Orbital fractures: Weighing criteria for timing of repair

December 1, 2014

Not all orbital fractures need to be repaired, and not all fractures need to be repaired early after the patient sustains an insult. However, early repair of orbital factures can be beneficial for some patients. Ferreting out who those patients involves some special consideration.

Take-Home Message

Not all orbital fractures need to be repaired, and not all fractures need to be repaired early after the patient sustains an insult. However, early repair of orbital factures can be beneficial for some patients. Ferreting out who those patients involves some special consideration.

 

By Lynda Charters; Reviewed by James C. Fleming, MD, FACS, and Brian Fowler, MD

Knoxville, TN-Not all orbital fractures need to be repaired, and not all fractures need to be repaired early after the patient sustains an insult. However, early repair of orbital factures can be beneficial for some patients. Ferreting out who those patients involves some special considerations.

There are two mechanisms involved in floor fractures of the orbit, i.e., the hydraulic theory forwarded by Smith and Regan in 1957 and the buckling theory (bone conduction theory) proposed by Fujino in 1974, according to James Fleming, MD.

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Smith and Regan coined the term “blow-out fracture.” Based on cadaver experiments, they theorized that the force transmitted from the trauma compresses the intraorbital contents, which in turn induce outward pressure on the orbital walls causing the weakest wall to fracture.  The weakest walls of the orbit are the medial wall and orbital floor. The hydraulic theory is widely maintained to be the most likely explanation for what actually happens, explained Brian Fowler, MD, clinical instructor, ophthalmic plastic and reconstructive surgery, at the University of Tennessee.

“Both mechanisms may be operative in varying degrees in different patients, as a result of the mechanism and location of the traumatic insult,” said Dr. Fleming, chairman and Lewis professor of ophthalmology, University of Tennessee, and Hamilton Eye Institute, Knoxville.

When considering the orbital architecture, Dr. Fleming demonstrated that the walls separate the compartments.

“An understanding of their configuration allows us to achieve reconstruction,” he commented, while also pointing out the shape of the medial wall and slope of the floor in the positive image and the floor tilt up and the bowing of the medial wall from a frontal view in the negative view.

When considering the reasons to repair an orbital fracture, Dr. Fleming cited the impact of permanent disability, that is, the resultant ocular movement disorder, facial deformity, and possibly neuralgia.

A look at the literature

A survey of the studies in the literature on the topic of orbital fracture repair revealed the published criteria for repairing orbital fractures. Specifically, a white eye blowout requires immediate repair. Early repair is defined as that occurring less than 2 weeks after injury, while late repair, by default, is that occurring longer than 2 weeks following the injury. Significant enophthalmos is that exceeding 2 millimeters or alternatively that which is symptomatic. Finally, significant diplopia is that described by the patient as symptomatic.

 

However, Dr. Fleming pointed out, many studies had limitations. Some were retrospective in nature with treatment protocols in place. The data were drawn from institutions and practices and not population-based samples, which can introduce selection bias. In addition, there can be biases related to the inclusion and exclusion treatment criteria. Finally, patient follow-up can be problematic in that, for example, knife and gun club individuals with injuries do not keep appointments.

Criteria for repair

The early intervention risk-to-benefit ratio raises two questions: Can delayed repair adversely affect the patient? And does early intervention speed healing and return the patient to normal productivity?

“Can we reasonably identify those patients who would benefit from early intervention, and when are we performing unnecessary surgery? One way to look at this dilemma is that we are attempting to solve a complex math problem with multiple variables, the most important of which are the overall patient health status and ability to safely undergo general anesthesia, diplopia, and degree of enophthalmos in that order,” Dr. Fleming said.

Regarding general anesthesia, Drs. Fleming and Fowler said the important questions to ask are: Is the patient sufficiently stable after a recent trauma to undergo surgery? And does the patient have medical comorbidities that place them at too high a risk for fracture repair?

If the patients are acceptable surgical candidates, we analyze their examination, reported symptoms, and imaging. It is useful to think of the orbit as a room in which the eye and the important surrounding structures, particularly the extraocular muscles, reside. The orbit is comprised of four walls--two side walls, a roof, and a floor. The floor is like a ramp slanting upwards as it moves posteriorly.  Thus, if the floor is fractured, the eye most often moves backwards (enophthalmos) and less often downwards (hypoglobus). The relative size of the floor fracture can be useful to predict the likelihood of enophthalmos. Further, the extraocular muscles, particularly the inferior rectus and surrounding orbital tissue, can become entrapped in the fractured bone or be displaced inferiorly into the maxillary sinus, both of which result in diplopia, Dr. Fowler explained.

 

He noted that factors causing diplopia are considered first because this is the most visually debilitating long term.

“I recommend repair for patients with diplopia secondary to restrictive strabismus with entrapment of the inferior rectus or surrounding orbit within the fracture or displacement of the inferior rectus into the maxillary sinus as noted on imaging. In children, entrapment is repaired urgently due to the risk of ischemia of the inferior rectus, i.e., the white eyed blowout fracture,” he said.

Enophthalmos is considered next and Drs. Fleming and Fowler recommend repair to patients with exceeding 2 mm to improve symmetry and normal eyelid height as ptosis occurs with significant posterior global displacement.  

For patients with less than 2 mm of enophthalmos and no diplopia, the course is less clear.

“I review their imaging. However, several well-designed studies that attempted to predict latent enophthalmos development, reported conflicting results, which suggests that we cannot predict this with perfect accuracy,” Dr. Fleming said.

The radiographic criteria that he considers most important when determining whether this group will develop latent enophthalmos and thus benefit from repair are the size of the floor fracture (>50% representing a large fracture), orbital content prolapse into the maxillary sinus, orbital strut disruption, and a floor fracture extending high up the medial wall of the orbit, he said.

“It makes sense that the larger the structural orbital defect, the more likely it is that there will be a change in the global position over time,” he emphasized. Observation is recommended for those without symptoms or enophthalmos and no radiographic criteria.

 

For patients meeting one or more of the radiographic criteria, Drs. Fleming and Fowler discussed with them the risk benefit ratio to repair.

“The more radiographic criteria the patient has the more likely I feel they will develop latent enophthalmos. Early repair will limit development of latent enophthalmos in some patients.  However, because of its imperfect nature, some fractures will be repaired that would have never developed enophthalmos. Orbital fracture repair is not without risk, albeit small, due to general anesthesia, worsening of diplopia, pupillary abnormalities, and loss of vision. Importantly however, those who are observed initially who develop latent enophthalmos are often more difficult to repair due to inferior orbital scarring. This may lead to higher complications and poorer patient outcomes,” Dr. Fleming cautioned.

Finally, patient age and occupation are considered. Dr. Fowler noted that repair is more likely for, for example, a young pilot who requires binocular vision than an elderly man or woman whose quality of life rests solely in his or her ability to watch TV and read. 

“Medicine will always involve decisions with black, white, and shades of gray. There are floor fractures for which the science clearly highlights the need for early repair. For others, the answer isn’t nearly as clear such as with latent enophthalmos. Like many areas in medicine, the repair of orbital floor fractures truly highlights the importance of the interplay of both the art and science of medicine,” Dr. Fleming concluded.

 

James C. Fleming, MD, FACS

E: jflemin@bellsouth.net

Dr. Fleming has no financial interest in any aspect of this report.

 

Brian Fowler, MD

E: btfowler@me.com

Dr. Fowler has no financial interest in any aspect of this report.