Three-dimensional printing a process

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Introduction:

Three-dimensional printing a process in which a physical model is constructed by laying down layers that is transferred from the Computer aided design to the 3d printer, also known as additive manufacturing and rapid prototyping. (Cohen, Laviv et al. 2009, Rengier, Mehndiratta et al. 2010, Hoy 2013)

Three-dimensional printing a process. This concept was first introduced in 1984 when Chuck Hull invented a process called stereolithography, in which the layers are added on top of each other’s by a curing photopolymers along with UV lasers (Hull 1986). Since then it went through major advancement worldwide, and hold importance in different fields including the medical field. The growing market for 3D desktop printers give rise to extensive research in that field; Three-dimensional printing a process the medical application may include: surgical planning, prosthesis, implanted structure, medical education and other applications.

Extensive research facilities trying to investigate the possibility 3d printing carry in the field of organogenesis; in which replacing damaged organs/tissue might be achieved to face organs damage caused by diseases and the shortage of organs needed for transplantation.

In this review paper, we aim to discuss the current application of 3D printing in the surgical field, Three-dimensional printing a process along with future perspective of this tool and how it affects the surgery practice

Different types of 3d printers:
Since first introduced, 3d printers went into a huge developments in the past three decades, different types of 3d printers were manufactured, depending on the uses, materials and accuracy.
Recently, range of developers and company urges to market the concept of the desktop 3d printers branding it as the new personal computers revolution, since then a huge development in that field was addressed to attract the consumers with a highly competitive atmosphere between all developers; medium sized companies and huge ones.
While desktop printers ranging from home assembled parts or 200 dollars to 3000 dollars the professional 3d printer unit can be expensive and could cost more than 500.000.000 dollars in price.
In the table below we aim to introduce a quick comparison between the most prominent 3d printer’s types,  Three-dimensional printing a process how it works, advantages, disadvantages, materials of each printers for better understanding of the 3d printing process.

Type Mechanism Advantages Disadvantages Material Other
SLA UV light is used to create the object by curing and solidifying a liquid resin. • High resolution prototypes

• Good finishing at the surface • Support structure is needed.

• Require post curing Resin; a curable laser photopolymer
Or other plastic like products. Layer thickness:
0.05~0.2mm
SLS laser fuses the layers of a powder material • Ability to produce complex/functional parts.

• Doesn’t require support structure

• High productivity • Surface finish is rough Plastic, nylon, polystyrene, metals; steel, titanium,
And composites.
Layer thickness: 0.06 – 0.10 – 0.12 – 0.15 – 0.18 mm
FDM Extruding small breads of the melted plastic material which harden after. • No post curing

• Easy material changeover

• Low cost machines compared to other • Slow processing especially on large parts.

• Low detailing accuracy

• Low surface finish integrity Filament of thermoplastic polymer; ABS, PLA. Layer thickness:
0.15-0.25mm (adjustable)

DLP DLP projector project the light into in a repetitive process • Good resolution

• Fast processing time • Support structure is needed.
Liquid resin Accuracy: 139µ
INKJET Spraying liquid or photopolymer depending on the type of the jetting; binder or material • Variety of material choice
• High precision
• Colored parts • Require post curing Plastic, metal And ceramics. Layer thickness:
Material: 0.013 mm (min)
Binder:
0.09 mm (min)

Methodology

Literature was searched through PubMed using keyword “3d printing” “surgery” “implantation” “education” “planning” “plastic and reconstructive” 146 papers were found, exclusion criteria was; papers not in English, papers in animals, papers before 10 years, and not full text papers, inclusion criteria was; original paper, Three-dimensional printing a process 80 paper were excluded, 66 remaining papers were evaluated. Papers included resemble the most relevant study data to our review.

Surgical planning:
As a part of any surgical intervention planning is a very important step in which the surgeon and the whole treating team collaborate to plan a successful surgery, it’s the key for understanding the disease and apply the knowledge in the right manner, surgical planning gain a lot of advancement with the ongoing development of the imaging techniques which gave the surgeon better visualization and better understanding for the anatomy and pathology.
While the current practice might be adequate for surgical planning in some cases, other complex cases required better understanding which will lead to better results, lower complications, and less time of surgery,  Three-dimensional  printing with its capability to produce exact similar structure models of body organs give rise to research interest in the field of planning among different surgical specialties. Different centres around the worlds present cases in which a fabricated models was created from the imaging modalities through the computer aided design which was the printed in a 3d printer and planning procedure took place then by the treating team.

