BACKGROUND
Naso-orbito-ethmoidal (NOE) fractures are complicated fractures of mid-face structure which include nasal, lacrimal, maxillary, frontal, and ethmoid bones. The central feature of NOE fracture is displacement of the medial orbital rim with the medial canthal ligament attached. The medial canthal tendon (MCT) splits before insertion into the frontal process of the maxilla. A fracture that separates the maxilla from the MCT attachment site results in fatal displacement.
This section has a unique feature that requires careful attention to return the fracture to its pre-injury state. One of the important goals of facial fracture treatment is to reconstruct the shape of the pre-traumatic face [1,2]. Another purpose is normal function recovery of facial structure [3].
Recent advances in reconstruction of the craniofacial skeleton have introduced new surgical methods for NOE fracture. New approaches to these NOE fractures have been introduced that minimize scarring and facilitate fracture fragment reduction. The approaches include endoscopic, bone tissue engineering, and methods for modifying existing approaches. But each of these approaches has advantages and disadvantages. Thus, the choice of approach may vary depending on the nature of the fracture and preference of the physician. This review will discuss advancements in several approaches to NOE fracture.
ETIOLOGY
NOE fractures are common with blunt trauma and are most commonly caused by vehicular accidents and assaults [4-7]. Because NOE fractures occur due to high energy, they often occur with other facial fractures [8]. Approximately 60% of NOE fractures are associated with orbital fractures, and approximately 20% are diagnosed with panfacial fractures [9]. Isolated NOE fracture accounts for approximately 5% of all facial fractures in adults and 16% in pediatric facial fractures [10,11].
The MCT is separated before insertion into the frontal process of the maxilla. Anterior limbs are inserted in the anterior lacrimal gland in the frontal process of the maxilla while posterior limbs are inserted in the posterior lacrimal crest on the lacrimal bone. These two limbs of the tendon surround the lacrimal fossa and establish soft tissue boundaries around the lacrimal sac fossa.
Because of this structure, telecanthus often occurs in NOE fractures. Traumatic telecanthus is observed at all stages except the first stage of NOE fracture, and distance between MCTs is increased. The patient has a distinctive appearance of telecanthus. Eyes may appear far apart, as in orbital hypertelorism [12,13]. Traumatic orbital hypertelorism (as compared to telecanthus) is an deformity characterized by increase in distance between orbits and ocular globes [7].
Because NOE fractures usually occur with severe trauma, evaluation of other critical areas before fracture evaluation should be completed. Patients with ocular damage or suspected visual anomalies should undergo full ophthalmologic examination to dismiss damage associated with the visual system, such as traumatic optic neuropathy [14].
DIAGNOSIS
NOE fractures can cause symptoms such as facial edema, flattening of the malar region, hemorrhage, diplopia, enophthalmos, telecanthus, and loss of nasal support [14,15]. Epiphora is typically associated with up to 50% of NOE fractures caused by nasolacrimal duct obstruction, direct damage to the lacrimal gland, or soft tissue edema [16].
Several classification systems have been introduced to assess severity of injury and for planning the type of reconstruction. The first classification system, first described by Gruss [2] in 1985, classified NOE fractures into five types with descriptions of specific treatment methods for each impairment pattern. Currently, the most frequently used classification system was detailed by Markowitz et al. [3] in 1991 for grading injuries. Extent of injury in this system is based on the MCT position and state of the central bone segment.
MANAGEMENT
An important goal of facial fracture treatment is to reconstruct facial appearance to its previous state. It is thus important to choose an appropriate approach that exposes the fracture site.
Despite much progress, surgical approach to NOE or Le Fort II fractures requiring extensive access, has remained largely unchanged. Coronal approach remains the gold standard for complicated NOE fractures, but it may be too invasive to treat simple NOE fractures, because of the need for large incisions. Additionally, it has risk of complications such as scalp paralysis, hair loss, and flap hematoma, and the operation is lengthy [17,18]. Also, if the fracture involves the lower level, coronal incision may not be sufficient to achieve the desired result [19].
To avoid these drawbacks, some authors have introduced a mid-facial degloving (MFD) approach that can provide an exposure of the entire mid-facial skeleton through the sublabial incision of the maxilla and expand to upper and lateral sides according to fracture extent. However, the MFD approach will also produce some nasal related complications, such as nasal cosmetic deformity, nasal obstruction, and temporary infraorbital anesthesia [19,20].
Recently, an endoscopic approach has been introduced. This approach has the advantage of producing similar outcomes with only small incisions, reducing patient morbidity, shortening operation duration and shortening patients’ recovery period. However, there remains a drawback in that additional instruments are needed and there is a learning curve [21].
In some cases, it may need additional skin incision such as infraorbital, subciliary, transconjunctival, and/or lateral rim incisions, which may lead to facial scarring [19]. A transcaruncular approach is often used, to access the nasofrontal suture. However, there were limitations in the possibility of injury to normal orbit structures, such as violating the posterior limb of the MCT, and limitation of surgical view. Sometimes a local cutaneous approach is used, but not often, unless it is a special case because of scarring [22-25]. The percutaneous MCT approach exposes the entire medial orbital wall, nose, and orbital apex by percutaneously with an incision of only 1.5 cm to 2.0 cm, which is more cosmetically acceptable than a lynch incision [26].
In cases of accompanying zygomaticomaxillary complex fracture, lateral canthotomy is often performed with transconjunctival incision, if exposure of zygomaticofrontal suture is needed [27,28]. There is an advantage of providing a wider surgical field of view and less possibility of lacrimal duct injury, than conventional transconjunctival incision alone. However, scar formation is possible, and asymmetric palpebral fissure length can be achieved, if accurate repair of the lateral canthus is not performed [29]. To overcome these shortcomings, approaching the blow out fracture through transconjunctival approach with paracanthal incision has been introduced [30,31].
CONCLUSION
Various approaches have been introduced to treat NOE fractures. These methods are common in that they were developed with the purpose of achieving maximum surgical effectiveness with minimal scar. Because NOE fracture is not constant and various types of fractures occur, we should accurately locate the fracture site by using advanced imaging technology and choose an appropriate approach.
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