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Stereolithographic Models andImplants

Policy History

Last Review

11/27/2020

Effective: 05/10/2002

Next

Review: 07/08/2021

Review History

Definitions

Additional Information

Clinical Policy Bulletin

Notes

Number: 0613

Policy *Please see amendment forPennsylvaniaMedicaid

at the end of this CPB.

Aetna considers the use of three-dimensional (3D)

stereolithographic models in penile surface mold

brachytherapy, plastic and reconstructive surgery experimental

and investigational because such modeling has not been

proven to improve surgical outcomes.

Aetna considers 3D printed cranial implant experimental and

investigational because of insufficient evidence of its

effectiveness.

Aetna considers the use of 3D printing of anatomic structures

for pre-operative planning and other applications experimental

and investigational because of insufficient evidence of its

effectiveness.

Background

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Stereolithography is an industrial process that uses data

generated from computer-assisted design (CAD) to generate

three-dimensional (3-D) models. The data drives a laser over

a bath of photosensitive resin which produces a series of

stacked slices, which produce a 3-D industrial prototype or

model. This technique has been investigated in Europe, and

has been used primarily by maxillo-facial surgeons to produce

3-D representations of facial bony structures using data from

computed tomography (CT) or magnetic resonance

imaging scans.

Stereolithographic bio-models allow visualization of the facial

skeleton, and have been used in a number of particular clinical

situations involving bony facial deformities. These models

have been used in the diagnosis and treatment planning of

congenital, developmental and post-traumatic conditions

affecting the facial region.

In particular, the models are intended to assist the

maxillofacial surgeon in appreciating spatial displacements in

all three dimensions and to make accurate measurement of

the deformity. The surgeon is able to practice the surgery on

the model, and better determine the osteotomies and bone

grafts that are required to achieve the desired results.

Proponents argue that these models can reduce operating

room time and increase the accuracy of the surgical outcomes.

However, prospective clinical studies are needed to

demonstrate the value of stereolithographic modeling in plastic

and reconstructive surgery. The literature on

stereolithographic modeling in plastic and reconstructive

surgery is limited to case reports and discussions about the

feasibility of the technique. There are no prospective studies

demonstrating that the use of stereolithographic models

improves outcomes of plastic and reconstructive surgical

procedures. Based on the lack of prospective clinical studies

in the peer-reviewed published medical literature proving the

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value of stereolithographic modeling in plastic and

reconstructive surgery, stereolithographic modeling is

considered experimental and investigational.

As Clark and Park (2001) noted that 3-D stereolithographic

models may someday have an established place in surgical

planning and implant design in plastic and reconstructive

surgery. In a discussion of "future and controversies" in plastic

and reconstructive surgery, the authors stated that "[u]se of

stereolithography to aid in planning complex cases may

become the routine."

Kakarala et al (2006) discussed the use of stereolithographic

models in the assessment of new surgical techniques. The

authors explained that variable properties and limited

availability are pitfalls in using cadaveric bones for implant

stability tests. Artificial bones avoid these, but tailoring them to

specific studies may be difficult. Stereolithography (SLA)

techniques produce tailor-made bones with realistic

geometries, but their lower Young's modulus might affect

outcomes. These researchers investigated whether implant

stability and cortical strains with SLA made bones match those

with stiffer artificial bones and, if not, whether a thicker cortex

to compensate the lower modulus gives a better match. Tibial

trays were cemented in place and cyclically loaded while

determining cortical strain and tray migration. Permanent and

cyclic migration of trays in both types of SLA model (range

of 13 to 28 and 58 to 85 mum) was within the range of those in

composite models (range of 4 to 62 and 51 to 105 microm).

Strains more distally were approximately inversely proportional

to the material stiffness and cortical thickness of the tibiae.

The authors concluded that this first study provided a strong

indication for SLA tibiae as a valid model for the biomechanical

assessment of new techniques in knee surgery and compared

favorably with previously utilized models.

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Ozan et al (2009) stated that pre-surgical planning is essential

to achieve esthetic and functional implants. The goal of this

clinical study was to determine the angular and linear

deviations at the implant neck and apex between planned and

placed implants using SLA surgical guides. A total of 110

implants were placed using SLA surgical guides generated

from CT. All patients used the radiographical templates during

CT scanning. After obtaining 3-D CT scans, each implant

insertion was simulated on the CT images. Stereolithography

surgical guides by means of a rapid prototyping method

including a laser beam were used during implant insertion. A

new CT scan was made for each patient after implant

insertion. Special software was used to match images of the

planned and placed implants, and their positions and axes

were compared. The mean angular deviation of all placed

implants was 4.1 degrees +/- 2.3 degrees, whereas mean

linear deviation was 1.11 +/- 0.7 mm at the implant neck and

1.41 +/- 0.9 mm at the implant apex compared with the

planned implants. The angular deviations of the placed

implants compared with the planned implants were 2.91

degrees +/- 1.3 degrees, 4.63 degrees +/- 2.6 degrees, and

4.51 degrees +/- 2.1 degrees for the tooth-supported, bone-

supported, and mucosa-supported SLA surgical guides,

respectively. The authors concluded that the findings of this

study suggested that SLA surgical guides using CT data may

be reliable in implant placement, and tooth-supported SLA

surgical guides were more accurate than bone- or mucosa-

supported SLA surgical guides.

In a pilot study, Chen et al (2010) introduced a novel bone

tooth-combined-supported surgical guide, which is designed

by utilizing a special modular software and fabricated via SLA

technique using both laser scanning and CT imaging, thus

improving the fit accuracy and reliability. A modular pre

operative planning software was developed for computer-

aided oral implantology. With the introduction of dynamic link

libraries and some well-known free, open-source software

libraries such as Visualization Toolkit (Kitware, Inc., New York,

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NY) and Insight Toolkit (Kitware, Inc.) a plug-in evolutive

software architecture was established, allowing for

expandability, accessibility, and maintainability in the system.

To provide a link between the pre-operative plan and the

actual surgery, a novel bone-tooth-combined-supported

surgical template was fabricated, utilizing laser scanning,

image registration, and rapid prototyping. Clinical studies

were conducted on 4 partially edentulous cases to make a

comparison with the conventional bone-supported templates.

The fixation was more stable than tooth-supported templates

because laser scanning technology obtained detailed dentition

information, which brought about the unique topography

between the match surface of the templates and the adjacent

teeth. The average distance deviations at the coronal and

apical point of the implant were 0.66 mm (range of 0.3 to 1.2)

and 0.86 mm (range of 0.4 to 1.2), and the average angle

deviation was 1.84 degrees (range of 0.6 to 2.8). The authors

concluded that this pilot study proves that the novel combined-

supported templates are superior to the conventional ones.

However, more clinical cases will be conducted to demonstrate

their feasibility and reliability.

D'haese et al (2012) reviewed data on accuracy and surgical

and prosthodontical complications using stereolithographical

surgical guides for implant rehabilitation. Only papers in

English were selected. A dditional references found through

reading of selected papers completed the list. A total of 31

papers were selected; 10 reported deviations between the pre

operative implant planning and the post-operative implant

locations. One in-vitro study reported a mean apical deviation

of 1.0 mm; 3 ex-vivo studies reported a mean apical deviation

ranging between 0.6 and 1.2 mm. In 6 in-vivo studies, an

apical deviation between 0.95 and 4.5 mm was found. Six

papers reported on complications mounting to 42 % of the

cases when stereolithographic guided surgery was combined

with immediate loading. The authors concluded that

substantial deviations in 3-D directions were found between

virtual planning and actually obtained implant position. This

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finding and additionally reported post-surgical complications

leads to the conclusion that care should be taken whenever

applying this technique on a routine basis.

