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Reconstruction of Post-Traumatic Orbital Defects and
Deformities with Custom-Made Patient-Specific Implants:
Evaluation of the Efficacy and Clinical Outcome
Yurii Chepurnyi, DDS, PhD1Denis Chernogorskyi, DDS1Oksana Petrenko, MD, MScD2
Andrii Kopchak, DDS, MScD1
1Department of Stomatology, O.O. Bogomolets National Medical
University, Kyiv, Ukraine
2Department of Ophthalmology, Pl Shupik National Medical Academy
of Postgraduate Study, Kiev, Ukraine
Craniomaxillofac Trauma Reconstruction Open 2019;3:e9–e17.
Address for correspondence Yurii Chepurnyi, DDS, PhD, Department
of Stomatology, O.O. Bogomolets National Medical University,
Zoologichna Street, 1 Kyiv 01601, Ukraine
(e-mail: 80667788837@ukr.net).
Despite the notable advances in reconstructive surgery techni-
ques,post-traumatic defects and deformities of theorbit remain
a majorchallengedue to the complex anatomy, variable trauma
patterns, and the need for an interdisciplinary approach. Inju-
ries of the orbital walls are associated with significant facial
disfiguration because of the eyeball displacement, and they
cause functional deficit (diplopia, restricted globe motility, and
a decrease or loss of vision). It complicates social adaptation of
the patients, and affects the psychological state.1–3
Traditional methodsfor restorationof the orbital volume and
anatomic shape include the usage of standard preformed
titanium plates and meshes available in different sizes, poly-
meric implants of thin polyethylene membranes, and autolo-
gous bone grafts.1,4 Bone grafts and standard titanium or
polymeric implants usually require prebending or intraopera-
tive bending and correction of the contours. It may be difficult
because of the lost anatomical landmarks and changes in
topographic anatomy of the orbit and its content. The proper
insertion and positioning of the implants or grafts inside the
orbit, especially in the region of the orbital ledge, remain
challenging.3,5 The problem could be solved with digital intrao-
perative navigation systems, but thehigh cost of the equipment
limitstheir use.Moreover, thesesystems donot ensurea precise
fit of the bone graft or implant if their geometry does not match
the contours of the defect or individual orbital shape.1,6,7
In orbital reconstruction procedures, the location of
implants or bone grafts and their conformity to the individual
anatomy of the damaged structures in size and shape deter-
mine the surgical strategy and the integral success rate.
Recent developments of computer-aided design/computer-
aided manufacturing(CAD/CAM) technologies and evidence of
their effective clinical application in management of facial
bone defects and deformities have generated an increased
interest to their usage in reconstructive surgery of the orbit.
Keywords
►orbital defects
►patient-specific
implants
►CAD/CAM
►reconstruction
Abstract The main purpose of this article is to evaluate the efficacy of patient-specificimplants
(PSI) in treatment of patients with post-traumatic orbital defects and deformities.
Twenty-three patients with post-traumatic orbital defects and deformities, who under-
went subsequent reconstructive procedures using PSI, were included in the study. All
the patients were examined according to the standard algorithm involving the local
status examination, vision assessment, and computed tomography before and after
surgery. The study findings show neither postoperative infectious complications nor
decreased visual acuity or loss of visual fields. Functional disorders resolved in 65.2%
of cases 1 month after the surgical intervention and in 86.96% of patients within a
3-month term. Positive aesthetic outcomes were seen in 95.7% of cases. Reconstruc-
tion with computer-aided design/computer-aided manufactured PSI is an effective
procedure that allows accurate restoring of the complex orbital anatomy.
received
September 22, 2018
accepted after revision
November 14, 2018
DOI https://doi.org/
10.1055/s-0039-1685505.
ISSN 2472-7512.
Copyright © 2019 by Thieme Medical
Publishers, Inc., 333 Seventh Avenue,
New York, NY 10001, USA.
Tel: +1(212) 584-4662.
