Enophthalmos and Orbital Volume Changes in Zygomaticomaxillary Complex Fractures: Is There a Correlation Between Them?

Association of fracture type with enophthalmos and intraorbital volume correction in orbital fractures: A computed tomographic study

PURPOSE

To determine the influence of different types of orbital fractures on the radiographic post-treatment outcomes.

METHODS

The investigation was a retrospective cohort study involving CT data of all patients who underwent delayed primary or secondary surgery for orbital/zygomatico-orbital trauma between 2019 and 2021. The sample was divided into three groups 1, 2, and 3: isolated floor, floor and medial wall, and combined orbit and zygomatic complex fractures. The type of orbital fracture was the exposure, while the outcome measures were reduction in enophthalmos and intraorbital volume and linear relationship between the two variables. Data were analyzed for variance between groups and association. Statistical significance was set at < 0.05.

RESULTS

Forty-four patients (3 females and 41 males) with a mean age of 28.6 years were included in the study. Reductions in enophthalmos ( P < 0.001) and intraorbital volume ( P = 0.003) demonstrated significant variance between the groups. For every cubic centimeter of reduction in volume, the reduction in enophthalmos was 0.78 mm ( P < 0.001) in isolated floor fractures, 0.60 mm ( P = 0.013) in combined fractures involving the floor and medial walls, and 0.24 mm ( P = 0.456) in combined fractures of the orbit and zygoma.

CONCLUSION

Correction of enophthalmos strongly depends on the type of orbital fracture. There exists a significant linear relationship between enophthalmos and intraorbital volume in fractures involving the internal orbit.

Volumetric Analysis of Orbital Volume Discrepancy as a Marker of Change in Globe Position After Three-Point Fixation of Zygomatic Complex Fractures

BACKGROUND

Many researchers have proposed incorporating orbital volume (OV) discrepancies between the affected and unaffected orbits into routine diagnostic processes as an indicator for early surgical repair of zygomatic complex fractures (ZMCFxs) to avoid postoperative ocular complications.

PURPOSE

The study aimed to determine the correlation between the preoperative OV discrepancy and postoperative globe position.

STUDY DESIGN, SETTING, SAMPLE

A retrospective cohort study was performed on patients with unilateral ZMCFxs associated with orbital floor fractures, treated at Al-Zahraa Hospital, Al-Azhar University, from January 2020 to July 2023. Patients with comminuted ZMCFxs, medial or superior orbital wall fractures, or corrective surgeries were excluded.

PREDICTOR VARIABLE

The predictor variable was the preoperative OV discrepancy between the affected and unaffected orbits.

OUTCOME VARIABLES

The outcome variables were the 3-month postoperative globe position, which was classified as normal, enophthalmos, or exophthalmos, and the orbital repair quality, that was categorized as well-corrected, under-corrected, or over-corrected.

COVARIATES

They included age, sex, ethnicity, side, etiology, type of orbital floor fractures, timing, and indication for surgery.

STATISTICAL ANALYSIS

χ2, Pearson's correlation, and linear regression analyses were used; the statistical significance was set at P < .05.

RESULTS

The study included 111 patients, with an average age of 30.3 ± 6.6 years and male predominance. The preoperative OV discrepancy between both orbits was 5.1± 1 cc3, associated with enophthalmos in the patients. Postoperatively, the OV discrepancy became 0.9 ± 0.7 cc3, but the globe position was heterogenic. Thirty-seven patients (33.3%) had normal globe position. Sixty-three (56.8%) subjects had enophthalmos. Eleven (9.9%) individuals had exophthalmos. The preoperative OV discrepancy and postoperative globe position had a significant weak positive linear correlation. For every one-cubic-centimeter change in OV, the globe moved 0.1 mm (P < .05). The majority of the patients had under-corrected orbits, followed by over-corrected and well-corrected orbits. Every category of globe position was recorded with every category of orbital repair, and the findings showed no correlation between globe position and orbital repair quality (P = .08).

