10.14639/0392-100X-N0549
Mandibular reconstruction is a primary concern for head and neck reconstructive surgeons because of the aesthetic restoration needs after ablative surgery, as well as for functional reasons: the mandible has a central functional role in speaking, swallowing and mastication. It is generally agreed that the gold standard for mandibular reconstruction is a bone free flap supported by a reconstructive titanium plate. The fibular flap represents the first choice for multi-segment mandibular reconstruction. The fibula, harvested as a single barrel graft, does not exhibit sufficient thickness to reach the original height of the native mandible; therefore, the positioning of dental implants is often deeper than that of the native alveolar crest. The aim of this study was to evaluate the positioning of the fibular free flap as it pertains to the restoration of vertical mandible height, by modifying the design of a 3D-printed titanium patient-specific implant (PSI). In this novel reconstructive workflow, the customised plate was projected to support the fibular flap at an alveolar bone position above the typical inferior mandibular border, and carried out on four patients. All patients were treated for benign neoplasms involving mandibular bone. Clinical outcomes and accuracy of the procedure are described. Our reconstructive proposal appears to be a valid alternative to the double-barrel technique in order to restore the vertical height of the reconstructed mandible.
text/xml
1827-675X
549
en
Leonardo Ciocca
https://creativecommons.org/licenses/by-nc-nd/4.0
ACTA Otorhinolaryngologica Italica
head and neck surgery
Mandibular reconstruction using a new design for a patient-specific plate to support a fibular free flap and avoid double-barrel technique
Text.Serial.Journal
https://www.actaitalica.it/
41
Head and neck
2021-07-07
2019-11-13
2021-07-08
2021-07-08
230-235
1
Leonardo Ciocca
2021/07/07
10.14639/0392-100X-N0549
230
Section of Oral Surgery, Department of Biomedical and Neuromotor Science, Alma Mater Studiorum University of Bologna, Bologna, Italy
1827-675X
head and neck surgery
en
235
Mandibular reconstruction using a new design for a patient-specific plate to support a fibular free flap and avoid double-barrel technique
https://www.actaitalica.it/article/download/549/621
41
ACTA OTORHINOLARYNGOLOGICA ITALICA 2021;41:230-235; doi: 10.14639/0392-100X-N0549




Head and neck


Mandibular reconstruction using a new design
for a patient-specific plate to support a fibular free
flap and avoid double-barrel technique
Ricostruzione mandibolare con lembo di fibula supportato da nuova tipologia
di placca personalizzata al fine di evitare la tecnica della doppia barra
Achille Tarsitano1, Salvatore Battaglia1, Giuseppe Corinaldesi2, Claudio Marchetti1, Gerardo Pellegrino2, Leonardo Ciocca2
1
 Maxillofacial Surgery Unit, Head and Neck Department, IRCCS Azienda Ospedaliera Universitaria di Bologna, Department of
Biomedical and Neuromotor Sciences, Alma Mater Studiorum University of Bologna; 2 Section of Oral Surgery, Department of
Biomedical and Neuromotor Science, Alma Mater Studiorum University of Bologna