THIEME
Original Article e9
The above technologies have contributed to improved diag-
nostics and initial assessment of the clinical case, facilitated
designing and manufacturing of orbital implants owing to the
virtual simulation of the surgical procedures, and ensured
highly predictable outcomes with significantly improved con-
ditions postoperatively.1,3,6,8,9 Previously, there were reports
about successful experience of custom-made patient-specific
implants (PSI) manufactured from either titanium by selective
laser sintering (SLS) or polyether-ether-ketone (PEEK)for facial
or cranial reconstructions.1–3,10–12 The authors noted the
complexityof conventional algorithms used for implant design
and manufacturing with increased probability of errors and
discrepancies.
One of the first orbital reconstructions with PSI was
reported by Williams and Revington.11 Later, the first series
of cases was presented by Gander et al.13 Several clinical
studies have documented the efficacy of orbital reconstruc-
tion with PSI since then. Most of the articles describe the
usage of titanium PSI. They differ in the number of patients
involved, the algorithms of the CAD procedures, the evalua-
tion criteria, a nd methods of implant manufactur ing. Despite
a considerable number of studies devoted to cranioplasty
and frontal bone reconstructions with PEEK implants, only
few reports present the outcomes of the orbital wall recon-
structions with PEEK PSI.14
It conditions the need for evidence-based improvement of
current approaches to the virtual simulation, manufacturing
and installation of PSI in reconstructive surgery of the orbit.
The aim of this study was to evaluate the clinical efficacy
of custom-made titanium and PEEK PSI in post-traumatic
orbital defects and deformations.
Material and Methods
Twenty-three patients with unilateral post-traumatic
defects and deformities of the orbit (15 males and 8 females,
aged 16 to 54 years, mean age 37.9 13.7 years), who
underwent orbital reconstruction procedures with PSI at
the Center for Maxillofacial Surgery and Stomatology, Kyiv
Regional Hospital, Ukraine from January 1, 2016 to Febru-
ary 28, 2018, were included to this study. In all cases, an
informed consent from patients for the treatment and parti-
cipation in the present study was obtained. The research was
approved by Bioethics Committee of Bogomolets National
Medical University, Kyiv, Ukraine (Protocol No. 104). The
exclusion criteria were the following: age under 16, bilateral
orbital trauma, endocrine orbitopathy, anophthalmia, one or
both side loss of vision, defects caused by gunshot injuries,
defects and deformities after tumor resections, radiation or
chemotherapy in anamnesis, mental illness, noncompliance
with medical recommendations and lack of interaction with
a doctor in the postoperative period, and refusal of the
patient to participate in the study.
The diagnostics and treatment of the above patients were
performed bya multidisciplinary team, whichincludedoral and
maxillofacial surgeons, ophthalmologists, and ENT surgeons.
All patients were examined preoperatively, first day after
surgery, 1 and 3 months after surger y following the stan-
dardized algorithm, including local status examination
(facial symmetry, scars, and position of the eyeball) and
evaluation of vision (visual acuity, diplopia, and ocular
mobility). Visual fields were also recorded. All patients
underwent 64-slice computed tomography (CT; Philips Dia-
mond Select Brilliance CT 64, Koninklijke Philips N.V.; slice
thickness—0.5 mm) before and after surgery (►Table 1).
Efficiency evaluation criteria included the duration of the
surgical intervention and the period of implant adaptation,
orbital volume measurements, early and long-term post-
operative complications, and changes in the aesthetics and
ophthalmologic status. Aesthetic outcomes of the treatment
were considered as unsatisfactory (where a residual cos-
metic defect was significant, obvious to the patient, and
requiring a secondary surgical correction), satisfactory (sur-
gical repair of residual cosmetic defect was not necessary or
only a small intervention on the paraorbital soft tissues was
required), or good (where both the surgeon and patient were
satisfied with the obtained result).
Design and Manufacturing of the Implants
Virtual simulation of surgical procedures and PSI designing
were performed in close collaboration between surgeons and
biomedical engineers. Preoperative CT data (Digital Imaging
and Communications in Medicine [DICOM] files without com-
pression) were provided to the manufacturer of the implants
(Imatek-Esco Ltd., Kyiv, Ukraine 3D Systems [USA] reseller).
