Key points
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Trapdoor fracture in children, globe dislocation or trapdoor fracture with a nonresolving oculocardiac reflex, bradycardia, heart block, nausea, vomiting, or syncope are indications for immediate surgery.
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Early enophthalmos, hypoglobus, and severe limitation of eye motility (<15°) are indications for early intervention.
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If there is no enophthalmos present, and the motility of the eye significantly improves within 10 to 14 days, surgery may be not indicated, and clinical findings overrule the computed tomography scan results in all occasions.
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If reconstruction is required, titanium is the current gold standard, because it has many advantages compared with autologous grafts and other alloplastic implants.
Introduction
The orbit is a complex area, because important and delicate anatomic structures are packed together into a small space. , With its midfacial position and its thin bony walls, the orbit is susceptible to fractures. The trauma mechanism consists of buckling forces applied to the orbital rim and/or the retropulsion of orbital content
Solitary orbital fractures are commonly caused by repulsion, leading to increased intraorbital pressure that is transmitted to all the orbital walls. The lateral wall and orbital roof are relatively strong and can sustain forces more easily, but the orbital floor and medial wall are relatively fragile. This dissipation of force through the 2 thin walls protects the globe, acting as a crumple zone, whereas the stronger roof protects the intracranial structures. In most cases, the increased periorbital pressure results in blowout fracture, where the comminuted orbital wall(s) will be dislocated to the adjacent sinuses ( Fig. 1 ). Occasionally, especially in pediatric patients, the trapdoor phenomenon is seen, wherein the periorbital contents are trapped as soon as the pressure wave decreases and the fracture snaps back into the original position. The viscosity of the bone of children contributes to this phenomenon ( Fig. 2 ). With loss of bony support, the orbital volume may increase, which can potentially result in the protrusion of the orbital contents into adjacent sinuses, with subsequent posterior displacement of the globe (enophthalmos) (arrow in Fig. 1 ). If most of the impact occurs as a buckling force to the orbital rim, the anterior part of the orbit may be fractured also. The loss of anterior support to the globe may result in vertical displacement of the globe, as well (hypoglobus) ( Fig. 3 ).
Apart from damage to the orbital walls, soft tissues will be disrupted also. If adipose and muscle tissues herniate into the fracture, the suspension system and periorbit will be affected to some extent. Initially, the actual damage may be difficult to assess because of emphysema, swelling, contusion of muscles, and the presence of hematoma ( Fig. 4 ).
For the orbital walls, the goal of reconstruction is to reposition the globe into its original position by placing an orbital implant to recontour the traumatized orbit and restore the pretraumatized anatomy as accurately as possible ( Fig. 5 ). This is mandatory for preventing volume increase of the orbit with clinical sequelae such as enophthalmos and hypoglobus and for adequate support in order to regain proper ocular function and prevent diplopia. On the soft tissue level, the incarcerated tissues also need to be released to restore orbital function. The regenerative capacities of the soft tissues (fat, muscles, septae, nerves) and the amount of damage caused by the surgery itself are highly unpredictable. This unpredictability possibly accounts for persisting debates on the various aspects of orbital fracture management. In the current literature, there is no uniformly accepted guideline for the treatment of orbital fractures.
The shape of the bony orbit and the intricate architecture of the soft tissue pose surgical challenges. , Orbital reconstruction is performed in a confined space with limited overview in close proximity to vital and delicate structures. Iatrogenic damage and surgical complications are not uncommon. , The key to successful treatment of orbital wall fractures may be found by carefully selecting the appropriate indications. , ,
Even if anatomic reconstruction has been achieved, functional rehabilitation does not always follow automatically, as both traumatic and surgical damage to soft tissue contents may induce scarring, entrapment, and fat atrophy. Therefore, persistent diplopia and enophthalmos are believed to be common complications after orbital fracture repair.
