Three-dimensional printing in surgery: a review of current surgical applications

Creation of a multidisciplinary and multicenter study group for the use of 3D printing in general thoracic surgery: lessons learned in our first year experience

Introduction: In recent years, the use of 3D printing in medicine has grown exponentially, but the use of 3D technology has not been equally adopted by the different medical specialties. Published 3D printing activity in general thoracic surgery is scarce and has been mostly limited to case reports. The aim of this report was to reflect on the results and lessons learned from a newly created multidisciplinary and multicenter 3D unit of the Spanish Society of Thoracic Surgery (SECT). Methods: This is a pilot study to determine the feasibility and usefulness of printing 3D models for patients with thoracic malignancy or airway complications, based on real data. We designed a point-of-care 3D printing workflow involving thoracic surgeons, radiologists with experience in intrathoracic pathology, and engineers with experience in additive manufacturing. Results: In the first year of operation we generated 26 three-dimensional models out of 27 cases received (96.3%). In 9 cases a virtual model was sufficient for optimal patient handling, while in 17 cases a 3D model was printed. Per pathology, cases were classified as airway stenosis after lung transplantation (7 cases, 25.9%), tracheal pathology (7 cases, 25.9%), chest tumors (6 cases, 22.2%) carcinoid tumors (4 cases, 14.8%), mediastinal tumors (2 cases, 7.4%) and Pancoast tumors (one case, 3.7%). Conclusion: A multidisciplinary 3D laboratory is feasible in a hospital setting, and working as a multicenter group increases the number of cases and diversity of pathologies thus providing further opportunity to study the benefits of the 3D printing technology in general thoracic surgery.

Towards Patient-Specific 3D-Printed Robotic Systems for Surgical Interventions

Surgical robots have been extensively researched for a wide range of surgical procedures due to the advantages of improved precision, sensing capabilities, motion scaling, and tremor reduction, to name a few. Though the underlying disease condition or pathology may be the same across patients, the intervention approach to treat the condition can vary significantly across patients. This is especially true for endovascular interventions, where each case brings forth its own challenges. Hence it is critical to develop patient-specific surgical robotic systems to maximize the benefits of robot-assisted surgery. Manufacturing patient-specific robots can be challenging for complex procedures and furthermore the time required to build them can be a challenge. To overcome this challenge, additive manufacturing, namely 3D-printing, is a promising solution. 3D-printing enables fabrication of complex parts precisely and efficiently. Although 3D-printing techniques have been researched for general medical applications, patient-specific surgical robots are currently in their infancy. After reviewing the state-of-the-art in 3D-printed surgical robots, this paper discusses 3D-printing techniques that could potentially satisfy the stringent requirements for surgical interventions. We also present the accomplishments in our group in developing 3D-printed surgical robots for neurosurgical and cardiovascular interventions. Finally, we discuss the challenges in developing 3D-printed surgical robots and provide our perspectives on future research directions.

Fabrication and mechanical characterization of 3D printed vertical uniform and gradient scaffolds for bone and osteochondral tissue engineering

Recent developments in 3D printing (3DP) research have led to a variety of scaffold designs and techniques for osteochondral tissue engineering; however, the simultaneous incorporation of multiple types of gradients within the same construct remains a challenge. Herein, we describe the fabrication and mechanical characterization of porous poly(ε-caprolactone) (PCL) and PCL-hydroxyapatite (HA) scaffolds with incorporated vertical porosity and ceramic content gradients via a multimaterial extrusion 3DP system. Scaffolds of 0 wt% HA (PCL), 15 wt% HA (HA15), or 30 wt% HA (HA30) were fabricated with uniform composition and porosity (using 0.2 mm, 0.5 mm, or 0.9 mm on-center fiber spacing), uniform composition and gradient porosity, and gradient composition (PCL-HA15-HA30) and porosity. Micro-CT imaging and porosity analysis demonstrated the ability to incorporate both vertical porosity and pore size gradients and a ceramic gradient, which collectively recapitulate gradients found in native osteochondral tissues. Uniaxial compression testing demonstrated an inverse relationship between porosity, ϕ, and compressive modulus, E, and yield stress, σy, for uniform porosity scaffolds, however, no differences were observed as a result of ceramic incorporation. All scaffolds demonstrated compressive moduli within the appropriate range for trabecular bone, with average moduli between 86 ± 14-220 ± 26 MPa. Uniform porosity and pore size scaffolds for all ceramic levels had compressive moduli between 205 ± 37-220 ± 26 MPa, 112 ± 13-118 ± 23 MPa, and 86 ± 14-97 ± 8 MPa respectively for porosities ranging between 14 ± 4-20 ± 6%, 36 ± 3-43 ± 4%, and 54 ± 2-57 ± 2%, with the moduli and yield stresses of low porosity scaffolds being significantly greater (p < 0.05) than those of all other groups. Single (porosity) gradient and dual (composition/porosity) gradient scaffolds demonstrated compressive properties similar (p > 0.05) to those of the highest porosity uniform scaffolds (porosity gradient scaffolds 98 ± 23-107 ± 6 MPa, and 102 ± 7 MPa for dual composition/porosity gradient scaffolds), indicating that these properties are more heavily influenced by the weakest section of the gradient. The compression data for uniform scaffolds were also readily modeled, yielding scaling laws of the form E ∼ (1 - ϕ)1.27 and σy ∼ (1 - ϕ)1.37, which demonstrated that the compressive properties evaluated in this study were well-aligned with expectations from previous literature and were readily modeled with good fidelity independent of polymer scaffold geometry and ceramic content. All uniform scaffolds were similarly deformed and recovered despite different porosities, while the large-pore sections of porosity gradient scaffolds were significantly more deformed than all other groups, indicating that porosity may not be an independent factor in determining strain recovery. Moving forward, the technique described here will serve as the template for more complex multimaterial constructs with bioactive cues that better match native tissue physiology and promote tissue regeneration. STATEMENT OF SIGNIFICANCE: This manuscript describes the fabrication and mechanical characterization of "dual" porosity/ceramic content gradient scaffolds produced via a multimaterial extrusion 3D printing system for osteochondral tissue engineering. Such scaffolds are designed to better address the simultaneous gradients in architecture and mineralization found in native osteochondral tissue. The results of this study demonstrate that this technique may serve as a template for future advances in 3D printing technology that may better address the inherent complexity in such heterogeneous tissues.