Then, biomedical engineers analyzed the clinical case, created
thedesignoftheimplantanddefined its optimal position inside
the orbit with the participation and under control of surgeons.
Computer-aided design procedures were performed in the
software environment (SimPlant 10.03; Materialise Dental) by
segmentation of the CT data, creating virtual models of the
orbit and editing them. The models were edited in multiple
slice modes (slice-by-slice) considering the contour of the
mirrored healthy orbit after its superimposition on DICOM
data of the damaged orbit using manual reposition. The
purpose of the editing procedure was to restore the integrity
of the orbital wallsfor creation of a constant surfacein all slices
without triangular mesh defects. STL model of the orbit after
multiple slice editing was exported to design software (Geo-
magic Freeform Plus). Further processing of the model
included wrapping, smoothing, and fixing procedures. The
design of the implant was obtained by creating the required
surface shape and its subsequent transformationinto an object
with defined thickness. Then, clearance of the object and holes
for fixation were created using boolean operations.
The design of the implants was aimed at repairing the
orbital wall defects and deformities of the orbital rim, thus
restoring a true-to-original shape of the damaged structures.
In all cases, retention points for precise intraoperative posi-
tioning of the implants and their stable retention after the
installation as well as additional elements with holes for
screw fixation to the orbital rim were modeled and created.
The diameter and shape of the holes corresponded to the
osteosynthesis system selected for fixation. In three cases,
the design of the implant allowed correcting deformities of
Craniomaxillofacial Trauma & Reconstruction Open Vol. 3 No. 1/2019
Evaluation of the Efficacy and Clinical Outcome of PSI Chepurnyi et al.e10
the orbital rims and defects of the bones adjacent to the orbit
(►Fig. 1).
Virtual three-dimensional models of PSI in STL format
were reimported to the software (SimPlant 10.03 with
cranio-maxillo-facial module) for CT data analysis, where
the surgeons performed the preoperative evaluation of PSI
location inside the orbit in relation to the bone (orbital floor)
and soft tissues (the optic and infraorbital nerves and mus-
cles). After validation and correction by clinicians, STL file was
sent for manufacturing. The implantswere made by milling of
radiopaque PEEK blocks (Merz Dental; 18 cases) on the
machines with numerical control or by SLS of the titanium
(Ti6Al4V) powder (DIN: 3.7165) according to ISO 5832-3 (in 5
cases). We preferred PEEK in cases where only orbital wall
reconstruction was indicated. However, we considered tita-
nium PSI as a method ofchoice in cases where the reconstruc-
tion of the orbitozygomatic complex with stabile fixation of
the orbital rim fragments was performed simultaneously with
orbital walls reconstruction. The implants were sterilized the
day before operation by autoclaving at 132°C.
Virtual orbital models of the damaged and intact sides
were generated for all cases before and after surgery. For this
purpose, a threshold value segmentation of the CT data was
performed with generation of the bony orbital model and
models of the soft tissue content (orbital models). These
orbital models were edited considering the contour of the
bony orbit and orbital margins. Their volumes were mea-
sured in the computer software and compared for each
individual case. Addit ionally, a superimpos ition of the virtual
models (mirrored intact and damaged) was performed after
trauma, after design of PSI, and after surgical treatment.15,16
Statistical analysis of the data included the calculation of
mean values, and standard deviation for each parameter
evaluated. Nonparametrical statistics was employed for
analysis of the data. The Mann–Whitney Utest was used
to compare the differences between these parameters in the
study group. The level of significance was set at p<0.05.
Statistical calculations were performed in SPSS Statistics
software environment (IBM Inc.).
Results
Post-traumatic defects and deformities resulted from blow-
out orbital fractures (five of them were combined with
orbitozygomatic fractures and two with fractures of the
orbital roof).
