Distraction osteogenesis of free flap reconstructed mandible following ameloblastoma resection for optimal functional rehabilitation

Abstract

This case highlights the use of a custom-made distractor (Synthes GmbH, Oberdorf, Switzerland), used to increase bone height prior to rehabilitation with implant placement, in a patient following excision of an ameloblastoma and reconstruction of her mandible with a fibular flap. A 27-year-old patient had her mandible reconstructed following wide resection of an ameloblastoma. Although a 2.0 LOCK reconstruction plate (Synthes GmbH, Oberdorf, Switzerland) was used for fixation of the fibular bone, the vertical deficiency between the reconstructed segment and the occlusal plane made oral rehabilitation impossible. To overcome this, the fibular bone segment was vertically distracted following a latency period of 4 days. Distractor was left in place for 20 weeks for bone consolidation. Following device removal implants were placed. The novelty of this approach included fixation of the lower arm of the distractor on the LOCK plate. The distractor was unidirectional with two arms of different length. The lower arm composed of a 2.0 mini-plate to fit exactly on the 2.0 LOCK plate whereas the upper arm used a standard 1.5 mini-plate. Advantages of this custom-made distractor included: (i) No need for removal of the reconstruction plate, (ii) no need for an extraoral surgical approach, and (iii) no need for additional drilling to fit the lower arm of the distractor. Technical details and limitations are presented.

