Closed reduction with minimal accesses for treating isolated zygomatic arch fractures: Case Series

Following nasal fractures, zygomatic fractures (ZF) are the second most prevalent of maxillofacial fractures. Isolated fractures of the zygomatic arch (IZAF) are rare, corresponding to less than 10% of all fractures involving the zygomaticmaxillary complex (ZMC). The choice of treatment for IZAF is controversial, and there is no defined consensus in the literature. We seek to evaluate the advantages of closed reductions with minimal accesses over open reductions through a case series and a 10-year literature review. All patients in our study obtained a satisfactory final result in terms of aesthetics and function of the zygomatic arch, with no complications involved. There are criteria established in the current literature on the indication of open surgery or closed reduction. Open reduction with rigid fixation has the most significant number of studies proving its clinical efficacy. However, closed reduction with minimal accesses has proven to be a suitable therapeutic option for IZAF, presenting satisfactory aesthetic results and fewer surgical risks.


Introduction
The zygomatic arch (ZA) is part of the zygomatic complex (ZC) and plays an essential role in the facial contour, specifically in the lateral projection. Its bony architecture maintains the midface stabilization and supports the normal masticatory load (Xie et al., 2009). The ZC is the third most commonly fractured facial area; however, isolated zygomatic arch fractures (IZAF) are rare, representing only 5-10% of ZC injuries reported in the literature (Adam et al., 2012;Yoon et al., 2014).
Disruption of the ZA position can affect the facial skeleton's structural, functional, and aesthetic appearances. Therefore, IZAF has to be appropriately diagnosed and treated for cosmetic and functional reasons (Ji et al., 2016;Ravi Raja Kumar et al., 2010).
The most related symptoms are pain, swelling, difficulty in mouth opening, and zygomatic arch sensitiveness on physical examination. Radiographic and tomographic images can be used to confirm IZAF diagnosis. The submentovertex is the radiographic view indicated to analyze the zygomatic arch symmetry. Computed tomography should be carefully considered for IZAF assessment because of its high radiation exposure and high cost Korkmaz et al., 2016). IZAF is mainly caused by road traffic accidents, falls, sports-related injuries, and civilian warfares. These injuries predominantly occur in male patients from the second to the third decade of life (Yamsani et al., 2016).
Management of IZAF must be accurate because improper ZA reductions may result in facial asymmetry and mastication disability (Ahn et al., 2015). Variable methods have been introduced for the treatment of IZAF. Occasionally, open reduction and rigid fixation are required for zygomatic arches fractured in several segments or grossly displaced (Prakasam et al., 2010). However, open operations carry possible complications, such as facial nerve injuries, unsatisfactory scarring, and hemorrhages (Xie et al., 2009). This study aimed to describe a series of 10 cases of IZAF treated with closed reductions through minimal percutaneous access and discuss the most appropriate choice of treatment according to a 10-year literature review.

Methodology
A retrospective study was carried out involving male and female patients of any age with isolated zygomatic arch fractures. The sample was determined by spontaneous demand at the emergency ward of a northeastern Brazilian hospital between January 2020 and January 2021 (1 year). After the treatment of each case, data were gathered, and a review of literature on this topic was also performed. The criteria used for the study of this case series relate to the qualitative, quantitative, and observational methods. Our sample of 10 cases was the quantitative factor, and the clinical signs and symptoms were the qualitative features. Therefore, a quali-quantitative analysis was followed along with a 10-year literature review for a detailed discussion on the selected cases (Pereira et al., 2018). This study was legally supported by Helsinki Declaration guidelines and patients' informed consent forms.

Results and Cases Presentation
Ten patients diagnosed with isolated zygomatic arch fractures from January 2020 and January 2021 are listed in Table   1. Their age ranged from 18 to 47. The ratio of males:females was 9:1 (nine males and one female). There were six cases of left zygomatic arch injuries and four on the right side. The occurrences of IZAF were prevalent in the second semester of the year 2020. Due to the social isolation established by the pandemic situation (Covid-19), lockdown's flexibilizations started only in July 2020 in Pernambuco, Brazil. Therefore, July shows the highest number of IZAF cases (6), following the logic of the scenario.
Depending on the zygomatic arch displacement level, clinical signs, cosmetic issues, access, and dental instruments were selected according to each case to provide the proper closed reduction to the IZAF. Supraorbital eyebrow percutaneous approaches were chosen for 70% of IZAF cases, and zygomatic arch body accesses were used only in 30% of patients. A molt periosteal elevator and a Barros hook were the two selected instruments for the closed reduction technique (Table 1).
Among the ten patients, the most related clinical features and symptoms (Graphic 2) were pain (100%), swelling (60%), reduced mouth opening (40%), and mastication disability (40%). The present case series included ten patients diagnosed with isolated zygomatic arch fractures treated by closed reduction and minimally invasive percutaneous access. All ten patients underwent a detailed clinical examination, routine hematological pre-operative investigations, and imaginological exams (Figure 1). None of them had any history of known systemic illness or drug allergies. In all cases, an evident clinical sign was the depression of the zygomatic arch, presenting itself through an asymmetric facial lateral contour (Figure 2). Patients with minor clinical complaints were submitted to surgical treatment with local anesthesia. 60% of the cases had a more extended hospital stay because they needed intravenous medication with corticosteroids before treatment to reduce edema.
Immediate treatments were performed only in patients without swelling (40%) to restore the appropriate facial contour and compare it to the contralateral side.

