOM of patients treated at the Maxillofacial Surgery Clinic of the Fryderyk Chopin Provincial Clinical Hospital in Rzeszów. The patients were operated on because of malignant tumours of the floor of the oral cavity and the necrosis of the mandibular corpus, requiring an extensive resection of the soft tissues and resection of the mandible. Familiarity with and the implementation of the developed procedure allowed doctors to plan the operation precisely and prepare the surgical templates and tools in terms of the expected accuracy of the procedures. The models obtained based on this procedure shortened the operation time and increased the accuracy of performance, which accelerated the patient’s rehabilitation in the further course of events.

Early preclinical evaluation of a novel, computer aided designed, 3D printed, bioresorbable posterior cricoid scaffold

OBJECTIVES

The posterior cricoid split with rib graft is a procedure that elegantly corrects pediatric posterior glottic stenosis and subglottic stenosis. Currently, the procedure requires harvesting of rib cartilage which leaves room for optimization. With use of three dimensional printing technology, our objective was to design a device that would negate the need for costal cartilage harvesting in this procedure.

METHODS

An optimized, novel polycaprolactone scaffold was designed using computer aided design software and three dimensional printing. A pilot proof of concept study was conducted with implantation of the device in three porcine animal subjects. Device was evaluated by post-procedural clinical course, endoscopic exams, post-mortem exam, and histological evaluation.

RESULTS

A series of variably sized scaffolds were created. The scaffolds showed structural integrity and successfully expanded the cricoid cartilage in the porcine model study. Post-operative endoscopy and clinical exams demonstrated no signs of implant instability or failure. Gross and histologic exams showed successful mucosalization over the scaffold and cartilage ingrowth by six weeks.

CONCLUSION

This porcine animal pilot study demonstrated early success of a computer-aided designed, 3D printed, bioresorbable PCL posterior graft scaffold. The scaffolds eliminate the need for costal cartilage harvesting and had excellent surgical usability. The scaffolds functioned as designed, offering proof of concept and grounds for further evaluation to expand on this small pilot study with larger animal studies and continued design refinement.

Three dimensional printed models of the airway for preoperative planning of open Laryngotracheal surgery in children: Surgeon's perception of utility

BACKGROUND

Preoperative planning of open laryngotracheal surgery is important for achieving good results. This study examines the surgeon's perception of the importance of using life size 3D printed models of the pediatric airway on surgical decision making.

METHODS

Life-size three-dimensional models of the upper airway were created based on CT images of children scheduled for laryngotracheal-reconstruction and cricotracheal resection with anastomosis. Five pediatric airway surgeons evaluated the three-dimensional models for determining the surgical approach, incision location and length, graft length, and need for single or double-stage surgery of seven children (median age 4.4 years, M:F ratio 4:3). They rated the importance of the three-dimensional model findings compared to the direct laryngoscopy videos and CT findings for each domain on a validated Likert scale of 1-5.

RESULTS

The mean rating for all domains was 3.6 ± 0.63 ("moderately important" to "very important"), and the median rating was 4 ("very important"). There was full agreement between raters for length of incision and length of graft. The between-rater agreement was 0.608 ("good") for surgical approach, 0.585 ("moderate") for incision location, and 0.429 ("moderate") for need for single- or two-stage surgery.

CONCLUSION

Patient-specific three-dimensional printed models of children's upper airways were scored by pediatric airway surgeons as being moderately to very important for preoperative planning of open laryngotracheal surgery. Large-scale, objective outcome studies are warranted to establish the reliability and efficiency of these models.

The Application of Three-Dimensional Technology Combined With Image Navigation in Nasal Skull Base Surgery

Three-dimensional (3D) technology including 3D reconstruction and 3D printing technology, has been widely used in clinical treatment, especially in surgical planning, and image navigation technology, which can make surgical procedures more accurate, now is also increasingly favored by surgeons. But the combination of those 2 technologies was rarely reported. Thus, this study will preliminarily investigate the feasibility and the effect of the combination of 2 technologies in endonasal skull base surgery. Eight patients were involved in this study (from October 2016 to July 2017 at The Affiliated Hospital of Qingdao University), 5 cases of nasal skull base tumors and 3 cases of foreign body perforation. All operations were done under the assistance of 3D technology and image guidance system. Surgical discussion with patient, preoperative planning and clinical teaching were investigated between 2D images and 3D models by voting. For all cases, 3D reconstruction model and 3D printed model were deemed to be more helpful than CT/MRI images in surgical discussion with the patient; surgical simulation on 3D model in preoperative planning was largely deemed to be helpful and very helpful; and in clinical teaching, 3D models combined with image guidance system were deemed to be more helpful in understanding the disease than using 2D images. Besides, all patients recovered well after surgery, no recurrence and complications were found in the follow-up. The combination of 3D technology and electromagnetic image guidance system could improve surgical efficiency and the quality of clinical teaching.