CONCLUSION

Preoperative OV discrepancies between both orbits should not be employed as the sole predictor of globe position because a one-cubic-centimeter change in OV affects globe position by only 0.1 mm.

The impact of polydioxanone (PDS) foil thickness on reconstruction of the orbital geometry after isolated orbital floor fractures

PURPOSE

The orbital floor is frequently involved in head trauma. Current evidence on the use of reconstruction materials for orbital floor repair is inconclusive. Accordingly, this study aimed to compare the impact of polydioxanone (PDS) foil thickness on reconstruction of the orbital geometry after isolated orbital floor fractures.

METHODS

Standardized isolated orbital floor fractures were symmetrically created in 11 cadaver heads that provided 22 orbits. PDS foils with thicknesses of 0.25-0.5 mm were inserted. Computed tomography (CT) scans of the native, fractured, and reconstructed orbits were obtained, and orbital volume, orbital height, and foil bending were measured.

RESULTS

Orbital volume and height significantly (p < 0.01) increased after the creation of isolated orbital floor fractures and significantly (p = 0.001) decreased with overcorrection of the orbital geometry after orbital floor reconstruction with PDS 0.25 mm or PDS 0.5 mm. The orbital geometry reconstruction rate did not differ significantly with respect to foil thickness. However, compared to PDS 0.5 mm, the use of PDS 0.25 mm resulted in quantitatively higher reconstructive accuracy and a restored orbital volume that did not significantly differ from the initial volume.

CONCLUSION

Orbital floors subjected to isolated fractures were successfully reconstructed using PDS regardless of foil thickness, with overcorrection of the orbital geometry. Due to its lower flexural stiffness, PDS 0.25 mm appeared to provide more accurate orbital geometry reconstruction than PDS 0.5 mm, although no significant difference in reconstructive accuracy between PDS 0.25 mm and PDS 0.5 mm was observed in this cadaveric study.

Does Intraoperative Navigation Improve Implant Position Accuracy in Orbital Fracture Repair?

Purpose: Our aim was to determine if intraoperative navigation (ION) improved radiographic outcomes in patients undergoing delayed primary/secondary orbital reconstruction for inferomedial defects, as measured by volume restoration, enophthalmos correction, and positional accuracy of implants. Patients and Methods: A prospective quasiexperimental study was performed to compare two groups of patients requiring orbital reconstruction. Use of ION was the exposure evaluated. Outcome measures were (i) intraorbital volume and enophthalmos evaluated radiologically, (ii) implant position accuracy, and (iii) procedural duration. Data were analyzed statistically to compare variance between groups. Results: Forty patients (6 females and 34 males) were recruited into the study with a mean age of 27.3 years. The study group demonstrated a greater reduction of intraorbital volume (0.49 cu.cm; p = 0.02) and enophthalmos (0.72 mm; p = 0.001). Implant positioning was more accurate using ION, with less mediolateral (p = 0.006) and yaw (p = 0.04) deviations. Surgical time for implant positioning was shorter by 17 min, with navigation (p < 0.001). Conclusion: The use of ION demonstrated radiographic improvements in volume restoration, enophthalmos correction, as well as accuracy of implant positioning, in patients requiring delayed primary/secondary orbital reconstruction.

Measuring orbital Volume Using Open Source Software and its Application in Orbitozygomatic Fractures

Study Design

Technical note.

Objective

Changes in orbital volume can lead to esthetic and functional complications of the orbit. In this article, the procedure to calculate the orbital volume using the open source software Aliza 3D DICOM is described.

Methods

This article describes the steps to use this novel software. To validate the software, the normal orbital volume was calculated bilaterally on CT scans with normal orbital anatomy. The volumes of unilateral orbitozygomatic fracture cases were compared.

Results

This open source software has easy access. The normal orbital volume calculated using this software was 24.4 cc ± 0.72. In the unilateral orbitozygomatic fracture cases, an increased orbital volume was calculated.

