INTRODUCTION
A blowout fracture is a bony defect deep within the orbit, classified by its location as a medial wall, inferior wall, or combined inferior-medial wall fracture. Since the medial orbital wall is thinner than the inferior orbital wall, fractures of the medial orbital wall are more common than those of the inferior orbital wall. However, medial orbital wall fractures are more challenging to diagnose using conventional radiography compared to floor fractures [1]. The introduction of facial bone computed tomography (CT) has significantly improved the detection of medial orbital fractures, resulting in a higher rate of surgical interventions. The primary goal of surgery for blowout fractures is to restore ocular motility and the original orbital shape, preventing enophthalmos [2,3]. Achieving this requires careful repositioning of the herniated orbital contents and fractured orbital wall, with precise implant placement being a key challenge. When the fracture extends deep into the bony orbit, accurately visualizing the internal structures becomes difficult, increasing the risk of optic nerve compression [4]. Fractures near the optic canal pose particular challenges, such as ensuring the complete repositioning of orbital contents, properly bridging the posterior fracture margin, and maintaining a safe distance between the implant and the optic nerve [5]. In a previous study, the author introduced a technique for treating medial orbital wall fractures using a combined transethmoidal and transcaruncular approach [6]. This method involves restoring the medial orbital wall from the ethmoid sinus using its primary bone fragments and placing temporary support within the sinus. During the ethmoid packing process, precise exploration and restoration are crucial, as the ethmoid sinus is located medial to the optic canal and inferior to the cranial base [6].
In this study, it is hypothesized that the use of surgical navigation could improve outcomes by enhancing precision, safety, and anatomical reconstruction in the senior author’s combined transethmoidal restoration and transcaruncular approach. The authors employed navigation during surgery for medial orbital wall fractures to verify the accurate restoration of the fractured orbital wall to its original anatomical position and to ensure the proper insertion of the orbital implant at the anteroposterior, superior, and inferior edges [7]. Navigation was also used to confirm the accuracy of ethmoid packing through the transethmoidal approach. Additionally, the study evaluated whether using navigation could improve postoperative functional and anatomical outcomes while minimizing complications.
METHODS
Patient and injury characteristics
In Korea, government approval for new health technologies utilizing navigation in the treatment of orbital wall fractures was granted in August 2022, along with insurance coverage for its use. As a result, navigation technology has only recently become available for clinical application. We compared the outcomes between two groups of patients: those who underwent surgery for orbital wall fractures prior to the use of navigation and those who had surgery after its introduction. This study was approved by the Institutional Review Board of our institution and conducted in accordance with the Declaration of Helsinki.
From September 2021 to November 2023, 228 patients underwent surgical treatment for orbital fractures. Medial wall involvement was identified in 87 cases (38.2%), with 48 patients (21.1%) presenting with isolated medial wall fractures and 39 (17.1%) exhibiting concomitant orbital floor fractures (Fig. 1). Among the 48 patients with isolated medial wall fractures, 38 were men and 10 were women, ranging in age from 12 to 74 years, with a mean age of 43.3 years. 23 cases involved the right orbit, while the remaining affected the left orbit. CT scans confirmed the diagnosis in all cases, with six patients exhibiting limited eye movement and 30 presenting with enophthalmos before surgery.
Surgical intervention was indicated in 48 cases. The surgery was performed using a combined transcaruncular approach and transethmoidal packing to repair the orbital fracture. Since January 2023, we have been utilizing navigation system (Naviol; Mega Medical) in orbital fracture reconstruction. Among these patients, 23 cases utilized navigation during surgery, while 25 cases did not. The outcomes were compared by dividing the patients into two groups.
Ophthalmic examination
All surgical candidates underwent a preoperative ophthalmologic evaluation to assess diplopia and extraocular motility. The severity of enophthalmos was measured using a Hertel exophthalmometer (Inami), with initial measurements taken 1 day before surgery. Patients returned for follow-up visits at our outpatient clinic at 2 weeks, 1 month, and 6 months after surgery. Hertel measurements were reassessed at the 6-month follow-up, coinciding with the completion of orbital soft tissue atrophy and scar formation.
CT scans and orbital volume measurements
Three-dimensional CT images were obtained using a GE Light-speed VCT scanner (GE Healthcare), with 1 mm thick in axial and coronal slices. CT scans were conducted both preoperatively and postoperatively, with the postoperative scans performed during the outpatient follow-up period, at least 6 months after surgery. The Rapidia Image Post-processing System (Infinitt) was used to measure orbital volume by delineating the orbital boundary on each CT image. The volume of the unaffected orbit was used as a reference to account for individual variations in orbital volume. The orbital volume ratio (OVR) was calculated by dividing the volume of the affected orbit by that of the normal side, with postoperative OVR determined using the same method.