Applications of 3D printing in small animal magnetic resonance imaging

Three-dimensional (3D) printing has significantly impacted the quality, efficiency, and reproducibility of preclinical magnetic resonance imaging. It has vastly expanded the ability to produce MR-compatible parts that readily permit customization of animal handling, achieve consistent positioning of anatomy and RF coils promptly, and accelerate throughput. It permits the rapid and cost-effective creation of parts customized to a specific imaging study, animal species, animal weight, or even one unique animal, not routinely used in preclinical research. We illustrate the power of this technology by describing five preclinical studies and specific solutions enabled by different 3D printing processes and materials. We describe fixtures, assemblies, and devices that were created to ensure the safety of anesthetized lemurs during an MR examination of their brain or to facilitate localized, contrast-enhanced measurements of white blood cell concentration in a mouse model of pancreatitis. We illustrate expansive use of 3D printing to build a customized birdcage coil and components of a ventilator to enable imaging of pulmonary gas exchange in rats using hyperpolarizedXe 129 . Finally, we present applications of 3D printing to create high-quality, dual RF coils to accelerate brain connectivity mapping in mouse brain specimens and to increase the throughput of brain tumor examinations in a mouse model of pituitary adenoma.

Anterior Lumbar Interbody Fusion Using a Personalized Approach: Is Custom the Future of Implants for Anterior Lumbar Interbody Fusion Surgery?

BACKGROUND

Spine surgery has the potential to benefit from the use of three-dimensional (3D) printing technology (additive manufacturing), particularly in cases of complex anatomic diseases. Custom devices have the potential to reduce operative times, reduce blood loss, provide immediate stability, and improve fusion rates.

CASE DESCRIPTION

A 34-year-old man presented with 3-year history of bilateral L5 radiculopathy caused by bilateral L5 pars defect, L5/S1 degenerative disc disease, and severe foraminal stenosis. Anterior lumbar interbody fusion surgery was determined to be the most efficacious method for distraction of the disc space to increase the foraminal volume and stabilization of the motion segment. Surgical decompression and reconstruction was performed in combination with a 3D printed custom interbody implant. Custom design features included corrective angulation to restore lumbar lordosis, preplanned screw holes in the 3D implant, and device end plate interface geometry designed to shape-match with the patient's end plate anatomy.

CONCLUSIONS

The use of patient-specific implants has reduced operative time significantly, which may offset costs of increased time spent preplanning the procedure. Surgical procedures can be preplanned using 3D models reconstructed from patient computed tomography and/or magnetic resonance imaging scans. Planning can be aided by 3D printed models of patient anatomy, which surgeons can use in training before performing complex procedures. When considering implants and prostheses, the use of 3D printing allows a superior anatomic fit for the patient compared with generic devices, with the potential to improve restoration of nonpathologic anatomy.

New Directions for Artificial Cells Using Prototyped Biosystems

Microfluidics has has enabled the generation of  a range of single compartment and multicompartment vesicles and bilayer-delineated droplets that can be assembled in 2D and 3D. These model systems are becoming increasingly used as artificial cell chassis and as biomimetic constructs for assembling tissue models, engineering therapeutic delivery systems, and screening drugs. One bottleneck in developing this technology is the time, expertise, and equipment required for device fabrication. This has led to interest across the microfluidics community in using rapid prototyping to engineer microfluidic devices from computer-aided-design (CAD) drawings. We highlight how this rapid-prototyping revolution is transforming the fabrication of microfluidic devices for artificial cell construction in bottom-up synthetic biology. We provide an outline of the current landscape and present how advances in the field may give rise to the next generation of multifunctional biodevices, particularly with Industry 4.0 on the horizon. Successfully developing this technology and making it open-source could pave the way for a new generation of citizen-led science, fueling the possibility that the next multibillion-dollar start-up could emerge from an attic or a basement.

Physical Simulation Models in Oral and Maxillofacial Surgery: A New Concept in 3-Dimensional Modeling for Removal of Impacted Third Molars

A medical-grade computed tomography scan of a mandible was obtained. A DICOM (Digital Imaging and Communications in Medicine) series was exported in 1-mm slices and digitally 3-dimensionally reconstructed to create a stereolithography file. The mandible stereolithography file was digitally manipulated to create sites for simulated placement of third molar teeth and then 3-dimensionally printed in a plastic material. Third molar tooth models were coated in red box wax, simulating a ligament space, and then submerged into the mandible site using laboratory stone. A layer of GI-Mask (Coltene/Whaldent AG, Altstätten, Switzerland) was placed over the impacted third molar site for soft tissue simulation.

Systematic review of the applications of three-dimensional printing in colorectal surgery

AIM

Three-dimensional (3D) printing has been recognized as a revolutionary technological innovation that has benefitted numerous disciplines, including medicine. The present systematic review aimed to demonstrate the current applications of 3D printing in colorectal surgery along with the limitations and potential future applications of this innovation.

METHOD

A PRISMA-compliant systematic literature search of studies that applied 3D printing in colorectal surgery in the period from January 1990 to July 2018 was conducted. Electronic databases including PubMed/Medline, Scopus and the Cochrane Library were searched. All full-text original articles were eligible for inclusion.

RESULTS

Nine studies including 58 patients with a median age of 60.7 years were reviewed. The studies assessed 3D printing in patients with planned stoma construction, colon cancer with liver metastasis, right colon cancer, rectal cancer, intractable constipation and anal fistula. The applications of 3D printing were classified into three categories: patient education, preoperative planning and evaluation of response of colorectal liver metastasis to chemotherapy. 3D printed models aided in planning resection of colorectal liver metastasis, facilitating D3 lymphadenectomy in complete mesocolic excision, improving the understanding of pelvic anatomy in laparoscopic rectal cancer treatment, guiding electrode implantation in sacral neuromodulation for intractable constipation, and elucidating the morphology of anal fistula tract and anal sphincter muscles.

CONCLUSION

Colorectal surgery may benefit from 3D printing in enhancing patient education before stoma construction, preoperative planning and evaluation of the response of liver metastasis to chemotherapy using 3D ultrasonography.

The Role of 3D Printing in Colorectal Surgery: Current Evidence and Future Perspectives

BACKGROUND

Three-dimensional (3D) printing is an emerging and evolving technology with a variety of possible applications in surgery. The purpose of this study was to examine its potential applications in the field of colorectal surgery, as a tool in pre-operative planning and peri-operative navigation, as well as in training. Its cost-efficiency was also examined.

MATERIALS AND METHODS

A literature review was conducted on articles specifically presenting various applications of 3D printing in the field of colorectal surgery. PubMed was the primary database researched.

RESULTS

A total of seven studies were found to meet the inclusion criteria. The majority of the articles employed 3D printing technology to produce patient-specific anatomic replicas to enhance pre-operative planning, providing satisfactory results. One study used 3D printing technology as a therapy tool, stating superior results over traditional methods.

CONCLUSION

3D printing is a novel technology with a broad spectrum of possible applications in colorectal surgery. Anatomic replicas specific to the anatomy of a patient with acceptable dimensional correlations can be produced using the currently available technology. Surgical and patient training can also be enhanced. Depending on the technology used, costs greatly vary and can thus hinder popularization of this technology in surgery.