Conclusions

This easy access, inexpensive, and convenient computer aided software can be used to calculate orbital volume facilitating treatment plan for correction of the orbit volume.

Correlation between Orbital Computed Tomography Scan Measurements and Clinical Enophthalmos in Acute Isolated Orbital Floor Fractures

Purpose

To analyze the correlation between orbital computed tomography (CT) scan measurements including the fracture area (FA), the fracture location, the soft-tissue herniation volume (HV), the fractured orbital volume ratio (OVR) to the normal orbit, and the clinical enophthalmos in acute isolated orbital floor fractures.

Methods

We enrolled 100 patients with acute isolated unilateral orbital floor fractures from May 2017 to January 2021. Based on the CT scan findings, we measured the FA, HV, OVR, and fracture site. We assessed enophthalmos using both clinical (CE) and radiographic (RE) measurements. Additionally, we investigated the correlation between CE and the measured parameters, along with the relationship between the pattern of diplopia and the fracture site.

Results

We identified enophthalmos in 81% and diplopia in 78% of the patients with an acute blowout orbital floor fracture. CE was moderately correlated with the FA (R 2 = 0.4341, P < 0.001). CE was weakly correlated with the HV (R 2 = 0.2861, P = 0.04). Anterior fractures caused diplopia in both vertical gazes, but posterior fractures were mostly associated with diplopia in the up gaze. OVR was strongly associated with RE (R 2 = 0.663, P < 0.0001) and moderately associated with CE (R 2 = 0.4378, P < 0.0001). The univariate regression analysis also showed that OVR could significantly predict CE and RE.

Conclusions

OVR surpasses other CT scan measurements such as FA and HV in the prediction of clinical enophthalmos. Thus, OVR could be utilized to estimate clinical enophthalmos at the time of presentation, especially when the acute clinical setting prohibits the proper clinical evaluation.

Efficacy and Safety of Expanded Polytetrafluoroethylene Implantation in the Correction of Long-Term Posttraumatic Enophthalmos

SUMMARY

Long-term enophthalmos is a common orbital fracture sequela. Various autografts and alloplastic materials have been studied in posttraumatic enophthalmos repair. However, expanded polytetrafluoroethylene (ePTFE) implantation in late enophthalmos repair has rarely been reported. The authors report novel use of ePTFE for late posttraumatic enophthalmos repair. This retrospective study included patients with posttraumatic long-term enophthalmos who underwent hand-carved ePTFE intraorbital implantation for enophthalmos correction. Computed tomography data were collected preoperatively and at follow-up. The volume of ePTFE, the degree of proptosis (DP), and enophthalmos were measured. Postoperative and preoperative DP and enophthalmos were compared using the paired t test. The correlation between ePTFE volume and DP increment was established using linear regression. Complications were identified by chart review. From 2014 to 2021, 32 patients were included, with a mean follow-up of 19.59 months. The mean volume of implanted ePTFE was 2.39 ± 0.89 mL. After surgery, the DP of the affected globe improved significantly, from 12.75 ± 2.12 mm to 15.06 ± 2.50 mm ( P < 0.0001). A significant linear correlation was found between ePTFE volume and DP increment ( P < 0.0001). Enophthalmos was substantially ameliorated from 3.35 ± 1.89 mm to 1.09 ± 2.07 mm ( P < 0.0001). Twenty-five patients (78.23%) had postoperative enophthalmos of less than 2 mm. Infection and implant dislocation were not observed. The authors concluded that ePTFE intraorbital implantation exhibited long-term efficacy and safety for late posttraumatic enophthalmos repair and represents an effective and predictable alternative.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Thin PDS Foils Represent an Equally Favorable Restorative Material for Orbital Floor Fractures Compared to Titanium Meshes

