2017 modabber-medial-approach-dcia-cad-cam

Please cite this article in press as: Modabber A, et al. Medial approach for minimally-invasive harvesting of a deep circumflex iliac
artery flap for reconstruction of the jaw using virtual surgical planning and CAD/CAM technology. Br J Oral Maxillofac Surg (2017),
http://dx.doi.org/10.1016/j.bjoms.2017.09.005
ARTICLE IN PRESSYBJOM-5266; No.of Pages6
British Journal of Oral and Maxillofacial Surgery xxx (2017) xxx–xxx
Available online at www.sciencedirect.com
ScienceDirect
Medial approach for minimally-invasive harvesting of a deep
circumflex iliac artery flap for reconstruction of the jaw
using virtual surgical planning and CAD/CAM technology
A. Modabbera,∗, N. Ayouba, A. Bocka, S.C. Möhlhenricha, B. Lethausa, A. Ghassemia,
D.A. Mitchellb, F. Hölzlea
a Department of Oral, Maxillofacial and Facial Plastic Surgery, RWTH Aachen University Hospital, Aachen, Germany
b Maxillofacial Unit, Calderdale and Huddersfield NHS Foundation Trust, England, UK
Received 8 July 2017; accepted 11 September 2017
Abstract
Donor site morbidity is the most common limitation of the deep circumflex iliac artery (DCIA) flap, so the purpose of this paper is to describe a
new, minimally-invasive, approach to its harvest using virtual surgical planning and CAD/CAM technology to reduce functional and aesthetic
morbidity at the donor site. Virtual surgical planning was based on preoperative computed tomographic data. A newly-designed surgical
guide made using CAD/CAM technology was used to transfer the virtual surgical plan to the site of operation. This enabled us to raise a
bicortical flap from the pelvis with preservation of the anterior superior iliac crest from the medial side with minimal muscular stripping. The
guide, designed at slightly less than 90◦
to the lateral cortex, allowed the cut segment of bone to be raised medially. The new virtual surgical
planning guide allowed a medial approach with reduced stripping of muscle and lower morbidity. No complications were encountered during
the operation or the healing phase. Patients treated in this way had a shorter recovery period, with minimal complaints about walking or loss
of profile of the hip. We conclude that virtual surgical planning can aid a minimally-invasive approach with predictable results. This allows a
medial approach to the harvest of DCIA with preservation of important anatomical structures, and a reduction in donor site morbidity.
© 2017 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Keywords: DCIA flap; medial approach; computer-assisted surgery; virtual surgical planning; surgical guide; jaw reconstruction
Introduction
The reconstruction of defects of the jaw should take into
consideration the restoration of eating and speech. Microvas-
cular bony flaps, such as the deep circumflex iliac artery
flap (DCIA), fibular flap, or scapular flap are commonly
used to reconstruct the jaw before dental rehabilitation using
∗ Corresponding author at: Department of Oral, Maxillofacial and Facial
Plastic Surgery, RWTH Aachen University Hospital, Pauwelsstr. 30, 52074
Aachen, Germany. Tel.: +49 241 8088231, fax: +49 241 8082430.
E-mail address: amodabber@ukaachen.de (A. Modabber).
intraosseous implants. The DCIA flap is characterised by a
large volume of well-vascularised bone and is suitable for
mandibular reconstruction.1
Postoperative donor site morbidity, particularly difficulty
in walking, may occur with fibular and DCIA flaps, which
is important for a patient’s quality of life. Methods to reduce
donor site morbidity are therefore of increasing importance
as these techniques become routine.
Computer-assisted operations have become increasingly
popular in maxillofacial surgery, possibly because we are
able to simulate many conditions accurately.2–4 Three-
dimensional modelling assisted by computed tomography
0266-4356/© 2017 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

2 A. Modabber et al. / British Journal of Oral and Maxillofacial Surgery xxx (2017) xxx–xxx
(CT) has been helpful in obtaining information for recon-
structive surgery, particularly for preparation of the flap at the
donor site before transplantation into the defect. Virtual sur-
gical planning translates digital CT data and 3-dimensional
software simulation into real-time operations, and also helps
to plan the size, shape, and exact placement of the bony flap,5
which may be of clinical benefit.