Cardiac surgery:
In a case presentation of 70 years old patient with extensive arteriosclerotic aneurysm reaching from the ascending aorta to the descending aorta the team decided to print a 3d model to evaluate how can that help taking the surgery option decision as the patient case was complicated and his comorbidities Includes: arterial hypertension and diabetes mellitus, Three-dimensional printing a process model was fabricated resembling the patient heart from CT scan processed images; decision was made to go for FET procedure and the treating team clearly stated that the model help them take the decision and also facilitated planning depth and diameter of the stent as well as the landing zone in the patient, although it might not be necessarily in each surgery it shows that it aided the planning in this complex case. 1

Other study was on two patients on the list for heart transplantation because of failing single ventricle repair and underwent medical and surgical intervention which were unsuccessful, the first patient was 2 years old boy with failing staged palliation of hypo plastic left heart syndrome, despite the surgical intervention he suffers from severe tricuspid regurgitation and heart failure, Three-dimensional printing a process the second patient was 14 years old girl with pulmonary atresia and hypo plastic right ventricle, shunt was done in the first month of her life followed by central shunt, she was doing well till she was admitted with signs of severe protein losing enteropathy and she was listed for heart transplantation also, 3d model of both patients hearts was fabricated using inkjet printer and it was sterilized and taken into the surgical theatre, the surgeon had the chance to develop the optimal approach and to anticipate the problems that might arise especially with the complex anatomy of the cases us they underwent more than one surgery in the past, Three-dimensional printing a process the team had the information about the special requirements and dimensions of the donor heart including the measurements of the inferior vena cava, pulmonary artery and aortic arch, that’s conclude that the use of 3d printing provided the surgeon with practical advantages of demonstrating exact anatomy of the patient prior to the surgery. 2

Case presentation of 70 years old patient with aortic valve stenosis for Transcatheter Valve Replacement is presented, a 3d model was fabricated using inkjet printer from the processed images from CT scans, intervention was stimulated with the flexible 3D model to anticipate the ease of the intervention, which according to the study maximizes surgical anticipation and may facilitate the decision of the size of the TAVI prosthesis. 3

Neuro surgery:
In the field of neurosurgery planning is very important as the area the surgeon dealing with is very sensitive, 3d printing is also part of this planning and neurosurgeons show interest in this tool, in a case presentation of 2 patients with lesions in the proximity of the motor cortex presents, 3d model was fabricated prior to the surgery from 3- tesla MRI images. The accuracy of these printed models were estimated both theoretically and by simulated phantom experiments with physical measurements and repeated MRI scan, 3d models gave the surgeons additional information can affect the entry point which may help in avoiding damage to eloquent cortical areas, more over the model gave a clear vision of both; depth and extension of the tumour, the models also can improve communication with the patient.

General surgery:
Small tumours in the liver which are candidate for surgery require adequate understanding of the structure, vascular branches and the decision that determine the area will be resected, in a case presentation of 2 cases with having synchronous multiple liver metastases in segments 2, 6, and 7
7 from rectal cancer, after chemotherapy treatment the tumour in the segment 2 was invisible by ultrasonography, MDCT was done and a 3d process images was created to fabricate a 3d model using technique stereo lithography after the production the surface was covered with support material which was washed later on and washed and coated with resin paint, the plan was carried out using that model which was segmentectomy of segment 2 with concomitant partial resection of segment 3 and posterior sectionectomy with concomitant resection of the dorsal segment of the anterior sector, resection was done successfully and result was confirmed by negative histologically margin, printing the model made the procedure easy and feasible, it also could be a good alternative especially when dealing with small tumours as the ultrasonography might be misleading because of probe angle which may give different vessels view. However cost of printing 70% scale liver was 420 U.S dollars approximately, and production speed which took 18 hours to print may be the limitations that needs improvement.