Cardiac patient-specific three-dimensional models as surgical planning tools

BACKGROUND

Three-dimensional printing is an additive manufacturing method that builds objects from digitally generated computational models. Core technologies behind three-dimensional printing are evolving rapidly with major advances in materials, resolution, and speed that enable greater realism and higher accuracy. These improvements have led to novel applications of these processes in the medical field.

METHODS

The process of going from a medical image data set (computed tomography, magnetic resonance imaging, ultrasound) to a physical three-dimensional print includes several steps that are described. Medical images originate from Digital Imaging and Communications in Medicine files or data sets, the current standard for storing and transmitting medical images. Via Digital Imaging and Communications in Medicine manipulation software packages, a segmentation process, and manual intervention by an expert user, three-dimensional digital and printed models can be constructed in great detail.

RESULTS

Cardiovascular medicine is one of the fastest growing applications for medical three-dimensional printing. The technology is more frequently being used for patient and clinician education, preprocedural planning, and medical device design and prototyping. We report on three case studies, describing how our three-dimensional printing has contributed to the care of cardiac patients at the University of Minnesota.

CONCLUSION

Medical applications of computational three-dimensional modeling and printing are already extensive and growing rapidly and are routinely used for visualizing complex anatomies from patient imaging files to plan surgeries and create surgical simulators. Studies are needed to determine whether three-dimensional printed models are cost effective and can consistently improve clinical outcomes before they become part of routine clinical practice.

Implementation of 3D printed superior mesenteric vascular models for surgical planning and/or navigation in right colectomy with extended D3 mesenterectomy: comparison of virtual and physical models to the anatomy found at surgery

BACKGROUND

Three-dimensional (3D) printing technology has recently been well approved as an emerging technology in various fields of medical education and practice; e.g., there are numerous studies evaluating 3D printouts of solid organs. Complex surgery such as extended mesenterectomy imposes a need to analyze also the accuracy of 3D printouts of more mobile and complex structures like the diversity of vascular arborization within the central mesentery. The objective of this study was to evaluate the linear dimensional anatomy landmark differences of the superior mesenteric artery and vein between (1) 3D virtual models, (2) 3D printouts, and (3) peroperative measurements.

METHODS

The study included 22 patients from the ongoing prospective multicenter trial "Safe Radical D3 Right Hemicolectomy for Cancer through Preoperative Biphasic MDCT Angiography," with preoperative CT and peroperative measurements. The patients were operated in Norway between January 2016 and 2017. Their CT datasets underwent 3D volume rendering and segmentation, and the virtual 3D model produced was then exported for stereolithography 3D printing.

RESULTS

Four parameters were measured: distance between the origins of the ileocolic and the middle colic artery, distance between the termination of the gastrocolic trunk and the ileocolic vein, and the calibers of the middle colic and ileocolic arteries. The inter-arterial distance has proven a strong correlation between all the three modalities implied (Pearson's coefficient 0.968, 0.956, 0.779, respectively), while inter-venous distances showed a weak correlation between peroperative measurements and both virtual and physical models.

CONCLUSION

This study showed acceptable dimensional inter-arterial correlations between 3D printed models, 3D virtual models and authentic soft tissue anatomy of the central mesenteric vessels, and weaker inter-venous correlations between all the models, reflecting the highly variable nature of veins in situ.

A small 3D-printing model of macroadenomas for endoscopic endonasal surgery

PURPOSE

This paper examines the application of 3D printing technology in the endoscopic endonasal approach for the treatment of macroadenomas.

METHODS

We have retrospectively analysed 20 patients who diagnosed with macroadenoma underwent endoscopic transsphenoidal surgery in Wuhan Union hospital from January 2017 to May 2017. Among the 20 patients, 10 patients received the service of 3D printing technology preoperatively. The data of 3D processing and clinical result were recorded for further evaluation.

RESULTS

The 10 patients who received the service had a successful 3D printed model of their tumors, it shows the anatomy of sphenoid sinus, tumor location which were in good agreement with our intraoperative observations. The 10 patients who received the service had a less operation time (127.0 ± 15.53 vs. 143.40 ± 17.89), blood loss (159.90 ± 12.31 vs. 170.00 ± 29.06) and less postoperative complication rate (20% vs. 40%). the design time of the 3D images varies 2 h 10 min to 4 h 32 min. the printing time of the 3D models varies 10 h 12 min to 22 h 34 min.

CONCLUSIONS

The use of 3D printing technology has unquestionable potential applications to endoscopic endonasal approach for macroadenomas, in particular reflecting the complicated anatomy of sphenoid sinus and tumor location. Owing to the advantages of 3D printing technology, it may help the patients get a good prognosis.

Preliminary application of 3D-printed coplanar template for iodine-125 seed implantation therapy in patients with advanced pancreatic cancer

AIM

To evaluate a 3D-printed coplanar template for iodine-125 seed implantation therapy in patients with pancreatic cancer.

METHODS

A retrospective analysis of our database was performed, and a total of 25 patients with pancreatic cancer who underwent iodine-125 seed implantation between January 2014 and November 2017 were analyzed. Of these, 12 implantations were assisted by a 3D-printed coplanar template (group A), and 13 implantations performed freehand were selected as a control group (group B). A 3D coplanar template was designed and printed according to a preoperative CT scan and treatment planning system. The iodine-125 seeds were then implanted using the template as a guide. Dosimetric verification was performed after implantation. Pre- and postoperative D90, V100, and V150 were calculated. The success rate of iodine-125 seed implantation, dosimetric parameters, and complications were analyzed and compared between the two groups.

RESULTS

Iodine-125 seed implantation was successfully performed in both groups. In group A, the median pre- and postoperative D90 values were 155.32 ± 8.05 Gy and 154.82 ± 16.43 Gy, respectively; the difference between these values was minimal and not statistically significant (P > 0.05). Postoperative V100 and V150 were 91.05% ± 4.06% and 64.54% ± 13.40%, respectively, which met the treatment requirement. A better dosimetric parameter was observed in group A than in group B, and the difference was statistically significant (V100: 91.05% ± 4.06% vs 72.91% ± 13.78%, P < 0.05). No major procedure-related complications were observed in either group. For group A, mild hemorrhage was observed in 1 patient with a peritoneal local hematoma due to mesenteric vein damage from the iodine-125 seed implantation needle. The hematoma resolved spontaneously without treatment. Postoperative blood amylase levels remained within the normal range for all patients.

CONCLUSION

A 3D-printed coplanar template appears to be a safe and effective iodine-125 seed implantation guidance tool to improve implantation accuracy and optimize dosimetric distribution.

The Applications of 3D Printing in Pulmonary Drug Delivery and Treatment of Respiratory Disorders

BACKGROUND

Pulmonary diseases are the third leading cause of morbidity worldwide, however treatment and diagnosis of these diseases continue to be challenging due to the complex anatomical structure as well as physiological processes in the lungs.