SUMMARY
Mandibular reconstruction is a primary concern for head and neck reconstructive surgeons
because of the aesthetic restoration needs after ablative surgery, as well as for functional
reasons: the mandible has a central functional role in speaking, swallowing and mastication.
It is generally agreed that the gold standard for mandibular reconstruction is a bone free
flap supported by a reconstructive titanium plate. The fibular flap represents the first choice
for multi-segment mandibular reconstruction. The fibula, harvested as a single barrel graft,
does not exhibit sufficient thickness to reach the original height of the native mandible;         Received: November 13, 2020
therefore, the positioning of dental implants is often deeper than that of the native alveolar     Accepted: April 29, 2021
crest. The aim of this study was to evaluate the positioning of the fibular free flap as it per-
tains to the restoration of vertical mandible height, by modifying the design of a 3D-printed      Correspondence
titanium patient-specific implant (PSI). In this novel reconstructive workflow, the custom-        Achille Tarsitano
ised plate was projected to support the fibular flap at an alveolar bone position above the        S. Orsola University Hospital, Head and Neck De-
                                                                                                   partment, DIBINEM – University of Bologna
typical inferior mandibular border, and carried out on four patients. All patients were treated
                                                                                                   via Massarenti 9, 40100 Bologna, Italy
for benign neoplasms involving mandibular bone. Clinical outcomes and accuracy of the              Tel. +39 051 2142463
procedure are described. Our reconstructive proposal appears to be a valid alternative to the      E-mail: achille.tarsitano2@unibo.it
double-barrel technique in order to restore the vertical height of the reconstructed mandible.
KEY WORDS: mandibular reconstruction, customised plate, fibula free flap, double-barrel            Funding
                                                                                                   None.
technique, head and neck surgery
                                                                                                   Conflict of interest
RIASSUNTO                                                                                          The Authors declare no conflict of interest.
La ricostruzione mandibolare è particolarmente rilevante per il chirurgo cervico-cefalico,
in quanto influenza significativamente i successi in termini di risultati estetici e funzionali      How to cite this article: Tarsitano A, Batt-
per il paziente. Il gold standard per tale ricostruzione è l’utilizzo di lembi ossei rivascola-      aglia S, Corinaldesi G, et al. Mandibular re-
rizzati, stabilizzati mediante una placca ricostruttiva in titanio. Il lembo di fibula rappre-       construction using a new design for a patient-
senta la prima scelta ricostruttiva laddove necessitino molteplici segmenti ossei. Tuttavia          specific plate to support a fibular free flap and
questo lembo, allestito secondo la tecnica della singola barra, non permette di ripristinare         avoid double-barrel technique. Acta Otorhi-
l’altezza mandibolare nativa, adeguata per una corretta riabilitazione masticatoria im-              nolaryngol Ital 2021;41:230-235. https://doi.
planto-supportata. Lo scopo di questo studio è quindi presentare un nuovo design di placca           org/10.14639/0392-100X-N0549
ricostruttiva custom-made, atta a posizionare il segmento osseo di fibula in una posizione
più coronale, evitando pertanto la necessità di allestire il lembo secondo la tecnica del-         © Società Italiana di Otorinolaringoiatria
                                                                                                   e Chirurgia Cervico-Facciale
la doppia barra. La placca custom-made contribuisce inoltre al mantenimento del profilo
mandibolare, garantendo il ripristino morfologico della ricostruzione. Questo protocollo
                                                                                                                  OPEN ACCESS
è stato eseguito su quattro pazienti sottoposti a resezione mandibolare per tumori benigni.
I risultati clinici e di accuratezza della procedura sono presentati. Il protocollo presentato     This is an open access article distributed in accordance with
                                                                                                   the CC-BY-NC-ND (Creative Commons Attribution-Non-
sembra una valida alternativa alla tecnica della doppia barra al fine di ripristinare l’altez-     Commercial-NoDerivatives 4.0 International) license. The
za mandibolare nativa.                                                                             article can be used by giving appropriate credit and mentio-
                                                                                                   ning the license, but only for non-commercial purposes and
PAROLE CHIAVE: ricostruzione mandibolare, placca personalizzata, lembo libero di                   only in the original version. For further information: https://
fibula, tecnica della doppia barra, chirurgia della testa e del collo                              creativecommons.org/licenses/by-nc-nd/4.0/deed.en