Plastic surgery:
In plastic and reconstructive surgery a good understanding of the defect and anatomical relations is crucial to achieve a better in excisional and reconstruction, in case presentation of 82 years old patient who underwent elective ankle replacement surgery complicated by wound dehiscence , infection and exposed prosthesis, after failing of serial debridement, patient was scheduled for soft tissue coverage with dead space filling, reconstruction with radial fore arm free flap was planned, computed tomographic angiography was done and 3d model was printed which enhances the understanding of the defect morphology and enabled hands on preoperative planning.

Another study includes 10 patients with different case presentations all candidates for osteoplastic flap surgery, three-dimensional model used to produce an onlay template of the frontal sinus and adjacent area is created using CT images, frontal sinus margins accurate up to a 5 mm range maximum, this method found to be consintetly accurate, osteoplastic flap margin within 1 mm of actual frontal sinus margin, although there is no data to compare this with the current mapping modalities, 3d model printing is likely more precise than the images showing in 2d like CT

Frontal sinus models and onlay templates in osteoplastic flap surgery

From previous studies along with other studies shown in table 2, its clear that a lot of the research and trails is going for 3d printing planning in the field of surgery, we will discuss these study limitations and future perspective in the discussion section.
Study title Authors Journal Objective of the study Year Result Conclusion
Three-Dimensional Printing for Perioperative
Planning of Complex Aortic Arch Surgery Daniel Schmauss, MD, Gerd Juchem, MD, Stefan Weber, Dr Ing,
Nicolas Gerber, Dr Ing, Christian Hagl, MD, and Ralf Sodian, MD The annals of thoracic surgery
• Evaluate the use of fabricated 3d model in surgical planning for a 70 years old patient with extensive
arteriosclerotic aneurysm reaching from the ascending
aorta to the descending aorta, patient’s comorbidities
Include: arterial hypertension and diabetes mellitus.

• The patient was referred for complete Aortic arch replacement. 2014 • Preoperative 3d model facilitated decision-making
process to perform a complex and high-risk FET
procedure

• The model facilitated planning
The depth and diameter of the stent as well as the landing zone in the patient.

• Not every patient undergoing aortic arch surgery is a
candidate for fabrication of stereo lithographic models Future studies
On higher scale of patients expected to show that stereo lithography
facilitates preoperative planning and decreases
the risk of complex aortic arch surgery.
Pediatric cardiac transplantation: Three-dimensional printing
of anatomic models for surgical planning of heart transplantation
in patients with univentricular heart Ralf Sodian, MD,a Stefan Weber, PhD,c Mathias Markert, MSc,c Markus Loeff, MD,b Tim Lueth, PhD,c Florian C. Weis, MD,a
Sabine Daebritz, MD,a Edward Malec, MD,a Christoph Schmitz, MD,a and Bruno Reichart, MD,a Munich and Garching, Germany The Journal of Thoracic and Cardiovascular Surgery • Evaluate the use of fabricated 3d model in surgical planning for 2 complicated cardiac paediatric cases for heart transplant 2008 • Develop the optimal surgical approach using the 3d fabricated models
• Anticipate the problems might face the surgeon
• Better understanding of the complex anatomy after multiple surgeries patients underwent The use of 3d printing provided the surgeon with practical advantages of demonstrating exact anatomy of the patient prior to the surgery.
Study title Authors Journal Objective of the study Year Result Conclusion
Three-Dimensional Printing of
Models for Preoperative Planning
and Simulation of Transcatheter
Valve Replacement Daniel Schmauss, MD, Christoph Schmitz, MD,
Amir Koshrow Bigdeli, MD, Stefan Weber, Dr-Ing,
Nicholas Gerber, MS, Andres Beiras-Fernandez, MD,
Florian Schwarz, MD, Christoph Becker, MD,
Christian Kupatt, MD, and Ralf Sodian, MD The annals of thoracic surgery Evaluate the use of fabricated 3d model in surgical planning for Transcatheter
Valve Replacement 2012 • maximizes surgical anticipation of problems

• may facilitate the decision concerning the
size of the TAVI prosthesis.

