Orbital fractures account for 25% of maxillofacial injuries presenting at tertiary care centers [1]. The most common mechanisms of injury are motor vehicle accidents and assaults. These injuries are easily noticeable and can have significant aesthetic and functional implications. Given the complexity of human facial anatomy, precise surgical planning is required; failure to adequately plan can result in suboptimal correction and functional disability. Current literature describes various techniques for restoring orbital anatomy [2].

Conventionally, complex maxillofacial reconstruction is planned using stereolithographic (STL) models of the patient. This approach is time-consuming and incurs additional costs, which limits its use in emergency surgeries. Despite computer-assisted planning, complications can still arise due to the lack of real-time feedback [3]. Defined surgical approaches also restrict the view of fracture morphology and the proximity of vital structures. Additionally, there is no universal implant that matches specific orbital dimensions. Common complications reported after orbital fracture repair include diplopia (20%–42.5% in cases of isolated orbital floor fractures; 86% in complex fractures involving multiple walls or the posterior third of the orbital floor), persistent enophthalmos (7%–27.5%), and infraorbital nerve hypesthesia (7%–59%) [4,5].

Restoration of orbital volume typically corrects globe projection and reduces the likelihood of residual diplopia. Proper placement of implants with adequate bony support helps prevent the delayed sagging of the mesh or plate and the recurrence of symptoms [6]. These essential surgical objectives have ushered in a new era of real-time surgical imaging that avoids radiation hazards by using infrared technology. Computed tomography (CT) image-guided navigation is one such modality that has demonstrated its importance across various surgical specialties. Computer-aided design/manufacturing software is available to create three-dimensional (3D) models of subjects and generate mirror images of anatomical subunits using Digital Imaging and Communications in Medicine (DICOM) image data [7]. These mirrored normal facial subunits are superimposed on the contralateral injured segment to plan accurate reductions and implant fixation. Intraoperative navigation, integrated with this virtually planned data, can provide real-time feedback to adjust the position of implants and the anatomical reduction of displaced fractured bony segments.

Over the past 20 years, various studies [8-14] have reported on the use of different modalities for preoperative data registration combined with intraoperative surgical navigation. These methods have been instrumental in identifying posterior bony landmarks and assisting with implant placement during anatomical orbital reconstruction. Most of these studies were retrospective analyses focused solely on pure orbital fractures, and none have prospectively examined their use in impure orbital fractures. Considering the available literature, we conducted a prospective cohort study design to evaluate the application of 3D-computer image-guided navigation in complex orbital reconstruction, incorporating minimally invasive preoperative planning.

This single-center prospective cohort study was conducted by the department of plastic surgery in collaboration with the department of ophthalmology from January 2020 to July 2021, spanning 19 months. The study received approval from the Institutional Ethical Committee, adhering to the guidelines established by the Indian Council of Medical Research in 1994 and the modified Helsinki Declaration of 2008. Written informed consent was obtained from all participants for both the research and clinical photography.

Demographic characteristics: The median age was 29 years (interquartile range [IQR], 22.5–38.5 years). Of the 12 patients, 10 were men and two were women (Table 3).

The orbit is a pyramidal structure with a broad rectangular base and a narrow apex. It is composed of seven bones, each contributing to a specific anatomical zone that influences both its function and aesthetics [16]. The orbital floor is thin, concave in the anterior two-thirds, and convex in the posterior third, resembling an italic “S” in the sagittal plane. The medial wall, which is the weakest, is formed by the perpendicular ethmoid lamina; it is convex and runs parallel to the sagittal plane. In contrast, the lateral walls are thick, shorter, and converge at a 45° angle, being more recessed with the rim aligning with the globe’s equator.

Traumatic disruption of this intricate conformation can lead to diplopia, enophthalmos, and dystopia. Therefore, anatomical reconstruction of the orbital walls is essential to restore ocular function and facial symmetry. This reconstruction begins at the orbit’s margins, which provide the reference framework, and proceeds with the reconstitution of its walls.