Ronca et al (2012) noted that the stereolithography process is

based on the photo-polymerization through a dynamic mask

generator of successive layers of photo-curable resin, allowing

the manufactory of accurate micro objects with high aspect

ratio and curved surfaces. In the present work, the

stereolithography technique is applied to produce nano

composite bioactive scaffolds from Computer Assisted Design

(CAD) files. Porous scaffolds are designed with computer

software and built with a composite poly(D,L-lactide)/nano

hydroxyapatite based resin. Triply-periodic minimal surfaces

are shown to be a more versatile source of biomorphic scaffold

designs and scaffolds with double-Gyroid architecture are

realized and characterized from morphological, mechanical

and biological point of view. The structures show excellent

reproduction of the design and good mechanical properties.

Human marrow mesenchymal cells (hMSC) are seeded onto

porous PDLLA composites for 3 weeks and cultured in

osteogenic medium. Presence of nano-hap seems to increase

the mechanical properties without affecting the morphology of

the structures. The composite double-Gyroid scaffolds exhibit

good biocompatibility and confirm that nano-hap enhances the

scaffold bioactive and osteo-conductive potential. The authors

concluded that the presented technology and materials enable

an accurate preparation of tissue engineering composite

scaffolds with a large freedom of design, and really complex

internal architectures. They stated that results indicated that

the scaffolds fulfill the basic requirements of bone tissue

engineering scaffold, and have the potential to be applied in

orthopedic surgery.

Morris and colleagues (2013) stated that stereolithographic

(SLA) models have become a resource in pre-operative

planning in maxillofacial reconstruction. These investigators

performed a defect specific analysis of the utility of SLA

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models. The goal was to determine the manner in which the

perceived benefit of pre-operative modeling translates to

measurable clinical advantages. Patients who underwent

reconstruction of defects of the mandible or mid-face using

SLA modeling between 2006 and 2011 were identified through

billing records. Based on the nature and extent of bony defect,

cases requiring nearly identical reconstruction, but without

modeling, were matched case-by-case for comparison. Given

the presumed efficiency of SLA modeling, a comparison of

total and reconstructive operative times was performed to see

if this could offset the cost of the model. There were 10

patients each in the "model" and "non-model" group. No

significant differences were observed for total operative time

between groups. Surprisingly, the total reconstructive time

was lower in the group not using SLA models (p = 0.05). The

authors concluded that SLA models provide several operative

planning advantages, but did not appear to decrease operative

time enough to sufficiently offset the cost of the model in this

group.

Chia et al (2015) stated that 3-D printing promises to produce

complex biomedical devices according to computer design

using patient-specific anatomical data. Since its initial use as

pre-surgical visualization models and tooling molds, 3-D

printing has slowly evolved to create one-of-a-kind devices,

implants, scaffolds for tissue engineering, diagnostic platforms,

and drug delivery systems. Fueled by the recent explosion in

public interest and access to affordable printers, there is

renewed interest to combine stem cells with custom 3-D

scaffolds for personalized regenerative medicine. These

investigators noted that before 3-D printing can be used

routinely for the regeneration of complex tissues (e.g., bone,

cartilage, muscles, vessels, nerves in the cranio-maxillo-facial

complex), and complex organs with intricate 3-D

microarchitecture (e.g., liver, lymphoid organs), several

technological limitations must be addressed. These

researchers reviewed the major materials and technology

advances within the last 5 years for each of the common 3-D

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printing technologies (Three Dimensional Printing, Fused

Deposition Modeling, Selective Laser Sintering,

Stereolithography, and 3D Plotting/Direct-Write/Bioprinting).

Examples were highlighted to illustrate progress of each

technology in tissue engineering, and key limitations were

identified to motivate future research and advance this

fascinating field of advanced manufacturing.

Lee and Cho (2015) noted that many researchers have

attempted to use computer-aided design (CAD) and computer-

aided manufacturing (CAM) to realize a scaffold that provides

a 3-D environment for regeneration of tissues and organs. As

a result, several 3-D printing technologies, including

stereolithography, deposition modeling, inkjet-based printing

and selective laser sintering have been developed. Because

these 3-D printing technologies use computers for design and

fabrication, and they can fabricate 3-D scaffolds as designed;

as a consequence, they can be standardized. Growth of

target tissues and organs requires the presence of appropriate

growth factors, so fabrication of 3-D scaffold systems that

release these biomolecules has been explored. A drug

delivery system (DDS) that administrates a pharmaceutical

compound to achieve a therapeutic effect in cells, animals and

humans is a key technology that delivers biomolecules without

side effects caused by excessive doses; 3-D printing

technologies and DDSs have been assembled successfully, so

new possibilities for improved tissue regeneration have been

suggested. The authors concluded that if the interaction

between cells and scaffold system with biomolecules can be

understood and controlled, and if an optimal 3-D tissue

regenerating environment is realized, 3-D printing technologies

will become an important aspect of tissue engineering

research in the near future.

Popescu and Laptoiu (2016) noted that SLA is a rapid

prototyping (RP) process used in the medical setting. These

investigators stated that there has been a lot of hype

surrounding the advantages of RP processes in a number of

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fields. They evaluated the effectiveness of patient-specific

surgical guides manufactured using RP in various orthopedic

surgical applications (e.g., bone tissue engineering). These

researchers performed a systematic review to identify and

analyze clinical and experimental literature studies in which

RP patient-specific surgical guides were used, focusing

especially on those that entailed quantifiable outcomes and, at

the same time, providing details on the guides' design and

type of manufacturing process. The authors stated that in this

field there are not yet medium- or long-term data, and no

information on revisions. In the reviewed studies, the reported

positive opinions on the use of RP patient-specific surgical

guides related to the following advantages: reduction in

operating times, low costs, and improvements in the accuracy

of surgical interventions. Moreover, they discussed

disadvantages and sources of errors that can cause patient-

specific surgical guide failures.

Yuan and colleagues (2017) stated that bone defects arising

from a variety of reasons cannot be treated effectively without

bone tissue reconstruction. Autografts and allografts have

been used in clinical application for some time, but they have

disadvantages. With the inherent drawback in the precision

and reproducibility of conventional scaffold fabrication

techniques, the results of bone surgery may not be ideal. This

is despite the introduction of bone tissue engineering that

provides a powerful approach for bone repair. Rapid

prototyping technologies have emerged as an alternative and

have been employed in bone tissue engineering, enhancing

bone tissue regeneration in terms of mechanical strength, pore

geometry, and bioactive factors, and overcoming some of the

disadvantages of conventional technologies. These

researchers focused on the basic principles and

characteristics of various fabrication technologies (e.g., SLA,

selective laser sintering, and fused deposition modeling) and

reviewed the application of RP techniques to scaffolds for

bone tissue engineering. The authors concluded that in the

near future, the use of scaffolds for bone tissue engineering

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prepared by RP technology might be an effective therapeutic

strategy for bone defects. Moreover, they noted that for further

development, RP-based 3D biochemical printing technology

and nanotechnology will be key in overcoming the

"development bottleneck". Ultimately, it is of great significance

to choose proper biomaterials, preparation processes, and

scaffold design. Bone tissue engineering will encounter

challenges in the innovation of materials and techniques,

optimization of scaffolds, treatment of interfaces, and

incorporation of biologically active factors.