Orbital floor fractures (OFFs) are common injuries of the midface and may result in long-term complications. The aim of this study was to compare two restoration materials, PDS foils and titanium meshes, with regards to (1) clinical outcome and (2) reduction in orbital volume. The monocentric discovery cohort was analyzed retrospectively and included 476 patients with OFFs treated between 2010 and 2020. A subcohort of 104 patients (study cohort) with isolated OFFs and available high-resolution imaging material was used for volume measurements. Postoperative complications were not significantly different between patients treated with different restoration materials. Prevalence of revision surgery was significantly higher in patients treated with thick PDS foils (25 mm). OFFs treated with PDS foils and titanium meshes showed a significant reduction in orbital volume (p = 0.0422 and p = 0.0056, respectively), however, this volume decrease was significantly less pronounced in patients treated with PDS foils alone (p = 0.0134). Restoration using PDS foil in an isolated OFF reduces the orbital volume to a lesser extent than titanium mesh. Class III patients according to the classification of Jaquiéry with a missing bony ledge medial to the infraorbital fissure particularly benefit from restoration with PDS foils due to a lower reduction in the orbital volume. Regarding short- and long-term postoperative complications, a PDS foil thickness of 0.15 mm appears equivalent to titanium mesh in the treatment of OFFs.

The Impact of Orbital Volume on Post-traumatic Enophthalmos: A Systematic Review and Meta-analysis

PURPOSE

Orbital volume increase has been previously linked with post-traumatic enophthalmos. However, this varies and some studies show no correlation. This systematic review and meta-analysis aimed to synthesize the correlation between orbital volume and enophthalmos and to determine if surgical intervention, enophthalmos measurement method, fracture location, or timing affect this correlation.

METHODS

Automation tools were used to assist in this review of 6 databases. Searches were performed across all dates. Included studies quantitatively reported orbital volume and enophthalmos following traumatic orbital wall fractures in at least 5 adult subjects. Correlational data were extracted or calculated. Random-effects meta-analysis was used with subgroup analyses for each of the secondary aims.

RESULTS

Twenty-five articles describing 648 patients were included. The pooled correlation between orbital volume and enophthalmos was r =0.71 ( R2 =0.50, P <0.001). Operative status, enophthalmos measurement method, and fracture location did not affect pooled correlation. The delay between trauma or surgery and enophthalmos measurement was not shown to modulate correlation for unoperated patients ( R2 =0.05, P =0.22) but showed a negative relationship for postoperative patients ( z =-0.0281, SE=0.0128, R2 =0.63, P =0.03), but this was heavily influenced by a single article. All results had high residual heterogeneity. Studies were rated as moderate, low, or very low quality with few stating explicit hypotheses or limitations.

CONCLUSIONS

Bony orbital volume expansion accounts for around 50% of post-traumatic enophthalmos. The other half is probably explained by soft tissue or geometric bony, rather than volumetric, changes.

Virtual Surgical Planning and 3-Dimensional Printing for the Treatment of Zygomaticomaxillary Complex and/or Orbital Fracture

BACKGROUND

Traditionally, in zygomaticomaxillary complex and orbital fractures, miniplates and titanium orbital mesh are used and adapted intraoperatively, which may cause fatigue of the metal and increase the surgical time. Recently, computer-assisted surgery and 3-dimensional printing enable the surgeon to employ 3-dimensional segmentation and mirroring tools, which mimic the pretraumatized anatomy on which the miniplates and titanium orbital mesh are preoperatively molded to precisely duplicate the orbital volume, enophthalmos, and zygomatic bone position.

AIM

To evaluate the results of computer technology using 3-dimensional printing model to prebend miniplates and titanium orbital mesh in the restoration of orbital volume, enophthalmos, and zygomatic bone position in the initial management of patients with zygomaticomaxillary complex and/or orbital fractures.

PATIENTS AND METHODS

This prospective clinical study included 10 Iraqi male patients who met the eligibility criteria and subjected to open reduction and internal fixation utilizing virtual surgical planning and a 3-dimensional model to prebend miniplates and titanium orbital mesh as a treatment modality for facial fractures. The data were analyzed according to the orbital volume, enophthalmos, zygomatic bone position, age, gender, etiology of the fracture, and complications. The patients were radiographically followed up with a computed tomography scan at 4 months postoperatively. The statistical analysis was performed using percentages, the mean±SD, Shapiro-Wilk test, Paired t test, One Way Anova, and Independent t test.