Controversies in orbital reconstruction
In orbital fracture management, the most controversial dilemmas are indication, optimal timing, and biomaterials. A scientifically substantiated answer to key questions in orbital reconstruction is therefore desired:
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What type of fracture needs to be reconstructed?
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What is the best timing for orbital reconstruction?
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Which materials are most suitable for the different types of orbital fracture?
What type of fracture needs to be reconstructed?
Several publications have shown that most surgeons base their decision regarding orbital fracture repair on clinical findings, and such data are increasingly obtained from computed tomography (CT) scans. , , From a clinical perspective, the presentation of patients with orbital fractures is variable ( Fig. 6 ). The most relevant clinical (nonradiological) symptoms that influence decision making are motility restrictions/diplopia, enophthalmos, and hypoglobus. , ,
Enophthalmos
Evident enophthalmos and hypoglobus are clear indications for surgery. Hypoglobus is caused by the loss of anterior support and is encountered in less than 5% of the patients with orbital fractures. Enophthalmos is most commonly caused by either an increase in bony orbital volume or a secondary decrease in soft tissue volume caused by fat atrophy or, rarely, a shrinking globe. Enophthalmos is only present in less than 18% of trauma patients with orbital fractures. , Spontaneous disappearance of enophthalmos can be seen in 50% of the patients with orbital fractures. This results from pseudo-enophthalmos, a phenomenon caused by swelling of the surrounding tissues, resembling an enophthalmos ( Fig. 7 ). Nevertheless, enophthalmos, which does require treatment, is frequently not present immediately after trauma but will occur over time ( Fig. 8 ). A CT scan is the gold standard in imaging for the severity assessment of orbital wall fractures. , Several studies have suggested that defects of at least 2 cm 2 can cause clinically significant enophthalmos. According to Christensen and colleagues , who performed among 442 American oral and maxillofacial surgeons, the defect size had the greatest influence on the surgeon’s decision to operate, despite absence of enophthalmos. The same trend has been shown by several systematic reviews: clinicians base their decision for surgery in almost half of the cases on CT findings. , , Specifically, a fracture greater than 50% of the surface area was the primary indication for orbital reconstruction in 19% to 30% of the cases. , , Although, other radiological observations such as herniated volume, orbital volume ratio, and location of the fracture and inferomedial strut are probably better predictors of enophthalmos ( Fig. 9 ).
Accurate quantification of size, location, and complexity of orbital defects is important in the diagnostic process. Nevertheless, accurate measurement or prediction of the defect size remains extremely difficult even on CT, , , and the average rate of overestimation is 76%. This overestimation may lead to overtreatment, because a defect size of 1.3 cm 2 is interpreted as greater than 2 cm 2 ( Fig. 10 A). Interestingly, 30% of the patients with a defect greater than 2 cm 2 have no signs of diplopia, motility disturbance, or enophthalmos. Jansen and colleagues showed that this principle is more evident in single-wall defects. In multiple-wall fractures, the third dimension is increasing the defect size by 27% ( Fig. 10 B). There seems to be a strong tendency to treat expected problems instead of those that are present. The predictability of the measurements on CT scans is highly questionable in combination with the uncertainty of occurrence of enophthalmos. In terms of indications for reconstruction, defect size should be used cautiously ( Figs. 11 ).
Diplopia and motility disturbances
As previously stated, radiological observations such as defect size and evidence of muscle entrapment are frequently used by most surgeons as strong indications for early intervention. , Clinical observations such as true muscle entrapment with a positive forced duction test are mainly seen in children ( Fig. 12 ) (76% <15 years) but are relatively rare in adults ( Fig. 13 ). A more common clinical symptom is motility restriction and diplopia caused by a blowout fracture ( Fig. 14 ). The survey of Christensen and colleagues and Aldekhayal and colleagues showed that approximately 4 of 5 surgeons have strong to very strong indications for surgical intervention if diplopia persisted for more than 15 days.