Guillaume and associates (2017) noted that fabrication of

composite scaffolds using SLA for bone tissue engineering

has shown great promises. However, in order to trigger

effective bone formation and implant integration, exogenous

growth factors are commonly combined to scaffold materials.

These researchers fabricated biodegradable composite

scaffolds using SLA and endowed them with osteo-promotive

properties in the absence of biologics. First, these

investigators prepared photo-crosslinkable poly(trimethylene

carbonate) (PTMC) resins containing 20 and 40 wt% of

hydroxyapatite (HA) nanoparticles and fabricated scaffolds

with controlled macro-architecture. Then, they conducted

experiments to investigate how the incorporation of HA in photo

crosslinked PTMC matrices improved human bone marrow stem

cells osteogenic differentiation in-vitro and kinetic of bone

healing in-vivo. These investigators observed that bone

regeneration was significantly improved using composite

scaffolds containing as low as 20 wt% of HA, along with

difference in terms of osteogenesis and degree of implant

osseo-integration. Further investigations revealed that SLA

process was responsible for the formation of a rich microscale

layer of HA corralling scaffolds. The authors stated that this

work is of substantial importance as it showed how the

fabrication of hierarchical biomaterials via surface-enrichment

of functional HA nanoparticles in composite polymer

stereolithographic structures could impact in-vitro and in-vivo

osteogenesis.

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Lee and co-workers (2017) 3-D bio-printing is a rapidly

emerging technique in the field of tissue engineering to

fabricate extremely intricate and complex biomimetic scaffolds

in the range of micrometers. Such customized 3-D printed

constructs can be used for the regeneration of complex tissues

(e.g., cartilage, nerves, and vessels). However, the 3-D

printing techniques often offer limited control over the

resolution and compromised mechanical properties due to

short selection of printable inks. To address these limitations,

these researchers combined SLA and electro-spinning

techniques to fabricate a novel 3-D biomimetic neural scaffold

with a tunable porous structure and embedded aligned fibers.

By employing 2 different types of bio-fabrication methods,

these investigators successfully utilized both synthetic and

natural materials with varying chemical composition as bioink

to enhance biocompatibilities and mechanical properties of the

scaffold. The resulting microfibers composed of

polycaprolactone (PCL) polymer and PCL mixed with gelatin

were embedded in 3-D printed hydrogel scaffold. These

findings showed that 3-D printed scaffolds with electrospun

fibers significantly improved neural stem cell adhesion when

compared to those without the fibers. Furthermore, 3-D

scaffolds embedded with aligned fibers showed an

enhancement in cell proliferation relative to bare control

scaffolds. More importantly, confocal microscopy images

illustrated that the scaffold with PCL/gelatin fibers greatly

increased the average neurite length and directed neurite

extension of primary cortical neurons along the fiber. The

authors concluded that the findings of this study demonstrated

the potential to create unique 3-D neural tissue constructs by

combining 3-D bio-printing and electro-spinning techniques.

Channasanon and co-workers (2017) noted that porous

oligolactide-hydroxyapatite composite scaffolds were obtained

by stereolithographic fabrication. Gentamicin was then coated

on the scaffolds afterwards, to achieve anti-microbial delivery

ability to treat bone infection. The scaffolds examined by

stereomicroscope, SEM, and μCT-scan showed a well-ordered

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pore structure with uniform pore distribution and pore inter

connectivity. The physical and mechanical properties of the

scaffolds were examined. It was shown that not only porosity

but also scaffold structure played a critical role in governing

the strength of scaffolds. A good scaffold design could create

proper orientation of pores in a way to strengthen the scaffold

structure. The drug delivery profile of the porous scaffolds was

also analyzed using microbiological assay. The authors

concluded that the release rates of gentamicin from the

scaffolds showed prolonged drug release at the levels higher

than the minimum inhibitory concentrations for S. aureus and

E. coli over a 2-week period, indicating a potential of the

scaffolds to serve as local antibiotic delivery to prevent

bacterial infection.

Aisenbrey and associates (2018) stated that damage to

articular cartilage can over time cause degeneration to the

tissue surrounding the injury. To address this problem,

scaffolds that prevent degeneration and promote neo-tissue

growth are needed. A new hybrid scaffold that combines a

stereolithography-based 3D printed support structure with an

injectable and photo-polymerizable hydrogel for delivering

cells to treat focal chondral defects is introduced. In this proof

of concept study, the ability to (a) infill the support structure

with an injectable hydrogel precursor solution, (b) incorporate

cartilage cells during infilling using a degradable hydrogel that

promotes neo-tissue deposition, and (c) minimize damage to

the surrounding cartilage when the hybrid scaffold is placed in-

situ in a focal chondral defect in an osteochondral plug that is

cultured under mechanical loading is demonstrated. The

authors concluded that with the ability to independently control

the properties of the structure and the injectable hydrogel, this

hybrid scaffold approach holds promise for treating chondral

defects.

Anderson and colleagues (2018) noted that CAD and CAM

technologies can leverage cone beam CT data for production

of objects used in surgical and non-surgical endodontics and

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in educational settings. These investigators reviewed all

current applications of 3D printing in endodontics and

speculated upon future directions for research and clinical use

within the specialty. They performed a literature search of

PubMed, Ovid and Scopus using the following terms:

stereolithography, 3D printing, computer aided rapid

prototyping, surgical guide, guided endodontic surgery, guided

endodontic access, additive manufacturing, rapid prototyping,

auto-transplantation rapid prototyping, CAD, CAM. Inclusion

criteria were articles in the English language documenting

endodontic applications of 3D printing. A total of 51 articles

met inclusion criteria and were utilized. The endodontic

literature on 3D printing is generally limited to case reports and

pre-clinical studies. Documented solutions to endodontic

challenges include: guided access with pulp canal obliteration,

applications in auto-transplantation, pre-surgical planning and

educational modelling and accurate location of osteotomy

perforation sites. Acquisition of technical expertise and

equipment within endodontic practices present formidable

obstacles to widespread deployment within the endodontic

specialty. The authors concluded that as knowledge

advances, endodontic postgraduate programs should consider

implementing 3D printing into their curriculums. They stated

that future research directions should include clinical outcomes

assessments of treatments employing 3D printed objects.

Three-Dimensional (3-D) Printed Cranial Implant

On February 18, 2013, the Food and Drug Administration

(FDA) granted Performance Materials (OPM) 510(k) clearance

for the OsteoFab Patient Specific Cranial Device (OPSCD).

OsteoFab is OPM’s brand for "additively manufactured (also

called 3-D Printing)" medical and implant parts produced from

PEKK polymer.

On January 19, 2017, OssDsign AB (Uppsala, Sweden)

received FDA 510(k) marketing clearance for its 3-D printed

OssDsign Cranial PSI (patient-specific implant). The

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customized implant is indicated for non-load-bearing

applications to reconstruct cranial defects in adults for whom

cranial growth is complete and with an intact dura with or

without duraplasty. The OssDsign Cranial PSI is made from a

calcium phosphate-based ceramic material, reinforced by a

titanium skeleton. The implant's inter-connecting tile design

purportedly allows fluid movement through the device.

Gilardino and colleagues (2015) stated that cranioplasty can

be performed either with gold-standard, autologous bone

grafts and osteotomies or alloplastic materials in skeletally

mature patients. Recently, custom computer-generated

implants (CCGIs) have gained popularity with surgeons

because of potential advantages, which include pre

operatively planned contour, obviated donor-site morbidity,

and operative time savings. A remaining concern is the cost of

CCGI production. These researchers compared the operative

time and relative cost of cranioplasties performed with

autologous versus CCGI techniques at the authors’ center.