METHODS

3D printing is progressively finding new avenues in the medical field and this technology is constantly being used for diseases where diagnosis and treatment heavily rely on the thorough understanding of complex structural-physiology relationships. The structural and functional complexity of the pulmonary system makes it well suited to 3D printing technology.

RESULTS

3D printing can be used to deconstruct the complex anatomy of the lungs and improve our understanding of its physiological mechanisms, cell interactions and pathophysiology of pulmonary diseases. Thus, this technology can be quite helpful in the discovery of novel therapeutic targets, new drugs and devices for the treatment of lung diseases.

CONCLUSION

The intention of this review is to detail our current understanding of the applications of 3D printing in the design and evaluation of inhalable medicines and to provide an overview on its application in the diagnosis and treatment of pulmonary diseases. This review also discusses other technical and regulatory challenges associated with the progression of 3D printing into clinical practice.

What we have achieved in the design of 3D printed metal implants for application in orthopedics? Personal experience and review

Purpose

This paper aims to review the latest applications in terms of three-dimensional printed (3DP) metal implants in orthopedics, and, importantly, the design of 3DP metal implants through a series of cases operated at The Second Hospital of Jilin University were presented.

Design/methodology/approach

This paper is available to practitioners who are use 3DP implants in orthopedics. This review began with the deficiency of traditional prostheses and basic concepts of 3DP implants. Then, representative 3DP clinical cases were summarized and compared, and the experiences using customized prostheses and directions for future potential development are also shown.

Findings

The results obtained from the follow-up of clinical applications of 3DP implants show that the 3D designed and printed metal implants could exhibit good bone defect matching, quick and safe joint functional rehabilitation as well as saving time in surgery, which achieved high patient satisfaction collectively.

Originality/value

Single center experiences of 3DP metal implants design were shared and the detailed technical points between various regions were compared and analyzed. In conclusion, the 3DP technology is infusive and will present huge potential to reform future orthopedic practice.

Three-Dimensional Printing for Procedure Rehearsal/Simulation/Planning in Interventional Radiology

With the advances in affordable three-dimensional (3D) printing technology, 3D reconstruction and patient-specific 3D printed models are establishing a crucial role in the field of medicine for both educational purposes and procedural planning. 3D printed models provide physicians with increased 3D perception and tactile feedback, and enable a team-based approach to operational planning. However, performing an effective 3D reconstruction requires an in-depth understanding of the software features to accurately segment and reconstruct the human anatomy of interest from preacquired image data from multiple modalities such as computer tomography, 3D angiography and magnetic resonance imaging, and the different 3D printers/materials available in the market today. Increased understanding of this technology may benefit radiologists by developing techniques and tricks specific to interventional radiology and establishing a criterion to determine when to use these. Thus, the purpose of this manuscript is to provide physicians with an update on currently available 3D reconstruction software as well as printers and materials. Our initial experience using this technology is introduced based on a specific case of developing a 3D printed aorta for a patient with severe stenosis of the abdominal aorta.

Polymethyl Methacrylate Custom-Made Prosthesis: A Novel Three-Dimension Printing-Aided Fabrication Technique for Cranial and/or Orbital Reconstruction

BACKGROUND

Over the years, many materials have been used in orbital reconstruction and cranioplasty. Among the materials in current use, polymethyl methacrylate (PMMA) offers a high degree of compatibility with human tissue.

OBJECTIVE

This work describes a new, custom-made, 3D printing-aided, prosthetic fabrication process for orbital and/or cranial reconstruction using PMMA.

METHODS

On the basis of information obtained from computerized tomography scanning processed in Digital Imaging and Communication in Medicine format and exported to treatment planning software, a 3D prosthesis master model was designed and digitally printed. This was then used to create an injection mold from which the prosthesis was cast in PMMA and implanted in the patient. Five patients with cranial and/or orbital defects of tumoral or traumatic etiology were treated by this method. After 5 to 7 years follow-up, no complications occurred to cause the removal of the prostheses.

CONCLUSION

This novel method makes it possible to produce customized PMMA prostheses to treat orbital and/or cranial defects that are cost-effective and individualized to each case.

The Patient-Specific Implant Created with 3D Printing Technology in Treatment of the Irreparable Radial Head in Chronic Persistent Elbow Instability

Successful treatment of the chronic persistent elbow instability is a challenge for orthopedic surgeons. In this form, it is important to recognize and restore the osseous stabilizer in order to obtain the concentric reduction. In the present report, we describe a case of such injury with irreparable radial head treated with patient-specific radial head prosthesis which was created with 3D printing technology. To our knowledge, this is the first report in clinical use of this kind of prosthesis for the radial head fracture. At a 24-month follow-up visit, the patient was satisfied with the functional outcomes. The Mayo Elbow Performance Index (MEPI) increased from 20 points at the preoperative day to 85 points, and the patient-based Disabilities of the Arm, Shoulder, and Hand (DASH) was reduced from 88.33 points to 28.33 points. Due to the favorable result, replacement of the radial head with the patient-specific implant could be a useful treatment for the irreparable radial head in chronic persistent elbow instability.

Three-dimensional Printing of Multilayered Tissue Engineering Scaffolds

The field of tissue engineering has produced new therapies for the repair of damaged tissues and organs, utilizing biomimetic scaffolds that mirror the mechanical and biological properties of host tissue. The emergence of three-dimensional printing (3DP) technologies has enabled the fabrication of highly complex scaffolds which offer a more accurate replication of native tissue properties and architecture than previously possible. Of strong interest to tissue engineers is the construction of multilayered scaffolds that target distinct regions of complex tissues. Musculoskeletal and dental tissues in particular, such as the osteochondral unit and periodontal complex, are composed of multiple interfacing tissue types, and thus benefit from the usage of multilayered scaffold fabrication. Traditional 3DP technologies such as extrusion printing and selective laser sintering have been used for the construction of scaffolds with gradient architectures and mixed material compositions. Additionally, emerging bioprinting strategies have been used for the direct printing and spatial patterning of cells and chemical factors, capturing the complex organization found in the body. To better replicate the varied and gradated properties of larger tissues, researchers have created scaffolds composed of multiple materials spanning natural polymers, synthetic polymers, and ceramics. By utilizing high precision 3DP techniques and judicious material selection, scaffolds can thus be designed to address the regeneration of previously challenging musculoskeletal, dental, and other heterogeneous target tissues. These multilayered 3DP strategies show great promise in the future of tissue engineering.

Comparison of Lateralizing Calcaneal Osteotomies for Varus Hindfoot Correction

BACKGROUND

There is limited consensus on the optimal operative technique for correcting heel varus in patients with Charcot-Marie-Tooth (CMT) disease. This comparative study evaluated the ability of 4 lateralizing calcaneal osteotomies, with and without Dwyer wedge resection and coronal rotation of the posterior tuberosity, to correct severe heel varus.