RESULTS

The age of the patients ranged from 18 to 66 years, with an average of 28.6 years and a SD of±14.5 years. Regarding gender, all patients were males. By utilizing virtual surgical planning and 3-dimentional model to prebend miniplates and titanium orbital mesh and concerning the fracture types, which include the zygomaticomaxillary complex, orbital, and combined fractures, there was no significant difference between the measurement of intact side and 4 months postoperatively in orbital volume, enophthalmos, and zygomatic bone position ( P >0.05).

CONCLUSION

This study demonstrated that computer-aided techniques, virtual planning, and the use of prebend miniplates and titanium orbital mesh enable anatomically precise reduction and fixation of the orbital, zygomaticomaxillary complex, and combined fractures regarding orbital volume, enophthalmos, and zygomatic bone position.

Comparison of Postoperative Enophthalmos Between Fresh and Delayed Unilateral Orbital Fractures After Orbital Reconstruction With Titanium Mesh Using Computer-Assisted Navigation

This study compares postoperative enophthalmos between fresh and delayed unilateral orbital fractures after orbital reconstruction with titanium mesh using computer-assisted navigation. The sample was composed of 45 patients with post-traumatic unilateral enophthalmos who were divided into the fresh fracture group and the delayed fracture group. They underwent orbital reconstruction with standard preformed orbital implants and computer-assisted navigation system. The following parameters were measured with computed tomography images: the degree of enophthalmos, orbital volume, and fracture defect area. Patients were reviewed preoperatively (T0), 1 week postoperatively (T1), and 6 months postoperatively (T2). Computed tomography measurements showed that in both groups, the degree of enophthalmos decreased after surgery but increased significantly from T1 to T2 ( P <0.05). ΔE (difference in the degree of enophthalmos between T1 and T2) was similar in patients with fresh and delayed fractures. There was a significant difference in the degree of ΔE between patients with single-wall orbital fractures and those with two-wall orbital fractures. The findings indicate that postoperative enophthalmos is common in both the groups and is closely related to the degree of preoperative enophthalmos. Furthermore, the recurrence of enophthalmos is similar between the 2 groups, but it is higher in patients with orbital fractures involving 2 walls.

Ultra-High Molecular Weight Polyethylene (marPOR) is a Suitable Material for the Reconstruction of Orbital Floor Fracture Defects in Human Cadavers

Purpose

Despite there being different materials for orbital floor reconstruction available today, outcomes are still not satisfying. In recent years, ultra-high molecular weight polyethylene (UHMWPE) has gained popularity in the field of orthopedic surgery due to its good biocompatibility and low infection rate. With its three-dimensional compound structure, it combines high stability and ductility, making it a potential material to be used for orbital floor reconstruction.

Methods

In a cadaver study, an overall of eighteen orbits were included. Fractures of the inferior wall were induced and then reconstructed using Polyglactin 910/PDS composite (Ethisorb) and UHMWPE (marPOR). Orbits were scanned by cone-beam CT in each condition: Intact, fractured and reconstructed with Ethisorb, marPOR 0.85 mm and marPOR 1.5 mm. Segmented orbital volumes were calculated by specialized software (Disior bonelogic CMF).

Results

All materials led to sufficient reconstruction of the initial orbital volumes (Ethisorb: p < 0.001; marPOR 0.85 mm: p = 0.003; marPOR 1.5 mm: p < 0.001). Orbits that were reconstructed with marPOR 0.85 mm showed the least mean volume difference from intact orbital volumes.

Conclusion

UHMWPE (marPOR) offers reliable reconstruction of orbital floor fractures combined with good stability, ductility and biocompatibility.