3D-Printed Models for Temporal Bone Surgical Training: A Systematic Review

OBJECTIVE

3D-printed models hold great potential for temporal bone surgical training as a supplement to cadaveric dissection. Nevertheless, critical knowledge on manufacturing remains scattered, and little is known about whether use of these models improves surgical performance. This systematic review aims to explore (1) methods used for manufacturing and (2) how educational evidence supports using 3D-printed temporal bone models.

DATA SOURCES

PubMed, Embase, the Cochrane Library, and Web of Science.

REVIEW METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, relevant studies were identified and data on manufacturing and validation and/or training extracted by 2 reviewers. Quality assessment was performed using the Medical Education Research Study Quality Instrument tool; educational outcomes were determined according to Kirkpatrick's model.

RESULTS

The search yielded 595 studies; 36 studies were found eligible and included for analysis. The described 3D-printed models were based on computed tomography scans from patients or cadavers. Processing included manual segmentation of key structures such as the facial nerve; postprocessing, for example, consisted of removal of print material inside the model. Overall, educational quality was low, and most studies evaluated their models using only expert and/or trainee opinion (ie, Kirkpatrick level 1). Most studies reported positive attitudes toward the models and their potential for training.

CONCLUSION

Manufacturing and use of 3D-printed temporal bones for surgical training are widely reported in the literature. However, evidence to support their use and knowledge about both manufacturing and the effects on subsequent surgical performance are currently lacking. Therefore, stronger educational evidence and manufacturing knowhow are needed for widespread implementation of 3D-printed temporal bones in surgical curricula.

Additive 3-dimensional printing as a novel tool for pre- and postsurgical evaluation and patient education: A clinical case series

BACKGROUND AND OVERVIEW

In contrast to subtractive 3-dimensional (3D) techniques synonymous with computer-aided design and computer-aided manufacturing, rapid progress in additive 3D printing, especially fused filament fabrication or fused deposition modeling, can change the practice of dentistry.

CASE DESCRIPTION

In this article, the authors outline the digital workflow for fused filament fabrication and fused deposition modeling 3D printing that involves converting a Digital Imaging and Communications in Medicine file (scan or radiograph) to a printable Standard Triangle Language file that can be modified (additions or manipulations) using a readily accessible software for 3D printing. The authors also present a clinical case series showing various applications for this technique, including clinician and patient education, treatment planning, and posttreatment evaluations.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The low cost and simple workflow of additive 3D printing has potential to improve precision and efficiency in clinical dentistry for both academic and private practices.

Osseointegrated implant-retained auricular prosthesis constructed using cone-beam computed tomography and a prosthetically driven digital workflow: a case report

Prosthetically driven workflows using CBCT, digital optical scanning, 3D-printed molds and frameworks, and dental implant component attachments to osseointegrated fixtures can produce anatomically accurate, esthetic, durable silicone ear replacements.

The suitability of scanning electron microscopy in the evaluation of bone structure surfaces and selection of alloplastic materials for facial skeletal reconstruction

INTRODUCTION

Functional and aesthetic problems can arise even from small losses created in the facial skeleton. Injuries and oncological surgeries are the most frequent causes of these losses within the facial skeleton. Advances in surgical interventions have allowed for ever-increasing degrees of resections, increasing oncological radicality as well as treatment effectiveness, providing the patient with the chance for a longer life. However, this subsequently requires the use of even more advanced reconstruction techniques in order to restore quality of life and comfort to the patient, as well as enable their return to professional and social activities. The necessity of reconstructive surgery applies not only to patients with cancer, but also to patients with impaired or failing sensory and organ function as a result of inflammatory conditions, injuries, or non-oncological surgeries. There are many available reconstruction procedures, which depend on the location of the loss, the type of tissue lost, the degree of loss and patient-dependent factors. Materials used in reconstruction surgeries may include the patients' tissues when available, and artificial reconstruction materials otherwise.