• Know exact position of crucial structure Use of the model not expected to change the basic surgical plan.

3D-model help us understand that extremely calcified aortic
root and sinus of Valsalva became small, inelastic, and
stiff. positive result may be achieved by deep implantation without occluding
the whole sinus of Valsalva

Three-dimensional printing of models for surgical planning in
patients with primary cardiac tumors Daniel Schmauss, MD,a Nicolas Gerber, MSc,b and Ralf Sodian, MDa The Journal of Thoracic and Cardiovascular Surgery Evaluate the use of fabricated 3d model in surgical planning in cardiac tumour surgery 2013 3d models may be helpful tool for
preoperative decision planning of surgical
intervention lead to better understanding position and infiltration of the cardiac tumour into cardiac
tissue especially when imaging modalities MRI, CT and echocardiography are insufficient.

3d printing model provides surgeons and interventionists with both theoretical and practical advantages
treating complex
pathology in cardiac surgery

Study title Authors Journal Objective of the study Year Result Conclusion
Preoperative three-dimensional model creation of magnetic resonance brain images as a tool to assist neurosurgical planning. Spottiswoode BS1, van den Heever DJ, Chang Y, Engelhardt S, Du Plessis S, Nicolls F, Hartzenberg HB, Gretschel A.
Stereotact Funct Neurosurg
Evaluate the use of fabricated 3d model in surgical planning for 2 cases of patients with lesions in the proximity of the motor cortex 2013 • 3d models gave the surgeons additional information can affect the entry point to avoid
• gave a clear vision of both; depth and extension of the tumour
• Improve communication with the patient. 3d models accuracy for brain surgery was acceptable; with a mean dimensional error of 0.5mm and this may be good tool for surgical training and planning
Application of a Three-dimensional Print of a Liver
in Hepatectomy for Small Tumours Invisible by Intraoperative
Ultrasonography: Preliminary Experience Tsuyoshi Igami Yoshihiko Nakamura
Tomoaki Hirose Tomoki Ebata Yukihiro Yokoyama
Gen Sugawara Takashi Mizuno
Kensaku Mori Masato Nagino World Journal of Surgery Evaluate the use of fabricated 3d model in surgical planning for 2 cases of patients with synchronous multiple liver metastases small tumours after receiving chemotherapy and compare that to ultrasonography 2014 • the plan was carried out using that 3d printing model

• 3d printing may be a good alternative for ultrasonography as it might be misleading due to probe handling
3d printed models for small tumours aid the surgery and made it easy and feasible, Three-dimensional printing a process however cost reduction, speed of production and automation of the post production steps are the current limitations.
3d printing haptic “reverse” model for preoperative planning in soft tissue reconstruction; a case report Chae MP1, Lin F, Spychal RT, Hunter-Smith DJ, Rozen WM
Journal of microsurgery Evaluate the use of fabricated 3d model in surgical planning for soft tissue reconstruction 2014 3d model enhances the understanding of the defect morphology

The model help preoperative planning Surgical outcomes might be improved using 3d models compared to current 2d imaging modalities
Frontal sinus models and onlay templates in osteoplastic flap surgery M Daniel, J Watson,
E Hoskison and A Sama The Journal of Laryngology & Otology Evaluate the use of the fabricated 3d model in surgery for frontal sinus mapping 2011 • These models where consistently accurate to within 1 mm
• 3d model printing is likely more precise than the images showing in 2d like CT 3d models can be used intra-operatively as an only guide to map frontal sinus mapping. comparison with other mapping techniques is needed

B. Surgical instruments printing:
Surgical instrument cost and handling is an important issue in the surgical field, with advancement in 3d printing a new era of printing these instrument may have a potential benefit on different aspects; printing patient-specific instruments, cost reduction of current instruments used in surgery and availability of instruments in less developed areas and in conflict zones, in a study navy retractor was printed using FDM printer, sterility was tested and mechanical strength of the instrument was also tested and it tolerates 11.3+0.57 kg and breaks at 15.9+0.8 kg, printing time was 90 minutes only, 1 kg of PLA material cost 27 dollars and can produce 61 costume retractor which is 1/10 compared to the current stainless steel.