Effect of orbital volume in unilateral orbital fracture on indirect traumatic optic neuropathy

PURPOSE

This retrospective study aimed to analyze the relationship between the volume of the fractured and the normal orbit in patients with unilateral orbital fractures with and without indirect traumatic optic neuropathy (TON).

SUBJECTS

Data of 25 patients with unilateral orbital fractures who underwent computer tomography between January 2016 and December 2020 were investigated. Emergency imaging was performed within 2 hours of arrival at the emergency room. The subjects were categorized into two groups: unilateral orbital fractures with and without TON.

METHODS AND MEASURES

The assessment of TON was performed during a comprehensive ophthalmologic examination by an ophthalmologist. The stereographic orbit was reconstructed, and the volume was calculated. Other variables examined included age, sex, and cause of orbital trauma. The variables were compared using paired t-tests. Statistical significance was set at p < 0.05.

RESULTS

The orbital volume of the non-fractured orbit was 27.50  ± 2.26 and 27.48  ±  2.64 cm³ in the groups with and without TON, respectively. The average volume of the fractured orbit in the TON group was 27.78  ± 2.56 cm³, and there was no significant volumetric difference between the fractured and non-fractured sides in this group. However, the average volume of the fractured orbit without TON was 28.76  ±  3.18 cm³, larger than that of the non-fractured orbit (p = 0.016).

CONCLUSIONS

Non-expansion of the fractured orbit was a risk factor for indirect TON in patients with unilateral orbital fractures. Volumetric analysis from primary imaging would expedite the diagnosis and treatment of TON, resulting in optimal outcomes.

Secondary Correction of Posttraumatic Enophthalmos

Posttraumatic enophthalmos (PE) arises when the ocular globe is displaced posteriorly and inferiorly in the orbital cavity due to a mismatch in orbital volume and orbital content. This most commonly happens after orbital fractures. The resulting disruptions to aesthetic form and ocular functions often necessitate surgical correction for reconstruction and restoration. The purpose of surgical management of PE is to reconstruct orbital shape and volume as well as to restore any herniated orbital content. This can be particularly challenging in cases involving large defects that require complex orbital reconstruction. Recent advancements in computer-aided surgery have introduced innovative and important tools to assist surgeons with these difficult cases. The ability to create customized, patient-specific implants can facilitate reconstruction involving complicated anatomy. Additionally, intraoperative imaging and intraoperative navigation can serve as useful guides for surgeons to more accurately place implants, especially in cases with limited visualization, in order to achieve optimal outcomes.

Customized and Navigated Primary Orbital Fracture Reconstruction: Computerized Operation Neuronavigated Surgery Orbital Recent Trauma (CONSORT) Protocol

ABSTRACT

Combined orbital medial wall and floor fractures and large isolated orbital floor fractures commonly require surgical treatment due to the high probability of diplopia and enophthalmos. Primary reconstruction of these orbital fractures requires a high-level surgeon with a great amount of technical surgical skill. The use of novel technology can greatly improve the accuracy of reconstruction and achieve satisfactory clinical outcomes. Hence, the authors aimed to present our findings and overall experience with respect to extensive floor and medial wall orbital fracture reconstruction according to the Computerized Operation Neuronavigated Surgery Orbital Recent Trauma (CONSORT) protocol, a workflow designed for the primary reconstruction of orbital fractures with customized mesh and intraoperative navigation. A total of 25 consecutively presenting patients presenting with unilateral extensive orbital floor fractures and orbital floor and medial wall fractures were treated following the CONSORT workflow from January 2017 to March 2020. Fractures were surgically treated with a customized implant and intraoperative navigation. Patients underwent surgery within 14 days of the trauma injury. Preoperative and postoperative functional and aesthetic outcomes are described herein. All fractures were successfully reconstructed. Postoperatively, all 19 patients with preoperative diplopia reported the resolution of diplopia. Enophthalmos resolved in 18/20 cases. No patients had major complications during follow-up. Thus, the authors conclude that the CONSORT protocol introduced by the authors is an adaptable and reliable workflow for the early treatment of orbital fractures and can clearly optimize functional and aesthetic outcomes, reduce costs and intensive time commitments, and make customized and navigated surgery more available for institutions.

