0613 stereolithographic models and implants · 2020. 1. 21. · devices, implants, scaffolds for...
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Stereolithographic Models and Implants - Medical Clinical Policy Bulletins | Aetna Page 1 of 45
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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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Code Code Description
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)
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Code Code Description
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)
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Code Code Description
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