Sir,
The fibula is the most common vascularised bone used for maxillary and mandibular
reconstruction. In patients with ectodermal dysplasia, a very rare condition, the
fibula can be used for alveolar reconstruction to increase the height of the bone
to enable placement of implants for dental rehabilitation.[[1]] The distal part of the harvested fibula bone is used for reconstruction, while
the proximal part is discarded by extra-periosteal dissection. However, during the
fine-tuning of the osteotomy, some part of the periosteum is retained along the vascular
pedicle. This vascularised periosteum attached to the vascular pedicle has osteogenic
potential.[[2]] This heterotopic periosteal ossification is a rare but known phenomenon;[[3]] however, symptomatic ossification requiring surgical management is uncommon.
We report a case of anhidrotic ectodermal dysplasia, reconstructed with free fibular
flap and osseointegrated implants, who developed trismus 2 years after the microvascular
reconstruction due to heterotopic ossification of the vascular pedicle.
An 18-year-old male patient with anhidrotic ectodermal dysplasia presented to us with
the absence of all teeth and underdeveloped upper and lower alveolar ridges. He needed
upper alveolar reconstruction, as the alveolar bone thickness below the maxillary
sinuses was barely 1 mm. In the lower jaw too, the bone height above the inferior
alveolar nerve was not sufficient for the placement of implants. However, in the central
segment, between the two mental foramina, the bone height was sufficient for implant
placement. In October 2015, a free fibula transfer was performed for the upper alveolar
reconstruction with fixation done using titanium miniplates [[Figure 1]]. In March 2017, the miniplates were removed, and osseointegrated implants were
placed in the upper and lower alveolus. His mouth opening at the time was good enough
to allow the intraoral manipulation necessary for implant insertion. However, the
patient then felt progressively increasing trismus and reduction in jaw movements,
until finally, he was unable to move his jaw at all. The orthopantomogram and the
computed tomography scan revealed the presence of a bony block on the left side between
the reconstructed maxilla and the ramus of the mandible below the coronoid process,
along the course of the vascular pedicle [[Figure 2]]. He was operated on for removal of the bony block under general anaesthesia in
January 2018. Through an intraoral incision along the upper gingivobuccal sulcus,
extraperiosteal removal of a 1 cm block of bone from the ossified vascular pedicle
was performed. Patient's inter-incisor distance improved from 1 cm to 4 cm in the
immediate post-operative period, with free movement of the lower jaw [[Figure 3]]. Histopathology confirmed that the excised block was showing normal bony architecture.
Three months after the procedure, the mouth opening and jaw movements have been maintained
and additional implants could be placed in his mandible [[Figure 4]].
Figure 1: Fixation of free fibula flap for the upper alveolar augmentation and the post -operative
orthopantomogram showing the fixation
Figure 2: Pre -operative orthopantomogram and three dimensional computer tomography scan showing
bony block along the course of vascular pedicle of the free fibula flap
Figure 3: Pre- and immediate post -operative photos of the patient showing improvement in mouth
opening
Figure 4: Post- operative orthopantomogram after removal of the bony block showing additional
implants being placed
Periosteum preserves its osteogenic potential, even after transposition, especially
in a re-vascularised flap. When the fibula is used for maxilla reconstruction, the
pedicle is usually routed to the neck near the mandibular ramus. Any periosteum retained
with the pedicle is likely to ossify and fuse with the ramus at points of contact,
thereby causing restriction of jaw movements, as in this case. Hence, care must be
taken while harvesting and shaping the fibula to ensure that the periosteum is cut
flush with the fibula, and no part of it stays with the pedicle.[[4]]
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understand that their names and initials will not be published and due efforts will
be made to conceal their identity, but anonymity cannot be guaranteed.
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Nil.