Secondary Reconstruction of the Zygomaticomaxillary Complex

Zygomaticomaxillary (ZMC) fractures are the second most common facial fractures after nasal bone fractures. The zygoma, with its location and multiple points of articulations, lends itself to both facial structure and esthetics. Secondary ZMC deformities are complications of inadequate primary correction, delayed repair, or lack of repair. Secondary revisions of ZMC aim to correct ZMC displacement and projection and to address orbital discrepancies. Extensive correction involving significant orbital and malar defects requires zygomatic repositioning osteotomies and would greatly benefit from the utilization of virtual surgical planning, intraoperative navigation, and imaging. Minor corrections in malar projection can be corrected by onlay grafting and soft tissue augmentation and resuspension. Isolated or minor orbital corrections can be managed by autogenous or alloplastic material to restore lost orbital volume and anatomy.

Prediction of Post-Traumatic Enophthalmos Based on Orbital Volume Measurements: A Systematic Review

PURPOSE

Enophthalmos greater than 2 mm should be considered clinically relevant and can be responsible for esthetic and functional morbidity. The difficulty has always been the best method to use to accurately determine when the orbital wall displacement will lead to clinically relevant enophthalmos. None of the currently used techniques is able to accurately predict for post-traumatic enophthalmos (PE). The aim of the present study was to systematically review the use of orbital volumetric tools in the prediction of PE after orbital fracture.

MATERIALS AND METHODS

The terms searched in each database were "(orbital volumetry) and enophthalmos," "volumetry and enophthalmos," "volume and enophthalmos," and "volumetric and enophthalmos." The relationship between PE and the orbital volume (OV) was assessed.

RESULTS

The initial search yielded 346 results. Of the 346 studies, 14 were included and analyzed. Every study reported a different numerical relationship between the OV and PE, with a mean enophthalmos of 0.80 mm after a 1-cm³ increase in the OV.

CONCLUSIONS

The present review found that most studies concluded that a direct relationship exists between the OV and PE and defined the degree of PE in relation to the OV expansion. Enophthalmos assessment using radiologic evaluation provides increased accuracy and reproducibility compared with clinical measurement using an exophthalmometer. It has been notoriously difficult to determine when orbital wall displacement will lead to clinically relevant enophthalmos. Measurement of the OV could have a role in the decision for surgical or conservative treatment.

Overview of tools for the measurement of the orbital volume and their applications to orbital surgery

There are numerous applications in craniofacial surgery with orbital volume (OV) modification. The careful management of the OV is fundamental to obtain good esthetic and functional results in orbital surgery. With the growth of computer-aided design - computer-aided manufacturing (CAD-CAM) technologies, patient-specific implants and custom-made reconstruction are being used increasingly. The precise measurement of the OV before surgery is becoming a necessity for craniofacial surgeons. There is no consensus on orbital volume measurements (OVMs). Manual segmentation of computed tomography (CT) images is the most used method to determine the OV, but it is time-consuming and very sensitive to operator errors. Here, we describe the various methods of orbital volumetry validated in the literature that can be used by surgeons in preoperative planning of orbital surgery. We also describe the leading software employed for these methods and discuss clinical use (posttraumatic enophthalmos prediction and orbital reconstruction) in which OVMs are important.

Intact Periorbita Can Prevent Post-Traumatic Enophthalmos Following a Large Orbital Blow-Out Fracture

Treatment of orbital floor fractures is predicated on the restoration of orbital volume to prevent enophthalmos or hypoglobus. Globe position is the result of a complex interplay between the bony orbital anatomy and the soft tissue envelope. Studies on orbital fractures have frequently suggested criteria for repair on the basis of bony defect size or volume change. In this report, we describe a case of a large orbital floor defect (4.8 cm²) with intact periorbita and no herniation of soft tissue contents in a young male following facial trauma. The patient was followed for 1-year clinically and did not develop enophthalmos. This case demonstrates that bony injury alone is not sufficient to produce enophthalmos, and that the interplay between the soft tissue and bony anatomy is a critical determinant of globe position following orbital trauma.

