Figure 1 Coronal view of the orbit. Note that the infraorbital nerve divides the orbital floor into a medial segment (gray; long and thin) and a lateral segment (white; short and thick).

indication of an endoscopic repair—an orbital blow-out fracture (with inferior rectus entrapment) and a concurrent hyphema. Endoscopy allows release of the muscle entrapment without globe retraction. Patients presenting with trap door and medial blow-out fractures are the best candidates for endoscopic repair. The dissection necessary for larger defects that extend lateral to the infraorbital nerve may place the infraorbital nerve at risk for iatrogenic injury and post operative paresthesias. Complex, 2-wall fractures cannot be managed endoscopically at this time. The surgical options and techniques should be discussed with the patient (ie, open versus endoscopic repair). Appropriate informed consent should be obtained to include the possibility of a transconjunctival incision in case the surgeon cannot repair the fracture endoscopically.

Surgical technique

Once the patient is intubated and the endotracheal tube is secured, the best position to accommodate the surgeon, assistant, and video monitor tower is arranged. Typically, a right-handed primary surgeon should be positioned on the patient’s right side with the bed turned 180° away from anesthesia or simply move the bed down further to create space at the head of the bed to view the video monitor tower. The assistant surgeon and nurse should be on the patients left. The monitor should be at the head of the bed to allow both the surgeon and the assistant to have a clear and comfortable view of the monitor. Ideally, 2 monitors can be used.

The upper buccal sulcus on the side of the injury is injected with 1% or 2% lidocaine with 1:100,000 epi-

nephrine and sublabial (Caldwell-Luc) incision is performed. The maxillary face is exposed in a subperisosteal plane and the dissection is extended to the level of the infraorbital nerve. Care is taken to avoid excessive traction on the infraorbital nerve. The antrostomy is placed in the thinnest area of the maxillary sinus wall. This can be performed with the osteotomes or with the oscillating saw. If the osteotomes is chosen, a 4-mm maxillary antrostomy is generated in the thin, central portion of the maxillary face. The antrostomy is enlarged with a 3-mm Kerrison. The final antrostomy should be approximately 1 2 cm and placed 1 to 2 mm below the infraorbital nerve and 1 to 2 mm lateral to the nasomaxillary buttress. Care must be taken to avoid injury to the dental roots, infraorbital nerve, or the nasal aperture. Finally, an endoscope “notch” is placed in the central portion of the antrostomy. This notch provides tactile feedback to the assistant surgeon, stabilizing the endoscope while keeping his/her eyes on the monitor. Alternatively, an oscillating saw can be used to make the antrostomy window. The bone can then be plated back in place at the completion of the procedure. This approach offers a more anatomic repair than the osteotome/Kerrison technique. It does, however, require greater precision and may place the infraorbital nerve, the piriform aperture, and the dental roots at greater risk.

A Greenberg retractor can be mounted to the head of the surgical table and positioned to retract the upper lip. A 90° bend at the distal 2 cm of the retractor helps catch the superior periosteal edge and keeps the buccal mucosa from slipping beneath the retractor and into the surgical field. If a Greenberg retractor is not available, a right angle retractor is used by the assistant to retract the lip and cheek. Excessive traction on the infraorbital nerve must be avoided. The sinus cavity is then visualized using a 30° endoscope (facing upward) with an irrigation sheath. Old blood is suctioned from the sinus, and the orbital floor anatomy is visualized. Depending on the acuteness of the fracture, the appearance of the fracture and contents will vary. More acute fractures will have a generalized ecchymotic appearance to the floor and herniated contents, whereas older fractures, because of the evolution of the hematoma, will have a more yellow– green appearance to the herniated contents and sinus mucosa (Figure 3).

The sinus ostium is most commonly located superiorly and posteriorly on the medial maxillary sinus wall. The infraorbital nerve appears as a white line running from the orbital apex to the infraorbital foramen. Both the sinus ostium and the infraorbital nerve should be identified and protected. A “pulse test” is performed to assess the fracture size, pattern, and degree of orbital prolapse.9 The test is performed by applying gentle pressure on the globe while visualizing the transmitted movement of the orbital floor from below (Figure 4). The location and extent of the fracture is determined.