We describe a new approach to the harvest of the DCIA
flap for mandibular reconstruction using virtual surgical plan-
ning and CAD/CAM technology to reduce the functional and
aesthetic morbidity at the donor site.
Material and methods
Virtual surgical planning
As previously described,6,7 preoperative angiographic CT
scans (128-row, multislice, CT Scanner, Somatom Definition
Flash, Siemens, Erlangen, Germany) of the facial skeleton
and ilium were used to investigate the arteries at the iliac
donor site and the dimensions of the mandibular defect.
Reconstructions were obtained in bone and soft tissue win-
dows, kernel (small matrix) 30/60 for head and neck and 70
for the pelvis. Scans for the head and neck were acquired in
slices 0.5 mm thick, and for the pelvis 1 mm thick.
These CT data (in DICOM file format) were imported into
ProPlan CMF Planning Software (Materialise NV, Leuven,
Belgium). The data were then segmented, in which all bony
structures of interest were isolated, and a high-quality, 3-
dimensional visualisation of the mandible, maxilla, and ilium
generated. If there were pre-existing mandibular defects, the
mirrored healthy side or previous CT data served as a ref-
erence for the virtual reconstruction of the affected part of
the mandible. The positions of the vessels that nourished the
DCIA flap were defined. This information allowed accurate
planning of the defect and its replacement (Fig. 1). Struc-
turally important areas in the pelvis, such as the anterior
superior iliac spine (ASIS), the iliac crest, and the adjacent
muscle attachments, can be preserved. To harvest the bony
flap from the medial side, the bony cuts should be made less
than 90◦ to the lateral cortex. The donor site was virtually cut
in this way and transferred into the virtual mandibular defect
in its correct relation to the maxilla.
The final planning data were imported into the 3-matic (a
finite element analysis) software program (Materialise NV,
Leuven, Belgium) as STL files. A custom-made surgical
guide that delineated the desired osteotomy lines, size of flap,
and angulation was designed for the harvest of the DCIA flap
based on the medial cortex to preserve the ASIS (Fig. 2A and
B). We produced this surgical guide with a slot to lead through
the pedicle of the flap before fixation using rapid prototyp-
ing selective laser sintering from polyamide powder. The flap
harvesting guide, additional mandibular resection guides or
Fig. 1. Three-dimensional virtual reconstruction of the left mandible with
the left deep circumflex iliac artery flap fitted perfectly into the defect.
skull models produced by the stereolithographic technique
linked the virtual surgical plan to the operation.
Surgical approach
To harvest a myo-osseous DCIA flap the skin is incised 2 cm
superior to the line that connects the ASIS and the pubic
tubercle. The incision is extended posteriorly over the iliac
crest and is carried down to the midportion of the crest. The
musculotendinous aponeurosis of the abdominal muscles is
cut at the sagittal midline. Subcutaneous fatty tissue should be
dissected between the femoral artery and the ASIS to identify
the external oblique fascia that forms part of the inguinal
ligament. The internal oblique muscle fibres are separated
and the pedicle of the flap becomes visible in the groove that
is formed by the transversus abdominus and iliacus muscles.
The pedicle should be isolated by ligation of the side branches
andtransectionoftheabdominalmuscles,preservingacuffof
these muscles and the iliacus muscle 1 cm below the pedicle.
This approach has been described previously.8
The course of the DCIA at the inner surface of the pelvic
curvature is 2–3 cm posterior to the ASIS and 2–3 cm inferior
to the inner rim. The distal DCIA is identified in the perios-
teum and is tied and divided before the harvesting guide is
positioned. This outlines the flap to match the virtual surgical
plan and preserves about 1.5 cm of the ASIS and iliac crest.