Discussion
The zygomatic complex (ZC) is a crucial component of the midface. Its position maintains the anteroposterior projection and facial contour. Due to its protruded shape, this bone is vulnerable to injuries, and zygomatic fractures (ZF) are considered the second most common facial fracture type. Following nasal fractures, ZF represents 13% of all maxillofacial fractures (Cinal et al., 2019). The zygomatic arch makes up for the anterior-lateral part of ZC. However, isolated zygomatic arch fractures (IZAF) are rare and comprise only 10% of all ZF and 5% of all facial bone fractures (Yoon et al., 2014).
IZAF commonly results in a V-shaped indentation of the lateral aspect of the face, a noticeable depression at the fracture site. Also, patients often relate limited mouth opening, possibly because of the zygomatic arch's impingement with the coronoid process (Ravi Raja Kumar et al., 2010). Other symptoms and clinical features reported by the literature and observed in our case series were swelling, pain, and mastication disability (Prakasam et al., 2010).
There are geographic and sociodemographic aspects in the epidemiology of craniofacial fractures. In our study, the etiological factors involving IZAF were road traffic accidents, falls, sports injuries, and violent aggressions, in agreement with the data found in the literature (Starch-Jensen et al., 2018). Traffic accidents were not prevalent only in studies conducted in places where safety measures, such as helmets and seat belts, are strictly followed. In another survey conducted at our institution on motorcycle accidents, it was concluded that helmet use leads to a lower number of fractures and severity of trauma compared to nonuse (Cavalcante et al., 2021;Yamsani et al., 2016).
The gender associated with this type of trauma was mainly male above female (in a 9:1 ratio), another similar finding from several reports (Rohit et al., 2021). The age group of our study also relies upon the studies mentioned by Yamsani et al., who found out that 80% of Nigerian patients with ZF were between 21 and 40 years (Yamsani et al., 2016).
Surgical restoration of lateral facial projection can be a challenge with IZAF because there are controversies regarding open or closed reduction. Usually, closed reductions are the most suitable treatment choice. However, some authors report the need for open surgery and rigid fixation in cases of IZAF with more than two fracture lines, very dislocated zygomatic arches, or combined fractures (Jang et al., 2021;Jardim et al., 2013). The clinical cases included in this study corroborate these data, as there are included only classic zygomatic arch fractures, totally isolated, with no other bone structures compromised.
IZAF with intact periosteum and minimal displacement may be repositioned via limited incisions. Many devices have been suggested for stable closed reductions, including bone hooks, molt periosteal elevators, and Kirschner wires (Strong & Gary, 2017). It is crucial to select adequate access and instrument to avoid improper zygomatic arch reductions and prevent instability, malunion, or asymmetry (Korkmaz et al., 2016).
Up to now, several approaches have been introduced for the closed reduction of IZAF. The most popular ones are Gillies' temporal technique, Keen's intra-oral access, percutaneous incision, and lateral eyebrow approach (Camilleri et al., 2005). Open surgery provides extended access and direct visualization of the fracture site. However, large incisions and wide dissections can increase operative time and the risk of post-surgical complications (Ji et al., 2016). These invasive approaches may result in massive bleeding, scarring, persistent edema, and numbness (Cheon et al., 2013).
The traditional closed reduction for IZAF can be achieved with digital palpation alone. However, this technique requires considerable skills on the surgeon's part to reduce an uneven and curved bone properly Xie et al., 2009).
Twelve different surgeons carried out a study of closed reduction with percutaneous transfacial Kirschner wire fixation (CRWF), most of them being junior surgeons with limited experience regarding the CRWF technique. It was assumed that the main clinical criteria to evaluate the quality of IZAF's closed reduction is facial symmetry by comparing the affected side to the healthy side (Giran et al., 2019).
Nevertheless, the closed reduction using traction instruments has proven to be undemanding such that training residents often perform these methods without complications, as applied in our study. Also, the instruments used for this reduction are widespread items, readily available at any maxillofacial surgery service, and very familiar to all surgeons in this field. Even though it is not a novel treatment, it is a low-cost and fast execution option, which mainly benefits the patient, avoiding late treatments (Ahn et al., 2015).
In our case series, minimal extraoral accesses for the closed reductions were adequate for all IZAF. Lateral eyebrow and percutaneous incisions were the two selected approaches for our study. Minimally invasive surgical procedures have shown satisfactory results in the literature. A Lever technique employed by Cinal et al. has proved that minimal access approaches are safe to perform, easy to learn, fast to apply, simple to conduct, and provides successful reduction (Cinal et al., 2019).
Closed reductions are still the least used techniques in the literature, hardly reaching the 10% mark when compared to open reductions (Adam et al., 2012;Strong & Gary, 2017). However, our case series included patients with low-velocity injuries resulting in IZAF, which are good candidates for closed reduction. All patients had early fracture repairs with stables reductions and satisfactory cosmetic results.

Conclusion
There is no consensus in the literature regarding the best treatment for zygomatic fractures, especially isolated zygomatic arch fractures (IZAF), which are rare. Following the most current literature, IZAF with moderate displacement and without bone fragmentation can be managed conservatively. The lack of dynamic actions in the zygomatic arch facilitates closed reduction approaches without the need for immobilization or fixation. Early treatments, small incisions, and closed reductions provide greater comfort to the patient because of the shorter surgical time and lower morbidity. Therefore, minimally invasive surgical procedures, such as closed reductions with minimal accesses, can be indicated for selected IZAF cases. It is suggested that surgeons properly diagnose IZAF with adequate imaging tests to indicate the best treatment. It is still necessary to develop new studies on closed reductions to treat IZAF for scientific support.