Virtual surgery simulation in orbital wall reconstruction: Integration of surgical navigation and stereolithographic models

Three-dimensional computer navigation in the reconstruction of complex unilateral orbital fractures: evaluation and review of applications

BACKGROUND

The eyes are the central aesthetic unit of the face. Maxillofacial trauma can alter facial proportions and affect visual function with varying degrees of severity. Conventional approaches to reconstruction have numerous limitations, making the process challenging. The primary objective of this study was to evaluate the application of three-dimensional (3D) navigation in complex unilateral orbital reconstruction.

METHODS

A prospective cohort study was conducted over 19 months (January 2020 to July 2021), with consecutive enrollment of 12 patients who met the inclusion criteria. Each patient was followed for a minimum period of 6 months. The principal investigator carried out a comparative analysis of several factors, including fracture morphology, orbital volume, globe projection, diplopia, facial morphic changes, lid retraction, and infraorbital nerve hypoesthesia.

RESULTS

Nine patients had impure orbital fractures, while the remainder had pure fractures. The median orbital volume on the normal side (30.12 cm3; interquartile range [IQR], 28.45-30.64) was comparable to that of the reconstructed orbit (29.67 cm3; IQR, 27.92-31.52). Diplopia improved significantly (T(10) = 2.667, p = 0.02), although there was no statistically significant improvement in globe projection. Gross symmetry of facial landmarks was achieved, with comparable facial width-to-height ratio and palpebral fissure lengths. Two patients reported infraorbital hypoesthesia at presentation, which persisted at the 6-month follow-up. Additionally, five patients developed lower lid retraction (1-2 mm), and one experienced implant impingement at the infraorbital border.

CONCLUSION

Our study provides level II evidence supporting the use of 3D navigation to improve surgical outcomes in complex orbital reconstruction.

Exploring the Practical Applications of Artificial Intelligence, Deep Learning, and Machine Learning in Maxillofacial Surgery: A Comprehensive Analysis of Published Works

Artificial intelligence (AI), deep learning (DL), and machine learning (ML) are computer, machine, and engineering systems that mimic human intelligence to devise procedures. These technologies also provide opportunities to advance diagnostics and planning in human medicine and dentistry. The purpose of this literature review was to ascertain the applicability and significance of AI and to highlight its uses in maxillofacial surgery. Our primary inclusion criterion was an original paper written in English focusing on the use of AI, DL, or ML in maxillofacial surgery. The sources were PubMed, Scopus, and Web of Science, and the queries were made on the 31 December 2023. The search strings used were "artificial intelligence maxillofacial surgery", "machine learning maxillofacial surgery", and "deep learning maxillofacial surgery". Following the removal of duplicates, the remaining search results were screened by three independent operators to minimize the risk of bias. A total of 324 publications from 1992 to 2023 were finally selected. These were calculated according to the year of publication with a continuous increase (excluding 2012 and 2013) and R2 = 0.9295. Generally, in orthognathic dentistry and maxillofacial surgery, AI and ML have gained popularity over the past few decades. When we included the keywords "planning in maxillofacial surgery" and "planning in orthognathic surgery", the number significantly increased to 7535 publications. The first publication appeared in 1965, with an increasing trend (excluding 2014-2018), with an R2 value of 0.8642. These technologies have been found to be useful in diagnosis and treatment planning in head and neck surgical oncology, cosmetic and aesthetic surgery, and oral pathology. In orthognathic surgery, they have been utilized for diagnosis, treatment planning, assessment of treatment needs, and cephalometric analyses, among other applications. This review confirms that the current use of AI and ML in maxillofacial surgery is focused mainly on evaluating digital diagnostic methods, especially radiology, treatment plans, and postoperative results. However, as these technologies become integrated into maxillofacial surgery and robotic surgery in the head and neck region, it is expected that they will be gradually utilized to plan and comprehensively evaluate the success of maxillofacial surgeries.