These researchers carried out a review of all autologous and

CCGI cranioplasties performed at their institution over the last

7 years. The following operative variables and associated

costs were tabulated: length of operating room, length of

ward/intensive care unit (ICU) stay, hardware/implants utilized,

and need for transfusion. Total average cost did not differ

statistically between the autologous group (n = 15;

$25,797.43) and the CCGI cohort (n = 12; $28,560.58).

Operative time (p = 0.004), need for ICU admission (p <

0.001), and number of complications (p = 0.008) were all

statistically significantly less in the CCGI group. The length of

hospital stay (LOS) and number of cases needing transfusion

were fewer in the CCGI group but did not reach statistical

significance. The authors concluded that the findings of this

study demonstrated no significant increase in overall treatment

cost associated with the use of the CCGI cranioplasty

technique. In addition, the latter was associated with a

statistically significant decrease in operative time and need for

ICU admission when compared with those patients who

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underwent autologous bone cranioplasty. Level of Evidence =

IV. The authors stated that this study had drawbacks that

forced cautious interpretation of the results. They stated that a

major drawback was that the findings represented a

preliminary study, based on an analysis of a small study

population.

Choi and Kim (2015) stated that 3-D printing has been widely

adopted in medical fields. Application of the 3-D printing

technique has even been extended to bio-cell printing for 3-D

tissue/organ development, the creation of scaffolds for tissue

engineering, and actual clinical application for various medical

parts. Of various medical fields, craniofacial plastic surgery is

one of areas that pioneered the use of the 3-D printing

concept. Rapid prototype technology was introduced in the

1990s to medicine via computer-aided design, computer-aided

manufacturing. These investigators examined the current

status of 3-D printing technology and its clinical application;

they performed a systematic review of the literature. In

addition, these researchers reviewed the benefits and

possibilities of the clinical application of 3-D printing in

craniofacial surgery, based on personal experiences with more

than 500 craniofacial cases conducted using 3-D printing

tactile prototype models. These investigators stated that 3-D

printing technology has the potential to be very beneficial to

patients and doctors in terms of patient-specific individualized

medicine.

The authors stated that 3-D printing techniques have been

most actively used in craniofacial surgery. However, some

obstacles need to be overcome. First, the computer software

used for craniofacial reconstruction should be much more

specifically designed. The pre-operative design of surgery is

not especially easy however. Because the segmentation

process in computer simulations is time consuming, it needs to

be more automated. If the various software programs were

more suitable and specific for craniofacial reconstruction, the

3-D printing technique could be more actively used. Second, a

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connection between the pre-operative simulations and the real

surgery environment should be made. Surgical wafers, such

as intermediate and final dental splints, would be an example

in orthognathic surgery. In addition, a navigational system

could act as a surgical guide to connect the pre-operative

simulation and the actual surgery. In order to apply the 3-D

printed titanium implant, the surgical cut or ostectomy should

be matched precisely with the pre-operative planning.

Because the 3-D printed implant is so solid that it is not easy to

cut or bend, planning and surgery should be identical and

efforts should be made to ensure that the pre-operative

planning and intra-operative defect are in agreement. Thus, a

surgical osteotomy guide should be made. A third issue is

accuracy. Although CT scans were made in very thin slices,

the imaging modality could only provide the accumulation of

the multiple slices. Error can inevitably occur between the

slices. In particular, the orbital wall was too thin to be

reconstructed by only a 3-D printing technique and a 3-D

printed orbit model represents the orbit as vacant fields.

Park and associates (2016) examined the efficacy of custom-

made 3-D printed titanium implants for reconstructing skull

defects. From 2013 to 2015, a total of 21 patients (aged 8 to

62 years, mean of 28.6; 11 females and 10 males) with skull

defects were treated. Total disease duration ranged from 6 to

168 months (mean of 33.6 months). The size of skull defects

ranged from 84 × 104 to 154 × 193 mm. Custom-made

implants were manufactured by Medyssey Co, Ltd (Jecheon,

South Korea) using 3-D CT data, Mimics software, and an

electron beam melting machine. The team reviewed several

different designs and simulated surgery using a 3-D skull

model. During the operation, the implant was fit to the defect

without dead space. Operation times ranged from 85 to 180

mins (mean of 115.7). Operative sites healed without any

complications except for 1 patient who had red swelling with

exudation at the skin defect, which was a skin infection and

defect at the center of the scalp flap reoccurring since the

initial head injury. This patient underwent re-operation for skin

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defect revision and replacement of the implant. A total of 21

patients were followed for 6 to 24 months (mean of14.1

months). Subjects were satisfied and had no recurrent wound

problems. Head CT following operation showed good fixation

of titanium implants and satisfactory skull-shape symmetry.

For the reconstruction of skull defects, the use of autologous

bone grafts has been the treatment of choice. However, bone

use depends on availability, defect size, and donor morbidity.

These investigators noted that as 3-D printing techniques are

further advanced, it is becoming possible to manufacture

custom-made 3-D titanium implants for skull reconstruction.

Tack and co-workers (2016) noted that 3-D printing has

numerous applications and has gained much interest in the

medical world. The constantly improving quality of 3-D printing

applications has contributed to their increased use on

patients. These researchers summarized the literature on

surgical 3-D printing applications used on patients, with a

focus on reported clinical and economic outcomes. Three

major literature databases were screened for case series

(more than 3 cases described in the same study) and trials of

surgical applications of 3-D printing in humans. A total of 227

surgical papers were analyzed and summarized using an

evidence table. These investigators described the use of 3-D

printing for surgical guides, anatomical models, and custom

implants; 3-D printing is used in multiple surgical domains,

such as orthopedics, maxillofacial surgery, cranial surgery, and

spinal surgery. In general, the advantages of 3-D printed parts

included reduced surgical time, improved medical outcome,

and decreased radiation exposure. The costs of printing and

additional scans generally increase the overall cost of the

procedure. The authors concluded that 3-D printing is already

well-integrated in medical practice. Applications vary from

anatomical models (mainly for surgical planning) to surgical

guides and implants. The main advantages stated by the

authors of the selected papers were reduced surgical time,

improved medical outcome, and decreased radiation

exposure. Unfortunately, the subjective character and lack of

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evidence supporting majority of these advantages did not

allow for conclusive statements. The increased cost of this

new technology, and the often limited or unproven

advantages, made it questionable whether 3-D printing is cost

effective for all patients and applications.

Francaviglia and colleagues (2017) noted that cranioplasty

represents a challenge in neurosurgery. Its goal is not only

plastic reconstruction of the skull but also to restore and

preserve cranial function, to improve cerebral hemodynamics,

and to provide mechanical protection of the neural structures.

The ideal material for the reconstructive procedures and the

surgical timing are still controversial. Many alloplastic

materials are available for performing cranioplasty and among

these, titanium still represents a widely proven and accepted

choice. These researchers presented their preliminary

experience with a "custom-made" cranioplasty, using electron

beam melting (EBM) technology, in a series of 10 patients;

EBM is a new sintering method for shaping titanium powder

directly in 3-D implants. To the best of the authors’

knowledge, this was the first report of a skull reconstruction

performed by this technique. In a 1-year follow-up, no post

operative complications had been observed and good clinical

and esthetic outcomes were achieved. The authors concluded

that costs higher than those for other types of titanium mesh, a

longer production process, and the greater expertise needed

for this technique were compensated by the achievement of

most complex skull reconstructions with a shorter operative

time.