METHODS

The computed tomography (CT) scan of a teenage CMT patient with severe hindfoot varus was used to create 3-dimensional (3D)-printed models of the talus, calcaneus, and cuboid. A custom jig facilitated precise replication of the osteotomy cuts. Four different configurations were created: oblique osteotomy with lateralization, oblique osteotomy with lateralization and internal rotation of the posterior tuberosity, Dwyer wedge resection with lateralization, and Dwyer wedge resection with lateralization and internal rotation. CT scans were performed on each model before and after osteotomy. Statistical analysis was used to evaluate differences in several predefined radiographic parameters.

RESULTS

The sequential transformations generated increasing lateral translation of the weight-bearing calcaneus. Dwyer wedge osteotomy significantly improved lateralization (effect = 8.0 mm), valgus hindfoot angle (effect = 6.1 degrees), and coronal calcaneal tilt (effect = -17.6 degrees) compared with the oblique osteotomy. Internal rotation of the posterior tuberosity further improved lateralization (effect = 3.3 mm), valgus hindfoot angle (effect = 2.5 degrees), and coronal calcaneal tilt (effect = -11.7 degrees). Dwyer osteotomy models had on average 5-mm shorter posterior tuberosity lengths than the oblique osteotomies. The addition of rotation did not significantly affect length.

CONCLUSIONS

Significant lateralization of the posterior tuberosity was achieved in all transformations. The Dwyer wedge osteotomy improved hindfoot valgus angle, coronal calcaneal tilt, and lateralization of the weight-bearing surface compared with oblique osteotomy. Posterior tuberosity internal rotation further lateralized the plantar surface and normalized weight bearing. Lateralization, combined with Dwyer osteotomy and coronal plane internal rotation, achieved the greatest correction of varus heel.

CLINICAL RELEVANCE

This study compares multiple lateralizing calcaneal osteotomies and proposes a combined technique of lateralization, Dwyer wedge resection, and coronal plane rotation to address advanced cavovarus hindfoot deformities.

First Detection of Photoinitiators and Metabolites in Human Sera from United States Donors

Photoinitiators (PIs), including benzophenones (BZPs), thioxanthones (TXs), and amine co-initiators (ACIs), are commonly used in photopolymerization systems, and their contamination in foodstuffs and the environment is attracting attention. Although humans are likely exposed to PIs, no data on human burdens of these chemicals are available. In this study, 18 PIs were detected in 50 individual human serum samples with concentrations of ΣPIs (sum of the detected PIs) from 423 to 2870 pg/mL (geometric mean, GM: 836 pg/mL). ΣBZPs (231-1240 ng/g,; GM: 593 pg/mL) were the dominant components, while ΣTXs (21.0-1431 ng/g; GM: 145 pg/mL) and ΣACIs (11.3-976 ng/g; GM: 48.5 pg/mL) were much lower. Data analysis found significantly higher concentrations of most PIs in the male sera than in the female ( p < 0.05). ΣPIs (2921-4139 ng/g; GM: 3621 pg/mL) were also detected in five pooled serum samples, each from at least 1000 donors, indicating the prevalent human burdens of PIs in a large population. Human liver S9 biodegradations of representative PIs, 2-isopropylthioxanthone (2-ITX) and 2,4-diethylthioxanthone (DETX), were conducted. Hydroxylation, sulfoxide, and sulfone metabolites of DETX and 2-ITX were identified by high resolution mass spectrometry in human liver S9 incubation systems. With synthesized standards, the sulfoxide and sulfone metabolites were successfully detected in the human serum samples, which contributed substantially to total human burdens. The ubiquitous presence of PIs in human sera indicates significant human exposure to PIs, although photopolymerization reaction has been generally considered a green technology.

Utilizing a low-cost desktop 3D printer to develop a "one-stop 3D printing lab" for oral and maxillofacial surgery and dentistry fields

Background

In the oral and maxillofacial surgery and dentistry fields, the use of three-dimensional (3D) patient-specific organ models is increasing, which has increased the cost of obtaining them. We developed an environment in our facility in which we can design, fabricate, and use 3D models called the "One-stop 3D printing lab". The lab made it possible to quickly and inexpensively produce the 3D models that are indispensable for oral and maxillofacial surgery. We report our 3D model fabrication environment after determining the dimensional accuracy of the models with different laminating pitches (; layer thickness) after fabricating over 300 3D models. Considerations were made for further reducing modeling cost and model print time. MDCT imaging was performed using a dry human mandible, and 3D CAD data were generated from the DICOM image data. 3D models were fabricated with a fused deposition modeling (FDM) 3D printer MF-2000 (MUTOH) with a laminating pitch of 0.2 mm, 0.3 mm, 0.4 mm, or 0.5 mm. Each 3D model was then subjected to reverse scanning to evaluate the modeling conditions and deformation during modeling. For the 3D image processing system, Volume Extractor 3.0 (i-Plants Systems) and POLYGONALmeister V2 (UEL) were used. For the comparative evaluation of CAD data, spGauge 2014.1 (Armonicos) was used.

Results

As the laminating pitch increased, the weight of the 3D model, model print time, and material cost decreased, and no significant reduction in geometric accuracy was observed.

Conclusions

The amount of modeling material used and preparation cost were reduced by increasing the laminating pitch. The "One-stop 3D printing lab" made it possible to produce 3D models daily. The use of 3D models in the oral and maxillofacial surgery and dentistry fields will likely increase, and we expect that low-cost FDM 3D printers that can produce low-cost 3D models will play a significant role.

Three-dimensional printing models in congenital heart disease education for medical students: a controlled comparative study

BACKGROUND

This study sought to assess, using subjective (self-assessment) and objective (MCQ) methods, the efficacy of using heart models with ventricular septal defect lesions produced with three-dimensional printing technology in a congenital heart disease curriculum for medical students.

METHODS

Three computed tomography datasets of three subtypes of ventricular septal defects (perimembranous, subarterial and muscular, one for each) were obtained and processed for building into and printing out 3D models. Then a total of 63 medical students in one class were randomly allocated to two groups (32 students in the experimental, and 31 the control). The two groups participated in a seminar with or without a 3D heart model, respectively. Assessment of this curriculum was carried out using Likert-type questionnaires as well as an objective multiple choice question test assessing both knowledge acquisition, and structural conceptualization. Open-ended questions were also provided for getting advice and suggestion on 3D model utilization in CHD education.

RESULTS

With these 3D models, feedback shown in the questionnaires from students in experimental group was significantly more positive than their classmates in the control. And the test results also showed a significant difference in structural conceptualization in favor of the experimental group.

CONCLUSION

It is effective to use heart models created using current 3D printing technology for congenital heart disease education. It stimulates students' interest in congenital heart disease and improves the outcomes of medical education.