Surgical techniques
The decision to proceed with surgical intervention was based on the criteria, including absolute indications such as restricted ocular motility and persistent diplopia, as well as relative indications like a fracture area exceeding 2 cm². Under general anesthesia, pledgets soaked in a solution of 1:100,000 epinephrine and 2% lidocaine were applied to the caruncle. A curvilinear incision measuring 10 to 12 mm was made through the lateral aspect of the caruncle, after retracting it medially and laterally with a 6-0 Prolene suture along the semilunar fold. This incision was extended superiorly and inferiorly into the fornices. Stevens tenotomy scissors were then used for spreading dissection, allowing incision of the periosteum and access to the medial orbital wall. Dissection was carried out between the medial orbital septum and Horner’s muscle. The posterior lacrimal crest was initially palpated with a blunt instrument, and a blade was used to vertically incise the periorbita along the lamina papyracea. Subperiosteal dissection was then performed using a periosteal elevator, exposing the entire medial orbital wall. To improve visualization, the globe was retracted laterally with an orbital retractor, and further subperiosteal dissection was carried out posteriorly to fully identify the fracture.
Medial wall restoration
During the procedure under general anesthesia, nasal congestion was relieved by applying epinephrine-soaked pledgets, and 2% lidocaine with 1:100,000 epinephrine was injected into the anterior root of the middle turbinate. Once the medial wall fracture was exposed through a transcaruncular incision, a straight Freer elevator was carefully introduced into the nasal cavity, navigating the ethmoid air cells without performing an ethmoidectomy to reach the medial aspect of the orbital wall fracture. A Freer elevator was used intraethmoidally to assist in lateralizing the fracture through a transnasal approach, carefully repositioning the medial wall bone fragments to their prior anatomical position, which was directly visualized through a transcaruncular approach. The herniated orbital contents that had protruded into ethmoid sinuses were relocated back into the orbit. The medial wall fracture was reconstructed by conserving the primary orbital wall fragment and returning it to its original position. To support the reconstructed orbital wall, Nasopore (Polyganics B.V.) was introduced into the ethmoid sinus via a transnasal approach, adjacent to the reconstructed medial orbital wall fragment. This material gradually dissolved over several weeks, eliminating the need for packing removal (Fig. 2G and H). A 0.5 mm thickness resorbable plate (RapidSorb; DePuy Synthes) was trimmed and placed at the fracture site through transcaruncular approach, with the size determined intraoperatively using real-time measurements obtained with a navigation probe (Fig. 2E and F). Following reduction of the orbital fracture, the periosteum and conjunctival incisions were closed with absorbable sutures.
Intraoperative guide with navigation
Before implementing the navigation system, anatomical landmarks of the patient were carefully correlated with corresponding reference points on CT images, and the accuracy of registration points was thoroughly verified. The navigation system enabled transnasal access to the ethmoid sinus for the restoration of the medial orbital wall. A navigational probe was inserted through the nasal passage to evaluate the ethmoidal air cells and facilitate precise transnasal reduction of the medial orbital wall fracture (Fig. 2B). Additionally, navigation was employed via a transcaruncular incision to confirm the dimensions and anteroposterior, superior and inferior extent of the orbital wall fracture (Fig. 2A). This system provided visualization of the deep posterior aspect of the medial orbital wall fracture, particularly near the optic nerve during dissection (Fig. 2C and D). Real-time assessment of the orbital fracture’s extent was conducted using the navigational probe.
Following the reduction of the medial wall fracture through the transnasal approach, the navigation system ensured the accurate restoration of the posterior margin of the medial wall fracture. After restoring the medial wall with ethmoidal packing and implants placement through transcaruncular approach, verification was carried out to ensure there was no compression on the optic nerve. The navigation system also facilitated continuous monitoring of the alignment between the repositioned wall and the preoperative plan.
Orbital volume measurement and statistical analysis
At the 6-month postoperative follow-up, evaluations included CT scans to assess orbital volumes and OVR. These assessments were conducted using semi-automatic segmentation with specialized software. Orbital volume, a widely recognized parameter for evaluating outcomes of orbital fracture treatment, was analyzed quantitatively and compared. Measurements of OVR and Hertel scale were analyzed for statistically significant differences between groups using the Mann-Whitney test or Wilcoxon signed-rank test. Statistical analyses were performed using SPSS version 20.0 for Windows (IBM Corp.), with a significance level of p < 0.05 considered statistically significant.
RESULTS
Orbital assessment
Among the 48 patients (25 control group A and 23 experimental group B) who underwent orbital reconstruction for medial blowout fractures, 30 patients experienced enophthalmos (14 in group A and 16 in group B), and six patients had limited extraocular movement (5 in group A and 1 in group B) preoperatively. After surgery, all patients fully recovered from ocular symptoms, including diplopia and limited extraocular movement. The mean Hertel exophthalmometer measurements were –0.76 mm in group A and –0.65 mm in group B preoperatively, and –0.52 mm in group A and –0.22 mm in group B postoperatively. In the control and experimental groups, the Hertel scale changed by 0.24 mm and 0.43 mm, respectively. The perioperative changes in the Hertel scale within each group, as well as the differences in preoperative and postoperative values between the two groups, were statistically nonsignificant (p > 0.05) (Table 1).