In a systematic review, Diment and associates (2017)

evaluated the efficacy and effectiveness of using 3-D printing

to develop medical devices across all medical fields. Data

sources included PubMed, Web of Science, OVID, IEEE

Xplore and Google Scholar. A double-blinded review method

was used to select all abstracts up to January 2017 that

reported on clinical trials of a 3-D printed medical device. The

studies were ranked according to their level of evidence,

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divided into medical fields based on the International

Classification of Diseases chapter divisions and categorized

into whether they were used for pre-operative planning, aiding

surgery or therapy. The Downs and Black Quality Index

critical appraisal tool was used to assess the quality of

reporting, external validity, risk of bias, risk of confounding and

power of each study. Of the 3,084 abstracts screened, 350

studies met the inclusion criteria. Oral and maxillofacial

surgery contained 58.3 % of studies, and 23.7 % covered the

musculoskeletal system. Only 21 studies were randomized

controlled trials (RCTs), and all fitted within these 2 fields. The

majority of RCTs were 3-D printed anatomical models for pre

operative planning and guides for aiding surgery. The main

benefits of these devices were decreased surgical operation

times and increased surgical accuracy. The authors

concluded that all medical fields that assessed 3-D printed

devices concluded that they were clinically effective. The

fields that most rigorously assessed 3-D printed devices were

oral and maxillofacial surgery and the musculoskeletal system,

both of which concluded that the 3-D printed devices out

performed their conventional comparators. However, the

efficacy and effectiveness of 3-D printed devices remained

undetermined for the majority of medical fields. These

investigators stated that this study was limited to a critical

appraisal of individual studies, rather than a meta-analysis,

because of the breadth of uses (from anatomical models and

surgical guides to therapeutic devices) and the lack of

comparable hypotheses; they stated that more rigorous and

long-term assessments are needed to determine if 3-D printed

devices are clinically relevant before they become part of

standard clinical practice.

Volpe and co-workers (2018) validated a design methodology

for the virtual surgery and the fabrication of cranium vault

custom plates. Recent advances in the field of medical

imaging, image processing and additive manufacturing (AM)

have led to new insights in several medical applications. The

engineered combination of medical actions and 3-D

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processing steps, foster the optimization of the intervention in

terms of operative time and number of sessions needed.

Complex craniofacial surgical intervention, such as for

instance severe hypertelorism accompanied by skull holes,

traditionally requires a 1st surgery to correctly "re-size" the

patient cranium and a 2nd surgical session to implant a

customized 3-D printed prosthesis. Between the 2 surgical

interventions, medical imaging needs to be performed to aid

the design the skull plate. Instead, this paper proposed a

CAD/AM-based one-in-all design methodology allowing the

surgeons to perform, in a single surgical intervention, both

skull correction and implantation. A strategy envisaging a

virtual/mock surgery on a CAD/AM model of the patient

cranium so as to plan the surgery and to design the final

shape of the cranium plaque is proposed. The procedure

relies on patient imaging, 3-D geometry reconstruction of the

defective skull, virtual planning and mock surgery to determine

the hypothetical anatomic 3-D model and, finally, to skull plate

design and 3-D printing. The methodology has been tested on

a complex case study. Results demonstrated the feasibility of

the proposed approach and a consistent reduction of time and

overall cost of the surgery, not to mention the huge benefits on

the patient that is subjected to a single surgical operation. The

authors concluded that despite a number of AM-based

methodologies have been proposed for designing cranial

implants or to correct orbital hypertelorism, to the best of the

their knowledge, the present work was the first to

simultaneously treat osteotomy and titanium cranium plaque.

Huang and colleagues (2019) examined the biomechanical

behaviors of the pre-shaped titanium (PS-Ti) cranial mesh

implants with different pore structures and thicknesses as well

as the surface characteristics of the 3-D printed Ti (3DP-Ti)

cranial mesh implant. The biomechanical behaviors of the PS-

Ti cranial mesh implants with different pore structures (square,

circular and triangular) and thicknesses (0.2, 0.6 and 1 mm)

were simulated using finite element analysis. Surface

properties of the 3DP-Ti cranial mesh implant were performed

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by means of scanning electron microscopy, X-ray diffraction

and static contact angle goniometer. It was found that the

stress distribution and peak Von Mises stress of the PS-Ti

cranial mesh implants significantly decreased at the thickness

of 1 mm. The PS-Ti mesh implant with the circular pore

structure created a relatively lower Von Mises stress on the

bone defect area as compared to the PS-Ti mesh implant with

the triangular pore structure and square pore structure.

Moreover, the spherical-like Ti particle structures were formed

on the surface of the 3DP-Ti cranial mesh implant. The

microstructure of the 3DP-Ti mesh implant was composed of α

and rutile-TiO2 phases. For wettability evaluation, the 3DP-Ti

cranial mesh implant possessed a good hydrophilicity surface.

The authors concluded that the 3DP-Ti cranial mesh implant

with the thickness of 1 mm and circular pore structure is a

promising biomaterial for cranioplasty surgery applications.

Penile Surface Mold Brachytherapy

D'Alimonte and colleagues (2019) described a technique of

penile surface mold high-dose-rate (HDR) brachytherapy and

early outcomes. A total of 5 patients diagnosed with a T1aN0

squamous cell carcinoma (SCC) of the penis were treated

using a penile surface mold HDR brachytherapy technique. A

negative impression of the penis was obtained using dental

alginate; CT images were acquired of the penile impression;

subsequently, a virtual model of the patient's penis was

generated. The positive model was imported into a computer-

assisted design program where catheter paths were planned

such that an optimized off-set of 5 mm from the penile surface

was achieved. The virtual model was converted into a custom

applicator. A total dose of 40 Gy was delivered in 10

fractions. Patients were followed at 1, 3, 6, and 12 months

after treatment and then every 6 months thereafter. Toxicities

were reported using Common Terminology Criteria for Adverse

Events v4.0. All patients tolerated treatment well. Acute grade

2 skin reactions were observed within the first month following

treatment. Median follow-up was 35 months. Late

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grade-1 skin toxicities were observed; 1 patient experienced a

urethral stricture requiring dilatation; and 2 patients developed

local recurrence. The authors concluded that this technique

allowed the delivery of penile HDR brachytherapy as an out

patient procedure with minimal discomfort to the patient during

each application and was a repeatable and accurate set-up.

These researchers stated that this technique needs validation

in larger series with longer follow-up.

3D Printing of Anatomic Structures for Pre-Operative Planning

Vukicevic and colleagues (2017) noted that as catheter-based

structural heart interventions become increasingly complex,

the ability to effectively model patient-specific valve geometry

as well as the potential interaction of an implanted device

within that geometry will become increasingly important.

