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

Unsuspected Limitations of 3D Printed Model in Planning of Complex Aortic Aneurysm Endovascular Treatment

OBJECTIVE

Static 3-dimensional (3D) printing became attractive for operative planning in cases that involve difficult anatomy. An interactive (low cost, fast) 3D print allowing deliberate surgical practice can be used to improve interventional simulation and planning.

BACKGROUND

Endovascular treatment of complex aortic aneurysms is technically challenging, especially in case of narrow aortic lumen or significant aortic angulation (hostile anatomy). The risk of complications such as graft kinking and target vessel occlusion is difficult to assess based solely on traditional software measuring methods and remain highly dependent on surgeon skills and expertise.

METHODS

A patient with juxtarenal AAA with hostile anatomy had a 3-dimensional printed model constructed preoperatively according to computed tomography images. Endovascular graft implantation in the 3D printed aorta with a standard T-Branch Cook (Cook® Medical, Bloomington, IN, USA) was performed preoperatively in the simulation laboratory enabling optimized feasibility, surgical planning and intraoperative decision making.

RESULTS

The 3D printed aortic model proved to be radio-opaque and allowed simulation of branched endovascular aortic repair (BREVAR). The assessment of intervention feasibility, as well as optimal branch position and orientation was found to be useful for surgeon confidence and the actual intervention in the patient. There was a remarkable agreement between the 3D printed model and both CT and X-ray angiographic images. Although the technical success was achieved as planned, a previously deployed renal stent caused unexpected difficulty in advancing the renal stent, which was not observed in the 3D model simulation.

CONCLUSION

The 3D printed aortic models can be useful for determining feasibility, optimizing planning and intraoperative decision making in hostile anatomy improving the outcome. Despite already offering satisfying accuracy at present, further advancements could enhance the 3D model capability to replicate minor anatomical deformities and variations in tissue density.

A Cost-Affordable Methodology of 3D Printing of Bone Fractures Using DICOM Files in Traumatology

Three-dimensional (3D) printing has gained popularity across various domains but remains less integrated into medical surgery due to its complexity. Existing literature primarily discusses specific applications, with limited detailed guidance on the entire process. The methodological details of converting Computed Tomography (CT) images into 3D models are often found in amateur 3D printing forums rather than scientific literature. To address this gap, we present a comprehensive methodology for converting CT images of bone fractures into 3D-printed models. This involves transferring files in Digital Imaging and Communications in Medicine (DICOM) format to stereolithography format, processing the 3D model, and preparing it for printing. Our methodology outlines step-by-step guidelines, time estimates, and software recommendations, prioritizing free open-source tools. We also share our practical experience and outcomes, including the successful creation of 72 models for surgical planning, patient education, and teaching. Although there are challenges associated with utilizing 3D printing in surgery, such as the requirement for specialized expertise and equipment, the advantages in surgical planning, patient education, and improved outcomes are evident. Further studies are warranted to refine and standardize these methodologies for broader adoption in medical practice.

Sculpting the future: A narrative review of 3D printing in plastic surgery and prosthetic devices

Background and Aims

The advent of 3D printing has revolutionized plastic surgery and prosthetic devices, providing personalized solutions for patients with traumatic injuries, deformities, and appearance-related conditions. This review offers a comprehensive overview of 3D printing's applications, advantages, limitations, and future prospects in these fields.

Methods

A literature search was conducted in PubMed, Google Scholar, and Scopus for studies on 3D printing in plastic surgery.

Results

3D printing has significantly contributed to personalized medical interventions, with benefits like enhanced design flexibility, reduced production time, and improved patient outcomes. Using computer-aided design (CAD) software, precise models tailored to a patient's anatomy can be created, ensuring better fit, functionality, and comfort. 3D printing allows for intricate geometries, leading to improved aesthetic outcomes and patient-specific prosthetic limbs and orthoses. The historical development of 3D printing, key milestones, and breakthroughs are highlighted. Recent progress in bioprinting and tissue engineering shows promising applications in regenerative medicine and transplantation. The integration of AI and automation with 3D printing enhances surgical planning and outcomes. Emerging trends in patient-specific treatment planning and precision medicine are potential game-changers. However, challenges like technical considerations, economic implications, and ethical issues exist. Addressing these challenges and advancing research in materials, design processes, and long-term outcomes are crucial for widespread adoption.

Conclusion

The review underscores the increasing adoption of 3D printing in healthcare and its impact on plastic surgery and prosthetic devices. It emphasizes the importance of evaluating the current state and addressing knowledge gaps through future research to foster further advancements.

3D-Printed Personalized Lattice Implant as an Innovative Strategy to Reconstruct Geographic Defects in Load-Bearing Bones

OBJECTIVE

Geographic defect reconstruction in load-bearing bones presents formidable challenges for orthopaedic surgeon. The use of 3D-printed personalized implants presents a compelling opportunity to address this issue. This study aims to design, manufacture, and evaluate 3D-printed personalized implants with irregular lattice porous structures for geographic defect reconstruction in load-bearing bones, focusing on feasibility, osseointegration, and patient outcomes.

METHODS

This retrospective study involved seven patients who received 3D-printed personalized lattice implants for the reconstruction of geographic defects in load-bearing bones. Personalized implants were customized for each patient. Randomized dodecahedron unit cells were incorporated within the implants to create the porous structure. The pore size and porosity were analyzed. Patient outcomes were assessed through a combination of clinical and radiological evaluations. Tomosynthesis-Shimadzu metal artifact reduction technology (T-SMART) was utilized to evaluate osseointegration. Functional outcomes were assessed according to the Musculoskeletal Tumor Society (MSTS) 93 score.

RESULTS

Multiple pore sizes were observed in porous structures of the implant, with a wide distribution range (approximately 300-900 um). The porosity analysis results showed that the average porosity of irregular porous structures was around 75.03%. The average follow-up time was 38.4 months, ranging from 25 to 50 months. Postoperative X-rays showed that the implants matched the geographic bone defect well. Osseointegration assessments according to T-SMART images indicated a high degree of bone-to-implant contact, along with favorable bone density around the implants. Patient outcomes assessments revealed significant improvements in functional outcomes, with the average MSTS score of 27.3 (range, 26-29). There was no implant-related complication, such as aseptic loosening or structure failure.

CONCLUSION

3D-printed personalized lattice implants offer an innovative and promising strategy for geographic defect reconstruction in load-bearing bones. This approach has the potential to match the unique contours and geometry of the geographic bone defect and facilitate osteointegration.

Just the gastrointestinal stromal tumor: A case report of medical modeling of a rectal gastrointestinal stromal tumor

A 54-year-old African-American male presented to the colorectal surgery clinic with the chief complaint of a painful anal swelling that had been ongoing for several weeks. An adequate rectal examination was not possible due to severe pain. Therefore, he was taken to the operating room for an exam under anesthesia where a presacral mass was identified. A transgluteal core needle biopsy was performed which was consistent with gastrointestinal stromal tumor. Computed tomography imaging identified a 16 cm ×10 cm ×9 cmrectal gastrointestinal stromal tumor. Given the size and location, the patient began treatment with neoadjuvant Imatinib. His progress was followed with serial computed tomography scans and clinic visits. A 3D model was created the tumor and surrounding structures to aide in pre- and intraoperative planning. The model was utilized during patient education and found to valuable in describing the potential for levator invasion and framing potential post-operative outcomes. The patient was able to undergo rectal preservation via a robotic low anterior resection with a transanal total mesorectal excision, coloanal anastomosis, and diverting ileostomy.

The clinical value of preoperative 3D planning and 3D surgical guides for Imhäuser osteotomy in slipped capital femoral epipysis: a retrospective study

BACKGROUND

Accurate repositioning of the femoral head in patients with Slipped Capital Femoral Epiphysis (SCFE) undergoing Imhäuser osteotomy is very challenging. The objective of this study is to determine if preoperative 3D planning and a 3D-printed surgical guide improve the accuracy of the placement of the femoral head.

