31.1 Goals

Orbital floor blowout fractures commonly occur as a result of blunt trauma to the orbit. The “blowout” occurs as the force of the trauma on the thick orbital rim transmits along the thin floor where buckling results in a fracture and posterior displacement of the globe results in pressurization of the orbital contents that displace this newly fractured floor segment outward. Diplopia can result from herniated entrapped muscle/soft tissues, muscle swelling, or cranial nerve injury. Early or late enophthalmos may also develop, particularly in larger fractures from an enlarged orbital volume but also from atrophy and displacement of orbital fat. Infraorbital nerve hypoesthesia may also occur. The goal of surgery is to free ensnared tissue and restore orbital volume. This results in correction of early enophthalmos, prevention of late enophthalmos, and correction of diplopia.

31.2 Advantages

Surgical repair in the case of the muscle entrapment within a non-displaced fracture can prevent permanent strabismus. Repair for large fractures or those with significant diplopia from displaced orbital tissue or ensnared orbital contents can result in a restoration of appearance and function. Early repair (i.e., within 10 days) has the advantage of an easier surgical field as fibrosis occurs within the orbit following trauma and progresses over the ensuing weeks and months. For patients who are not operative candidates due to other comorbidities or injuries, or do not seek medical care within this 10-day period, delayed repair may also be performed with good results. However, a longer operative time and possibility of less favorable outcomes may occur with delayed repair secondary to formation of scar tissue within the orbit.

31.3 Expectations

Surgical repair reposits prolapsed orbital tissues, restoring preinjury orbital volume and resulting in correction of enophthalmos, prevention of late enophthalmos, and correction of diplopia. However, as diplopia often initially worsens after surgery due to surgical manipulation of tissues and a resulting increase in intraorbital edema, patients must be counseled that diplopia may take weeks to months to resolve. In addition, they must be counseled that if diplopia is due to muscle or nerve damage from the injury, it may not resolve, and strabismus surgery may be necessary in the future. Patients must be counseled as to the risks of surgery (see section “Complications”), and careful informed consent should be obtained.

31.4 Key Principles

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  Orbital floor fracture repair should restore orbital volume by replacing orbital tissues to their anatomical position within the orbit and reconstructing the orbital bony anatomy.

  
  
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  Any entrapped orbital tissues should be freed from the fracture site at the time of surgery, releasing any mechanical strabismus which should be verified at the end of surgery with forced duction testing.

31.5 Indications

Surgical repair of orbital blowout fractures is not always indicated, and smaller fractures without significant diplopia or enophthalmos may often be observed.

Urgent surgical repair is recommended for true muscle entrapment or “white-eyed blowout fractures.” ¹ These injuries are classically seen in children, where the flexible bone segment springs back into anatomic nondisplaced position, tamponades bleeding, ensnares the orbital contents, and can cause necrosis of extraocular muscles. As such, the presentation is that of a quiet-appearing eye with markedly restricted motility, guarding on motility exam and restricted forced ductions secondary to muscle incarceration. These patients may also display the oculocardiac reflex of bradycardia, nausea, vomiting, syncope, or heart block associated with ocular movements. Muscle ischemia can occur as early as 8 hours after injury and repair should be as early as possible.

Indications for early surgical repair (within 10 days) include large fractures (more than 50% of the orbital floor area), early enophthalmos or hypoglobus, and persistent diplopia without improvement over a short period of observation. However, individual patient characteristics and preferences must be considered in the decision whether to repair. For example, an elderly patient with multiple medical comorbidities, diplopia only in extreme upgaze and little concern with facial asymmetry from enophthalmos may not warrant surgical repair, but a young patient who is an athlete with a similar fracture and the same symptoms may desire or require repair.

31.6 Contraindications

With the exception of the true muscle entrapment in a nondisplaced blowout fracture, patients with relative medical contraindications to surgery may be observed given that they are counseled on the risks of persistent diplopia and enophthalmos. In patients with active or unstable ocular injuries such as a ruptured globe or retinal detachment, surgery should be deferred until the active ocular issues are treated and stabilized, and a retinal specialist clears the patient for surgery. Manipulation of the globe during fracture repair may worsen an existing retinal or globe injury. Monocular patients incapable of developing diplopia should also be aware of the indications for repair.

31.7 Preoperative Preparation

Preoperative oral antibiotics and steroids may be given depending on surgeon’s preference with stronger indications for use in cases of preexisting sinus disease. Nose blowing should be avoided prior to surgery particularly if the medial wall is fractured. Perioperative intravenous antibiotics and steroids are preferred by the author. Informed consent is obtained, and the patient is given ample opportunity to ask questions about the surgery and expected postoperative course.