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Introduction
Mandibular reconstruction is a primary concern for head
and neck reconstructive surgeons because of the aesthetic
restoration needs after ablative surgery, as well as for func-
tional reasons: the mandible has a central functional role
in speaking, swallowing and mastication. It is generally
agreed that the gold standard for mandibular reconstruction
is a bone free flap supported by a reconstructive titanium
plate 1. The fibular flap represents the first choice for multi-
segment mandibular reconstruction 2.
Multiple papers 3 have reported optimal anatomic and aes-
thetic outcomes of mandibular reconstruction after cancer
ablative surgery when computer-aided design/computer-
aided manufacturing (CAD/CAM) technology was used;                 Figure 1. Tumour resection planning.
however, the prosthetic workflow to restore masticatory ef-
ficiency remains a challenge 4. Although digital planning is
known to be accurate, detailed and efficient, the reconstruc-      the right leg, based both on the final position of the fibula
tive plate that supports the fibular segments runs along the       in the mandible with respect to the best bicorticalism for
inferior border of the mandible, thus requiring the surgeon        implants and the best anchoring surface to screw into the
to perform bony reconstruction at the basal bone position.         bone plate and on the vascular pedicle anatomy (Fig. 2).
The fibula, harvested as a single barrel graft, does not ex-       Selection was also made with consideration of the number
hibit sufficient thickness to reach the original height of the     of necessary segments and the angulation of the segments
native mandible; therefore, the positioning of dental im-          within the mandibular defect, based on the appropriate
plants is often deeper than that of the native alveolar crest,     pedicle length for microvascular anastomoses. The resec-
resulting in poor aesthetics and inappropriate hygiene 1.          tion cutting guides and osteotomy guides for the bony free
The aim of this study was to evaluate the positioning of the       flap were designed based on resection and reconstruction
fibular free flap as it pertains to the restoration of vertical    planning with TRI MATIC software (Materialise, Leuven,
mandible height by modifying the design of a 3D-printed            Belgium).
titanium patient-specific implant (PSI).
                                                                   Occlusion-driven design of double-level anatomy
Description of the clinical techniques                             During the simulation of reconstructive surgery, the posi-
                                                                   tion of teeth in the native mandibular arch is considered to
and technology                                                     preserve occlusion and function. When a unilateral edentu-
This study was approved by the S. Orsola Hospital Ethics           lous area was observed in the affected side, the positions of
Committee (approval no. 57/2011/O/Disp).                           teeth on the healthy side were mirrored and correct occlusal
                                                                   relationships were simulated using MIMICS software (Ma-
3D segmentation of the fibular flap                                terialise, Leuven, Belgium). By contrast, if the contralateral
Digital Imaging and Communications in Medicine (DI-                arch was edentulous, a radiographic guide was constructed
COM) format files obtained from pre-operative head and             with radiopaque teeth and used during CT examination to
neck computed tomography (CT) and donor-site CT angi-              allow reproduction of the teeth in their maxillomandibular
ography scans of the legs were processed by the surgeons           relationship.
using MIMICS software (Materialise, Leuven, Belgium)               Bicorticalism is necessary for the best osteointegration and
in order to obtain the 3D virtual models. Resection virtual        primary stability of oral implants in the fibular flap, and
planning was performed considering radical resection of            thus the position of the fibula was determined with respect
the tumour within safe margins (Fig. 1).                           to the occlusal plane. The three-dimensional fibula posi-
Simulation of reconstruction began with virtual restoration        tioning was simulated in order to obtain better dental im-
of the native mandibular profile and contour. The recon-           plant\bone surface contact (Fig. 2).
structive procedure was virtually performed on 3D objects          In our novel protocol, the design of the bone plate was
obtained from DICOM files of the donor-site CT angiog-             modified to allow mimicry of double-level anatomy – i.e.,
raphy scan. During this step, the surgeon chose the left or        increasingly lateral basal bone inferior mandible margin



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A. Tarsitano et al.




                                        A                                            B                                                                  C




Figure 2. Positioning of the fibula as related to occlusion, implants and alveolar bone height from lateral (A, B) and occlusal views (C).


and increasingly medial alveolar bone position. Therefore,
the fibula reproduced alveolar bone. Otherwise, the inferior
border was reproduced by the plate. Two or more vertical
arms were designed from the top border of the bone plate
to support the bony segment and secure it in the necessary
upper position.