Full text

Annals of Maxillofacial Surgery | July - December 2014 | Volume 4 | Issue 2 237
Distraction osteogenesis of free flap reconstructed
mandible following ameloblastoma resection for optimal
functional rehabilitation
V. A. Bousdras, N. Kalavrezos1
Private Practice, Al Mihailidi 9, Thessaloniki 54640 Greece, 1Clinical Head and Neck Centre, University
College Hospital, London NW1 2PG, United Kingdom
Address for correspondence:
Mr. Vasilios Bousdras, Maxillofacial Surgeon, Al Mihailidi 9,
Thessaloniki 54640 Greece.
E-mail: vbousdras@yahoo.com
This case highlights the use of a custom-made distractor (Synthes GmbH, Oberdorf, Switzerland), used to increase bone height
prior to rehabilitation with implant placement, in a patient following excision of an ameloblastoma and reconstruction of her
mandible with a fi bular fl ap. A 27-year-old patient had her mandible reconstructed following wide resection of an ameloblastoma.
Although a 2.0 LOCK reconstruction plate (Synthes GmbH, Oberdorf, Switzerland) was used for fi xation of the fi bular bone, the
vertical defi ciency between the reconstructed segment and the occlusal plane made oral rehabilitation impossible. To overcome
this, the fi bular bone segment was vertically distracted following a latency period of 4 days. Distractor was left in place for 20 weeks
for bone consolidation. Following device removal implants were placed. The novelty of this approach included fi xation of the
lower arm of the distractor on the LOCK plate. The distractor was unidirectional with two arms of diff erent length. The lower arm
composed of a 2.0 mini-plate to fi t exactly on the 2.0 LOCK plate whereas the upper arm used a standard 1.5 mini-plate. Advantages
of this custom-made distractor included: (i) No need for removal of the reconstruction plate, (ii) no need for an extraoral surgical
approach, and (iii) no need for additional drilling to fi t the lower arm of the distractor. Technical details and limitations are presented.
Keywords: Ameloblastoma, distraction osteogenesis, free fl ap, mandible
INTRODUCTION
Extensive mandibular bone defects, as a result, from trauma,
infection or tumor resection are commonly reconstructed with
vascularized fi bular fl aps[1] due to their suffi cient length, good
quality of bone and vascularization. The main drawback is its
limited diameter, which when compared with the height of the
mandible it often leads to a considerable defi cient vertical distance
between the reconstructed segment and the occlusal plane.[2]
In order to overcome problems with insuffi cient bone height
distraction osteogenesis of the fi bular bony fl ap through either an
extraoral,[3] or intraoral[4] approach has being increasingly gaining
popularity. Preliminary results have shown the formation of good
quality bone for implant osseointegration. An intraoral approach
without necessary removal of the reconstruction plate could offer
advantages in terms of less invasive surgery and intervention.
In this report, a young patient had treatment at University
College London Hospital, for ameloblastoma, following a wide
resection and a hemi-mandibulectomy and vascularized fi bula
fl ap reconstruction initially. Prior achieving oral rehabilitation
with implants, vertical distraction of the reconstructed mandible
was carried out in order to achieve optimal bone dimensions for
successful treatment.
Novel distractor
A novel custom-made distractor (Synthes, Switzerland) was
fabricated. The distractor was unidirectional with two arms of
different length and plate thickness [Figure 1]. The lower arm
ABSTRACT
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Bousdras and Kalavrezos: Distraction Osteogenesis of free flap reconstructed mandible
Annals of Maxillofacial Surgery | July - December 2014 | Volume 4 | Issue 2238
Figure 3: (a) Orthopantomograph of the distractor intraorally fi tted on the
Uni-Lock reconstruction plate (b) Fixation of the custom -made distractor
on the Uni-Lock plate
b
a
Figure 4: (a and b) Orthopantomograph of the same patient demonstrating
vertical bone gain of 9 mm
b
a
composed of a 2.0 mm plate to fi t exactly on the 2.0 LOCK
plate (Synthes, Switzerland) while the upper arm used a standard
thickness 1.5 mm mini-plate.
The custom-made distractor had 2 arms, of different size
and of maximum opening 15 mm. Advantages of this
custom-made distractor included: (i) No need for removal of
the reconstruction plate, (ii) no need for an extraoral surgical
approach, and (iii) no need for additional drilling to fi t the
lower arm of the distractor.
The protocol followed at University College Hospital for all
patients undergoing hemi-mandibulectomy/maxillectomy, and
free fl ap reconstruction is to use the 2.0 Uni-LOCK plate for
better fi xation of the fl ap segment.[5] The novelty of this approach
included fi xation of the lower arm of the distractor on the
Uni-LOCK plate, avoiding removal of the plate.
CASE REPORT
Pa ent and surgical approach
A 42-year-old patient had his left mandible reconstructed
following wide resection of an ameloblastoma in 2004. While
a 2.0 Unilock reconstruction plate was used for fi xation of
the fi bular bone (right neo-mandible), the vertical defi ciency
between the reconstructed segment and the occlusal plane
made oral rehabilitation impossible [Figure 2a and b]. To
overcome this, the fibular bone segment was vertically
distracted (rate of 0.75 mm/day twice daily [2 × 0.375 mm])
for 12 days, following a latency period of 6 days. The distractor
was left in place for 16 weeks for bone consolidation. The
distractor was relatively simple to insert and was tolerated
well by the patient. No mucosa breakdown was noted during
the healing phase.
The novelty of this approach included fi xation of the lower
arm of the distractor on the Uni-Lock plate [Figure 3a and b].
Vertical distraction of the fi bular fl ap was uneventful. The overall
increase of vertical height was 9 mm [Figure 4a and b] ensuring
adequate bone height of optimal oral rehabilitation. Three
implants were placed in June 2008 and oral rehabilitation was
achieved 2 years later.
DISCUSSION
Extensive mandibular bone defects, as a result, from trauma,
infection or tumor resection are commonly reconstructed with
free fi bular fl aps.[1,6] This fl ap was fi rst used by Hidalgo in 1989[7]
for reconstruction of mandibular defects and presents many
advantages as:
• Suffi cient length of the bony segment with adequate length
of the vascular pedicle
• Good quality and shape of bone
• Good vascularization.
The main drawback is it's limited diameter/height, which when
compared with the height of the mandible often leads to a
considerable defi cient vertical distance between the reconstructed
segment and the occlusal plane of the dentate mandible. This
can cause both functional and aesthetic problems.[4] Moreover,
in cases with reconstructed dentate mandibles rehabilitation with
implants can be challenging[2] due to: (i) Bulk of soft tissues and
(ii) poor retention of the over denture.
In order to overcome these problems, a number of alternative
approaches have been introduced:
• Interpositional and/or onlay bone grafting
• The double-barrel fi bula fl ap[6]
• Distraction osteogenesis of the fi bular bony fl ap.
Figure 1: The custom-made distractor’s lower arm composed of a 2.0
mini-plate to fi t exactly on the 2.0 Uni-Lock plate, while the upper arm
used a standard 1.5 mm mini-plate Figure 2: (a and b) Reconstructed mandible following wide resection of
an ameloblastoma in 2004. A 2.0 Unilock reconstruction plate was used
for fi xation of the fi bular bone
b
a
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Bousdras and Kalavrezos: Distraction Osteogenesis of free flap reconstructed mandible
Annals of Maxillofacial Surgery | July - December 2014 | Volume 4 | Issue 2 239
While the fi rst two approaches are not popular due to higher
infection, morbidity and risk of the pedicle, vertical distraction
through an extraoral[3,8] or intraoral[4] approach has been
increasingly gaining popularity. Preliminary results have shown
the formation of good quality bone for implant osseointegration.
A variety of distractors has been used with intraoral (MOD,
Gebruder Martin GmbH and Co, Tuttlingen, Germany),[4] and
extraoral (MODUS ARS1.4/V Medartis AG, Basel)[3] approaches.
To the authors’ knowledge this is the first case report that
distraction osteogenesis was introduced with an intraoral
distractor fi tted on the initially placed reconstruction plate, which
had been used to fi x the fi bular fl ap to the native mandible.
This distractor can be used to increase bone height prior to oral
rehabilitation, in patients with vertical bone defi ciency following
mandibular reconstruction with a fi bular free fl ap.
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Cite this article as: Bousdras VA, Kalavrezos N. Distraction osteogenesis
of free fl ap reconstructed mandible following ameloblastoma resection for
optimal functional rehabilitation. Ann Maxillofac Surg 2014;4:237-9.
Source of Support: Nil, Confl ict of Interest: None declared.
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