Endoscopic Transantral Orbital Floor Repair With Antral Bone Grafts

Objective  To evaluate the endoscopic transantral insertion of antral bone grafts into the orbit for repair of orbital floor defects.

Design  A retrospective analysis with a mean follow-up of 5.3 months.

Patients  Eleven patients who underwent surgical repair of orbital floor fractures.

Setting  Municipal hospital.

Main Outcome Measures  Preoperative and postoperative Hess screen tests and the presence of diplopia, enophthalmos, donor site complications, cosmetic deformity, infection, and graft extrusion.

Results  Subjectively, 3 patients with diplopia had complete resolution of their symptoms after surgery, and 8 patients had improvement of their symptoms. Objectively, 11 patients had significant improvement in the postoperative Hess area ratio compared with the preoperative Hess area ratio. In 1 patient with a floor defect measuring 2.5 cm, enophthalmos existed after surgery, but reoperation was not performed in this case because diplopia was improved. There were no donor site complications, cosmetic deformity, infection, or graft extrusion.

Conclusions  The endoscopic transantral insertion of antral bone grafts through the floor defect into the orbit is an effective technique that prevents injury to the lower eyelid, carries minimal donor site morbidity, and provides an optimal support function for the globe. It merits consideration in cases of orbital defects less than 2 cm in diameter.

A variety of approaches to orbital floor fractures have been proposed, such as the subciliary approach,¹ transconjunctival approach,² endonasal approach,³ or transantral approach.^4,5 Subciliary and transconjunctival approaches have a 3% to 42% incidence of ectropion.^6,7 However, using the transantral orbital floor approach prevents injury to the lower eyelid–supporting structures.⁵

Orbital floor defects have been repaired with various types of alloplastic⁵ and autogenous materials.^1,2,8 Using antral bone grafts for repair eliminates the external incision, additional surgical time to harvest and mold the graft, and additional management of donor site morbidity.⁸

We recommend use of the transantral approach with antral bone grafts for blowout fracture of the orbital floor.

This study is a retrospective analysis of 11 patients who underwent surgical repair of orbital floor fractures between April 1998 and February 2004. The 8 male patients and 3 female patients were aged 11 to 33 years (mean age, 19.6 years). These patients underwent primary repair of pure orbital blowout fractures and were followed up for at least 3 months after surgery (mean follow-up, 5.3 months). One patient also sustained a fracture of the nasal bone. Records of preoperative and postoperative Hess screen tests and the presence of diplopia, enophthalmos, donor site complications, cosmetic deformity, infection, and graft extrusion were reviewed

Preoperative and postoperative examinations were performed to determine disturbance of ocular motility as evaluated with the Hess screen test (Figure 1).^3,9-11 The Hess area ratio is calculated as follows: a perpendicular grid and a horizontal grid that include the central point are counted on a Hess chart. One grid square is counted as 1. The approximate value of the Hess area is calculated by multiplying the number of perpendicular grid squares times the number of horizontal grid squares. The ratio of the impaired side to the normal side is calculated. The difference in the preoperative and postoperative Hess area ratios in patients was compared using the paired t test.

Indications for surgery included disabling diplopia 1 week after trauma, radiographic evidence of herniation of orbital fat, and positive results from a forced duction test (Figure 2 and Figure 3). All fractures were approached via a gingivobuccal incision. Surgical repair of blowout fracture was performed under general anesthesia.

The surgical site is injected with 1% lidocaine hydrochloride with a 1:100 000 dilution of epinephrine. A 4-cm incision is made about 5 mm above and parallel to the upper gingival line. The periosteum and overlying soft tissues are gently elevated from the anterior wall of the maxillary antrum. An antral bone flap 2 to 3 cm in diameter is created in the anterior maxillary wall above the canine root, and this bone is set aside.

Using a 4-mm, 70° endoscope, the orbital floor fracture is visualized (Figure 4). The surgeon holds the endoscope in the left hand and forceps in the right hand. The infraorbital nerve is identified and protected. Bony fragments and periorbita, which entrap the orbital contents, are minimally removed and opened, respectively, using forceps, elevators, and scalpels until improvement of forced duction testing is achieved during surgery.

The antral wall segment that had previously been set aside is trimmed with heavy scissors to be longer than the defect in length and shorter in width and is then inserted through the floor defect with forceps⁵ (Figure 5). The bone is rotated to rest on the stable posterior, lateral, medial, and anterior orbital shelves (Figure 2 and Figure 4). The surgeon ensures that the bone graft does not traumatize the infraorbital nerve. If the whole bone graft cannot be inserted onto the orbital shelves, the bone can be hooked onto part of the ledge (Figure 3) or adapted directly to the undersurface of the orbital floor, and then it will be supported by a ureteral balloon inserted into the maxillary sinus through a 1-cm hole created on the inferior nasal meatus. Then, 8 to 15 mL of physiological saline solution is introduced into the balloon at the tip of the catheter. The nose is lightly packed with gauze, and the incision is closed. The catheter can be removed 7 days after surgery.