METHODS

This retrospective study compared outcome parameters of patients who underwent a classic Imhäuser osteotomy from 2009 to 2013 with those who underwent an Imhäuser osteotomy using 3D preoperative planning and 3D-printed surgical guides from 2014 to 2021. The primary endpoint was improvement in Range of Motion (ROM) of the hip. Secondary outcomes were radiographic improvement (Southwick angle), patient-reported clinical outcomes regarding hip and psychosocial complaints assessed with two questionnaires and duration of surgery.

RESULTS

In the 14 patients of the 3D group radiographic improvement was slightly greater and duration of surgery was slightly shorter than in the 7 patients of the classis Imhäuser group. No difference was found in the ROM, and patient reported clinical outcomes were slightly less favourable.

CONCLUSIONS

Surprisingly we didn't find a significant difference between the two groups. Further research on the use of 3D planning an 3D-printed surgical guides is needed.

TRIAL REGISTRATION

Approval for this study was obtained of the local ethics committees of both hospitals.

Survival analysis of 3D printed acetabular implants in revision total hip arthroplasty associated with severe pelvic discontinuities

BACKGROUND

Surgeons still face difficulties when performing aseptic acetabular revision on patients with extensive defects. Advances in three-dimensional printing technology (3DP) have afforded to the surgeons to create a patient-specific implant matching the morphology and topography of the defect.

OBJECTIVE

The aim of the current research was to determine the survivorship in the treatment of acetabular bone defects with pelvic discontinuity (PD).

METHODS

In order to reconstruct Paprosky type III defects with PD, twenty-three patients underwent revision total hip arthroplasty (THA) utilizing 3D-printed implants (Mobelife). The primary outcomes were the implant-associated failure rate correlated with survivorship. As secondary variables, complications and the effect of age, sex, comorbidities, history of infections and the presence of other lower limb arthroplasties on a new revision were analyzed.

RESULTS

Patients were followed out to a mean of 67.22 ± 39.44 months (range, 0.9-127 months). Mobelife implant mean survival was 102.57 ± 9.90 months (95% CI 83.17-121.96). The cohort's implant one-year survival rate was 87%; at ten years, it dropped to 78.3%. There were four revisions: three due to periprosthetic joint infection (PJI) and one case due to aseptic loosening. Cox regression analysis did not identify any variable as predictor of failure.

CONCLUSION

The use of 3DP patient-specific acetabular components has shown encouraging results and it is a viable treatment option for addressing acetabular defects with combined PD in aseptic THA revision.

Photopolymerization-Based Three-Dimensional Ceramic Printing Technology

Ceramics have many applications in mechanics, electronics, aerospace, and biomedicine because of their high mechanical strength, high-temperature resistance, and excellent chemical stability. Three-dimensional (3D) printing is a fast, efficient, and intelligent technology that has revolutionized the manufacturing of complex structural parts. Among many ceramic 3D printing technologies, photopolymerization-based 3D printing techniques print out molded ceramic components with high molding accuracy and surface finish and have received widespread attention. This article reviews the current research status and problems experienced by three mainstream ceramic photocuring technologies, namely stereoscopic, digital light processing, and two-photon polymerization.

Myth or fact: 3D-printed off-the-shelf prosthesis is superior to titanium mesh cage in anterior cervical corpectomy and fusion?

BACKGROUND

To find out if three-dimensional printing (3DP) off-the-shelf (OTS) prosthesis is superior to titanium mesh cages in anterior cervical corpectomy and fusion (ACCF) when treating single-segment degenerative cervical spondylotic myelopathy (DCSM).

METHODS

DCSM patients underwent ACCF from January 2016 to January 2019 in a single center were included. Patients were divided into the 3DP group (28) and the TMC group (23). The hospital stays, operation time, intraoperative blood loss, and the cost of hospitalization were compared. The Japanese Orthopedic Association (JOA) scores and Neck Disability Index (NDI) were recorded pre-operatively, 1 day, 3, 6, 12, and 24 months post-operatively. Radiological data was measured to evaluate fusion, subsidence, and cervical lordosis. Patients were sent with SF-36 to assess their health-related quality of life (HRQoL).

RESULTS

The differences in operative time, intraoperative blood loss, and hospital stay were not statistically significant between groups (p > 0.05). Postoperative dysphagia occurred in 2 cases in the 3DP group and 3 cases in the TMC group, which all relieved one week later. The difference in improvement of JOA and NDI between the two groups was not statistically significant (p > 0.05). No hardware failure was found and bony fusion was achieved in all cases except one in the 3DP group. The difference in cervical lordosis (CL), fused segmental angle (FSA), mean vertebral height (MVH), and subsidence rates between groups at each follow-up time point was not statistically significant and the results of the SF-36 were similar (p > 0.05). The total cost was higher in the 3DP group with its higher graft cost (p < 0.05).

CONCLUSION

In treating single-segment DCSM with ACCF, both 3DP OTS prosthesis and TMC achieved satisfactory outcomes. However, the more costly 3DP OTS prosthesis was not able to reduce subsidence as it claimed.

Teaching hypospadias repair by utilising a novel 3D-printed silicon model: An initial assessment using structured trainee and trainer feedback

INTRODUCTION

Simulated paediatric surgical training is inherently advantageous and flourishing. Moreover, several working conditions resulted in reduced training hours, index and subspecialty cases encountered, and the COVID-19 pandemic affected elective surgery backlogs, hence training opportunities. Hypospadias repair is technically-demanding and requires a spectrum of dissective and reconstructive skills. We therefore aimed to test a 3D-printed silicon model for hypospadias repair, in the context of hands-on surgical training.

MATERIAL AND METHODS

Twenty-Seven trainees, under the supervision of 15 instructors, completed the activity. They were given a seminar to show the relevant anatomy, and 8 key steps of the exercise: (1)-degloving; (2)-urethral plate marking; (3)-incision; (4)-tubularisation; (5)-glansplasty/glanuloplasty; (6)-dartos layer preparation; (7)-preputioplasty and (8)-skin closure. Each trainee completed a structured feedback assessment. An on-site trainer supervised and evaluated each exercise. Trainees and trainers rated the model through the above steps from unsatisfactory-(1/5) to excellent-(5/5), presented herein via cross-sectional analysis.

RESULTS

Eleven-(40.7 %) trainees were in years:1-3 of specialist training, 10-(37 %) were in years:4-6, and 6-(22.2 %) were beyond year-6. Two-(7.4 %) trainees had nil-hypospadias experience, 16-(59.2 %) previously assisted in procedures or performed steps, 5-(18.5 %) performed whole procedures supervised and 4-(14.8 %) independently. Twenty-(74 %) trainees and 15-(100 %) instructors judged the model to resemble the anomaly. Seventeen-(63 %) trainees and 13-(86.6 %) instructors rated the material needle-penetrability ≥3/5, compared to human tissue. Sixteen-(59 %) trainees and 13-(86.6 %) instructors rated the material suture holding ≥3/5. Eleven-(73.3 %) trainees and 13-(86.6 %) instructors rated sutures' evenness and edge coaptability ≥3/5.

DISCUSSION

Hypospadias is an index operation, which requires precision skills. Simulated training in Paediatric Surgery and Urology is gaining importance. 3D-printed models are gaining a key role in simulated training. The study presents a novel 3D-printed high-fidelity silicon-based hypospadias model designed for hands-on training. A structured pathway to divide a standard hypospadias repair into key steps is displayed to ensure skill acquisition and stabilisation.

CONCLUSION

This 3D-printed silicon-based hypospadias model is proven useful for hands-on training. The fidelity can still improve, especially regarding suture holding of the material.

LEVEL OF EVIDENCE

LEVEL III.

Surgical Treatments and Long-Term Outcomes for Pediatric Patients With Lumbar Spinal Tumors

STUDY DESIGN

Retrospective case‒control study.

OBJECTIVES

This study aimed to report the effects of surgical intervention on spinal stability recovery and to assess the long-term outcomes of children and adolescents with lumbar tumors.