Design of the customised reconstructive plate
In this novel CAD/CAM workflow, the customised plate
was projected to support the fibular flap at an alveolar bone
position above the typical inferior mandibular border. A
new containing deck was designed using Geomagic Free-
form Plus software (3D Systems, Rock Hill, SC, USA) to
support the bony flap in the higher position; this border
allowed distribution of occlusal loading onto bone screws
                                                                                    Figure 3. Virtual design of the containing deck for sustaining the fibular bone
and directly onto the PSI structure (Fig. 3). Therefore, the                        segments (red arrow).
customised plate fully restored the mandibular bony shape
of the inferior border, while allowing the surgeon to po-
sition fibular segments in the alveolar region, providing a
more feasible and aesthetic contour (Fig. 4).
On the inferior portion of the PSI, a grid was designed to
allow the repositioning of oral floor muscles at the original
bone insertion (Fig. 4). The plate had a 2.4 mm thickness
and was fixed to the native mandible using a 2.4 mm fixa-
tion system.

3D-printing of surgical devices
At the end of the process, the surgeons validated and veri-
fied the project with MAGICS software (Materialise, Leu-
ven, Belgium). The Standard Tessellation Language (STL)
interface format files of the customised reconstructive plate
were processed, and the plate was then manufactured via
direct metal laser sintering with a DMLS M280 system                                Figure 4. Mandibular reconstructive plate design according to the native
(Electro-Optical Systems, GmbH, Krailling, Germany) us-                             mandibular anatomy.



232
                                                                                                    Mandibular plate mimicking double barrel technique




ing a titanium alloy with an additive-in layer technique. In                 volving mandibular bone. The mandibular symphysis was
the same manner, laser sintering following the STL files                     resected in two of the patients. Mandibular resection was
of the resection and fibular cutting guides was performed                    completed in accordance with resection virtual planning,
using the SLS FORMIGA P110 system (Electro-Optical                           using cutting guides. Fibular segmentation and flap inser-
Systems, GmbH, Krailling, Germany).                                          tion were performed in accordance with virtual planning
                                                                             in all patients. The average follow-up was 12 months. No
Fibula free flap harvesting                                                  intraoperative complications were recorded. No post-oper-
For all cases, the fibula has been harvested both as exclu-                  ative complications were registered in terms of inflamma-
sively bone flap and as composite osteo-muscular flap.                       tion or plate exposure.
Since all recruited patients were affected by benign bone
tumours, no large amount of soft tissues removal has been                    Evaluation of fibular positioning accuracy
required and no need for skin paddle harvesting was iden-                    To verify fibular positioning and angulation, the STL file
tified. Oral mucosal lining was preserved for all patients                   used for virtual planning and the STL file of the postopera-
in order to improve dental rehabilitation in the future im-                  tive CT scan were imported into a mesh-processing soft-
plants. A fibular cutting guide was used to segment the                      ware using MeshLab (Visual Computing Lab – ISTI-CNR,
bony flap. The guide was fixed to the fibula using 2.0 mo-                   Pisa, Italy). After alignment of the two resulting meshes,
no-cortical screws. It allowed accurate bone segmentation,                   the software automatically overlapped the meshes based
as pre-planned. Also, the holes in the fibular cutting guides                on fixed reference landmarks (screw holes on the plate).
were in the same locations as those of the reconstructive                    Reconstruction accuracy was determined by evaluating the
plates, allowing the surgeon to correctly and rapidly place                  average error of fibular unit inclination, relative to the hori-
bony segments during reconstruction.                                         zontal plane (craniocaudal inclination) (Fig. 5).
                                                                             The mean error of total reconstruction among all patients
Clinical outcomes                                                            was 1.2 mm (range 0.8-1.3 mm). The mean surface error
The previously described protocol was carried out on four                    of PSI intraoperative positioning was 0.86 mm (range,
patients. All patients were treated for benign neoplasms in-                 0-2.1 mm).




Figure 5. Accuracy assessed by colour map obtained from superimposition between pre-operative planning and post-operative CT-scan.



