Discussion
Zygomatic arch is the second most common site of facial bone to get
fractured and its treatment requires outmost care as it has both
cosmetic and functional significance. Conventional plain radiography and
computed tomography (CT) scans are the basic diagnostic tools for
maxillofacial injuries. Computed tomography (CT) can provide three
dimensional assessment of fracture, but high radiation exposure, high
cost and difficulty in transporting make its intra-operative use to
assess the reduction difficult [4]. Further, it cannot be used in
pregnant women and in those with cervical spine injuries. Again,
fluoroscan assisted closed reduction using C-arm has the same problem of
high exposure to radiation [5] for the use of intra-operatively.
Although, the use of USG in dentistry has been increasingly developed
and widely studied in recent years and its role in maxillofacial trauma
surgery is less recognized [6]. Sonographic evidence may be treated
as an alternative diagnostic imaging modality to radiology by which the
use of conventional radiographs may not be required [7]. USG has
shown high accuracy in the detection of nasal bone fracture with a
sensitivity ranging from 90% to 100%, specificity of 98-100% and high
predictive value [8] and so it can also be used in assessment of
zygomatic arch fracture pre- and post-operatively. In this case report
the patient‘s zygomatic arch fracture was observed clearly in USG
(Fig:9).
The zygomatic arch fracture is commonly managed by indirect reduction
without fixation which is done through various approaches like Gille’s
temporal approach [9], BalaSubrahmaniam upper buccal sulcus
approach, Quinn approach [10] and Keen’s lateral coronoid approach
.The patient in the present case report is also managed by close
reduction, but with the guidance of ultrasonogram to confirm the
accurate reduction. Although gross swelling and emphysema make the
ultrasonographic visualization of bony surfaces difficult, this problem
of this was overcome by choosing an ultrasound frequency of 7.5 MHz or
less.
Reduction of the zygomatic arch fracture is conventionally done by blind
method and the position of the fragments is usually confirmed by
radiography or palpation during the operation. Radiography is not always
feasible because of difficulties in managing the patient or the risk of
X-ray exposure, and palpation by the surgeon is often unreliable
[11]. Conversely, ultrasonography is non-invasive, safe, easily
reproducible and portable and gives information in real-time, and thus
it overcomes the disadvantages of radiography and palpation [11].
In this study, the fracture reduction of zygomatic arch was confirmed by
ultrasonography intra-operatively and re-confirmed by submentovertex
view post-operatively. Use of USG in fracture reduction was followed in
this case as it is simple and relatively easy with minimal or no
complications and the armamentarium required for this technique are
readily available. Thus, ultrasonography can be a reliable method as an
alternative to other imaging modalities in cases of close reduction for
zygomatic arch fractures.