METHODS

From January 2016 to June 2021, 42 pediatric patients with lumbar tumors were selected and separated into different groups based on the surgical method used (total en bloc resection (TER) group, n = 21; piecemeal resection (PR) group, n = 21; titanium mesh (TM) group n = 23; artificial vertebrae (AV) group n = 19). The clinicopathological characteristics, treatments and related outcomes were described in detail and compared between groups, with P value ≤.05 indicating statistically significant differences.

RESULTS

The average follow-up duration was 24.89 months, and the mean age was 14.89 ± 2.41 years. There were no significant differences in the mean operation time, average blood loss, complication rate, or length of hospital stay between the groups. The ODI, VAS and JOA scores at the final follow-up (FF) were elevated after surgery in all groups. The FF local angular drift (LOD) and lumbar angular drift (LUD) were greater in the TM group than in the AV group (P = .03, P = .001).

CONCLUSIONS

After surgery, pediatric patients with lumbar tumors can obtain satisfactory spinal stability, effective relief of pain symptoms and substantial improvements in neurological function. There was no significant difference in the invasiveness, safety or timeliness between the 2 surgical methods, so TER is recommended due to its low postoperative recurrence rate and good local control. Spinal fusion in the AV group resulted in better spinal stability.

Additive manufacturing and three-dimensional printing in obstetrics and gynecology: a comprehensive review

Three-dimensional (3D) printing, also known as additive manufacturing, is a technology used to create complex 3D structures out of a digital model that can be almost any shape. Additive manufacturing allows the creation of customized, finely detailed constructs. Improvements in 3D printing, increased 3D printer availability, decreasing costs, development of biomaterials, and improved cell culture techniques have enabled complex, novel, and customized medical applications to develop. There have been rapid development and utilization of 3D printing technologies in orthopedics, dentistry, urology, reconstructive surgery, and other health care areas. Obstetrics and Gynecology (OBGYN) is an emerging application field for 3D printing. This technology can be utilized in OBGYN for preventive medicine, early diagnosis, and timely treatment of women-and-fetus-specific health issues. Moreover, 3D printed simulations of surgical procedures enable the training of physicians according to the needs of any given procedure. Herein, we summarize the technology and materials behind additive manufacturing and review the most recent advancements in the application of 3D printing in OBGYN studies, such as diagnosis, surgical planning, training, simulation, and customized prosthesis. Furthermore, we aim to give a future perspective on the integration of 3D printing and OBGYN applications and to provide insight into the potential applications.

Stability of Three-Dimensional Printed Custom-Made Metaphyseal Cone for Tibial Bone Defects Reconstruction: A Finite Element Analysis and Biomechanical Study

OBJECTIVES

The reconstruction of bone defects in tibial revision knee arthroplasty is challenging. In this study, we evaluated the primary stability of a novel three-dimensional (3D)-printed custom-made metaphyseal cone for Anderson Orthopedic Research Institute (AORI) IIb or III bone defect reconstruction in tibial revision knee arthroplasty using the combination of finite-element analysis and biomechanical experiments.

METHODS

In the finite-element analysis, AORI II b and III medial tibial bone defects were designed at varying depths. A novel 3D-printed custom-made metaphyseal cone was designed and used to reconstruct the bone defect with or without a stem in simulated revision total knee arthroplasty (RTKA). A no-stem group and a stem group were established (based on whether a stem was used or not). Von Mises stress and micromotion were calculated with varying depths of bone defects, ranging from 5 mm to 35 mm, and then micromotions at the bone-implant interface were calculated and compared with the critical value of 150 μm. In the biomechanical experiment, the no-stem group was used, and the same bone defects were made in four synthetic tibias using patient-specific instruments. Micromotions at the bone-implant interface were investigated using a non-contact optical digital image correlation system and compared with the critical value of 150 μm.

RESULTS

When the bone defect was <30 mm, micromotions at the bone-implant interface in the finite-element analysis were all below 150 μm both in the stem groups and no-stem groups, whereas those in the biomechanical experiment were also below 150 μm in the no-stem group.

CONCLUSIONS

The 3D-printed custom-made metaphyseal cone in RTKA has excellent primary stability and does not require stems in reconstructing tibial AORI type IIb or III bone defects with a depth of <30 mm.

Influence of the Print Envelope Temperature on the Morphology and Tensile Properties of Thermoplastic Polyolefins Fabricated by Material Extrusion and Material Jetting Additive Manufacturing

Additive manufacturing (AM) nowadays has become a supportive method of traditional manufacturing. In particular, the medical and healthcare industry can profit from these developments in terms of personalized design and batches ranging from one to five specimens overall. In terms of polymers, polyolefins are always an interesting topic due to their low prices, inert chemistry, and crystalline structure resulting in preferable mechanical properties. Their semi-crystalline nature has some advantages but are challenging for AM due to their shrinkage and warping, resulting in geometrical inaccuracies or even layer detaching during the process. To tackle these issues, process parameter optimization is vital, with one important parameter to be studied more in detail, the print envelope temperature. It is well known that higher print envelope temperatures lead to better layer adhesion overall, but this investigation focuses on the mechanical properties and resulting morphology of a semi-crystalline thermoplastic polyolefin. Further, two different AM technologies, namely material jetting (ARBURG plastic freeforming-APF) and filament-based material extrusion, were studied and compared in detail. It was shown that higher print envelope temperatures lead to more isotropic behavior based on an evenly distributed morphology but results in geometrical inaccuracies since the material is kept in a molten state during printing. This phenomenon especially could be seen in the stress and strain values at break at high elongations. Furthermore, a different crystal structure can be achieved by setting a specific temperature and printing time, also resulting in peak values of certain mechanical properties. In comparison, better results could be archived by the APF technology in terms of mechanical properties and homogeneous morphology. Nevertheless, real isotropic part behavior could not be managed which was shown by the specimen printed vertically. Hence, a sweet spot between geometrical and mechanical properties still has to be found.

Evaluation of 3D-printed bolus for radiotherapy using megavoltage X-ray beams

A radiotherapy bolus is a tissue-equivalent material placed on the skin to adjust the surface dose of megavoltage X-ray beams used for treatment. In this study, the dosimetric properties of two 3D-printed filament materials, polylactic acid (PLA) and thermoplastic polyether urethane (TPU), used as radiotherapy boluses, were investigated. The dosimetric properties of PLA and TPU were compared with those of several conventional bolus materials and RMI457 Solid Water. Percentage depth-dose (PDD) measurements in the build-up region were performed for all materials using 6 and 10 MV photon treatment beams on Varian linear accelerators. The results showed that the differences in the PDDs of the 3D-printed materials from the RMI457 Solid Water were within 3%, whereas those of the dental wax and SuperFlab gel materials were within 5%. This indicates that PLA and TPU 3D-printed materials are suitable radiotherapy bolus materials.

Three-Dimensional Printing Applications in Thoracic Surgery

Advances in technology allowing the combination of medical imaging and three-dimensional printing have greatly benefitted thoracic surgery, allowing for the creation of complex prostheses. Surgical education is also a significant application of three-dimensional printing, especially for the development of simulation-based training models. Aiming to show how three-dimensional printing can benefit patients and clinicians in thoracic surgery, an optimized method to create patient-specific chest wall prosthesis using three-dimensional printing was developed and clinically validated. An artificial chest simulator for surgical training was also developed, replicating the human anatomy with high realism and accurately simulating a minimally invasive lobectomy.

3-D Printed Fracture Models Improve Resident Performance and Clinical Outcomes in Operative Fracture Management

OBJECTIVE

To determine if preoperative examination of patient additive manufactured (AM) fracture models can be used to improve resident operative competency and patient outcomes.

DESIGN

Prospective cohort study. Seventeen matched pairs of fracture fixation surgeries (for a total of 34 surgeries) were performed. Residents first performed a set of baseline surgeries (n = 17) without AM fracture models. The residents then performed a second set of surgeries randomly assigned to include an AM model (n = 11) or to omit it (n = 6). Following each surgery, the attending surgeon evaluated the resident using an Ottawa Surgical Competency Operating Room Evaluation (O-Score). The authors also recorded clinical outcomes including operative time, blood loss, fluoroscopy duration, and patient reported outcome measurement information system (PROMIS) scores of pain and function at 6 months.