Table 1 Patient demographic and clinical features
Patient Age Sex Timing Material Aesthetic
outcomes
Post-traumatic
diplopia
Diplopia 3 months
after surgery
118M>1 month PEEK Good Yes No
246M>1 month Titanium Satisfactory No No
316F>1 month Titanium Satisfactory Yes Yes
427M>1 month Titanium Good No No
525M>2weeksto<1month PEEK Good Yes No
648M>2weeksto<1month PEEK Good Yes No
728F>1 month Titanium Satisfactory Yes No
829F<2 weeks PEEK Satisfactory Yes Yes
944F<2weeks PEEK Good Yes No
10 46 M >1 month PEEK Good Yes No
11 52 F >1 month PEEK Good Yes No
12 43 M >1 month PEEK Good Yes No
13 27 M >1month PEEK Satisfactory Yes No
14 53 F >1 month Titanium Good Yes No
15 48 F >1 month PEEK Satisfactory Yes Yes
16 42 M <2weeks PEEK Good Yes No
17 49 M >2weeksto<1month PEEK Good Yes No
18 59 F >1 month PEEK Good Yes No
19 47 M <2weeks PEEK Good No No
20 24 M >2weeksto<1month PEEK Good Yes No
21 27 M <2weeks PEEK Good Yes No
22 57 M <2weeks PEEK Good Yes No
23 16 M <2weeks PEEK Good Yes No
Abbreviation: PEEK, polyether-ether-ketone.
Craniomaxillofacial Trauma & Reconstruction Open Vol. 3 No. 1/2019
Evaluation of the Efficacy and Clinical Outcome of PSI Chepurnyi et al. e11
The preoperative examination revealed diplopia in all
fields of view in 16 patients, diplopia in two fields of view
(when looking downward and upward, or downward and
inward) was found in 3 patients, and in one field of view
(when looking downward) in 1 patient. In three cases, no
functional disorders were observed.
Facial asymmetry caused by post-traumatic enophthal-
mos was noted in 17 cases; in five patients, it was associated
with eyeball vertical displacement. In two cases, the aes-
thetic deficiency resulted from the deformity of the orbital
rims. Concomitant post-traumatic deformities of the eyelids,
lateral or medial telecanthus, in five cases also contributed to
the worsening of the appearance and deterioration of the
aesthetic condition.
In our series, the orbital floor was broken in all cases; the
medial wall was damaged in 14 cases, orbital roof in
two cases. Post-traumatic deformities of the orbital rims
were recorded in five cases. Orbital floor or medial wall
Fig. 1 Steps for patient-specific implant (PSI) design in orbital wall reconstruction. (A, B) Deformity of the orbital walls after blowout fracture:
computed tomography (CT) data; (C, D) mirroring of the intact orbit and its comparison with the model of the damaged orbit; (E) editing of the
CT-based three-dimensional vir tual model of the orbit with the creation of a constant surface; (F–H) design and position of the PSI into the orbit;
(I) evaluation and comparison of orbital volumes; (J–L) CT control after orbital reconstruction with PSI).
Craniomaxillofacial Trauma & Reconstruction Open Vol. 3 No. 1/2019
Evaluation of the Efficacy and Clinical Outcome of PSI Chepurnyi et al.e12
reconstructions in all cases were performed via subciliary
approach. Further reposition of the orbital content, implant
insertion, and fixation to the orbital rim were accomplished
by placing the eyeball to proper position. In three cases, we
employed a coronal approach for reconstruction of the
damaged orbitozygomatic complex and orbital roof.
Difficulties in proper positioning of the implant inside the
orbit were seen only in two cases. They were associated with
incomplete reposition of orbital content. In one case, the
fixation hole was in the projection of the bone defect (in an
area of incomplete osteogenesis).
In three cases, implants were us ed both for reconstruction
of the orbital walls and correct ion of the orbital rim anatomic
shape.
In this series, the average period of CAD procedures was
4.04 2.9 days. The average time spent on manufactur ing of
the PEEK PSI was 1.8 0.7 days vs. 23.7 4.9 days spent on
the manufacturing of the titanium PSI with delivery from the
United States or European Union. The average duration of the
surgical interventions was 58.8 17.3 minutes.