C. Surgical education:
Surgical resident exposure to different cases along with understanding the exact anatomical help better education environment, it is also important on the level of medical student to understand different pathologies and anatomical variation demonstrated in a clear manner, recently 3d printing was an area of interest in that field also, to help better understanding of patients condition and anatomical variation on a 3d model rather than 3d image on a flat 2d screen. In a study a 3d models of portal veins and hepatic veins was created by Current selective laser sintering technique from images of CT and MRI, cost was less than $100 per model, these models have the privilege to be patient specific in which it can be used to teach the residents and medical students on the surgical intervention and it’s also as a physical model easier than easier than imaging which needs knowledge in the way to interpretation. As dissection is more beneficial than passive observation that example of hands on experience may be applied here too.

Another example is printing anomalies in the heart like VSD, in a study a model of each type of the 5 common VSD was fabricated using poly jet 3d printer from MRI images, these module was demonstrated in a session for students and a pre and post session assessment questionnaire was given, results were as follows: the knowledge acquisition result on a scale of 1-10 was 3.22 before the seminar and 7.02 after the seminar, knowledge reporting was 2.16 before the seminar and 6.60 after the seminar and structural conceptualization was 2.17 before the seminar and 6.31 after the seminar, (P value < .0001)

Study title Authors Journal Objective of the study Year Result Conclusion
A Low-Cost Surgical Application of Additive Fabrication Robert A. Watson, MD Journal of Surgical Education Evaluate the use of 3d printing models in surgical education for residents and medical students 2014 • Patient specific 3d models can be used to teach the residents and medical students on the surgical intervention

• As a physical model it’s; unlike CT & MRI doesn’t need imaging interpretation skills

• Hands on experience superior to observation 3d models may have a value in education applications with a great potential in intra-abdominal and intra-thoracic anatomical & surgical education
Utilizing three-dimensional printing technology to assess the feasibility of high-fidelity synthetic ventricular septal defect models for simulation in medical education Costello JP, Olivieri LJ, Krieger A, Thabit O, Marshall MB, Yoo SJ, Kim PC, Jonas RA, Nath DS.
World journal of paediatric congenital heart surgery

Evaluate the use of 3d printing models in medical education 2014 knowledge acquisition, knowledge reporting, structural conceptualization was significtally improved after the session with 3d models of different % common VSD types 3d printing is a feasible modality to use in medical education and it is a foundation for stimulation based education.

D: 3d printing for implants

What the ads of using alloplastic materials for medicine give brief description.

Are there not any more??
Implants are very important in medicine, in the variety of cases structure need to be replaced or repaired by an implant, in some cases, these implants are not available in the manufactures or it’s not suitable for the patient’s specific cases
In a study successful implant of airway stent was done, for a child born with tracheobronchomalacia which started to have chest retraction at age of 6 weeks but progressive deterioration happened at age of 2 months and require endotracheal intubation but that ventilation to prevent the cardiopulmonary arrests could not be maintained custom-fabricated resorbable polycaprolactone airway splint was printed by a 3d printer to provides resistance against collapse and to allow simultaneously flexion, extension, and expansion with the growth process, FDA approved the use of this implant under the emergency-use exemption, the implant was placed and bronchoscopy was done which revealed normal patency of the bronchus without collapse, 21 days after the procedure the ventilation was discounted, and in the 1 year postoperatively follow up imaging and endoscopy showed patent left mainstem bronchus, no complication was observed.
Bioresorbable Airway Splint Created with a Three-Dimensional Printer

In another case presentation of patients presented with no weight bearing maxillofacial deformities due to congenital anomalies, trauma and tumour resection, reconstruction was carried out using inkjet printer custom-made artificial bone (IPCAB) for both cases in this study; 55 years old lady with post-surgical facial deformity twenty years back she had partial resection of tongue, segmental osteotomy of mandible, reconstruction was done with skin flap and autologous costochondral graft. Preceded by autologous iliac bone graft due to resorption of costochondral graft, despite these treatments face deformity persisted and she was a candidate for the (IPCAB), another case was 23 years old gentleman with the deviation of the mandible with malocclusion which was treated by bilateral…