SETTING

Single-center academic level one trauma center.

PARTICIPANTS

Twelve orthopaedic residents, between postgraduate year (PGY) 2 and 5, participated in this study.

RESULTS

Residents significantly improved their O-Scores between the first and second surgery when they trained with AM models for the second surgery (p = 0.004, 2.43 ± 0.79 versus 3.73 ± 0.64). Similar improvements were not observed in the control group (p = 0.916, 2.69 ± 0.69 versus 2.77 ± 0.36). AM model training also significantly improved clinical outcomes, including surgery time (p = 0.006), fluoroscopy exposure time (p = 0.002), and patient reported functional outcomes (p = 0.0006).

CONCLUSIONS

Conclusions: Training with AM fracture models improves the performance of orthopaedic surgery residents during fracture surgery.

3D-Printing Applications in Ostomy Device Creation and Complex Intestinal Fistula Management: A Scoping Review

Background  This scoping review aims to provide a summary of the use of three-dimensional (3D) printing in colorectal surgery for the management of complex intestinal fistula and ostomy creation. Methods  A systematic database search was conducted of original articles that explored the use of 3D printing in colorectal surgery in EMBASE, MEDLINE, Cochrane database, and Google Scholar, from inception to March 2022. Original articles and case reports that discussed 3D printing in colorectal surgery relating to complex intestinal fistulae and ostomies were identified and analyzed. Results  There were 8 articles identified which discussed the use of 3D printing in colorectal surgery, of which 2 discussed ostomy creation, 4 discussed complex fistulae management, and 2 discussed patient models. Conclusion  3D printing has a promising role in terms of management of these conditions and can improve outcomes in terms of recovery, fluid loss, and function with no increase in complications. The use of 3D printing is still in its early stages of development in colorectal surgery. Further research in the form of randomized control trials to improve methodological robustness will reveal its true potential.

Utilizing 3D printing to assist pre-procedure planning of transjugular intrahepatic portosystemic shunt (TIPS) procedures: a pilot study

BACKGROUND

3D (three-dimensional) printing has been adopted by the medical community in several ways, procedure planning being one example. This application of technology has been adopted by several subspecialties including interventional radiology, however the planning of transjugular intrahepatic portosystemic shunt (TIPS) placement has not yet been described. The impact of a 3D printed model on procedural measures such as procedure time, radiation exposure, intravascular contrast dosage, fluoroscopy time, and provider confidence has also not been reported.

METHODS

This pilot study utilized a quasi-experimental design including patients who underwent TIPS. For the control group, retrospective data was collected on patients who received a TIPS prior to Oct 1, 2020. For the experimental group, patient-specific 3D printed models were integrated in the care of patients that received TIPS between Oct 1, 2020 and April 15, 2021. Data was collected on patient demographics and procedural measures. The interventionalists were surveyed on their confidence level and model usage following each procedure in the experimental group.

RESULTS

3D printed models were created for six TIPS. Procedure time (p = 0.93), fluoroscopy time (p = 0.26), and intravascular contrast dosage (p = 0.75) did not have significant difference between groups. Mean radiation exposure was 808.8 mGy in the group with a model compared to 1731.7 mGy without, however this was also not statistically significant (p = 0.09). Out of 11 survey responses from interventionists, 10 reported "increased" or "significantly increased" confidence after reviewing the 3D printed model and all responded that the models were a valuable tool for trainees.

CONCLUSIONS

3D printed models of patient anatomy can consistently be made using consumer-level, desktop 3D printing technology. This study was not adequately powered to measure the impact that including 3D printed models in the planning of TIPS procedures may have on procedural measures. The majority of interventionists reported that patient-specific models were valuable tools for teaching trainees and that confidence levels increased as a result of model inclusion in procedure planning.

The Last 40 Years of Orthognathic Surgery: A Bibliometric Analysis

PURPOSE

Bibliometric analyses provide information on the effectiveness, performance, trends, and various other characteristics of research by using mathematical and statistical analysis methods for data related to scientific publications. This study aims to determine the focus of studies in the field of orthognathic surgery, map it, and present the results in a simplified manner through a comprehensive bibliometric analysis of the relevant literature.

METHODS

In this bibliometric analysis study, orthognathic surgery publications from 1980 to 2022 were retrieved from the Web of Science Core Collection database. The independent variables were co-citations, while the outcome variables included cross-country collaboration analysis, keyword analysis, co-citation analysis, and cluster analysis of the co-citation network. Covariates were the number of publications, number of citations, year range, centrality value, and silhouette value. The bibliometric analysis was conducted using CiteSpace, VOSviewer, and R-Studio software.

RESULTS

A total of 7,135 publications and 75,822 references were included in the analysis, and the annual growth rate of publications was 9.52%. The co-citation clustering analysis revealed that the orthognathic surgery literature was organized into 16 subject headings. Patient satisfaction was found to be the most widely published topic. The youngest clusters, representing new topics in the field, were virtual planning and examination of condylar changes after orthognathic surgery.

CONCLUSION

Bibliometric analysis methods were used to evaluate the 40-year history of the orthognathic surgery literature. The analysis identified the most influential publications, the topics in which the literature is divided, and hot spots in the field. By conducting similar bibliometric research studies in the future, the progress and future direction of the literature can be monitored based on evidence.

A pH-neutral bioactive glass coated 3D-printed porous Ti6Al4V scaffold with enhanced osseointegration

Osseointegration is vital for the success of non-degradable implants like those made of titanium alloys. In order to promote osseointegration, implants are made porous, providing space for bone ingrowth. Despite extensive optimization of the pore geometry and porosity, bone ingrowth into implants is still marginal; further modification to promote bone ingrowth as well as osseointegration becomes paramount. In this study, a pH neutral bioactive glass with the composition of 10.8% P₂O₅-54.2% SiO₂-35% CaO (mol%; hereinafter referred to as PSC) was successfully coated on 3D-printed porous Ti6Al4V scaffolds using an in situ sol-gel method. This PSC coating is strongly bonded to the substrate and quickly induces the formation of hydroxyapatite on the scaffold surface upon contact with body fluid. In vitro, the PSC-coated Ti6Al4V scaffolds showed superior biocompatibility, cell proliferation promotion, cell adhesion, osteogenic differentiation and mineralization compared to their bare counterparts, implying better osseointegration. In vivo experiments confirmed this expectation; after being implanted, the coated scaffolds had more bone ingrowth and osseointegration, and consequently, higher push-out strength was achieved, proving the validity of the proposed concept in this study. In conclusion, PSC coating on 3D-printed porous Ti6Al4V scaffolds can improve osteogenesis, bone ingrowth, and osseointegration. Together with the versatility of this in situ sol-gel coating method, titanium alloy implants with better biological performances may be developed for immediate clinical applications.

3D Printing of Dental Prostheses: Current and Emerging Applications

Revolutionary fabrication technologies such as three-dimensional (3D) printing to develop dental structures are expected to replace traditional methods due to their ability to establish constructs with the required mechanical properties and detailed structures. Three-dimensional printing, as an additive manufacturing approach, has the potential to rapidly fabricate complex dental prostheses by employing a bottom-up strategy in a layer-by-layer fashion. This new technology allows dentists to extend their degree of freedom in selecting, creating, and performing the required treatments. Three-dimensional printing has been narrowly employed in the fabrication of various kinds of prostheses and implants. There is still an on-demand production procedure that offers a reasonable method with superior efficiency to engineer multifaceted dental constructs. This review article aims to cover the most recent applications of 3D printing techniques in the manufacturing of dental prosthetics. More specifically, after describing various 3D printing techniques and their advantages/disadvantages, the applications of 3D printing in dental prostheses are elaborated in various examples in the literature. Different 3D printing techniques have the capability to use different materials, including thermoplastic polymers, ceramics, and metals with distinctive suitability for dental applications, which are discussed in this article. The relevant limitations and challenges that currently limit the efficacy of 3D printing in this field are also reviewed. This review article has employed five major scientific databases, including Google Scholar, PubMed, ScienceDirect, Web of Science, and Scopus, with appropriate keywords to find the most relevant literature in the subject of dental prostheses 3D printing.