MATERIAL AND METHODS

The analysis involved fragments of bone tissue removed during surgery. Due to the nature of the medical procedure and the inability to replant the tissue, it was regarded as medical waste. The preparations used were observed under an optical microscope and an electron scanning microscope, and a chemical analysis was performed. The chemical composition of samples was analysed using a low vacuum detector (LVD) at an accelerating voltage of 15 kV and 10 kV and at a spot size of 4 and 3.5. The observations were performed in a secondary electron (SE) detection system.

RESULTS

Observation of parameters under an optical microscope and of images obtained using an electron scanning microscope showed the presence of typical, compact bone tissue with varied surface shapes in each case (various degrees of unevenness and porosity). Chemical composition analysis confirmed the presence of compounds from the CaO-P2O5-H20 system. The Ca/P (calcium/phosphorus) ratio obtained from the chemical analysis varied from 1.33 to 2.1, and indicated a varied morphology of calcium phosphates forming the bone structures of the facial skeleton.

CONCLUSIONS

1. Calcium phosphates are characterised by excellent biocompatibility because of their chemical affinity to bone, and are ideal for the reconstruction of bone losses within the facial skeleton. 2. Biodegradable polymers have the highest functional potential among several groups of biomaterials used in tissue engineering because of their ability to be tailored individually, in addition to their high biocompatibility.

3D Printed Biomimetic Rabbit Airway Simulation Model for Nasotracheal Intubation Training

Rabbit inhalation anesthesia by endotracheal intubation involves a higher risk among small animals owing to several anatomical and physiological features, which is pathognomonic to this species of lagomorphs. Rabbit-specific airway devices have been designed to prevent misguided intubation attempts. However, it is believed that expert anesthetic training could be a boon in limiting the aftermaths of this procedure. Our research is aimed to develop a novel biomimetic 3D printed rabbit airway model with representative biomechanical material behavior and radiodensity. Imaging data were collected for two sacrificed rabbit heads using micro-computed tomography (μCT) and micro-magnetic resonance imaging for the first head and cone beam computed tomography (CBCT) for the second head. Imaging-based life-size musculoskeletal airway models were printed using polyjet technology with a combination of hard and soft materials in replicates of three. The models were evaluated quantitatively for dimensional accuracy and radiodensity and qualitatively using digital microscopy and endoscopy for technical, tactic, and visual realism. The results displayed that simulation models printed with polyjet technology have an overall surface representation of 93% for μCT-based images and 97% for CBCT-based images within a range of 0.0-2.5 mm, with μCT showing a more detailed reproduction of the nasotracheal anatomy. Dimensional discrepancies can be caused due to inadequate support material removal and due to the limited reconstruction of microstructures from the imaging on the 3D printed model. The model showed a significant difference in radiodensities in hard and soft tissue regions. Endoscopic evaluation provided good visual and tactile feedback, comparable to the real animal. Overall, the model, being a practical low-cost simulator, comprehensively accelerates the learning curve of veterinary nasotracheal intubation and paves the way for 3D simulation-based image-guided interventional procedures.

The Impact of 3D Technology in Optimizing Midface Fracture Treatment-Focus on the Zygomatic Bone

PURPOSE

In the context of the ongoing development and expanding availability of 3-dimensional (3D) printing, there is increasing interest in designing simplified workflows that would encourage more medical practitioners to include 3D printing in their current practice. The purpose of this study is to present our experience regarding the use of 3D printing in the preoperative planning and management of acute midface trauma, an area less explored by existing studies.

METHODS

We performed a retrospective case series study including admitted patients who underwent surgical repair of midface fractures, in which 3D-printed stereolithic models were used preoperatively for shaping the osteosynthesis material. We recorded standard information about the patients, imaging method used, and type of midface fracture. We also logged the details and durations of each main step in the preoperative 3D printing workflow and documented the durations and outcomes of each surgical procedure.

RESULTS

We identified 29 cases of midface fractures that benefited of a preoperative stereolithic model. From the 2 main methods of obtaining the virtual model, mirroring and virtual fracture reduction, the longest duration was recorded in a case in which the later method was used. The longest stereolithic model printing time was found in a complex midface fracture case. All the prebent osteosynthesis material was used intraoperatively and fitted the reduced fracture sites, also serving as an intraoperative guide for correct fracture reduction. The particularities, benefits, as well as the possible challenges associated with the application of 3D printing in acute trauma cases are discussed.