Seventeen patients underwent repair of orbital floor fracture between 1998 and 2004. Six patients were excluded from the study because of inadequate follow-up. The intervals until fracture repair in the remaining 11 patients ranged from 6 to 19 days. There were a total of 11 pure blowout fractures and 1 that was complicated with nasal bone fracture. The size of defects ranged from 0.3 to 2.5 cm. The length of follow-up ranged from 3 to 15 months (mean follow-up, 5.3 months).

Subjectively, 3 patients with diplopia had complete resolution of their symptoms after surgery, and 8 patients had improvement. These 8 patients continued to have diplopia on extreme gaze at last follow-up but were without diplopia in their cardinal fields of gaze.

Objectively, the postoperative Hess area ratio was significantly improved in comparison with the preoperative Hess area ratio in 11 patients (Figure 6; paired t test, P<.001). Figure 1 shows typical charts of the preoperative and postoperative Hess screen test in a representative case (case 1). Figure 2 shows the preoperative and postoperative computed tomographic findings in the same case. No patients developed diplopia after surgery, either subjectively or objectively.

Postoperative computed tomographic scans and magnetic resonance images were not obtained routinely because all patients showed steady clinical improvement. A coronal view of a high-resolution computed tomographic scan demonstrated adequate integration of the orbital floor without any evidence of resorption of the bone graft (Figure 2 and Figure 3). In case 1, in which the graft was inserted through the floor defect and placed on the orbital shelve (Figure 4), the integration of the bone floor was adequate (Figure 2). In case 2, in which the graft was not totally inserted onto the orbital shelve but rather hooked onto part of its ledge, the graft was in an acceptable position. There were no surgical site complications with respect to cosmetic deformity, infection, or graft extrusion.

In 1 patient with a floor defect measuring 2.5 cm, enophthalmos existed after surgery, but reoperation was not performed in this case because diplopia was improved.

The transantral approach for repair of pure orbital floor blowout fractures is not new.⁵ Orbital floor repair supported by the transantral approach has been described elsewhere. Reports include the placement of iodophor gauze, hydroxy-appetite block scaffolding, and sinus balloons.^12,13 However, these techniques were limited by inexact positioning of the orbital floor, and in 18% to 60% of the cases in these reports, residual enophthalmos occurred. Because of inadequate globe positioning, these methods have essentially been discontinued.

Established methods for orbital floor repair include lower eyelid crease, subciliary, and transconjunctival incisions. Although these procedures are optimal for direct visualization of orbital floor defects, they can leave unsightly facial scars and have a 3% to 42% incidence of ectropion.^6,7 These factors prompted a reexamination of the transantral approach for the evaluation and repair of orbital blowout fractures.⁵ There were no external incisions or scars with the intraoral approach. With the advent of endoscopic equipment, transantral endoscopic fracture evaluation and repair are possible. The transantral endoscopic approach allows direct visualization of orbital floor fracture to determine size, configuration, and need for repair.⁵

The choice between autogenous and alloplastic materials for the orbital fractures represents a trade-off between ease of use and better biocompatibility.² Despite the convenience afforded by alloplastic materials, autogenous tissue offers greater biocompatibility and decreased morbidity and is theoretically preferred. However, in actual practice, the use of alloplastic materials for repair of these fractures prevails. Increasing reports of problems with alloplastics resulting in late-onset infection, displacement or extrusion raise some concern.^14-16

In 1966, Kaye⁸ reintroduced the concept of using bone from the anterior wall of the maxillary antrum. Since then, however, this useful technique has had relatively little recognition in the literature. There are distinct advantages to using maxillary antral bone. This bone can be readily harvested during the transantral approach. The procedure obviates the need for a 2-team approach, which is often required for iliac or rib bone grafts, and thereby decreases the duration of the surgical procedure.¹ The postoperative pain and complications that can occur with harvesting of bone grafts from distant anatomic sites are also eliminated. More recently, Lee et al¹ reported again on the merits of orbital floor reconstruction with maxillary bone. However, they approached the orbital floor via subciliary or transconjunctival incision. Our method, which uses a transantral approach with maxillary antral bone grafts, prevents injury to the lower eyelid.

Our study revealed no evidence of graft extrusion. The use of similar membranous bone of equivalent thickness makes the antral wall bone graft ideally suited for reconstruction of the orbital floor.¹ Osseous tissue from the maxilla is more biocompatible than most alloplastic implants in use today. However, as Lee et al¹ reported, the quantity of maxillary bone is limited and lacks the bulk that other autogenous bone donor sources can provide. Its usefulness may also be limited in cases of severely comminuted fractures or defects larger than 2.5 cm and in the unusual instance of a hypoplastic maxillary antrum. In our study, we noted enophthalmos after surgery in a floor defect measuring 2.5 cm. In such a case, reconstruction via a subciliary or transconjunctival approach using iliac crest bone grafts, rib grafts, or tibial grafts might be better.

In conclusion, the transantral method of orbital fracture reconstruction prevents injury to the lower eyelid. The antral wall bone is an ideal implant material for the reconstruction of orbital floor defects because of its biocompatibility and lack of donor site morbidity.

Correspondence: Suetaka Nishiike, MD, PhD, Department of Otolaryngology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama 701-0192, Japan (nishiike@med.kawasaki-m.ac.jp).

Submitted for Publication; April 8, 2005; accepted May 2, 2005.

Financial Disclosure: None.