Three-Dimensional Printing: A Novel Approach to the Creation of Obturator Prostheses Following Palatal Resection for Malignant Palate Tumors

BACKGROUND

A subgroup of patients who have an oronasal fistula live in areas that have limited access to oral prosthetics. For these individuals, a temporary prosthesis, such as a palatal obturator, may be necessary in order to speak, eat, and breath properly. The creation of an obturator, which requires a highly trained prosthodontist, can take time and can be expensive. Through the current proof-of-concept study, there is an attempt to create a patient-specific palatal obturator through use of free and publicly available software, and a low-cost desktop 3-dimensional printer. The ascribed study may provide a means to increase global access to oral prosthetics if suitable biomaterials are developed.

METHODS

Computerized tomography data were acquired from a patient who had an oronasal fistula. Through use of free software, these data were converted into a 3-dimensional image. The image was manipulated in order to isolate the patient's maxilla and was subsequently printed. The palatal obturator models were designed, and reformed, in correspondence with the maxilla model design. A final suitable obturator was determined and printed with 2 differing materials in order to better simulate a patient obturator.

RESULTS

Creating a suitable palatal obturator for the specified patient model was possible with a low-cost printer and free software.

CONCLUSIONS

With further development in biomaterials, it may be possible to design and create an oral prosthesis through use of low-cost 3-dimensional printing technology and freeware. This can empower individuals to attain good healthcare, even if they live in rural, developing, or underserviced areas.

3D printing of normal and pathologic tricuspid valves from transthoracic 3D echocardiography data sets

Aims

To explore the feasibility of using transthoracic 3D echocardiography (3DTTE) data to generate 3D patient-specific models of tricuspid valve (TV).

Methods and Results

Multi-beat 3D data sets of the TV (32 vol/s) were acquired in five subjects with various TV morphologies from the apical approach and analysed offline with custom-made software. Coordinates representing the annulus and the leaflets were imported into MeshLab (Visual Computing Lab ISTICNR) to develop solid models to be converted to stereolithographic file format and 3D print. Measurements of the TV annulus antero-posterior (AP) and medio-lateral (ML) diameters, perimeter (P), and TV tenting height (H) and volume (V) obtained from the 3D echo data set were compared with those performed on the 3D models using a caliper, a syringe and a millimeter tape. Antero-posterior (4.2 ± 0.2 cm vs. 4.2 ± 0 cm), ML (3.7 ± 0.2 cm vs. 3.6 ± 0.1 cm), P (12.6 ± 0.2 cm vs. 12.7 ± 0.1 cm), H (11.2 ± 2.1 mm vs. 10.8 ± 2.1 mm) and V (3.0 ± 0.6 ml vs. 2.8 ± 1.4 ml) were similar (P = NS for all) when measured on the 3D data set and the printed model. The two sets of measurements were highly correlated (r = 0.991). The mean absolute error (2D - 3D) for AP, ML, P and tenting H was 0.7 ± 0.3 mm, indicating accuracy of the 3D model of <1 mm.

Conclusion

Three-dimensional printing of the TV from 3DTTE data is feasible with highly conserved fidelity. This technique has the potential for rapid integration into clinical practice to assist with decision-making, surgical planning, and teaching.

Clinical significance of three-dimensional skeleton-arterial model in the management of delayed reconstruction of acetabular fractures

BACKGROUND

Delayed reconstruction of acetabular fractures remains a challenging task for orthopedists because of malunion, fracture line absorption, and scar formation. Accurate osteotomy, interfragmentary release, and proper adaptation of plates are keys to successful surgery. Prevention of superior gluteal artery (SGA) injury induced by cleaning of the osteotylus and reduction of the sciatic notch is also important. Therefore, sufficient preoperative planning is essential. However, traditional planning methods do not readily provide direct visual and tactile feedback to surgeons. Rapid prototyping (RP) models have provided new opportunities in the preoperative planning of delayed reconstruction of acetabular fractures. We hypothesized that a three-dimensional (3D) skeleton-arterial model would improve both preoperative planning in the management of fractures and arteries and intraoperative assistance during delayed reconstruction of complex acetabular fractures.

METHODS

Eight patients were enrolled in this study. Data on the skeleton and arteries were obtained from computed tomography and angiography scans and used to produce RP models. Preoperative surgical planning and intraoperative assistance were performed using these models as references.

RESULTS

All 3D skeleton-arterial models were extremely accurate. Reduction and fixation were performed programmatically and smoothly, and management of the SGA was reliably executed according to a thorough preoperative plan. The mean surgical time and intraoperative blood loss were 224.4 min and 1250 ml, respectively. Among the eight patients, four underwent anatomic reduction and five had excellent functional outcomes at the final follow-up. No significant complications occurred.

CONCLUSIONS

This 3D skeleton-arterial model is helpful for orthopedists in preoperative planning and intraoperative assistance.

Preliminary results of a 3D-printed acetabular component in the management of extensive defects

INTRODUCTION

The treatment of extensive bone loss and massive acetabular defects can be compounded by several challenges and pitfalls. The survivorship following acetabular revision with extensive bone loss is still unsatisfactory. The goal of the present study was to analyse the outcomes of 3D-printed patient-specific acetabular components in the management of extensive acetabular defects and combined pelvic discontinuity (PD).

METHODS

9 patients underwent revision THA using 3D-printed custom acetabular components to reconstruct extensive acetabular defects. The Paprosky classifications were determined in all patients. The primary outcome measure was the implant-associated failure rate.

RESULTS

1 out of 9 patients suffered an implant-associated complication (11%). The overall implant-associated survival rate was 89%. The overall complication rate was 56%.

CONCLUSIONS

The patient-specific acetabular component technique shows promise for the treatment of patients with severe acetabular defects in revision THA. Further research aimed at reducing costs and improving the complication rate are warranted.

Advanced Endoscopic Navigation: Surgical Big Data, Methodology, and Applications

Interventional endoscopy (e.g., bronchoscopy, colonoscopy, laparoscopy, cystoscopy) is a widely performed procedure that involves either diagnosis of suspicious lesions or guidance for minimally invasive surgery in a variety of organs within the body cavity. Endoscopy may also be used to guide the introduction of certain items (e.g., stents) into the body. Endoscopic navigation systems seek to integrate big data with multimodal information (e.g., computed tomography, magnetic resonance images, endoscopic video sequences, ultrasound images, external trackers) relative to the patient's anatomy, control the movement of medical endoscopes and surgical tools, and guide the surgeon's actions during endoscopic interventions. Nevertheless, it remains challenging to realize the next generation of context-aware navigated endoscopy. This review presents a broad survey of various aspects of endoscopic navigation, particularly with respect to the development of endoscopic navigation techniques. First, we investigate big data with multimodal information involved in endoscopic navigation. Next, we focus on numerous methodologies used for endoscopic navigation. We then review different endoscopic procedures in clinical applications. Finally, we discuss novel techniques and promising directions for the development of endoscopic navigation.