CONCLUSIONS

Our 3D printing protocol was applicable and rendered favorable outcomes in the acute midface trauma setting. Proper understanding of the steps involved in achieving the stereolithic model is key for the adaptation of 3D printing to the current management of acute midface trauma.

Three-Dimensional Bioprinting: Role in Craniomaxillary Surgery Ethics and Future

Three-dimensional (3D) printing and bioprinting is gaining lot of momentum, especially in surgical specialties. These two technologies have wide array of applications in presurgical, surgical, and in vitro scenarios. Bioprinting can generate customized patient specific tissue engineered from specialized cells. This technology can be a gold standard in reconstructive and regenerative surgeries, if used in regulated and ethical environment. This communication focuses on basics of these technologies, their role in surgical specialties, ethical issues specific to these technologies, and its future.

The Syndrome of Elongated Styloid Process, the Eagle's Syndrome-From Anatomical, Evolutionary and Embryological Backgrounds to 3D Printing and Personalized Surgery Planning. Report of Five Cases

Background and Objectives: The symptoms of Eagle's syndrome are associated with the elongated styloid process of the temporal bone or calcification of the stylohyoid ligament. The first mention of pain syndrome associated with the elongated styloid process dates back to 1937, when it was described by Watt Weems Eagle. Over the last decade, experts in the field have shown a lively interest in the issue of the relationship between the elongated styloid process and various symptoms. This article presents the correlation between the clinical signs of Eagle's syndrome and alterations in surrounding anatomical structures. It includes a brief review of the evolutionary, embryological and clinical anatomical background of the elongated styloid process. Materials and Methods: Between 2018 and 2019, five patients were admitted to our workplace with 1-3-year history of bilateral or unilateral throat pain, otalgia and pharyngeal foreign body sensation. As a therapeutic novelty in the surgical approach to this condition, we used individual 3D printed models to measure and identify the exact location of the resection of the styloid process without damaging the surrounding anatomical structures, such as the facial, accessory, hypoglossal, and vagal nerves; the internal jugular vein; and the internal carotid artery. Results: Compared to traditional surgical methods without 3D models, 3D models helped to better identify cutting edges and major landmarks used in surgical treatment of Eagle's syndrome. Printed models provided assistance with the exact location of the styloid process resection position without damaging the surrounding anatomical structures such as the facial, accessory, hypoglossal, and vagal nerves; the internal jugular vein; and the internal carotid artery. Conclusion: In our clinical report, we used 3D printed models for navigation and planning during surgical procedures involving resections of the elongated styloid process. Additionally, we can formulate a new hypothesis: the elongated styloid process is a form of atavism of the bony hyoid apparatus in our evolutionary ancestors that is evolutionarily encoded or arises from disrupted degeneration of the middle portion of embryonal Reichert´s cartilage of the second pharyngeal arch. Under normal conditions, this portion does not ossify but degenerates and transforms into a connective tissue band, the future stylohyoid ligament.

3D Printing Technologies: Recent Development and Emerging Applications in Various Drug Delivery Systems

The 3D printing is considered as an emerging digitized technology that could act as a key driving factor for the future advancement and precise manufacturing of personalized dosage forms, regenerative medicine, prosthesis and implantable medical devices. Tailoring the size, shape and drug release profile from various drug delivery systems can be beneficial for special populations such as paediatrics, pregnant women and geriatrics with unique or changing medical needs. This review summarizes various types of 3D printing technologies with advantages and limitations particularly in the area of pharmaceutical research. The applications of 3D printing in tablets, films, liquids, gastroretentive, colon, transdermal and intrauterine drug delivery systems as well as medical devices have been briefed. Due to the novelty and distinct features, 3D printing has the inherent capacity to solve many formulation and drug delivery challenges, which are frequently associated with poorly aqueous soluble drugs. Recent approval of Spritam® and publication of USFDA technical guidance on additive manufacturing related to medical devices has led to an extensive research in various field of drug delivery systems and bioengineering. The 3D printing technology could be successfully implemented from pre-clinical phase to first-in-human trials as well as on-site production of customized formulation at the point of care having excellent dose flexibility. Advent of innovative 3D printing machineries with built-in flexibility and quality with the introduction of new regulatory guidelines would rapidly integrate and revolutionize conventional pharmaceutical manufacturing sector.