3D Printed Patient-Specific Cutting Guides for Bone Grafting in Reverse Shoulder Arthroplasty: A Novel Technique

Glenoid bone loss remains a challenge in shoulder arthroplasty. Addressing substantial bone loss is essential to ensure proper function and stability of the shoulder prosthesis and to prevent baseplate loosening and subsequent revision surgery. Current options for creating and shaping glenoid bone grafts include free-hand techniques and simple reusable cutting guides that cut the graft at a standard angle. There is currently no patient-specific device available that enables surgeons to accurately prepare the bone graft and correct glenoid deformity. We present a novel surgical technique using three-dimensional (3D)-printed cutting guides to create a patient-specific bone graft to address glenoid deformity in the setting of reverse shoulder arthroplasty.

An Overview of 3D Anatomical Model Printing in Orthopedic Trauma Surgery

Introduction

3D object printing technology is a resource increasingly used in medicine in recent years, mainly incorporated in surgical areas like orthopedics. The models made by 3D printing technology provide surgeons with an accurate analysis of complex anatomical structures, allowing the planning, training, and surgery simulation. In orthopedic surgery, this technique is especially applied in oncological surgeries, bone, and joint reconstructions, and orthopedic trauma surgeries. In these cases, it is possible to prototype anatomical models for surgical planning, simulating, and training, besides printing of instruments and implants.

Purpose

The purpose of this paper is to describe the acquisition and processing from computed tomography images for 3D printing, to describe modeling and the 3D printing process of the biomodels in real size. This paper highlights 3D printing with the applicability of the 3D biomodels in orthopedic surgeries and shows some examples of surgical planning in orthopedic trauma surgery.

Patients and Methods

Four examples were selected to demonstrate the workflow and rationale throughout the process of planning and printing 3D models to be used in a variety of situations in orthopedic trauma surgeries. In all cases, the use of 3D modeling has impacted and improved the final treatment strategy.

Conclusion

The use of the virtual anatomical model and the 3D printed anatomical model with the additive manufacturing technology proved to be effective and useful in planning and performing the surgical treatment of complex articular fractures, allowing surgical planning both virtual and with the 3D printed anatomical model, besides being useful during the surgical time as a navigation instrument.

Application of 3D-printed prosthesis in revision surgery with large inflammatory pseudotumour and extensive bone defect: A case report

BACKGROUND

Hip revision surgery is the final treatment option for the failure of artificial hip joints, but it is more difficult than the initial operation. For patients with hip joint loosening around the prosthesis combined with large inflammatory pseudotumours and large segment bone defects, hip revision is even more difficult, and clinical reports are rare.

CASE SUMMARY

Male, 59 years old. The patient underwent left hip replacement 35 years ago and was now admitted to hospital due to massive masses in the left thigh, shortening of the left lower extremity, and pain and lameness of the left hip joint. X-ray, computed tomography and magnetic resonance imaging revealed prosthesis loosening, left acetabular bone defect (Parprosky IIIB type), and a bone defect of the left proximal femur (Parprosky IIIA type). Inflammatory pseudotumours were seen in the left hip and left thigh. Hip revision surgery was performed using a 3D-printed custom acetabular prosthesis was used for hip revision surgery, which was produced by Arcam Electron Beam Melting system with Electron Beam Melting technology. The operation was successful, and the patient was followed up regularly after the operation. The custom-made acetabular prosthesis was well matched, the inflammatory pseudotumour was completely removed, the postoperative hip prosthesis was stable, and the old greater trochanter fracture was well reduced and fixed. The patient was partially weight-bearing with crutches 3 mo after the operation and walked with full weight-bearing after 6 mo. The hip prosthesis was stable, and there was no recurrence of inflammatory pseudotumours at the last follow-up. The Visual Analogue Scale was 3, and the Harris hip score was 90.

CONCLUSION

The use of 3D-printed personalized custom prostheses for complex hip revision surgery has satisfactory surgical results and has great clinical application value.

Point-of-Care Virtual Surgical Planning and 3D Printing in Oral and Cranio-Maxillofacial Surgery: A Narrative Review

This paper provides an overview on the use of virtual surgical planning (VSP) and point-of-care 3D printing (POC 3DP) in oral and cranio-maxillofacial (CMF) surgery based on a literature review. The authors searched PubMed, Web of Science, and Embase to find papers published between January 2015 and February 2022 in English, which describe human applications of POC 3DP in CMF surgery, resulting in 63 articles being included. The main review findings were as follows: most used clinical applications were anatomical models and cutting guides; production took place in-house or as "in-house-outsourced" workflows; the surgeon alone was involved in POC 3DP in 36 papers; the use of free versus paid planning software was balanced (50.72% vs. 49.27%); average planning time was 4.44 h; overall operating time decreased and outcomes were favorable, though evidence-based studies were limited; and finally, the heterogenous cost reports made a comprehensive financial analysis difficult. Overall, the development of in-house 3D printed devices supports CMF surgery, and encouraging results indicate that the technology has matured considerably.

Aplicação da tecnologia de impressão 3D no tratamento da pseudartrose da fratura de Hoffa*

Objetivo Avaliar uma proposta de processo de impressão tridimensional (3D) de um biomodelo preparado com o auxílio da tecnologia de modelagem por deposição de material fundido (fused deposition modeling, FDM, em inglês) a partir de imagens de tomografia computadorizada (TC) de um indivíduo com pseudartrose de fratura coronal do côndilo femoral (fratura de Hoffa).

Materiais e Métodos Para tanto, utilizamos imagens de TC, que permitem estudar a reconstrução volumétrica 3D do modelo anatômico, além da arquitetura e geometria óssea de sítios de anatomia complexa, como as articulações. Também permite o planejamento cirúrgico virtual (PCV) em um programa de desenho assistido por computador (computer-aided design, CAD, em inglês). Essa tecnologia possibilita a impressão de modelos anatômicos em escala real que podem ser utilizados em simulações cirúrgicas para o treinamento e a escolha do melhor posicionamento do implante de acordo com o PCV. Na avaliação radiográfica da osteossíntese da pseudartrose de Hoffa, verificou-se a posição do implante no modelo anatômico impresso em 3D e no joelho do paciente.

Resultados O modelo anatômico impresso em 3D apresentou características geométricas e morfológicas semelhantes às do osso real. O posicionamento dos implantes em relação à linha de pseudartrose e pontos anatômicos foram bastante precisos na comparação do joelho do paciente com o modelo anatômico impresso em 3D.

Conclusão A utilização do modelo anatômico virtual e do modelo anatômico impresso em 3D com a tecnologia de manufatura aditiva (MA) foi eficaz e auxiliou o planejamento e a realização do tratamento cirúrgico da pseudartrose da fratura de Hoffa. Desta forma, foi bastante preciso na reprodutibilidade do planejamento cirúrgico tanto virtual quanto no modelo anatômico impresso em 3D.

Fused Deposition Modeling 3D Printing in Oral and Maxillofacial Surgery: Problems and Solutions

Three-dimensional (3D) printing technology in medicine is one of the new and innovative technology for fabricating 3D models of complex anatomical structures that can be observed both visually and haptically. Patient-specific 3D models fabricated through this process are currently being used for various purposes, including surgical simulation, training, and medical education. Most of the personal use/low-end desktop 3D printers that are becoming widespread are fused deposition modeling (FDM) 3D printers. Compared to professional/high-end 3D printers, the price of the personal use/low-end desktop FDM 3D printer itself, filament, and running costs are lower; it can lower the economic bottleneck for introducing 3D printing technology into clinical practice, such as surgical simulation. With a desktop FDM 3D printer and a general-purpose PC, anyone can now rapidly fabricate 3D models on their own without having to rely on 3D printing labs and specialized technicians. However, it is also true that FDM 3D printers, due to their mechanical characteristics, encounter many difficulties and problems that emerge during the 3D printing process. Knowledge, know-how, and tips about FDM 3D printers have been introduced in various media, and it has become easy to know about them worldwide via the Internet. However, there has been no comprehensive technical review to date to produce osseous 3D models for use in oral and maxillofacial surgery. In this report, to create 3D models according to the characteristics of maxillofacial and oral surgery, we enable surgeons themselves to create 3D models smoothly by presenting ideas for CT scanning, points to note when exporting Digital Imaging and Communications in Medicine (DICOM) image data, how to create optimal stereolithography (STL) models, and problems and solutions for 3D printing.