Post-traumatic enophthalmos secondary to orbital fat atrophy: a volumetric analysis

PURPOSE

To investigate via volumetric analysis whether orbital fat atrophy occurs in late post-traumatic enophthalmos.

METHODS

An IRB-approved retrospective cohort study identified patients with diagnoses of both orbital fracture and enophthalmos with a CT orbits >3 months after injury. Exclusion criteria were surgical repair, other orbital disease or surgery, adjacent sinus disease, and an abnormal contralateral orbit. Images were analyzed using OsiriX imaging software (v.9.0.2, Pixmeo, Switzerland). Total orbital volume and orbital fat volume for the fractured and normal contralateral orbits were measured via three-dimensional volume rendering assisted region-of-interest computation. Enophthalmos was measured radiographically. Paired samples t-tests were used to compare orbital fat and total orbital volumes between the fractured and normal contralateral orbits.

RESULTS

Thirteen patients met the inclusion criteria. The numbers of patients with each fracture pattern were floor (4), medial wall (4), floor/medial wall (3), zygomaticomaxillary complex (floor+lateral wall) (1), zygomaticomaxillary complex+medial (inferior/medial/lateral walls) (1). Mean time from injury to CT scan was 21.8 ± 16.3 months. Comparing the fractured and normal contralateral orbits, there was a statistically significant decrease in orbital fat volume (mean difference 0.9 ml (14.2%), p = .0002) and increase in total orbital volume (mean difference 2.0 ml (7.0%), p = .0001). One ml orbital volume change was responsible for 0.83 mm enophthalmos.

CONCLUSIONS

In addition to an increase in total orbital volume, orbital fat loss occurs with late post-traumatic enophthalmos due to unrepaired fractures. This suggests correction of bony change alone may be insufficient in some cases, and the use of custom implants may compensate for fat atrophy.

Defining the Zygomaticosphenoidal Angle as a Guide to Anatomic Zygomaticomaxillary Complex Fracture Reduction

BACKGROUND

Alignment of the zygomaticosphenoid suture is fundamental to reduction of zygomaticomaxillary complex fractures. To prevent a rotational deformity, the correct angle of the zygoma relative to the cranial base must be restored. Clinically, this can be a challenge, especially when there is comminution of the zygomaticosphenoid suture. Defining a zygomaticosphenoidal angle would provide a reference for use with stereotactic navigation to achieve anatomic reduction.

METHODS

A single-center retrospective analysis of 100 patients was designed to determine normative zygomaticosphenoidal angle values. An angle subtended by the midline and a best-fit line through the zygomaticosphenoid suture on axial computed tomography was measured bilaterally in patients with isolated mandibular or nasal fractures. The mean of this measurement for 3 vertically adjacent cuts was calculated with position of central cut determined by the equator of the globe and trigone of the sphenoid. Multivariate regression was completed to identify changes in zygomaticosphenoidal angle with age, sex, and race.

RESULTS

The mean zygomaticosphenoidal angle was 47° (range 39°-55°). 97% of angles were within 2 standard deviations (8°) of mean. Regression analysis demonstrated no significant change in angle with age (P = 0.74) or sex (P = 0.89). For each angle, the variation across the 3 sample cuts was ≤4.5°. Patients demonstrated high fidelity in zygomaticosphenoidal angle bilaterally with mean difference of 3°.

CONCLUSION

The zygomaticosphenoidal angle is a useful reference, in conjunction with stereotactic navigation, for reduction of zygomaticomaxillary complex fractures. Contralaterally obtained patient-specific data may be used to guide unilateral repair. Normative values may serve as reference in bilateral injury.