Fluoroscopic and Gait Analyses for the Functional Performance of a Custom-Made Total Talonavicular Replacement

The present study evaluated the restoration of joint function in a special clinical case: a professional rock climber who underwent an original total talonavicular replacement with a custom-made prosthesis after a complex articular fracture. Full body gait analysis and 3-dimensional joint kinematics using single-plane fluoroscopy were performed on the same day at the 30-month follow-up examination. Gait analysis was performed using stereophotogrammetric, dynamometric, electromyographic, and baropodometric systems. Gait analysis showed good restoration of rotation, as well as moment patterns in the main lower limb and foot joints in the operated leg. At the artificial tibiotalar joint, videofluoroscopic analysis revealed a flexion capability of about 20°, together with a few degrees of motion in the frontal and transverse planes. The neighboring joints of the foot did not present with severe kinematic abnormalities. A full talonavicular replacement can be a viable and effective solution for complex ankle injury sequelae, even in patients with highly demanding functionality.

Ophthalmic gels: Past, present and future

Aqueous gels formulated using hydrophilic polymers (hydrogels) along with those based on stimuli responsive polymers (in situ gelling or gel forming systems) continue to attract increasing interest for various eye health-related applications. They allow the incorporation of a variety of ophthalmic pharmaceuticals to achieve therapeutic levels of drugs and bioactives at target ocular sites. The integration of sophisticated drug delivery technologies such as nanotechnology-based ones with intelligent and environment responsive systems can extend current treatment duration to provide more clinically relevant time courses (weeks and months instead of hours and days) which will inevitably reduce dose frequency, increase patient compliance and improve clinical outcomes. Novel applications and design of contact lenses and intracanalicular delivery devices along with the move towards integrating gels into various drug delivery devices like intraocular pumps, injections and implants has the potential to reduce comorbidities caused by glaucoma, corneal keratopathy, cataract, diabetic retinopathies and age-related macular degeneration. This review describes ophthalmic gelling systems with emphasis on mechanism of gel formation and application in ophthalmology. It provides a critical appraisal of the techniques and methods used in the characterization of ophthalmic preformed gels and in situ gelling systems along with a thorough insight into the safety and biocompatibility of these systems. Newly developed ophthalmic gels, hydrogels, preformed gels and in situ gelling systems including the latest in the area of stimuli responsive gels, molecularly imprinted gels, nanogels, 3D printed hydrogels; 3D printed devices comprising ophthalmic gels are covered. Finally, new applications of gels in the production of artificial corneas, corneal wound healing and hydrogel contact lenses are described.

3D printing objects as knowledge artifacts for a do-it-yourself approach in clinical practice

Purpose

The purpose of this paper is to investigate the phenomenon of the digital do-it-yourself (DiDIY) in the medical domain. In particular, the main contribution of the paper is the analysis and discussion of a questionnaire-based user study focused on 3D printing (3DP) technology, which was conducted among clinicians of one of the most important research hospital group in Lombardy, Italy.

Design/methodology/approach

A general reflection on the notion of knowledge artifacts (KAs) and on the use of 3DP in medicine is followed by the research questions and by a more detailed analysis of the specialist literature on the usage of 3DP technology for diagnostic, training and surgical planning activities for clinicians and patients. The questionnaire-based user study design is then emerging from the conceptual framework for DiDIY in healthcare. To help focus on the main actors and assets composing the 3DP innovation roles in healthcare, the authors model: the DiDIY-er as the main initiator of the practice innovation; the available technology allowing the envisioning of new practices; the specific activities gaining benefits from the innovative techniques introduced; and the knowledge community continuously supporting and evolving knowledge practices.

Findings

The authors discuss the results of the user study in the light of the four main components of our DiDIY framework and on the notion of KA. There are differences between high expertise, or senior, medical doctors (MDs) and relatively lower expertise MDs, or younger MDs, regarding the willing to acquire 3DP competences; those who have seen other colleagues using 3DP are significantly more in favor of 3DP adoption in medical practices, and those who wish to acquire 3DP competence and do-by-themselves are significantly more interested in the making of custom-made patient-specific tools, such as cutting guides and templates; there are many recurrent themes regarding how 3DP usage and application may improve medical practice. In each of the free-text questions, there were comments regarding the impact of 3DP on medical knowledge practices, such as surgical rehearsal, surgery, pathology comprehension, patient-physician communication and teaching.

Originality/value

The 3DP adoption in healthcare is seen favorably and advocated by most of the respondents. In this domain, 3DP objects can be considered KAs legitimately. They can support knowledgeable practices, promote knowledge sharing and circulation in the healthcare community, as well as contribute to their improvement by the introduction of a new DiDIY mindset in the everyday work of MDs.

Three-dimensional printed prosthesis demonstrates functional improvement in a patient with an amputated thumb: A technical note

BACKGROUND AND AIM

Three-dimensional printer is widely used in industry, biology, and medical fields. We report a finger prosthesis produced by a three-dimensional scanner and printer for a 67-year-old man with a right thumb amputation above the metacarpophalangeal joint.

TECHNIQUE

His right amputated and left intact hands were scanned with a three-dimensional scanner, and the left-hand image was rotated to the right side to design the right thumb prosthesis. The designed prosthesis was printed with a three-dimensional printer using the fused filament fabrication output system.

DISCUSSION

The Jebsen-Taylor hand function test and Box and Block Test scores improved after application of the prosthesis. Most Quebec User Evaluation of Satisfaction with Assistive Technology results were "very satisfied," and most Orthotics and Prosthetics Users' Survey results were "very easy." Preparing the prosthesis made by three-dimensional scanner and three-dimensional printer was faster and cheaper than preparing a conventional prosthesis. Clinical relevance Using three-dimensional scanning and printing technique, we can easily produce specifically shaped finger prostheses for specific movements in amputated patients with low cost.

A Method of Accurate Bone Tunnel Placement for Anterior Cruciate Ligament Reconstruction Based on 3-Dimensional Printing Technology: A Cadaveric Study

PURPOSE

To explore a method of bone tunnel placement for anterior cruciate ligament (ACL) reconstruction based on 3-dimensional (3D) printing technology and to assess its accuracy.

METHODS

Twenty human cadaveric knees were scanned by thin-layer computed tomography (CT). To obtain data on bones used to establish a knee joint model by computer software, customized bone anchors were installed before CT. The reference point was determined at the femoral and tibial footprint areas of the ACL. The site and direction of the bone tunnels of the femur and tibia were designed and calibrated on the knee joint model according to the reference point. The resin template was designed and printed by 3D printing. Placement of the bone tunnels was accomplished by use of templates, and the cadaveric knees were scanned again to compare the concordance of the internal opening of the bone tunnels and reference points.

RESULTS

The twenty 3D printing templates were designed and printed successfully. CT data analysis between the planned and actual drilled tunnel positions showed mean deviations of 0.57 mm (range, 0-1.5 mm; standard deviation, 0.42 mm) at the femur and 0.58 mm (range, 0-1.5 mm; standard deviation, 0.47 mm) at the tibia.