In this series, no inflammatory complications, decreased
visual acuity, or loss of visual fields were observed within the
postoperative period. The average duration of hospital stay
was 4.2 1.6 days.
The aesthetic outcomes of the treatment were good in 17
cases and satisfactory in 6 cases. In five patients with
satisfactory aesthetic outcomes, additional corrections of
paraorbital soft tissues were indicated. Depending on the
status, these patients underwent surgical repair of the eyelid
deformities or ptosis, and reshaping the scars.
Mobility disorders were totally absent in 22 cases (95.7%)
1 month after surgery, and in onlyone case they were partially
preserved; however, a significant improvement was seen.
One monthafter surgery,diplopia waspresent in 8 cases, but
3 months after surgery it was absent in 20 patients. Another
three patients reported a significant decrease in diplopia.
Mydriasis was noted in three cases with recovery after a
year follow-up. Sensory disturbances on the second branch
of the fifth cranial nerve 3 months after surgery were present
in nine patients but after a 6-month follow-up they resolved.
In one case, aesthetic and functional outcomes were
unsatisfactory due to the restriction of the eyeball mobility,
caused by compression of the medial rectus muscle with the
edge of the implant. The patient underwent a secondary
surgery to eliminate the compression of the muscle. The final
functional and aesthetic outcomes were satisfactory.
Thus, in our series, positive aesthetic results were
obtained in 95.7% of patients. Functional disorders resolved
in 65.2% of cases in a month term after surgery, in 86.96% of
patients within 3 months.
The measurements of the orbital volumes on the intact
side before and after surgery (actually, this volume did not
change) showed the minor differences in all cases, which can
be recognized as measurement error. On average, they con-
stituted 0.45 0.35 cm
3
and were statistically nonsignifi-
cant (U¼262; Z¼0.055; p¼0.956).
The average volume of the orbit on the intact side was
25.6 2.5 cm
3
, whereas the average volume of the damaged
orbits in our study significantly increased and constituted
29.8 4.3 cm
3
(U¼112; Z¼3.35; p¼0.001). The mean
difference was 4.2 3.0 cm
3
.
After reconstructive surgery in this series, the average
volume of the damaged orbits reduced to 25.8 2.6 cm
3
.
The average difference with intact orbits after the surgical
interventions was only 0.77 0.6 cm
3
and there were no
significant differences between the mean volumes of the
damaged and intact orbits (U¼231; Z¼736; p¼0.462)
(►Table 2). Analysis of the orbital virtual model superimposi-
tion found a high degree of congruence between the shape of
the mirrored intact and damaged orbits.
Discussion
Reconstruction of the orbit is always a challenge for surgeons
due to the complexity of the anatomy, small size, and excep-
tional importance of the eye for the human life.2The main
objectives to besolved in the treatment of orbital injuries are as
follows: (1) the repair of the orbital wall defects by restoration
of the orbital volume, (2) the reconstruction of the normal
orbital shape, taking into account the individual anatomic
features, and (3) the correction of the globe position.3The first
objective is traditionally accomplished by the use of standard
preformed implants made of different materials (titanium,
polytetrafluoroethylene, silicone, polyethylene, etc.) or auto-
logousgrafts (bone and cartilage).The main problem is that the
process of their adaptation to the parameters of the damaged
orbit is complex and time-consuming.3,4 The proper position-
ing of the standard implants or grafts inside the orbit is difficult
to achieve, and it is the main reason for unsatisfactory treat-
ment outcomes.6,7 However, according to Zieliński et al,17 the
use of standard titaniummeshes was not associatedwith worse
functional outcomes as compared with PSI, but it required
time-consuming intraoperative adaptation and demonstrated
higher blood loss during surgery.
The most difficult task that cond itions functional recovery
and a high aesthetic outcome of treatment is the accurate
restoration of the orbital shape, taking into account indivi-
dual parameters of the anatomical structure. This is espe-
cially important for the lower and medial walls, which form a
ledge near the orbital apex area.3,5 Other important intraor-
bital structures which should be considered for proper
reconstruction are the inferior orbital fissure (IOF), intraor-
bital buttress (IOB), and posterior ledge (PL). Their safety or
damage is determined by the severity of trauma, surgical
strategy, shape of the orbit after reconstruction (due to
design and positioning of the implant or graft).3,5,18
Restoration of the orbital shape can be achieved by
individualization of the standard implants (giving them a
specific shape during or before operation, manually or with
the use of special equipment). CAD/CAM technologies are
one of the most effective approaches to solve these problems.