Measurements of orbital volume
The preoperative difference in the OVR between the control and experimental groups (–2.45%) was not significant (106.58% in group A vs. 109.03% in group B). However, 6 months postoperatively, CT imaging showed a significant decrease in the OVR in both groups based on volumetric analysis (104.01% in group A vs. 104.80% in group B). The experimental group exhibited a more substantial decrease in OVR (4.23%) compared to the control group (2.57%) (p < 0.05) (Table 2).
DISCUSSION
Orbital medial wall fractures, which are more common than inferior wall fractures, have traditionally been challenging to diagnose using conventional radiography. However, the advent of CT has greatly improved diagnostic accuracy and increased the rates of surgical intervention. The most common symptoms of a medial orbital fracture include periorbital edema, ocular discomfort and orbital emphysema following nasal insufflation [2]. Although less frequent than inferior wall fractures, medial wall fractures can lead to pain during eye movements and movement restrictions if the extraocular muscles become entrapped [1,6]. Additionally, because the medial wall normally protrudes convexly into the orbit, a fracture that results in a loss of this convexity may cause enophthalmos after the initial swelling subsides.
Surgical indications for orbital fractures include restricted ocular motility, persistent diplopia, and the presence of a bone defect larger than 2 cm² detected on CT imaging, due to the risk of developing enophthalmos [2]. The primary surgical procedure involves repositioning herniated orbital tissue and restoring the fractured orbital wall to its original configuration, with the goal of preserving the eye’s anatomical and functional integrity. However, the optimal surgical approach and technique remain subjects of ongoing debate among orbital surgeons [2].
In a previous study, our team used a combined transnasal and orbital approach to restore fractured medial orbital walls extending into the ethmoid sinus. This method offered advantages over the transorbital technique by facilitating the smooth recovery of herniated orbital tissue by applying pressure from the ethmoid sinus [6]. When using a transorbital approach, the orbital tissues must be pulled and repositioned back into the orbit, which can exacerbate traction damage to the tissues and potentially increase separation damage to the orbital wall fracture fragments [2]. However, accessing the ethmoid sinus via a transnasal approach allows for simultaneous pressure application to the fractured orbital wall and ethmoidal mucosa, reducing traction-induced damage and minimizing fracture fragment separation [2]. Temporary support with absorbable foam inserted into the ethmoid sinus helped maintain the restored medial wall for several weeks post-surgery. Ethmoid packing was crucial in providing support, preventing reherniation, and promoting optimal healing [2,6].
The ethmoid sinus is situated between the superior aspect of the nasal cavity and the medial aspect of the orbit, separated from the cranial base by a thin skull base and positioned anatomically close to the optic canal posteriorly. Applying pressure to the medial orbital wall from the ethmoid sinus to restore a fractured orbital wall through a transnasal approach, or performing packing in the ethmoid sinus to support the restored medial orbital wall, may risk damaging the skull base or the optic canal [4,8]. Therefore, meticulous attention is essential during the surgical correction of a medial orbital wall fracture using a transethmoidal approach to minimize the risk of optic nerve damage and ensure accurate restoration of the fractured orbital wall.
Key challenges in orbital fracture surgery include restoring the orbital wall and accurately positioning the implant. Medial orbital wall fractures near the optic canal are particularly difficult due to the narrow operative field and the risk of postoperative complications, such as optic nerve injury and blindness. Intraoperative navigation addresses these challenges by providing real-time assessment of the orbital cavity’s geometry, especially its posterior extent. This capability allows the surgeon to continuously monitor the device’s position within the orbit, ensuring safety during restoration and minimizing the risk to the optic nerve [9,10].
Navigation guidance enhances the accuracy of implant placement and supports the customization and adjustment of malleable implants during surgery. It facilitates the precise execution of pre-planned restoration procedures, reducing the need for subsequent corrections [10,11]. Additionally, the navigation system enables multiple evaluations of orbital wall reconstruction and plate positioning throughout the procedure, improving overall accuracy and outcomes [11]. In severe fractures, particularly those involving multiple regions, determining whether the orbital contents have been fully repositioned, if the posterior edge of the fracture has been bridged, and whether the implant is safely distanced from the optic nerve can be particularly challenging [11,12]. Once an orbital implant is in place, navigation should be used to confirm its position and shape, making any necessary adjustments to achieve the desired contouring. Navigation addresses crucial concerns in orbital wall restoration by allowing real-time verification of proper wall restoration and prevention of optic nerve damage.
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