The gluteus medius, tensor fasciae latae, and the sartorius
muscles do not need to be cut or stripped from the lateral
and anterior side of the pelvis or ASIS (Fig. 3). The pedicle
should be directed through the slot before the guide is fixed
to the medial cortex with conventional osteosynthesis screws
(Fig.4).TheDCIAflapisremovedfromthepelvicboneusing
an oscillating saw to cut through both cortices. The pedicle
should be carefully protected during the osteotomy. If the cut
is made slightly less than 90◦ to the lateral cortex using the

A. Modabber et al. / British Journal of Oral and Maxillofacial Surgery xxx (2017) xxx–xxx 3
Fig. 2. A. Three-dimensional design of the surgical guide, generated from the optimally constructed virtual transplant data, positioned on the left pelvic bone
(medial view). B. Three-dimensional design of the surgical guide, generated from the optimally constructed virtual transplant data, positioned on the left pelvic
bone (lateral view).
Fig. 3. Illustration of the harvested left deep circumflex iliac artery flap using
the medial approach. Neither the gluteus medius, nor the tensor fasciae latae,
nor the sartorius muscles need to be cut or stripped from the lateral and
anterior side of the pelvis or anterior superior iliac spine.
guide, it allows raising of the cut segment of bone medially
(Fig. 5). Residual muscle fibres of the gluteus medius muscle
are transected and bleeding stopped.
Fig. 4. The surgical guide is temporarily fixed on the medial side of the left
pelvic bone using osteosynthesis screws, ready for sawing. The lateral side
is completely untouched. The white arrow points to the deep circumflex iliac
artery and the black arrow indicates the anterior superior iliac spine.
Fig. 5. The exactly sawn and cut deep circumflex iliac artery flap during
raising of the cut segment of bone medially. The white arrow points to
the deep circumflex iliac artery and the black arrow indicates the anterior
superior iliac spine.
Results
We used this medial approach three times to harvest the
myo-osseous DCIA flap. Virtual surgical planning allowed

Fig. 6. Reconstructed left mandible with the deep circumflex iliac artery flap
fixed by miniplates. The cervical anastomosis of the flap is marked with the
white arrow and a green foil.
preplanning of the shape and size of the DCIA flap and the
site of osteotomy during operation. The temporary fixation
of the surgical guide on to the medial side of the pelvic bone
simplified the procedure. The new design of the harvesting
guide proved to be effective. Angulation of the osteotomies at
slightly less than 90◦ to the lateral cortex made it easy to raise
the segment of bone medially. The guide allowed insertion
of the DCIA flap into the mandibular defect without major
adjustments (Fig. 6). The flaps worked in all cases, and no
complications were encountered either during the operations
or while they were healing (Fig. 7). All patients had a short
convalescence and no main complications at the donor site,
such as complaints about walking and loss of the anatomical
profile of the hip have occured.
Discussion
The DCIA flap is a widely used method of reconstruction
of the mandible1 and the maxilla9 internationally because of
its anatomical shape and thickness, and the possibility that
it allows to harvest large amounts of bone. In contrast to the
superficial circumflex iliac artery, the DCIA is the most reli-
able vessel for the blood supply of the bony flap.10 A skin
island from the inguinal region can be integrated as an osteo-
musculocutaneous DCIA flap for soft tissue reconstruction,
or parts of the internal oblique muscle for the lining of intrao-
ral defects.11,12 Both the quality and the quantity of the bone
are ideal for the insertion of intraosseous implants for dental
rehabilitation.13
Virtual surgical planning shortens the ischaemic time
of the flap, increases precision and control, and minimises
the process of shaping the flap.7 It can help to choose the
most suitable bony part of the flap, and evaluate the size
of the defect and the relations with neighbouring structures
to achieve the best possible reconstruction plan. It also pro-
vides an accurate three-dimensional model by matching the
standards of the defect, and accurately facilitates further
treatment.14,15
The conventional DCIA guide is located at the lateral
side of the ilium and placed on the planned bony flap. The
osteotomies are made around the outer border of the guide. In
contrast, the surgical guide for the medial approach is located
at the medial side of the ilium around the planned dimensions
of the flap (Fig. 2A and B) to avoid injuries to the deep cir-
cumflex iliac artery and the connecting bony perforators. The
medial cutting guide has to have a small slot (which lies pos-
teriorly), to allow placement and to negotiate the pedicle,
which is placed anteriorly so that, when the inner surface of
the guide is cut around, the slot is cut across.