Comparison of Bone Segmentation Software over Different Anatomical Parts

Three-dimensional bone shape reconstruction is a fundamental step for any subject-specific musculo-skeletal model. Typically, medical images are processed to reconstruct bone surfaces via slice-by-slice contour identification. Freeware software packages are available, but commercial ones must be used for the necessary certification in clinics. The commercial software packages also imply expensive hardware and demanding training, but offer valuable tools. The aim of the present work is to report the performance of five commercial software packages (Mimics®, AmiraTM, D2PTM, SimplewareTM, and Segment 3D PrintTM), particularly the time to import and to create the model, the number of triangles of the mesh, and the STL file size. DICOM files of three different computed tomography scans from five different human anatomical areas were utilized for bone shape reconstruction by using each of these packages. The same operator and the same hosting hardware were used for these analyses. The computational time was found to be different between the packages analyzed, probably because of the pre-processing implied in this operation. The longer “time-to-import” observed in one software is likely due to the volume rendering during uploading. A similar number of triangles per megabyte (approximately 20 thousand) was observed for the five commercial packages. The present work showed the good performance of these software packages, with the main features being better than those analyzed previously in freeware packages.

Reconstruction for Massive Proximal Tibial Bone Defects Using Patient‐Customized Three‐Dimensional‐Printed Metaphyseal Cones in Revision Total Knee Arthroplasty

Objective

To review the clinical outcomes of revision total knee arthroplasty (RTKA) with massive proximal tibial bone defects using patient‐customized three‐dimensional (3D) printed highly porous metaphyseal cones.

Methods

A retrospective study of all patients at our institution who underwent RTKA with the Anderson Orthopaedic Research Institute type III tibial defects using patient‐customized 3D‐printed highly porous metaphyseal cones was performed from 2016 to 2018. Seven patients were enrolled in this study. General results (age, sex, and body mass index); intraoperative results (interface compatibility and stability, and operating time); and perioperative complications (total blood loss, blood transfusion rate, and deep venous thrombosis) were recorded and analyzed. Clinical improvement and functional evaluation (survivorship of implant, improvement of Hospital for Special Surgery Score and McMaster Universities Osteoarthritis Index, and improvement of range of motion [ROM]), and radiographic improvement and implant evaluation (progressive radiolucent lines or radiographic loosening, and mechanical alignment) were evaluated at 2 weeks, 6 weeks, 3 months, 6 months, 1 year, 2 years, and then annually, postoperatively.

Results

The mean age at diagnosis was 68 (61–77) years. The mean follow‐up was 25.3 (19–36) months. At the latest follow‐up, no aseptic loosening, prosthetic joint infection, or other complications were noted. The mean Hospital for Special Surgery Score increased from 49 (39–63) to 78 (70–83) (P < 0.01), whereas the mean Western Ontario and McMaster Universities Osteoarthritis Index increased from 59 (46–73) to 26 (12–38) (P < 0.01). All patients achieved improved postoperative ROM with the mean flexion angle increasing from 66° (30°–80°) to 93° (80°–100°), and improved mechanical alignment with all hip–knee–ankle (HKA) angles within ±3°.

Conclusions

The patient‐customized 3D‐printed metaphyseal cone is useful technique for reconstructing massive proximal tibial bone defects, with encouraging clinical and radiological outcomes in RTKA.

Additive Manufacturing in Orthopedics: A Review

Additive manufacturing is an advanced manufacturing manner that seems like the industrial revolution. It has the inborn benefit of producing complex formations, which are distinct from traditional machining technology. Its manufacturing strategy is flexible, including a wide range of materials, and its manufacturing cycle is short. Additive manufacturing techniques are progressively used in bone research and orthopedic operation as more innovative materials are developed. This Review lists the recent research results, analyzes the strengths and weaknesses of diverse three-dimensional printing strategies in orthopedics, and sums up the use of varying 3D printing strategies in surgical guides, surgical implants, surgical predictive models, and bone tissue engineering. Moreover, various postprocessing methods for additive manufacturing for orthopedics are described.

Technique tip: 3D printing surgical guide for pes cavus midfoot osteotomy

BACKGROUND

Pes cavus can be defined as an abnormal elevation of the longitudinal arches, which is often secondary to a muscle imbalance. This deformity affects the foot's three dimensions (3D) and our osteotomies are usually planned on a lateral (two-dimension) X-ray. Are we really considering all the spatial components of the deformity? The aim of this study is to present a technique tip to identify the apical plane of the pes cavus deformity and perform a midfoot dorsal-based wedge resection osteotomy by using customized 3D printed surgical guides.

METHODS

Three patients underwent the presented technique, all for the indication of symptomatic neuromuscular pes cavus with both anterior and posterior deformity.

RESULTS

3D-printed patient-specific guides help the surgeon to minimize human error, improving intraoperative accuracy, while reducing surgical time and intraoperative X-ray exposure.

CONCLUSIONS

Closing wedge midfoot osteotomy to correct anterior pes cavus may be an interesting indication to use customized 3D printed surgical guides.

Novel robotic technology for the rapid intraoperative manufacture of patient-specific instrumentation allowing for improved glenoid component accuracy in shoulder arthroplasty: a cadaveric study

BACKGROUND

Accurate prosthesis placement in arthroplasty is an important factor in the long-term success of these interventions. Many types of guidance technology have been described to date often suffering from high costs, complex theater integration, time inefficiency, and problems with day-to-day usability. We present a novel, intraoperative robotics platform, capable of rapid, real-time manufacture of low-cost patient-specific guides while overcoming many of the issues with existing approaches.

METHODS

A prototype robotics platform was assessed in a 24-specimen cadaveric trial during sequential simulated shoulder arthroplasty procedures. The platform consisted of a tableside robot with sterile drapes and sterile disposable components. The robot itself comprised a 3D optical scanner, a 3-axis sterile robotic drill, and a 2-axis receptacle into which the disposable consumables were inserted. The consumable was composed of a region of rapidly setting moldable material and a clip allowing it to be reversibly attached to the robot. Computed tomographic (CT) imaging was obtained for all cadaveric specimens, and a surgical plan was created focusing on glenoid component position-specifically, guidewire position to allow for accurate glenoid preparation before implant insertion. Intraoperatively, for every specimen, the relevant osseous anatomy was exposed and humeral and glenoid preparation undertaken in the usual manner. The sterile disposable was used to create a mold of the joint surface. Once set, the mold was inserted into the robot and an optical scan of the surface was undertaken followed by automatic surface registration with the CT data and surgical plan. An automatic guide hole was subsequently drilled into the molded blank, which was removed from the robot and placed back into the patient, with the melded surface ensuring exact replacement. The guidewire was then driven through the guide hole in accordance with the preoperative plan.

RESULTS

The novel robotic platform achieved average angular accuracies of 1.9° (standard deviation [SD] 1.3) version and 1.2° (SD 0.7) inclination with positional accuracy of 1.1 mm (SD 0.7) compared to a preoperative plan.

DISCUSSION

We have described a novel robotics platform that is able to reliably produce patient-specific intraoperative guides to allow for accurate guidewire placement. Guidance is provided using a portable intraoperative device. The results suggest achieved accuracy levels may be equivalent to those seen in other existing guidance technologies; however, eventual in vivo trials and analysis is required. This technology has potential transferability to improve accuracy in other areas of arthroplasty.

Teaching Radial Endobronchial Ultrasound with a Three-Dimensional–printed Radial Ultrasound Model

Background

Peripheral pulmonary lesion (PPL) incidence is rising because of increased chest imaging sensitivity and frequency. For PPLs suspicious for lung cancer, current clinical guidelines recommend tissue diagnosis. Radial endobronchial ultrasound (R-EBUS) is a bronchoscopic technique used for this purpose. It has been observed that diagnostic yield is impacted by the ability to accurately manipulate the radial probe. However, such skills can be acquired, in part, from simulation training. Three-dimensional (3D) printing has been used to produce training simulators for standard bronchoscopy but has not been specifically used to develop similar tools for R-EBUS.