CONCLUSIONS

The accuracy of bone tunnel placement for ACL reconstruction in cadaveric adult knees based on 3D printing technology is high.

CLINICAL RELEVANCE

This method can improve the accuracy of bone tunnel placement for ACL reconstruction in clinical sports medicine.

Three-Dimensional Technology to Diagnose Unilateral Cervical Atresia in Obstructive Hemivagina with Ipsilateral Renal Anomaly: A Case Report and Review of the Literature

BACKGROUND

Congenital atresia of the cervix in the setting of an obstructed hemivagina with ipsilateral renal anomaly (OHVIRA) is an unusual occurrence that is frequently missed using preoperative imaging modalities.

CASE

A 14-year-old female adolescent presented to a tertiary care facility with abdominal pain associated with a mass. Initial imaging with ultrasound and magnetic resonance suggested OHVIRA but 3-D magnetic resonance imaging (MRI) also correctly identified unilateral cervical atresia on the obstructed left side.

SUMMARY AND CONCLUSION

Three-dimensional MRI in the setting of OHVIRA was used successfully in this case to preoperatively identify cervical atresia and to guide preoperative surgical counseling and planning. The use of 3-D MRI for this purpose has, to our knowledge, never been described in the literature. Three-dimensional printed models derived from 3-D MRI can play an evolving role in the management of Müllerian anomalies as preoperative planning and surgical counseling tools.

L5 En-Bloc Vertebrectomy with Customized Reconstructive Implant: Comparison of Patient-Specific Versus Off-the-Shelf Implant

BACKGROUND

Spine surgery has the potential to benefit from additive manufacturing/3-dimensional printing (3DP) technology with complex anatomical pathologies requiring reconstruction, with the potential to customize surgery to reduce operative times, reduce blood loss, provide immediate stability, and potentially improve fusion rates. We report a unique case of intraoperative trial placement of a custom patient-specific implant (PSI) versus the final implantation of a customizable off-the-shelf (OTS) implant. Data collected for comparison included time to implant, ease of implantation, firmness of press-fit, and fixation options after implantation.

CASE DESCRIPTION

A 64-year-old man presented with low back pain. Computed tomography and magnetic resonance imaging revealed a solitary lesion in the L5 vertebral body, confirmed by positron emission tomography scan. Removal of the L5 vertebral body was performed, and reconstruction was achieved with an expandable cage. The time of implant insertion was minimal with the PSI (90 seconds) versus the OTS (>40 minutes). Immediate press-fit and "firmness" of implantation was clearly superior with the PSI, although this was an intraoperative subjective assessment. Other benefits include integral fixation that is predetermined with the PSI, reduced time and blood loss, and ease of bone grafting with a PSI.

CONCLUSIONS

Use of 3DP has been able to reduce operative time significantly. Surgeons can train before performing complex procedures, which enhances their presurgical planning, with the goal to maximize patient outcomes. When considering implants and prostheses, the use of 3DP allows a superior anatomical fit for the patient, with the potential to improve restoration of anatomy.

Evaluation of Dimensional Changes of 3D Printed Models After Sterilization: A Pilot Study

Objectives

To assess the effect of two of the most commonly used sterilization techniques on 3D printed clinical objects.

Materials & Methods

The two sterilization methods used in our hospital and investigated in this paper are: Steam heat and Gas plasma. Three objects were printed and tested in this study: a tooth replica, an orthognathic final splint, a surgical cutting guide for the purpose of mandible reconstruction. For each of the 3 objects, 4 copies were made: one original STL object, one copy of the object pre-sterilization, one copy of post-steam heat sterilization, and one copy of post-gas plasma sterilization. Each printed object was scanned using a high resolution CBCT protocol and the compared (morphologically and volumetrically).

Results

At the level of volumetric changes, no difference was found between pre and post-sterilization for both methods evaluated. As for the morphological changes, only differences were noticed with the orthognathic splint object indicating deformation of the printed splints after sterilization. Larger differences were observed with heat sterilization, making it less reliable.

Conclusion

Sterilization of dental objects to be used in a clinical setting may lead to deformation of the printed model, especially for heat sterilization. Further investigations are needed to confirm these findings.

Three-dimensional printing model improves morphological understanding in acetabular fracture learning: A multicenter, randomized, controlled study

Conventional education results in unsatisfactory morphological understanding of acetabular fractures due to lack of three-dimensional (3D) details and tactile feedback of real fractures. Virtual reality (VR) and 3D printing (3DP) techniques are widely applied in teaching. The purpose of this study was to identify the effect of physical model (PM), VR and 3DP models in education of morphological understanding of acetabular fractures. 141 students were invited to participate in this study. Participants were equally and randomly assigned to the PM, VR and 3DP learning groups. Three-level objective tests were conducted to evaluate learning, including identifying anatomical landmarks, describing fracture lines, identifying classification, and inferring fracture mechanism. Four subjective questions were asked to evaluate the usability and value of instructional materials. Generally, the 3DP group showed a clear advantage over the PM and VR groups in objective tests, while there was no significant difference between the PM and VR groups. 3DP was considered to be the most valuable learning tool for understanding acetabular fractures. The findings demonstrate that 3DP modelling of real fractures is an effective learning instrument that can be used to understand the morphology of acetabular fractures and promote subjective interest.

Take away body parts! An investigation into the use of 3D-printed anatomical models in undergraduate anatomy education

Understanding the three-dimensional (3D) nature of the human form is imperative for effective medical practice and the emergence of 3D printing creates numerous opportunities to enhance aspects of medical and healthcare training. A recently deceased, un-embalmed donor was scanned through high-resolution computed tomography. The scan data underwent segmentation and post-processing and a range of 3D-printed anatomical models were produced. A four-stage mixed-methods study was conducted to evaluate the educational value of the models in a medical program. (1) A quantitative pre/post-test to assess change in learner knowledge following 3D-printed model usage in a small group tutorial; (2) student focus group (3) a qualitative student questionnaire regarding personal student model usage (4) teaching faculty evaluation. The use of 3D-printed models in small-group anatomy teaching session resulted in a significant increase in knowledge (P = 0.0001) when compared to didactic 2D-image based teaching methods. Student focus groups yielded six key themes regarding the use of 3D-printed anatomical models: model properties, teaching integration, resource integration, assessment, clinical imaging, and pathology and anatomical variation. Questionnaires detailed how students used the models in the home environment and integrated them with anatomical learning resources such as textbooks and anatomy lectures. In conclusion, 3D-printed anatomical models can be successfully produced from the CT data set of a recently deceased donor. These models can be used in anatomy education as a teaching tool in their own right, as well as a method for augmenting the curriculum and complementing established learning modalities, such as dissection-based teaching. Anat Sci Educ 11: 44-53. © 2017 American Association of Anatomists.