Conventional reconstruction techniques lack objective criteria for achieving precise conformation. Extensive tissue dissection is necessary to visualize the posterior ledge in a limited space, which is often misinterpreted, leading to improper implant fixation. Additionally, even after employing STL models to achieve the desired contouring of the orbital implant, there is no intraoperative feedback available to confirm the accuracy of the anatomical reconstruction. These limitations are effectively addressed using 3D navigation technology.

Our study demonstrated that 3D computer navigation-guided orbital reconstruction precisely restores orbital volume to match that of the contralateral normal orbit, exhibiting a high linear correlation. The study group was heterogeneous, consisting of 75% of patients with impure orbital fractures that involved the orbital margins. The sample size of our study was comparable to that reported in the current published literature regarding outcomes in complex orbital fractures (Table 5).

The normal orbital volume is approximately 30 mL, with the globe occupying 7 mL of this space. When orbital walls are fractured, the densely packed contents of the orbit can herniate. The accuracy of calculating orbital volume in a traumatized eye is compromised by difficulties in identifying depressed and comminuted fracture walls, leading to variations among observers. In this study, to minimize potential bias, automated measurements were conducted using the Brainlab software’s auto-segmentation tool, which generated a 3D replica of the orbital cavity. Our study revealed that navigation-guided surgery corrects orbital volume within a range of 0.45 cm 3 difference. The difference in volume between the reconstructed and normal orbits was found to be consistent with findings reported in the existing literature (Table 6).

Diplopia following orbital trauma is primarily caused by increased orbital volume, muscle incarceration in fracture segments, nerve paresis, and differential globe projection. The displacement of the anterior orbital margin and floor traps the inferior rectus, while changes in the posterior volume impact globe suspension and projection, leading to ocular motility disorders. Subperiosteal release of the entrapped tissue from the fractured margin and resuspension of the periorbita to the anatomically reconstructed walls effectively correct diplopia without recurrence. This study demonstrated a statistically significant improvement in diplopia following surgical intervention. However, this finding has limitations, as perimetry, the gold standard for diplopia charting, was not performed. Perimetry examination is challenging in cases of acute traumatic maxillofacial injury because it requires the patient to position their face within the examination machine. The diplopia grading used in this study was customized, as it is not possible to tabulate diplopia in all cardinal gazes for comparative analysis. Bly et al. [17] reported similar results in their series, which utilized a case-control study design with navigation-guided orbital reconstruction and developed their own diplopia severity score.

Asymmetrical projection of the eyeball significantly influences a person’s appearance when facing forward. Enophthalmos is traditionally defined as the posterior displacement of the eyeball into the bony orbit. Alterations in the bony structure beyond the globe’s transverse axis, specifically involving the lateral wall, medial wall, and floor, markedly impact the normal projection of the globe. Contributing factors also include long-term consequences of orbital fat atrophy, loss of ligament support (specifically the Lockwood ligament), and scar contracture [23,24]. In this study, there was no significant improvement in enophthalmos. Several factors contributed to this finding. The majority of patients in the sample had an impure fracture, and all were assessed using a Hertel exophthalmometer by a single observer. The presence of an associated zygoma fracture introduced a measurement error due to the displacement of the lateral orbital rim, which served as a false reference point. Consequently, a CT scan was performed for each patient to evaluate the globe’s position relative to the inter-zygomatic line (Cannabis Index) [25], which is subject to the same limitation. Clinically evident, refractory enophthalmos has been noted in numerous studies even after optimal orbital reconstruction. It has been observed that despite adequate restoration of orbital volume, enophthalmos may persist in long-term follow-ups of complex orbital trauma. This persistence can be attributed to orbital fat atrophy, scar contracture, fibrosis of the injured extraocular muscles, or inadequate soft tissue repair.