These investigators combined the technologies of high-spatial

resolution cardiac imaging, image processing software, and

fused multi-material 3D printing, to demonstrate that patient-

specific models of the mitral valve apparatus could be created

to facilitate functional evaluation of novel trans-catheter mitral

valve repair strategies. Clinical three-dimensional (3D) trans-

esophageal echocardiography (TEE) and computed

tomography (CT) images were acquired for 3 patients being

evaluated for a catheter-based mitral valve repair. Target

anatomies were identified, segmented and reconstructed into

3D patient-specific digital models. For each patient, the mitral

valve apparatus was digitally reconstructed from a single or

fused imaging data set. Using multi-material 3D printing

methods, patient-specific anatomic replicas of the mitral valve

were created. 3D print materials were selected based on the

mechanical testing of elastomeric TangoPlus materials

(Stratasys, Eden Prairie, MN) and were compared to freshly

harvested porcine leaflet tissue. The effective bending

modulus of healthy porcine MV tissue was significantly less

than the bending modulus of TangoPlus (p < 0.01). All

TangoPlus varieties were less stiff than the maximum tensile

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elastic modulus of mitral valve tissue (3697.2 ± 385.8 kPa

anterior leaflet; 2582.1 ± 374.2 kPa posterior leaflet) (p <

0.01). However, the slopes of the stress-strain toe regions of

the mitral valve tissues (532.8 ± 281.9 kPa anterior leaflet;

389.0 ± 156.9 kPa posterior leaflet) were not different than

those of the Shore 27, Shore 35, and Shore 27 with Shore 35

blend TangoPlus material (p > 0.95). These investigators

have demonstrated that patient-specific mitral valve models

can be reconstructed from multi-modality imaging data-sets

and fabricated using the multi-material 3D printing technology

and they provided 2 examples to show how catheter-based

repair devices could be evaluated within specific patient 3D

printed valve geometry. Moreover, the authors concluded that

the use of 3D printed models for the development of new

therapies, or for specific procedural training has yet to be

defined.

Leng and associates (2017) provided a framework for the

development of a quality assurance (QA) program for use in

medical 3D printing applications. An inter-disciplinary QA

team was built with expertise from all aspects of 3D printing. A

systematic QA approach was established to examine the

accuracy and precision of each step during the 3D printing

process, including: image data acquisition, segmentation and

processing, and 3D printing and cleaning. Validation of printed

models was performed by qualitative inspection and

quantitative measurement. The latter was achieved by

scanning the printed model with a high resolution CT scanner

to obtain images of the printed model, which were registered

to the original patient images and the distance between them

was calculated on a point-by-point basis. A phantom-based

QA process, with 2 QA phantoms, was also developed. The

phantoms went through the same 3D printing process as that

of the patient models to generate printed QA models. Physical

measurement, fit tests, and image based measurements were

performed to compare the printed 3D model to the original QA

phantom, with its known size and shape, providing an end-to

end assessment of errors involved in the complete 3D printing

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process. Measured differences between the printed model

and the original QA phantom ranged from -0.32 mm to 0.13

mm for the line pair pattern. For a radial-ulna patient model,

the mean distance between the original data-set and the

scanned printed model was -0.12 mm (ranging from -0.57 to

0.34 mm), with a standard deviation of 0.17 mm. The authors

concluded that this study described the development of a

comprehensive QA program for 3D printing in medicine.

These researchers hoped that the methodologies described

would contribute toward the growing body of work needed to

establish standards for QA programs for medical 3D printing.

The authors stated that this study had several drawbacks.

First, the protocols were based on experience with a single

type of 3D printer and with segmentation software from a

single vendor. The general framework and concepts of this

QA program, though, can be extended to other types of

printers with appropriate adjustments made according to the

specific printing technology and to type of segmentation

software. Second, the authors’ experience relied heavily on

the use of CT imaging data that was used for the majority of

their models as CT provided high spatial resolution and high

geometric accuracy, both of which were critical for 3D printed

models used in medicine. However, general principles

outlined in this study applied to 3D printing using other imaging

modalities too; MRI data were increasing used as an adjunct

to the CT data as higher resolution MRI imaging sequences

are being developed. The use of 3D ultrasound (US) data is

still in early stages of exploration for 3D printing. Finally, the

QA program did not provide specific and quantifiable standard

for 3D printing. As this technology evolves, substantial QA

data from multiple institutions need to be accumulated over

time so that appropriate specific and quantifiable QA standard

could be developed and adopted by the medical 3D printing

community.

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Pucci and co-workers (2017) stated that 3D printers are a

developing technology penetrating a variety of markets,

including the medical sector. Since its introduction to the

medical field in the late 1980s, 3D printers have constructed a

range of devices, such as dentures, hearing aids, and

prosthetics. With the ultimate goals of decreasing healthcare

costs and improving patient care and outcomes,

neurosurgeons are utilizing this dynamic technology, as well.

Digital Imaging and Communication in Medicine (DICOM) can

be translated into stereolithography (STL) files, which are then

read and methodically built by 3D printers. Vessels, tumors,

and skulls are just a few of the anatomical structures created

in a variety of materials, which enable surgeons to conduct

research, educate surgeons in training, and improve pre

operative planning without risk to patients. Due to the infancy

of the field and a wide range of technologies with varying

advantages and disadvantages, there is currently no standard

3D printing process for patient care and medical research. In

an effort to enable clinicians to optimize the use of additive

manufacturing (AM) technologies, the authors outlined the

most suitable 3D printing models and computer-aided design

(CAD) software for 3D printing in neurosurgery. These

researchers noted that 3D printing applications and the

limitations of 3D printers must be overcome before this

technology can significantly impact the field of neurosurgery.

Barber and colleagues (2018) noted that otolaryngologists

increasingly use patient-specific 3D-printed anatomic physical

models for pre-operative planning. However, few reports

described concomitant use with virtual models. These

investigators employed a 3D-printed patient-specific physical

model with lateral skull base navigation for pre-operative

planning; reviewed anatomy virtually via augmented reality

(AR); and compared physical and virtual models to intra-

operative findings in a challenging case of a symptomatic

petrous apex cyst; CT imaging was manually segmented to

generate 3D models; AR facilitated virtual surgical planning.

Navigation was then coupled to 3D-printed anatomy to

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simulate surgery using an endoscopic approach. Intra-

operative findings were comparable to simulation. Virtual and

physical models adequately addressed details of endoscopic

surgery, including avoidance of critical structures. The authors

concluded that complex lateral skull base cases may be

optimized by surgical planning via 3D-printed simulation with

navigation. Moreover, these researchers stated that future

studies are needed to examine if simulation could improve

patient outcomes, including patient safety.

Lin and associates (2018) noted that using 3D printing to

create individualized patient models of the skull base, the optic

chiasm and facial nerve can be pre-visualized to help identify

and protect these structures during tumor removal surgery.

Pre-operative imaging data for 2 cases of sellar tumor and 1

case of acoustic neuroma were obtained. Based on these

data, the cranial nerves were visualized using 3D T1-weighted

turbo field echo sequence and diffusion tensor imaging-based

fiber tracking. Mimics software was used to create 3D

reconstructions of the skull base regions surrounding the

tumors, and 3D solid models were printed for use in simulation

of the basic surgical steps. The 3D printed personalized skull

base tumor solid models contained information regarding the

skull, brain tissue, blood vessels, cranial nerves, tumors, and

other associated structures. The sphenoid sinus anatomy,

saddle area, and cerebello-pontine angle region could be

visually displayed, and the spatial relationship between the

tumor and the cranial nerves and important blood vessels was

clearly defined. The models allowed for simulation of the

operation, prediction of operative details, and verification of

accuracy of cranial nerve reconstruction during the operation.

Questionnaire assessment showed that neurosurgeons highly

valued the accuracy and usefulness of these skull base tumor

models. The authors concluded that 3D printed models of

skull base tumors and nearby cranial nerves, by allowing for

the surgical procedure to be simulated beforehand, facilitated

pre-operative planning and may help prevent cranial nerve

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injury. Moreover, these investigators noted that although 3D

printed models in neurosurgery have been reported, these

models lacked some details and practical significance.