The above technologies demonstrated significant benefits in
reconstruction of facial and cranial bones. In orbital recon-
struction, CAD/CAM technologies are used for accurate eva-
luation of the injury pattern, exact measurements of the
orbital volume and its changes, designing and manufacturing
Craniomaxillofacial Trauma & Reconstruction Open Vol. 3 No. 1/2019
Evaluation of the Efficacy and Clinical Outcome of PSI Chepurnyi et al. e13
of the implant for orbital shape restoration, considering the
anatomical landmarks of the damaged orbit, and the geo-
metry of the intact orbit. An implant designed in computer
software can be created with specific elements and indivi-
dually shaped to ensure fixation and placement inside the
orbit only in one predetermined position. Thus, virtual
design of the implants and the rapid prototyping become
an effective alternative to traditional surgical methods of the
orbital reconstruction.3,19,20
Our series of patients showed high efficiency of the offered
algorithms of PSI modeling and manufacturing. In our experi-
ence, mirroringof the intact bony orbit enablesvirtual repair of
bone defects of the damaged orbit only under the following
conditions: the proper safety of IOF, IOB, PL, high CTresolution,
sufficient thickness, and/or X-ray density of the bone walls of
the intact orbit. The important role of these anatomical land-
marks is to ensure an exact match between the mirrored
model and the model of the damaged orbit. From the surgical
and bioengineering points of view, PL assured the proper
support for the distal edge of the PSI; the IOF conditioned
the position of distal and lateral borders of the PSI. The IOB
supported the medial border of the PSI and provided an exact
reconstruction of the orbital shape.
In the absence of one or more of the above-mentioned
conditions, the virtual model of the damaged orbit needed to
be edited in automatic/semiautomaticor manual mode af ter the
mirroring of the intact orbital model. The complexity of editing
(“virtual sculpturing”) depended on the severity of the injury. If
the extent of the bony landmarks destruction was higher, the
time spent on manual editing increased as well as the need for
virtual sculpturing of such structures as IOB and PL. The
destruction of the IOB resulted in increased implant surface
due to the need to ensure its support in the area of the medial
orbital wall. The use of anatomic landmarks in combination with
mirroring of the contralateral orbit and “virtual sculpturing”
assured accurate reproduction of the orbital anatomicalshape in
the software environment. Thus, the design of the implant was
based on clinical status, geometry, and localization of the defect.
Some clinical trials report the outcomes of the PSI applica-
tion for orbital reconstruction by the use surgical navigation
and/or intraoperative CT to control the implant position inside
the orbit.14,21 However, in our study, the presence of specific
elements (curves and legs) provided in each case allowed
precise placement of the implants in the exact optimal/desired
position with due consideration of specificclinicalandanato-
mical conditions (►Fig. 2). However, in some cases it required
Table 2 Injury patterns in patients included in the study
Patient Fracture Damaged zone
(according to AOCMF
classification system
for orbital fractures16)
Damaged
IOF
a
Damaged
IOB
b
Damaged
posterior
ledge
Volu me di ffe rence
before surgery
(damaged/intact)
mm
3
Volu me di fference
after surgery
(damaged/intact)
mm
3
1 Blowout W2 (im) A(i) Yes Yes Yes 8,913 440
2 Combined R(li)W1(im)2(im) Yes Yes Yes 5,148 935
3 Combined R(im)W1(im) 2(im) No Yes No 3,736 1,984
4 Combined R(il)W2(il) Yes No No 457 275
5 Blowout W1(i)2(i) No Yes No 3,708 48
6 Blowout W1(mi)2(1) A(i) Yes Yes Yes 7,605 625
7 Combined W1(i)2(iml) A(i) Yes Yes Yes 1,210 634