The significance of aesthetics in orbital fracture reconstruction is not explicitly addressed in the present literature. Orbital fractures involving the zygomatic bone can significantly disrupt facial symmetry due to the loss of malar projection. If the reduction is not anatomical, it can lead to an increased face width and a sunken eye appearance. Despite these challenges, gross facial and orbital symmetry was consistently achieved during the study, except in cases with significant soft tissue damage. Over time, facial morphological features undergo changes due to delayed wound retraction and tissue atrophy, adding a temporal dimension to these alterations. When the repair of the overlying soft tissue does not align anatomically with the underlying bone injury, facial asymmetry may result. Damage to the compartmentalized orbital fat pad can lead to sunken eyelid deformities. Similarly, loss of the buccal fat pad, whether from trauma or surgical intervention, tends to make the cheekbones and jawline more prominent. The breakdown of superficial and deep fascial planes, along with the retaining ligaments, negatively impacts facial contour and expression. A displaced buccal fat pad can cause noticeable sagging of the face, an accentuated nasolabial fold, and apparent flattening in the infraorbital area. For aesthetic reconstruction, it is crucial to mobilize the soft tissues subperiosteally and suture them back into their anatomical positions across the face. Subperiosteal sutures should be placed anteriorly to anchor the periorbita to the reconstructed inferior orbital rim. The aponeurotic layer of the dissected cheek tissue should be plicated and secured to the robust zygomatic periosteum. A layered closure with proper canthal anchoring is essential to match the dimensions of the opposite eyelid. Extensive dissection and inadequate lid suspension can lead to scleral show due to lower lid retraction. Therefore, only precise, goal-directed surgical dissection combined with anatomical reconstruction can ensure symmetrical outcomes. Current navigation technology primarily guides bony reconstruction, leaving soft tissue adjustments to the discretion of the surgeon. Accurate surgical planning complemented by intraoperative navigation may reduce the extent of surgical dissection and enhance aesthetic results compared to conventional approaches.

No re-intervention was required for any patient, and no major complications were encountered during the perioperative period or in the subsequent follow-up period of 6 months to 1 year. During the surgical procedure, navigation feedback was used to accurately identify the posterior ledge of the maxillary slope. However, the implant chosen for reconstruction had certain limitations. Patients with complex orbital fractures involving more than two walls and comminuted fractures require adequate posterior bony support for contoured implants to prevent delayed sagging. Due to financial constraints, a patient-specific implant was not affordable; therefore, manual molding of the implant or pre-contoured mesh plate was employed to reconstruct the deficient walls. This approach may lead to human errors in judgment when matching the anatomical profile of the orbit. The use of a patient-specific implant and further validation by intraoperative CT scan would have objectively matched the reconstructed orbit, thereby eliminating registration and operative errors [26,27].

The study had some flaws, including the absence of a comparable control group, the use of a universal orbital implant, and undefined fracture morphology in relation to the orbital axis. Additionally, the proposed study group was subject to measurement errors, selection bias, and normal anatomical variance of the orbit. To establish a standardized treatment protocol, further randomized controlled trials with larger sample sizes and extended study periods are necessary.

Over the past two decades, navigation-guided surgery has gained widespread acceptance in various reconstructive procedures, though it still falls short in some critical areas. To improve predictability and outcomes, it is necessary to integrate real-time imaging and artificial intelligence for image analysis during surgery. This integration can enhance the clinical knowledge and skills of less experienced surgeons, bringing them closer to the level of expertise held by seasoned professionals in the field. A significant limitation of navigation technology is its inadequate guidance for soft tissues and the reliance on fixed registration reference points in cases involving mobile structures like the mandible. Furthermore, the assumption of facial symmetry is often incorrect, as research has demonstrated subtle variations in orbital volumes between the two orbits of an individual [28]. Despite concerns regarding cost and time, the superior outcomes and reduced revision rates provided by navigation surgery justify its use, especially in complex facial injuries caused by high-velocity trauma.