Alyaev (2018) developed a non-biological 3D printed simulator

for training and pre-operative planning in percutaneous

nephrolithotripsy (PCNL), which allowed doctors to master and

perform all stages of the operation under US and fluoroscopy

guidance. The 3D model was constructed using multi-slice

spiral CT (MSCT) images of a patient with staghorn

urolithiasis. The MSCT data were processed and used to print

the model. The simulator consisted of 2 parts: a non-biological

3D printed soft model of a kidney with reproduced intra-renal

vascular and collecting systems; and a printed 3D model of a

human body. Using this 3D printed simulator, PCNL was

performed in the interventional radiology operating room under

US and fluoroscopy guidance. The designed 3D printed

model of the kidney completely reproduced the individual

features of the intra-renal structures of the particular patient.

During the training, all the main stages of PCNL were

performed successfully: the puncture, dilation of the

nephrostomy tract, endoscopic examination, intra-renal

lithotripsy. The authors concluded that their proprietary 3D

printed simulator was a promising development in the field of

endourologic training and pre-operative planning in the

treatment of complicated forms of urolithiasis.

Dong and co-workers (2018) reported their experience with

customized 3D printed models of patients with brain arterio

venous malformation (bAVM) as an educational and clinical

tool for patients, doctors, and surgical residents. Using CT

angiography (CTA) or digital subtraction angiography (DSA)

images, the rapid prototyping process was completed with

specialized software and "in-house" 3D printing service. Intra-

operative validation of model fidelity was performed by

comparing to DSA images of the same patient during the

endovascular treatment process; 3D bAVM models were used

for pre-operative patient education and consultation, surgical

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planning, and resident training. 3D printed bAVM models were

successfully made. By neurosurgeons' evaluation, the printed

models precisely replicated the actual bAVM structure of the

same patients (n = 7, 97 % concordance, range of 95 % to 99

% with average of less than 2 mm variation). The use of 3D

models was associated shorter time for pre-operative patient

education and consultation, higher acceptable of the

procedure for patients and relatives, shorter time between

obtaining intra-operative DSA data and the start of

endovascular treatment. A total of 30 surgical residents from

residency programs tested the bAVM models and provided

feedback on their resemblance to real bAVM structures and

the usefulness of printed solid model as an educational tool.

The authors concluded that further study of 3D printing

technology application in neurovascular disease still needs to

be performed. The use of 3D printed models has highest

value in aneurysm clipping, pre-operative simulation, and

accurate understanding of the local anatomy. With printed

bAVM models, the surgeon could be aware of the structural

property of nidus and related vessels, guiding in treatment

planning. However, the models still have some limitations.

Fabrication cost and time varied with model size and the

authors’ models did not yet give information regarding detailed

structures directly inside the nidus; models that could

overcome these limitations are the efforts of these

researchers’ ongoing study on human bio-modeling.

Qiu and colleagues (2018) stated that medical errors are a

major concern in clinical practice, suggesting the need for

advanced surgical aids for pre-operative planning and

rehearsal. Conventionally, CT and MRI scans, as well as 3D

visualization techniques, have been used as the primary tools

for surgical planning. While effective, it would be useful if

additional aids could be developed and employed in

particularly complex procedures involving unusual anatomical

abnormalities that could benefit from tangible objects providing

spatial sense, anatomical accuracy, and tactile feedback.

Recent advancements in 3D printing technologies have

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facilitated the creation of patient-specific organ models with

the purpose of providing an effective solution for pre-operative

planning, rehearsal, and spatiotemporal mapping. These

investigators reviewed the state-of-the-art in 3D printed, patient-

specific organ models with an emphasis on 3D printing material

systems, integrated functionalities, and their corresponding

surgical applications and implications; they also discussed prior

limitations, current progress, and future perspectives in this

field.

The authors stated that significant advances in 3D printing

organ models and their corresponding surgical applications

have been achieved. However, there is still plenty of room for

further improvement in the field, and future studies are

expected to focus on several different directions. First, most

3D printed organ models were static, meaning they lacked the

ability to simulate dynamic conditions of organ models, such

as pulsations of the heart. Thus, incorporation of convenient

and accurate dynamic functionalities (such as actuation) into

the organ models will be useful for more realistic surgical

rehearsal. Second, although the initial integration of 3D

printed soft electronics has been achieved, the functionalities

are still limited. For more complicated, multi-dimensional

feedback applications, different types of conformal electronics

with more powerful functionalities need to be developed and

integrated into the organ models. Third, virtual and assisted

reality tools could be used in conjunction with the organ

models for visualization of fine features such as vasculature

during surgical simulation. Fourth, the 3D printed organ

models with integrated functionalities should be evaluated in

real-use cases under various surgical environments for

statistical surveys of surgical outcomes and patient safety to

accurately and quantitatively evaluate their effectiveness with

large data assessment criteria. Finally, anisotropic properties

could possibly be introduced into the 3D printed organ models

by controlling the orientation of printing pathways and

imbedding fillers.

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In a retrospective study, Ma and colleagues (2020) examined

the feasibility of arthroplasty with varisized 3D printing lunate

prosthesis for the treatment of advanced Kienbock's disease

(KD). This trial was carried out from November 2016 to

September 2018 for patients with KD in the authors’ hospital.

A total of 5 patients (2 men, 3 women) were included in this

study. The mean age of the patients at the time of surgery

was 51.6 years (range of 37 to 64 years). Varisized prosthesis

identical to the live model in a ratio of 1:0.85, 1:1, and 1:1.1

were fabricated by 3D printing. All patients (1 in Lichtman IIIA

stage, 2 in Lichtman IIIB stage, 1 in Lichtman IIIC stage, and 1

in Lichtman IV stage) were treated with lunate excision and 3D

printing prosthetic arthroplasty. Visual analog scale score

(VAS), the active movement of wrist (extension, flexion) and

strength were assessed pre-operatively and post-operatively.

The Mayo Modified Wrist Score (MMWS), Disabilities of the

Arm, Shoulder and Hand (DASH) Score, and patient's

satisfaction were evaluated during the follow-up. Prosthesis

identical to the live model in a ratio of 1:0.85 or 1:1 were

chosen for arthroplasty. The mean operation time (range of 45

to 56 mins) was 51.8 ± 4.44 mins. Follow-up time ranged from

11 months to 33 months with the mean value of 19.4 months.

The mean extension range of the wrist significantly increased

from pre-operative 44° ± 9.6° to post-operative 60° ± 3.5° (p <

0.05). The mean flexion range of the wrist significantly

increased from pre-operative 40° ± 10.6° to post-operative 51°

± 6.5° (p < 0.05). The active movement of wrist and strength

were improved significantly in all patients. VAS was

significantly reduced from 7.3 pre-operatively to 0.2 at the

follow-up visit (p < 0.05). The mean DASH score was 10

(range of 7.2 to 14.2), and the mean MMWS was 79 (range of

70 to 90). There were no incision infection. All patients were

satisfied with the treatment. The authors concluded that for

patients suffering advanced KD, lunate excision followed by

3D printing prosthetic arthroplasty could reconstruct the

anatomical structure of the carpal tunnel, alleviate pain, and

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improve wrist movement. These preliminary findings from a

small (n = 5) study need to be validated by well-designed

studies.

Dental Implant Placement Using a Full Digital Planning Modality and Stereolithographic Guides

Lopez and colleagues (2019) reviewed potential deviation

factors in stereolithographic surgical guides for dental

implantology, warnings, and limitations of the system. These

researchers carried out an electronic search in data-bases

Embase, the Cochrane Library, and PubMed to collect

information on the accuracy of static computer-guided implant

placement to summarize and analyze the overall accuracy.