Computational technology for nasal cartilage-related clinical research and application

Surgeons need to understand the effects of the nasal cartilage on facial morphology, the function of both soft tissues and hard tissues and nasal function when performing nasal surgery. In nasal cartilage-related surgery, the main goals for clinical research should include clarification of surgical goals, rationalization of surgical methods, precision and personalization of surgical design and preparation and improved convenience of doctor-patient communication. Computational technology has become an effective way to achieve these goals. Advances in three-dimensional (3D) imaging technology will promote nasal cartilage-related applications, including research on computational modelling technology, computational simulation technology, virtual surgery planning and 3D printing technology. These technologies are destined to revolutionize nasal surgery further. In this review, we summarize the advantages, latest findings and application progress of various computational technologies used in clinical nasal cartilage-related work and research. The application prospects of each technique are also discussed.

3D Bioprinting Strategies for the Regeneration of Functional Tubular Tissues and Organs

It is difficult to fabricate tubular-shaped tissues and organs (e.g., trachea, blood vessel, and esophagus tissue) with traditional biofabrication techniques (e.g., electrospinning, cell-sheet engineering, and mold-casting) because these have complicated multiple processes. In addition, the tubular-shaped tissues and organs have their own design with target-specific mechanical and biological properties. Therefore, the customized geometrical and physiological environment is required as one of the most critical factors for functional tissue regeneration. 3D bioprinting technology has been receiving attention for the fabrication of patient-tailored and complex-shaped free-form architecture with high reproducibility and versatility. Printable biocomposite inks that can facilitate to build tissue constructs with polymeric frameworks and biochemical microenvironmental cues are also being actively developed for the reconstruction of functional tissue. In this review, we delineated the state-of-the-art of 3D bioprinting techniques specifically for tubular tissue and organ regeneration. In addition, this review described biocomposite inks, such as natural and synthetic polymers. Several described engineering approaches using 3D bioprinting techniques and biocomposite inks may offer beneficial characteristics for the physiological mimicry of human tubular tissues and organs.

Application of 3D reconstruction for midline glossectomy in OSA patients

OBJECTIVE

To explore the application of three-dimensional (3D) reconstruction technology for midline glossectomy in patients with obstructive sleep apnea (OSA).

METHODS

Fifteen patients with OSA were included in this study. Each of them received computed tomography angiography (CTA) examination of lingual arteries in the resting tongue position and fully extended tongue position respectively. The two-dimensional CTA images were converted to 3D models using 3D reconstruction technology. We simulated the midline glossectomy in different tongue positions with a safe margin of 3 mm. The differences in the distances between bilateral lingual arteries, the depths of the lingual arteries and the surgical resectable volumes of the tongue were compared between different tongue positions in 3D models.

RESULTS

The depths of the lingual arteries, the distances between bilateral lingual arteries based on three measuring sections and the surgical resectable volumes of the tongue in the fully extended tongue position were significantly smaller than those in the resting tongue position (P < 0.01 or 0.05).

CONCLUSION

The 3D reconstruction technology can show the course of lingual artery stereoscopically and visually, and can be more beneficial to guide surgery than two-dimensional examination. Lingual artery examination in the fully extended tongue position has higher specificity in displaying intraoperative actual situation.

3D Printed Personalized Corneal Models as a Tool for Improving Patient’s Knowledge of an Asymmetric Disease

Additive manufacturing is a vanguard technology that is currently being used in several fields in medicine. This study aims to evaluate the viability in clinical practice of a patient-specific 3D model that helps to improve the strategies of the doctor-patient assistance. Data obtained from a corneal topographer were used to make a virtual 3D model by using CAD software, to later print this model by FDM and get an exact replica of each patient’s cornea in consultation. Used CAD and printing software were open-source, and the printing material was biodegradable and its cost was low. Clinic users gave their feedback by means of a survey about their feelings when perceiving with their senses their own printed cornea. There was 82 surveyed, 73.8% (9.74; SD: 0.45) of them considered that the model had helped them a lot to understand their disease, expressing 100% of them their intention of taking home the printed model. The majority highlighted that this new concept improves both quality and clinical service in consultation. Custom-made individualized printed models allow a new patient-oriented perspective that may improve the communication strategy from the ophthalmologist to the patient, easing patient’s understanding of their asymmetric disease and its later treatment.