Objective

We report the development of a novel ultrasound-compatible, anatomically accurate 3D-printed R-EBUS simulator and evaluation of its utility as a training tool.

Methods

Computed tomography images were used to develop 3D-printed airway models with ultrasound-compatible PPLs of “low” and “high” technical difficulty. Twenty-one participants were allocated to two groups matched for prior R-EBUS experience. The intervention group received 15 minutes to pretrain R-EBUS using a 3D-printed model, whereas the nonintervention group did not. Both groups then performed R-EBUS on 3D-printed models and were evaluated using a specifically developed assessment tool.

Results

For the “low-difficulty” model, the intervention group achieved a higher score (21.5 ± 2.02) than the nonintervention group (17.1 ± 5.7), reflecting 26% improvement in performance (P = 0.03). For the “high-difficulty” model, the intervention group scored 20.2 ± 4.21 versus 13.3 ± 7.36, corresponding to 52% improvement in performance (P = 0.02). Participants derived benefit from pretraining with the 3D-printed model, regardless of prior experience level.

Conclusion

3D-printing can be used to develop simulators for R-EBUS education. Training using these models significantly improves procedural performance and is effective in both novice and experienced trainees.

Mid- and Long-Term Follow-Up Efficacy Analysis of 3D-Printed Interbody Fusion Cages for Anterior Cervical Discectomy and Fusion

OBJECTIVE

To evaluate the safety and stability of 3D-printed interbody fusion cages (3D-printed cages) in anterior cervical discectomy and fusion (ACDF) by investigating the mid- and long-term follow-up outcomes.

METHODS

In this prospective study, the clinical data of 30 patients with CSM admitted to the Second Hospital of Shanxi Medical University from May 2012 to May 2014 were analyzed. The cohort comprised 18 males and 12 females with an average age of 60.22 ± 3.2 years. All patients were examined by X-ray, CT and MRI before the operation. A total of 30 cases of CSM were treated by ACDF with 3D printed cage implantation. Mid- and long-term follow-ups were performed after the surgery. Clinical efficacy was evaluated by comparing the JOA score, SF-36 score, change in neurological function, cervical curvature index (CCI), vertebral intervertebral height (VIH) and fusion rate before the operation, 6 months after the operation, and at the last follow-up.

RESULTS

Two of the 30 patients were lost to follow-up. The remaining patients were followed up for 48-76 (65.23 ± 3.54) months. The patients recovered satisfactorily with a significant clinical effect. The JOA score increased meanfully and the improvement rate was 89.4% at the final follow-up. The SF-36 score increased significantly from pre- to postoperatively. The height of the intervertebral space at the last follow-up was not statistically significantly different from that at 6 months after surgery (P > 0.05), showing that the height of the intervertebral space did not change much and the severity of cage subsidence (CS) decreased. The CCI improved from pre- to postoperatively. The CCI did not change much from the 6-month follow-up to the last follow-up. and the cage rate (CR) was 100% at the 6-month and last follow-ups. No severe complications, such as spinal cord injury, esophageal fistula, cerebrospinal fluid leakage, cervical hematoma or wound infection, occurred in any of the patients.

CONCLUSION

The clinical and radiological results show that the application of 3D-printed cages in ACDF can significantly relieve symptoms. Moreover, 3D-printed cages can restore the curvature of the cervical spine, effectively maintain the intervertebral height for a long time, and prevent complications related to postoperative subsidence.

Computer Assisted Surgery and 3D Printing in Orthopaedic Oncology: A Lesson Learned by Cranio-Maxillo-Facial Surgery

Primary bone sarcomas are rare tumors and surgical resection in combination with chemo and radiation therapy is the mainstay of treatment. Some specific anatomical sites still represent a reconstructive challenge due to their complex three-dimensional anatomy. In recent years, patient specific instruments along with 3D printing technology has come to represent innovative techniques in orthopaedic oncology. We retrospectively reviewed 23 patients affected by primary bone sarcoma treated with patient-specific instruments and 3D printing custom made prostheses. At follow up after approximately two years, the infection rate was 26%, mechanical complication rate 13%, and local recurrence rate 13% (with a five-years implant survival rate of 74%). Based on our experience, patient-specific instruments and 3D custom-made prostheses represents a reliable and safe technique for improving the accuracy of resection of primary bone tumour, with a particular use in pelvic surgery ameliorating functional results.

Does vaporized hydrogen peroxide sterilization affect the geometrical properties of anatomic models and guides 3D printed from computed tomography images?

Background

Material extrusion is used to 3D print anatomic models and guides. Sterilization is required if a 3D printed part touches the patient during an intervention. Vaporized Hydrogen Peroxide (VHP) is one method of sterilization. There are four factors to consider when sterilizing an anatomic model or guide: sterility, biocompatibility, mechanical properties, and geometric fidelity. This project focuses on geometric fidelity for material extrusion of one polymer acrylonitrile butadiene styrene (ABS) using VHP.

Methods

De-identified computed tomography (CT) image data from 16 patients was segmented using Mimics Innovation Suite (Materialise NV, Leuven, Belgium). Eight patients had maxillary and mandibular defects depicted with the anatomic models, and eight had mandibular defects for the anatomic guides. Anatomic models and guides designed from the surfaces of CT scan reconstruction and segementation were 3D printed in medical-grade acrylonitrile butadiene styrene (ABS) material extrusion. The 16 parts underwent low-temperature sterilization with VHP. The dimensional error was estimated after sterilization by comparing scanned images of the 3D printed parts.

Results

The average of the estimated mean differences between the printed pieces before and after sterilization were − 0,011 ± 0,252 mm (95%CI − 0,011; − 0,010) for the models and 0,003 ± 0,057 mm (95%CI 0,002; 0,003) for the guides. Regarding the dimensional error of the sterilized parts compared to the original design, the estimated mean differences were − 0,082 ± 0,626 mm (95%CI − 0,083; − 0,081) for the models and 0,126 ± 0,205 mm (95%CI 0,126, 0,127) for the guides.

Conclusion

This project tested and verified dimensional stability, one of the four prerequisites for introducing vaporized hydrogen peroxide into 3D printing of anatomic models and guides; the 3D printed parts maintained dimensional stability after sterilization.

A Parametric Tool for Studying a New Tracheobronchial Silicone Stent Prototype: Toward a Customized 3D Printable Prosthesis

The management of complex airway disorders is challenging, as the airway stent placement usually results in several complications. Tissue reaction to the foreign body, poor mechanical properties and inadequate fit of the stent in the airway are some of the reported problems. For this reason, the design of customized biomedical devices to improve the accuracy of the clinical results has recently gained interest. The aim of the present study is to introduce a parametric tool for the design of a new tracheo-bronchial stent that could be capable of improving some of the performances of the commercial devices. The proposed methodology is based on the computer aided design software and on the finite element modeling. The computational results are validated by a parallel experimental work that includes the production of selected stent configurations using the 3D printing technology and their compressive test.

Comparative accuracy of lower limb bone geometry determined using MRI, CT, and direct bone 3D models

Advancements in imaging and segmentation techniques mean that three dimensional (3D) modeling of bones is now increasingly used for preoperative planning and registration purposes. Computer tomography (CT) scans are commonly used due to their high bone-soft tissue contrast, however they expose subjects to radiation. Alternatively, magnetic resonance imaging (MRI) is radiation-free: however, geometric field distortion and poor bone contrast have been reported to degrade bone model validity compared to CT. The present study assessed the accuracy of 3D femur and tibia models created from "Black Bone" 3T MRI and high resolution CT scans taken from 12 intact cadaveric lower limbs by comparing them with scans of the de-fleshed and cleaned bones carried out using a high-resolution portable compact desktop 3D scanner (Model HDI COMPACT C210; Polyga). This scanner used structured light (SL) to capture 3D scans with an accuracy of up to 35 μm. Image segmentation created 3D models and for each bone the corresponding CT and MRI models were aligned with the SL model using the iterative closest point (ICP) algorithm and the differences between models calculated. Hausdorff distance was also determined. Compared to SL scans, the CT models had an ICP error of 0.82 ± 0.2 and 0.85 ± 0.2 mm for the tibia and femur respectively, whilst the MRI models had an error of 0.97 ± 0.2 and 0.98 ± 0.18 mm. A one-way analysis of variance found no significant difference in the Hausdorff distances or ICP values between the three scanning methods (p > .05). The black bone MRI method can provide accurate geometric measures of the femur and tibia that are comparable to those achieved with CT. Given the lack of ionizing radiation this has significant benefits for clinical populations and also potential for application in research settings.