The use of virtual surgical planning permits calculation of
the shape of the defect and the geometry of the donor site, as
well as the angulation of the pelvic bony segment to allow
harvest of an exact bicortical vascularised segment of bone.
Preservation of the ASIS and crest without detachment of the
gluteus medius, tensor fasciae latae, or the sartorius muscles
minimises postoperative morbidity.
Many approaches to the harvest of microvascular bone
flaps and avascular bone grafts of the ilium have been
described. David et al16 presented the method of the rais-
ing the split iliac crest bone flap, and Shenaq et al described
Fig. 7. The perfectly healed deep circumflex iliac artery flap during the removal of the osteosynthesis plates after six months.

A. Modabber et al. / British Journal of Oral and Maxillofacial Surgery xxx (2017) xxx–xxx 5
the osteomyocutaneous DCIA flap with modification of the
split inner cortex.17 These modifications also aimed to reduce
donor site morbidity. However, the harvesting of the inner
cortex of the ilium may result in a thin layer of bone that is
not sufficient to take dental implants. It is also easier to break
the thin inner cortex inadvertently, because the width of the
ilium varies. Hall et al described the medial approach for
obtaining avascular iliac bone grafts for maxillofacial recon-
structive procedures, which is currently routine in clinical
practice.18 It is also possible to obtain bone grafts of can-
cellous, partial, or full-thickness segments using the crestal
window technique.19
Our medial approach using virtual surgical planning for
harvesting a myo-osseous DCIA flap combines the benefits
of the avascular window technique from the medial side with
the advantages of the microvascular full-thickness bony flap.
There are no limitations to the amount of bone or shaping of
the flap compared with the conventional lateral technique.
Theoretically it is also possible using this technique to
take osteomusculocutaneous DCIA flaps including the skin,
but we do not use the skin because of this flap’s wellknown
problems with venous drainage. It is possible to raise the
more common myo-osseous DCIA flap including the inter-
nal oblique muscle without any limitations using the medial
approach.
Donor site morbidity is the most discussed limitation of
the DCIA flap. Out of 31 patients, Valentini et al described
25.8% complaints about walking 60 days or more postoper-
atively, and 38.7% loss of hip profile, which correlated with
the harvest of the ASIS in their patients.20 There seems to be
a correlation between donor site morbidity on the one hand,
and the amount of bone harvested and postoperative compli-
cations on the other.21,22 Our minimally-invasive approach
allows preservation of the ASIS as well as the crest, which
eliminates possible donor site morbidity resulting from their
absence. If the attachments to neighbouring muscles are pre-
served, the risk of haematoma, seroma, and abdominal hernia
are reduced and the convalescence is shorter. Virtual surgical
planning also minimises the quantity of harvested bone to
the required amount. A randomised prospective trial with a
larger sample will be required to evaluate further the benefits
of this approach.
In conclusion we have described a medial approach using
virtual surgical planning and a CAD/CAM-designed guide
to harvest the DCIA flap. This allows preservation of impor-
tant anatomical structures while the flap is being raised and
reduces donor site morbidity while improving functional and
aesthetic outcomes.
Conflict of interest
We have no conflicts of interest.
Ethics statement/confirmation of patients’ permission
Ethics approval not required. Written informed consent was
obtained from each patient.
Acknowledgement
The authors thank Ms. Alexandra Vent for her valuable con-
tribution of the artistic illustration.
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