Effectiveness of personalized 3D printed models for patient education in degenerative lumbar disease

OBJECTIVE

Three-dimensional printing may play an important role in patients' education. The objective of this study was to assess the effectiveness of personalized 3D printed models for increasing patient understanding of their medical condition and surgical plan.

METHODS

Forty-five patients with degenerative lumbar diseases were randomized by block design into three groups: educational program presented by CT & MRI imaging (care-as-usual), 3D reconstructions, or personalized 3D printed models. Patients' level of understanding and satisfaction were evaluated by two questionnaires one day after education.

RESULTS

Patients educated with personalized 3D printed models demonstrated an expanded level of understanding than patients educated with CT & MRI imaging (care-as-usual) (P ＜ 0.05) and 3D reconstructions (P ＜ 0.05). Personalized 3D printed models also resulted in a higher degree of patient satisfaction (P ＜ 0.05).

CONCLUSIONS

Personalized 3D printed models and 3D reconstructions can simplify and enhance understanding of lumbar anatomy, physiology, and patients' disease and surgical plan. Personalized 3D printed models also enhance patients' subjective satisfaction.

PRACTICE IMPLICATIONS

Personalized 3D printed models for patient education are feasible and could be generalized for degenerative lumbar diseases.

Implementations of 3D printing in ophthalmology

PURPOSE

The purpose of this paper is to provide an in-depth understanding of how to best utilize 3D printing in medicine, and more particularly in ophthalmology in order to enhance the clinicians' ability to provide out-of-the-box solutions for unusual challenges that require patient personalization. In this review, we discuss the main applications of 3D printing for diseases of the anterior and posterior segments of the eye and discuss their current status and implementation. We aim to raise awareness among ophthalmologists and report current and future developments.

METHODS

A computerized search from inception up to 2018 of the online electronic database PubMed was performed, using the following search strings: "3D," "printing," "ophthalmology," and "bioprinting." Additional data was extracted from relevant websites. The reference list in each relevant article was analyzed for additional relevant publications.

RESULTS

3D printing first appeared three decades ago. Nevertheless, the implementation and utilization of this technology in healthcare became prominent only in the last 5 years. 3D printing applications in ophthalmology are vast, including organ fabrication, medical devices, production of customized prosthetics, patient-tailored implants, and production of anatomical models for surgical planning and educational purposes.

CONCLUSIONS

The potential applications of 3D printing in ophthalmology are extensive. 3D printing enables cost-effective design and production of instruments that aid in early detection of common ocular conditions, diagnostic and therapeutic devices built specifically for individual patients, 3D-printed contact lenses and intraocular implants, models that assist in surgery planning and improve patient and medical staff education, and more. Advances in bioprinting appears to be the future of 3D printing in healthcare in general, and in ophthalmology in particular, with the emerging possibility of printing viable tissues and ultimately the creation of a functioning cornea, and later retina. It is expected that the various applications of 3D printing in ophthalmology will become part of mainstream medicine.

Functional outcomes after glossectomies: Pilot study on use of a thrombin-fibrinogen biosponge (TachoSil)

OBJECTIVE

The aim of this study was to investigate whether the use of a thrombin-fibrinogen biosponge (TachoSil) has any advantage in tongue healing.

STUDY DESIGN

A retrospective study with 30 patients treated with partial glossectomy (below half a tongue) was designed. We compared the results from a group using the biosponge (n =15 patients) and a control group (n = 15). Variables taken into consideration were bolus clearance, frenulum flexibility, and oral transit time. With these parameters, we formulated a "tongue remaining functional" (TRF) scale to assess tongue functionality after the surgery. We also evaluated long-term quality of life by using the Functional Intraoral Glasgow Scale (FIGS).

RESULTS

In this study, TRF score, bolus clearance, oral transit time, and frenulum flexibility were significantly improved in the biosponge group. However, there were no differences between the 2 groups in the FIGS scores.

CONCLUSIONS

The use of the biosponge in this pilot study showed positive long-term effects in lingual healing and functionality after partial glossectomies.

Three-dimensional Printing in Maxillofacial Surgery: Hype versus Reality

Three-dimensional printing technology is getting more attention recently, especially in the craniofacial region. This is a review of literature enlightening the materials that have been used to date and the application of such technology within the scope of maxillofacial surgery.