31.8 Operative Technique

Both eyes are prepped and draped in the typical manner for oculoplastic surgery. The surgery is begun with forced duction testing, which may be compared with the contralateral eye if indicated. A transconjunctival surgical approach is recommended, and this may be carried out in the preseptal or retroseptal planes (Fig. 31‑1). In the preseptal approach, an incision is made in the conjunctiva at the inferior border of the tarsus. Blunt dissection is carried down to the orbital rim in the preseptal plane. This has the benefit of preserving the septum which can keep the extraconal orbital fat out of the surgical field. It is slightly more cumbersome and given the periosteum is violated from the fracture in most cases, the orbital fat is often encountered nonetheless. In the retroseptal approach, the orbital rim is exposed and soft tissues displaced using a Desmarres retractor for the eyelid and malleable retractor for the orbital contents. An incision is made using Bovie cautery on a needle tip (Colorado Needle, Stryker, Portage, MI) in the conjunctiva, and dissection is carried down to the periosteum of the orbital rim posterior to the arcus marginalis in this fashion. In either approach, the periosteum is then incised with the Bovie cautery. A Freer elevator is used to dissect the periosteum off the orbital floor, taking care to preserve the integrity of the periosteum. The incision should extend from the lateral limbus to just medial to the punctum across the inferior orbital rim to fully access the fracture. This exposes the infraorbital nerve to the inferior oblique, both of which should be purposefully identified and protected. The infraorbital nerve is often unroofed as the lateral extent of the fracture typically ends at the infraorbital canal. The orbital contents often adhere to both the exposed infraorbital nerve and the sinus mucosa requiring careful blunt dissection. A blood vessel extending from the nerve to the inferior oblique is often encountered and can be ligated with cautery. ² The inferior oblique can be disinserted with an elevator under the periosteum of its origin but should never be cut. If disinserted, it does not need to be reattached. The dissection is carried as far posteriorly, medially, and laterally as is necessary to identify all borders of the fracture. All prolapsed orbital contents are gently lifted using the Freer elevator, taking care to avoid damage to the tissues. If further exposure is needed, the incision can be extended laterally into a lateral canthotomy and cantholysis or medially in a curvilinear manner into a retrocaruncular incision.

An implant is then placed. Several options are available, including porous polyethylene, titanium mesh, titanium mesh with porous polyethylene overlay, nylon sheets, silicone sheets, and absorbable materials (Fig. 31‑2). Titanium-containing materials are visible on postoperative imaging and hold a molded shape well. They can be custom bent by the surgeon freehand or with the assistance of a three-dimensional model. Pre-bent “anatomic” plates are available. Being rigid, if placed in the wrong location they can cause unintended damage to extraocular muscles or the optic nerve. Nonporous materials have the advantage of being flexible and as such can mold to the fracture site on their own. Being nonporous, they will not biointegrate and a capsule will form around them which can result in late infection or extrusion. Porous polyethylene sheets are rough enough to not require fixation and will biointegrate and, hence, once placed will not migrate. A theoretical downside to large pore porous materials and titanium has been orbital contents adherence, but this has not been demonstrated to be of clinical significance. Even so, dual layered implants exist that have smaller pore surfaces that face the orbital contents. Surgeon’s preference largely dictates the materials selected and familiarity with multiple implant types is recommended.

The implant is selected and cut to size (if applicable), taking care to bend the posterior-most edge of the implant inferiorly to avoid impingement on the optic nerve. A small cutout at the anterior medial edge is also created to allow space for the inferior oblique muscle. It is then positioned such that it overlies the fracture defect, with its borders supported by stable bone, and the posterior edge resting on the posterior ledge of the fracture, taking care to ensure that no orbital contents are beneath the plate. If a titanium mesh implant is used, this is fixated to the orbital rim with 4- or 5-mm self-drilling titanium screws. If porous polyethylene is used, this does not necessarily require fixation if the implant is stable, but may be fixated in the same fashion if there is any doubt as to its stability. A nylon sheet can be fixated with a screw or by cutting a U-shaped tab at the anterior end and tucking this into the maxillary sinus. Forced duction testing is then repeated, and if any restriction is noted, the implant is checked thoroughly and any residual soft tissues trapped underneath are freed. If desired, a drain can be placed such as a ¼” Penrose drain to be removed the following day. It is not necessary to close a transconjunctival approach, although some surgeons do so with a single 6–0 plain gut suture. Some surgeons place a 6–0 nylon frost suture tarsorrhaphy to prevent chemosis, align the lid tissue, and protect the cornea from the drain. Patching has the benefit of helping with any bleeding to prevent retrobulbar hemorrhage but prevents checking vision postoperatively. Patients can either be discharged home or be admitted overnight for observation. A postoperative CT scan can be performed to assess implant placement, particularly if there is concerning motility postoperatively (e.g., a down gaze deficit from inferior rectus manipulation is normal but a severe upgaze deficit is of concern).