8 Blowout W1(i)2(i) No Yes No 1,553 1,385
9 Blowout W1(i)2(i) No No No 1,083 351
10 Blowout W1(im)2(im) A(m) No Yes No 9,737 909
11 Blowout W1(is)2(i) Yes Yes Yes 2,972 868
12 Blowout W1(im)2(im) No No Yes 2,294 174
13 Combined R(il)W1(sm)2(lim)A(im) Yes Yes Yes 9,838 2,408
14 Combined R(li)W1(i)2(lm) Yes No Yes 7,232 1,764
15 Blowout W1(im)2(im) No Yes Yes 1,830 428
16 Combined W1(mi)2(im) No Yes No 5,780 1,562
17 Blowout W1(im)2(im) No Yes No 5,463 654
18 Blowout W1(i)2(i) No No No 3,241 353
19 Blowout W1(i)2(i) No No No 1,145 240
20 Blowout W1(im)2(im) Yes Yes Yes 6,342 315
21 Blowout W1(im)2(im) No No No 429 280
22 Blowout W1(i)2(i) No No No 5,160 231
23 Blowout W1(i)W(mi) No Yes Yes 2,567 843
a
Inferior orbital fissure.
b
Intraorbital buttress.
Craniomaxillofacial Trauma & Reconstruction Open Vol. 3 No. 1/2019
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to increase the size of implants to fit an orbital anatomy, which
demand more wide surgical approaches.
The use of different types of materials in treatment of
our patients was conditioned by the different clinical goals
and the limitations of manufacturing processes. Individua-
lized titanium PSI provided the possibility of both orbital
walls reconstruction and stabile fixation of the orbital rim
fragments in cases of complex orbitozygomatic fractures.
We also took into consideration the manufacturer’srecom-
mendations which made it possible to produce the
implants with the thickness of 0.6 mm by milling of PEEK
and of 0.9 to 1 mm (depending on geometry) by titanium
sintering (►Fig. 3). For isolated orbital wall defects the
thinner plates from PEEK were more appropriate. Thus, the
shape and dimensions of the PSI influenced the choice of
the material.
The only limitation in the production of PSI by milling was
the presence of “a negativeangle”in the region of the orbital rim
when it was necessary to reshape it, which made it impossible
to mill the inner surface of the implant. In such cases, we
preferred SLS titanium implants. With respect to SLS technol-
ogy, wall thickness conditioned the limitations for the manu-
facturing of thin sections of the implants (mostly retention
points and fixing elements).
Our results did not allow us to give a comparative descrip-
tion of the titanium and PEEK PSI application due to the
presence of significant individual variations in the trauma
patterns, as well as different indications for their use. At the
same time, we did not observe any complications or any
significant differences in the accuracy of restoring the shape
and volume of the orbits. The principles of modeling and the
time spent on the CAD procedures were not different, as well
as inquiries in time of manufacturing were determined by
subjective factors. All this exclude the possibility to deter-
mine evidence-based recommendations of the material
selection for PSI manufacturing.
According to the literary data, PEEK is a widely used
biocompatible polymer with numerous physical character-
istics that are favorable for craniofacial reconstruction.2,12 It
is a semicrystalline and thermoplastic material with good
imaging properti es,stiffness, durability, light weight, fatigue,
and chemical resistance. PEEK implants can be repeatedly
sterilized without the degradation of their structure and
mechanical properties.
Fig. 2 Patient K with blowout fracture of the right orbit, 3 weeks after trauma (A–C) computed tomography (CT) slices of the damaged orbital
walls; (D, E) virtual mode of the PSI, positioned into the orbit; (F–H) control CT of the reconstructed orbit with patient-specificimplant.
Craniomaxillofacial Trauma & Reconstruction Open Vol. 3 No. 1/2019
Evaluation of the Efficacy and Clinical Outcome of PSI Chepurnyi et al. e15
In addition, the modulus of elasticity of this material is close
to the cortical bone, thus avoiding stress shielding effect.