With the aid of sinus instruments (ie, ostium finder, Blakesley forceps, periosteal elevator, and gauze packer), the maxillary mucosa is stripped circumferentially around the fracture site when dealing with a medial fracture, or along the lateral free margin when dealing with a trap door fracture. Once delineated, the trap door fracture is

repaired by reducing the prolapsed orbital fat with a malleable retractor and “closing” the trap door. The reduced bone fragment is held in place by interfragmentary resistance. Treatment of medial blow-out fractures requires complete removal of all bone fragments to circumferentially define the bony defect (Figure 5). Once the site is prepared, a 0.4-mm Medpor implant (Porexsurgical, Newnan, GA) is cut slightly larger than the defect size. The implant is introduced into the sinus via the osteotomy. Once in the sinus, the implant is inserted above the stable posterior shelf. The instruments are then “walked” forward on the implant, seating it on the anterior shelf (orbital rim). With the implant in place, the stability is checked by placing gentle pressure on the globe while visualizing the implant from the sinus. If the implant is stable, a forced duction test is performed to insure free

movement without entrapment and displacement of the implant (Figure 6). The sinus is then irrigated and the vestibular incision is closed with 3-0 chromic gut sutures. The anterior sinus wall defect may be replaced if the antrostomy window had been preserved.

Complications

Potential complications associated with endoscopic repair are the same as open repair, with the exception of eyelid injury. These complications include blindness, diplopia, and globe malposition. Meticulous bone removal is essential. Incomplete bone removal can result in displacement of bone fragments into the orbital cavity, which may compromise

Figure 3 Endoscopic view of an early repair of an orbital blowout fracture. Note the appearance of the mucosa and herniated contents. (Color version of figure is available online.)

vision and cause impediment of movement. The incidence of long-term infraorbital nerve paresthesia with this procedure is unknown. The surgeon must use meticulous surgical technique and avoid excessive traction or manipulation of the infraorbital nerve.

Discussion

Although recent attention has been given to endoscopic repair of orbital floor fractures, the surgical goals remain unchanged: anatomic reconstruction of the bony orbit. The single largest hurdle to an anatomic reconstruction is accurate placement of the implant on the stable posterior shelf

Figure 5 Appearance of the orbital floor fracture after removing of the mucosa to expose the fracture. (Color version of figure is available online.)

(Figure 6). Visualization deep in the orbit is very challenging, and orbital repairs can humble even the most experienced surgeons. The surgeon must balance the need for adequate exposure with the risk of iatrogenic injury to the orbit. Endoscopy provides the surgeon with an excellent view of the posterior orbit, and it can be used with virtually any approach with which the surgeon feels comfortable. It facilitates the dissection, allowing complete reduction of the herniated orbital contents and thus increasing the chances of an optimal repair.

Endoscopic examination of the orbital floor can also be used to assess the need for surgical repair. By definition, patients with zygomaticomaxillary complex fractures have an orbital component to the injury. The orbital floor fracture can be exacerbated by reduction of the zygoma. Some authors have advocated exploration of the orbital floor after

Figure 4 Illustration of a pulse test. Mild pressure is applied to the globe, and the fracture is inspected from below with a 30° endoscope.

Figure 6 View of a repaired orbital blow out fracture with a Medpore implant in place being retained by pressure from the orbital contents. (Color version of figure is available online.)

fracture reduction to evaluate the need for orbital floor repair. Endoscopy allows the surgeon to use the preexisting sublabial incision and maxillary face fracture to visualize the orbital floor defect, perform a pulse test, and decide if surgical repair is indicated.

Another application for the endoscopic, transmaxillary approach is patients with a hyphema and extraocular muscle entrapment. Although extraocular muscle entrapment is considered an absolute indication for immediate surgical repair, traditional open approaches require globe retraction. In the presence of a hyphema, increased intraocular pressure can result in secondary hemorrhage and visual loss. Therefore, most surgeons delay the repair for at least 3 to 5 days, despite the fact that this may result in permanent extraocular muscle injury. The transmaxillary endoscopic approach offers an excellent solution to this dilemma, without the need for globe retraction. The periorbital tissues can be released, and the definitive repair can be performed at the same time or in a delayed fashion.

Although endoscopy has many advantages, it is a “tech- nology”-driven technique with a moderate learning curve. The surgeon must feel comfortable with endoscopic instruments and the lack of depth perception. The authors recommend that surgeons interested in learning the endoscopic technique have the endoscopic equipment available for all orbital blow out and zygomaticomaxillary complex fractures. The surgeon can then insert the endoscope on routine open cases and become familiar with what the fracture looks

like endoscopically. The combined approach will allow the surgeon to validate his/her endoscopic assessment and result in a more accurate implant placement. Once adequate experience has been accrued, a pure endoscopic repair can be performed.

References

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