The latter included a search for correlations between factors

such as support (teeth/mucosa/bone), number of templates,

use of fixation pins, jaw, template production, guiding system,

and guided implant placement in articles related to guided

surgery with stereolithographic static systems. Studies

published between 2012 and 2017 were reviewed. From 761

identified articles, a total of 24 articles were reviewed, which

included 2,767 dental implants. Data from studies analysis

had shown a mean deviation of 3.08 degrees in angular

position, 1.14 at the entry point, and 1.46 at apex position.

Involved deviation factors were related to planning, laboratory,

and surgical phases. The authors concluded that guided

surgery may have a limited precision as technique, which

surgeons need to be aware in the planning process. This

review suggested some security measures in guided surgery

process.

Skjerven and associates (2019) examined the clinical value of

a guided implant surgery procedure performed without any

manual processes, by assessing the in-vivo results following a

digital planning and placement of dental implants using

surgical templates. Eligible patients were screened and

enrolled in this prospective clinical study. A cone beam

computed tomography (CBCT) scan was acquired, and the

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remaining dentition and soft tissues were recorded by an intra-

oral scanner after enrollment. The CBCT data and intraoral

scan were fused in the planning software. The prosthetic

reconstructions were digitally designed by a prosthodontist,

and the ideal position of the dental implants was determined.

The surgical template was digitally designed based on this

plan, and a guide design was exported and manufactured in a

stereolithographic process. The entire surgical procedure was

performed with the aid of the template. An intra-oral scan was

performed 10 days after stage-2 surgery using scan bodies

placed on the implants. Digital pre-operative and post

operative models were compared, and the metric difference

between the planned and achieved implant positions was

calculated. A total of 27 implants were placed in 20 patients

using tooth-supported surgical templates after a digital

planning procedure. No implants were lost during the study

period. The mean lateral deviation measured at the coronal

point was 1.05 mm (SD: 0.59; range of 2.74 to 0.36). The

mean lateral deviation measured at the apical point was 1.63

mm (SD: 1.05; range of 5.16 to 0.56). The mean depth

displacement was + 0.48 mm (SD: 0.50; range of 1.33 to

-0.52). The mean angle deviation was 3.85 degrees (SD:

1.83; range of 8.6 to 1.25). The authors concluded that a

simplified full digital planning procedure yielded results

comparable to conventional guided implant surgery. The main

deviation between the planned and achieved implant positions

in this prospective clinical study was angular. The authors

concluded that more clinical studies are needed to verify the

procedure further.

Kiatkroekkrai and co-workers (2020) noted that data from

CBCT and optical scans (intra-oral or model scanner) are

needed for computer-assisted implant surgery (CAIS). These

researchers compared the accuracy of implant position when

placed with CAIS guides produced by intra-oral and extra-oral

(model) scanning. A total of 47 patients received 60 single

implants by means of CAIS. Each implant was randomly

assigned to either the intra-oral group (n = 30) (Trios Scanner,

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3Shape) or extra-oral group (n = 30), in which

stereolithographic surgical guides were manufactured after

conventional impression and extra-oral scanning of the stone

model (D900L Lab Scanner, 3Shape). CBCT and surface

scan data were imported into coDiagnostiX software for virtual

implant position planning and surgical guide design. Post

operative CBCT scans were obtained. Software was used to

compare the deviation between the planned and final

positions. Average deviation for the intra-oral versus model

scan groups was 2.42° ± 1.47° versus 3.23° ± 2.09° for implant

angle, 0.87 ± 0.49 mm versus 1.01 ± 0.56 mm for implant

platform, and 1.10 ± 0.53mm versus 1.38 ± 0.68mm for

implant apex; there was no statistically significant difference

between the groups (p > 0.05). The authors concluded that

CAIS conducted with stereolithographic guides manufactured

by means of intra-oral or extra-oral scans appeared to result in

equal accuracy of implant positioning.

CPT Codes / HCPCS Codes / ICD-10 Codes

Information in the [brackets] below has been added for clarification purposes. Codes requiring a 7th character are represented by "+":

Code Code Description

There are no specific codes for stereolithography:

Other CPT codes related to the CPB:

21076 -

21088

Impression and custom preparation

21100 Application of halo type appliance for

maxillofacial fixation, includes removal

(separate procedure)

21110 Application of interdental fixation device for

conditions other than fracture or dislocation,

includes removal

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21120 -

21196

Repair, revision, and/or reconstruction bones of

face

21206 Osteotomy, maxilla, segmental (e.g.,

Wassmund or Schuchard)

21210 Graft, bone; nasal, maxillary or malar areas

(includes obtaining graft)

21246 Reconstruction of mandible or maxilla,

subperiosteal implant; complete

30400 -

30465

Rhinoplasty

42200 -

42225

Palatoplasty

76376 3D rendering with interpretation and reporting

of computed tomography, magnetic resonance

imaging, ultrasound, or other tomographic

modality with image postprocessing under

concurrent supervision; not requiring image

postprocessing on an independent workstation

76377 requiring image postprocessing on an

independent workstation

77316 Brachytherapy isodose plan; simple (calculation

[s] made from 1 to 4 sources, or remote

afterloading brachytherapy, 1 channel),

includes basic dosimetry calculation(s)

77317 intermediate (calculation[s] made from 5 to

10 sources, or remote afterloading

brachytherapy, 2-12 channels), includes basic

dosimetry calculation(s)

Proprietary





77318 complex (calculation[s] made from over 10

sources, or remote afterloading brachytherapy,

over 12 channels), includes basic dosimetry

calculation(s)

77767 Remote afterloading high dose rate

radionuclide skin surface brachytherapy,

includes basic dosimetry, when performed;

lesion diameter up to 2.0 cm or 1 channel

77768 lesion diameter over 2.0 cm and 2 or more

channels, or multiple lesions

77770 Remote afterloading high dose rate

radionuclide interstitial or intracavitary

brachytherapy, includes basic dosimetry, when

performed; 1 channel

77771 2-12 channels

77772 over 12 channels

77799 Unlisted procedure, clinical brachytherapy

CPT codes not covered for indications listed in the CPB:

0559T Anatomic model 3D-printed from image data set

(s); first individually prepared and processed

component of an anatomic structure

+ 0560T each additional individually prepared and

processed component of an anatomic structure

(List separately in addition to code for primary

procedure)

0561T Anatomic guide 3D-printed and designed from

image data set(s); first anatomic guide

+ 0562T each additional anatomic guide (List

separately in addition to code for primary

procedure)

Proprietary





ICD-10 codes not covered for indications listed in the CPB:

Z01.818 Encounter for other preprocedural examination

The above policy is based on the following references:

1. Aisenbrey EA, Tomaschke A, Kleinjan E, et al. A

Stereolithography-based 3D printed hybrid scaffold for

in situ cartilage defect repair. Macromol Biosci.

2018;18(2).

2. Anderl H, Zur Nedden D, Muhlbauer W, et al. CT-

guided stereolithography as a new tool in craniofacial

surgery. Br J Plast Surg. 1994;47(1):60-64.

3. Anderson J, Wealleans J, Ray J. Endodontic applications

of 3D printing. Int Endod J. 2018;51(9):1005-1018.

4. Antony AK, Chen WF, Kolokythas A, et al. Use of virtual

surgery and stereolithography-guided osteotomy for

mandibular reconstruction with the free fibula. Plast

Reconstr Surg. 2011;128(5):1080-1084.

5. Bajaj P, Chan V, Jeong JH, et al. 3-D biofabrication using

stereolithography for biology and medicine. Conf Proc

IEEE Eng Med Biol Soc. 2012;2012:6805-6808.

6. Bian W, Li D, Lian Q, et al. Design and fabrication of a

novel porous implant with pre-set c

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