Allergic reactions to PEEK are extremely rare. PEEK implants
can be easilymodified using high-speedburs and it is easy to fix
them with conventional screws to the bone edges. In our series,
neither clinical nor radiological manifestations of inflamma-
tory complications, including sinusitis, caused by PEEK
implants were observed (a maximum follow-up of 2 years).
Design and the way of implant insertion conditioned the
choice of surgical approach. We used a subciliar y approach as
optimal one for mobilization of the orbital content, place-
ment of the eyeball in the proper position, and insertion of
the PSI into the orbit. According to our observations, the
presence of a scar in the subciliary area did not affect the
integral aesthetic outcomes of the treatment.
Virtual preoperative simulation was employed for the
estimation of the implant position inside the orbit, and its
interrelationships with bony structures, nerves, and oculomo-
tor muscles. In the cases where collisions between the implant
and anatomical structures were seen the design was changed.
Preoperative planning allows the precise measurement of
orbital volume and analysis of its changes caused by traumatic
injury and surgical interventions. The results of this study
demonstratedthe effectiveness of the offeredalgorithm for PSI
design and manufacturing. It enabled adequaterecovery of the
orbital volume and shape after reconstructive surgery so that
the differences between volume of damaged and intact orbits
became nonsignificant (►Fig. 4).
Fig. 3 Patient D with post-traumatic deformity of the left orbitozygomatical complex (A) three-dimensional (3D) computed tomography before surgery,
(B) virtual model of the patient-specific implant (PSI) and surgical guide for zygoma reposition;(C) removed titanium þpolyethylene implant and titanium
PSI; (D) 3D after surgery).
Fig. 4 Superimposition of the virtual models after surgery: mirrored
intact and damaged orbits.
Craniomaxillofacial Trauma & Reconstruction Open Vol. 3 No. 1/2019
Evaluation of the Efficacy and Clinical Outcome of PSI Chepurnyi et al.e16
The main advantage of the offered surgical approach was
accurate reconstruction of the orbital shape, especially in “the
key area,”according to Hammer,22 which ensured high aes-
thetic outcomes of treatment. Postoperative CT images of
patients, who were treated by the use of the offered algorithm,
showed the high accuracy of implants positioning inside the
orbit and the restoration of its anatomical structure in the vast
majority of observations. PSI location was almost similar to the
preoperative planning. The difficultiesin positioning were due
to scarring andpresence of small bone fragments that werenot
adequately reflected on the CT slices.
The results obtained correlate with those reported by
other authors. Zieliński et al17 reported the presence of
motility disorders after CAD/CAM-assisted orbital recon-
structions in 29 and 13% of cases 1 and 6 months after
surgery, respectively. According to the multicenter study by
Zimmerer et al,21 there was a statistically significant reduc-
tion in the time of surgical intervention when PSI were used.
An average time of surgery in this study was 60 minutes,
which correspond to the results obtained in present study.
Motility disorders after orbital reconstruc tion with the use of
PSI were in 15.8% of cases 1 month and in 3.3% 4 months after
surgery. Diplopia was found in 35.8% of cases 1 month after
surgery. The value decreased to 24.6% 4 m onths after surgery.
These results are almost similar to those obtained in our
study. However, our study had following limitation, such as
subjective evaluation of the facial asymmetry and diplopia,
absence of the control group with “hand-bent”implants and
enophthalmos evaluation, as well as failure to determine the
relationship between clinical and radiological objective data,
absence of long-term follow-up, a relatively small number of
observations with various trauma patterns. Accordingly, all
these issues require further research and in-depth analysis.
Conclusion
The obtained results confirm the advantages of CAD/CAM
technology and PSI in treatment of orbital defects and
deformities. The use of anatomical landmarks in combina-
tion with mirroring of the contralateral orbit and “virtual
sculpturing”ensured accurate reproduction of the anatomi-
cal shape of the orbit in the software environment. Both
titanium and PEEK can be effectively used for PSI manufac-
turing, depending on clinical situation, surgical purposes,
and geometry of the orbit.
Conflict of Interest
None.
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