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A. Tarsitano et al.




Discussion                                                           using metal, simulating native anatomy whenever possible,
                                                                     or mirroring the healthy side when a unilateral disease-af-
Repair of long-span mandibular defects with a free fibu-             fected site was present. Furthermore, the alveolar portion
lar flap is now a routine procedure. Several studies have            of mandibular bone can be restored.
provided evidence regarding the accuracy of CAD/CAM                  Disadvantages of this technique include the cost of CAD/
technology applied to mandibular reconstruction with fibu-           CAM technology and confinement of this technique to the
lar free flap harvested as single graft 4. In fact, a fibular flap   treatment of benign tumours.
is typically projected to restore the basal bone to preserve         Regarding this first issue, many approaches to minimising
the mandibular contour and maintain correct anatomy of               costs while simultaneously optimising patient treatment are
the facial profile. However, the bone height of the neo-             potentially available. The principal area for such efforts is
mandible after reconstruction with a fibular flap is about           the theatre, as reducing the operating time can considerably
half that of the dentulous mandible. When a fibular graft is         affect the overall cost 5. In a previously published paper, we
placed only at the inferior border of the mandible, the re-          estimated that our institutional cost per minute of theatre
sulting vertical discrepancy between the graft segment and           time was € 30. Considering that the average time gained
the occlusal plane can adversely affect implant mechanics            using CAD-CAM surgery was 115.5 min, the money saved
or denture stability and retention.                                  resulting from the time gain was € 3,450. This cost corre-
To overcome this problem, many surgical solutions have               sponds approximately to the total price of the CAD-CAM
been proposed:                                                       surgery 5. Another area that should be considered is the rate
1. A double-barrel fibular flap can be harvested.                    of complications experienced by mandibular reconstruction
2. A different type of bony free flap as well as scapula or          patients who undergo the CAD-CAM technique versus the
   iliac crest flap can be used.                                     freehand technique. In fact, complications can add costs in
The double-barrel fibular flap presents the advantage of             terms of needing secondary revision procedures or hospi-
best restoring the correct alveolar and basal height, but            talisation. Thus, CAD-CAM surgery can be considered as a
sometimes the surgical risks of reduced blood supply due             useful tool to improve the quality of the reconstruction and
to bending may lead to vascular complications. Another               reduce the need for secondary revision procedures (flap re-
limit still existing for both double barrel fibular flap and         positioning for occlusion restoration or plate dislocation).
other bony free flaps is the length of mandibular arch to            Moreover, guided surgery has the potential not only to re-
restore. For mandibular defects larger than 10 cm, many              duce surgical time, but also to reduce ischaemic time for
authors do not suggest a double-barrel technique because             the fibular flap 5,6.
the fibula length usually required is excessive, which would         Regarding the second issue, we have to highlight that the
result in shortening too much the pedicle 1. However, both           amount of titanium needed for this type of restoration can
for lateral and moderate mandibular defects it remains the           increase the risk of plate exposure after radiotherapy.
first reconstruction option. Virtual surgical planning can al-       For this reason, we propose this technique for patients af-
low surgeons to better assess bone segments positioning 4.           fected by benign tumours. Further studies are needed to de-
Alternatives to the double-barrel fibular flap may be folded         termine whether this protocol is useful in treating patients
scapula or iliac crest free flaps. The first appears to be valid     with malignant cancer, as well as to determine the long-
donor sites for cases with large soft tissue and minimal             term outcomes of this approach.
bone requirements1. Differently, the iliac crest free flap is
limited by short vascular pedicle, higher morbidity at donor
site and restricted bone length 1. The fibula donor site re-
                                                                     Acknowledgements
mains the first choice for cases with large bony defects re-         The authors thank Andrea Sandi for his valuable work on
quiring multiple osteotomies and for dental rehabilitation 1.        CAD.
In this report, we propose a modification of the design of
the mandibular reconstructive plate in order to position the         References
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