3D Printing of Physical Organ Models: Recent Developments and Challenges

Physical organ models are the objects that replicate the patient-specific anatomy and have played important roles in modern medical diagnosis and disease treatment. 3D printing, as a powerful multi-function manufacturing technology, breaks the limitations of traditional methods and provides a great potential for manufacturing organ models. However, the clinical application of organ model is still in small scale, facing the challenges including high cost, poor mimicking performance and insufficient accuracy. In this review, the mainstream 3D printing technologies are introduced, and the existing manufacturing methods are divided into "directly printing" and "indirectly printing", with an emphasis on choosing suitable techniques and materials. This review also summarizes the ideas to address these challenges and focuses on three points: 1) what are the characteristics and requirements of organ models in different application scenarios, 2) how to choose the suitable 3D printing methods and materials according to different application categories, and 3) how to reduce the cost of organ models and make the process simple and convenient. Moreover, the state-of-the-art in organ models are summarized and the contribution of 3D printed organ models to various surgical procedures is highlighted. Finally, current limitations, evaluation criteria and future perspectives for this emerging area are discussed.

Assisting Difficult Liver Operations Using 3D Printed Models

Liver cancer is estimated to be the fifth most common in the world, while it is also considered the third leading cause of cancer death. In cases of primary liver cancer, surgery in combination with chemotherapy and radiotherapy can lead to a complete cure or significantly increase the patient’s life expectancy. Since the liver is an organ that performs several critical functions in the human body, the precise estimation of the disease (position and size of tumors and its vicinity to vessels) plays a vital role in a successful operation. In some cases, the removal of the tumor may be successful, but the percentage of the hepatic remnant may not be sufficient to sustain life. Therefore, accurate imaging of the tumor of the liver and proper planning of a difficult surgery to remove tumor(s) from a patient’s liver can be a lifesaver and lead to a complete cure of the disease. The aim of the present study is the initial accurate representation of the liver (parenchyma, tumors, vessels) as a digital three-dimensional (3D) model using advanced image processing and machine learning techniques and its 3D printing in 1:1 scale representing the full size of the liver with the tumor(s). A model of this type has been used at our University surgical department to plan complex hepatobiliary surgeries, provide more accurate information to the patients and their families, as well as improve the training of medical students and resident surgeons and fellows.

Bone density optimized pedicle screw instrumentation improves screw pull-out force in lumbar vertebrae

Pedicle screw instrumentation is performed in the surgical treatment of a wide variety of spinal pathologies. A common postoperative complication associated with this procedure is screw loosening. It has been shown that patient-specific screw fixation can be automated to match standard clinical practice and that failure can be estimated preoperatively using computed tomography images. Hence, we set out to optimize three-dimensional preoperative planning to achieve more mechanically robust screw purchase allowing deviation from intuitive, standard screw parameters. Toward this purpose, we employed a genetic algorithm optimization to find optimal screw sizes and trajectories by maximizing the CT derived bone mechanical properties. The method was tested on cadaveric lumbar vertebrae (L1 to L5) of four human spines (2 female/2 male; age range 60-78 years). The main boundary conditions were the predefined, level-dependent areas of possible screw entry points, as well as the automatically located pedicle structures. Finite element analysis was used to compare the genetic algorithm output to standard clinical planning of screw positioning in terms of the simulated pull-out strength. The genetic algorithm optimization successfully found screw sizes and trajectories that maximize the sum of the Young's modulus within the screw's volume for all 40 pedicle screws included in this study. Overall, there was a 26% increase in simulated pull-out strength for optimized compared to traditional screw trajectories and sizes. Our results indicate that optimizing pedicle screw instrumentation in lumbar vertebrae based on bone quality measures improves screw purchase as compared to traditional instrumentation.

3D Printing for Cardiovascular Applications: From End-to-End Processes to Emerging Developments

3D printing as a means of fabrication has seen increasing applications in medicine in the last decade, becoming invaluable for cardiovascular applications. This rapidly developing technology has had a significant impact on cardiovascular research, its clinical translation and education. It has expanded our understanding of the cardiovascular system resulting in better devices, tools and consequently improved patient outcomes. This review discusses the latest developments and future directions of generating medical replicas ('phantoms') for use in the cardiovascular field, detailing the end-to-end process from medical imaging to capture structures of interest, to production and use of 3D printed models. We provide comparisons of available imaging modalities and overview of segmentation and post-processing techniques to process images for printing, detailed exploration of latest 3D printing methods and materials, and a comprehensive, up-to-date review of milestone applications and their impact within the cardiovascular domain across research, clinical use and education. We then provide an in-depth exploration of future technologies and innovations around these methods, capturing opportunities and emerging directions across increasingly realistic representations, bioprinting and tissue engineering, and complementary virtual and mixed reality solutions. The next generation of 3D printing techniques allow patient-specific models that are increasingly realistic, replicating properties, anatomy and function.

3D printed rodent skin-skull-brain model: A novel animal-free approach for neurosurgical training

In neuroscience, stereotactic brain surgery is a standard yet challenging technique for which laboratory and veterinary personnel must be sufficiently and properly trained. There is currently no animal-free training option for neurosurgeries; stereotactic techniques are learned and practiced on dead animals. Here we have used three-dimensional (3D) printing technologies to create rat and mouse skin-skull-brain models, specifically conceived for rodent stereotaxic surgery training. We used 3D models obtained from microCT pictures and printed them using materials that would provide the most accurate haptic feedback for each model—PC-ABS material for the rat and Durable resin for the mouse. We filled the skulls with Polyurethane expanding foam to mimic the brain. In order to simulate rodent skin, we added a rectangular 1mm thick clear silicone sheet on the skull. Ten qualified rodent neurosurgeons then performed a variety of stereotaxic surgeries on these rat and mouse 3D printed models. Participants evaluated models fidelity compared to cadaveric skulls and their appropriateness for educational use. The 3D printed rat and mouse skin-skull-brain models received an overwhelmingly positive response. They were perceived as very realistic, and considered an excellent alternative to cadaveric skulls for training purposes. They can be made rapidly and at low cost. Our real-size 3D printed replicas could enable cost- and time-efficient, animal-free neurosurgery training. They can be absolute replacements for stereotaxic surgery techniques practice including but not limited to craniotomies, screw placement, brain injections, implantations and cement applications. This project is a significant step forward in implementing the replacement, reduction, and refinement (3Rs) principles to animal experimentation. These 3D printed models could lead the way to the complete replacement of live animals for stereotaxic surgery training in laboratories and veterinary studies.

PolliRS: A 3D-printed Pollicization Retractor System that Improves Access and Autonomy during the Surgical Procedure

We demonstrate the design, manufacture, and deployment of the first custom-made 3-dimensional (3D)-printed hand retractor for the pollicization procedure. Radiological images of the patient’s hand were taken preoperatively to measure anatomical dimensions and guide the design of the device in a patient-precise manner. The 3D-printed, sterilizable, device was autoclaved and successfully used on a patient that underwent a pollicization procedure in our unit. The radiolucency of the device and the fluency enabled by the ability to exchange between different positions demonstrated the potential of this device in increasing the overall autonomy afforded to the lead-surgeon during the operation and demonstrated the potential of rapid-prototyping techniques such as 3D printing for producing patient-precise tools on-the-fly that taken account the specific needs of the patient.