Accuracy of surgical navigation for patient-specific reconstructions of orbital fractures: A systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis aimed to review the recent literature on the technical accuracy of surgical navigation for patient-specific reconstruction of orbital fractures using a patient-specific implant, and to compare surgical navigation with conventional techniques.

MATERIALS AND METHODS

A systematic literature search was conducted in PubMed (Medline), Embase, Web of Science, and Cochrane (Core Collection) databases on May 16, 2023. Literature comparing surgical navigation with a conventional method using postoperative three-dimensional computed tomography imaging was collected. Only articles that studied at least one of the following outcomes were included: technical accuracy (angular accuracy, linear accuracy, volumetric accuracy, and degree of enophthalmos), preoperative and perioperative times, need for revision, complications, and total cost of the intervention. MINORS criteria were used to evaluate the quality of the articles.

RESULTS

After screening 3733 articles, 696 patients from 27 studies were included. A meta-analysis was conducted to evaluate volumetric accuracy and revision rates. Meta-analysis proved a significant better volumetric accuracy (0.93 cm3 ± 0.47 cm3) when surgical navigation was used compared with conventional surgery (2.17 cm3 ± 1.35 cm3). No meta-analysis of linear accuracy, angular accuracy, or enophthalmos was possible due to methodological heterogeneity. Surgical navigation had a revision rate of 4.9%, which was significantly lower than that of the conventional surgery (17%). Costs were increased when surgical navigation was used.

CONCLUSION

Studies with higher MINORS scores demonstrated enhanced volumetric precision compared with traditional approaches. Surgical navigation has proven effective in reducing revision rates compared to conventional approaches, despite increased costs.

Image-guided navigation in posterior orbital tumour surgery: a comparative cohort study

PURPOSE

The posterior orbit is a confined space, harbouring neurovascular structures, frequently distorted by tumours. Image-guided navigation (IGN) has the potential to allow accurate localisation of these lesions and structures, reducing collateral damage whilst achieving surgical objectives.

METHODS

We assessed the feasibility, effectiveness and safety of using an electromagnetic IGN for posterior orbital tumour surgery via a comparative cohort study. Outcomes from cases performed with IGN were compared with a retrospective cohort of similar cases performed without IGN, presenting a descriptive and statistical comparative analysis.

RESULTS

Both groups were similar in mean age, gender and tumour characteristics. IGN set-up and registration were consistently achieved without significant workflow disruption. In the IGN group, fewer lateral orbitotomies (6.7% IGN, 46% non-IGN), and more transcutaneous lid and transconjunctival incisions (93% IGN, 53% non-IGN) were performed (p = .009). The surgical objective was achieved in 100% of IGN cases, with no need for revision surgery (vs 23% revision surgery in non-IGN, p = .005). There was no statistically significant difference in surgical complications.

CONCLUSION

The use of IGN was feasible and integrated into the orbital surgery workflow to achieve surgical objectives more consistently and allowed the use of minimal access approaches. Future multicentre comparative studies are needed to explore the potential of this technology further.

Modified individualized titanium mesh in orbital floor reconstruction for preventing exposure

Objective

To describe a novel method of medial fixation of titanium mesh with a right-angled screwdriver for orbital floor and maxillary reconstruction and to compare the reconstruction outcome of orbital floor reconstruction with modified and traditional methods.

Methods

The data of 23 patients who underwent maxillectomy and orbital floor defect reconstruction by individualized titanium mesh in Peking University School and Hospital of Stomatology between 2018 and 2021 were retrospectively reviewed. While eight patients received modified orbital floor reconstruction with titanium mesh and angled screwdriver (group A), 15 patients received traditional orbital floor reconstruction (group B). The contact area with buccal flap for titanium mesh in groups A and B was calculated. Titanium mesh deformation, fracture or exposure was recorded. Postoperative ophthalmic function and success of esthetic restoration were assessed.

Results

Mean follow-up was for 15.7 months (range, 9-22 months). The contact area with buccal flap for the modified titanium mesh in group A (13.11 ± 1.41 cm2) was significantly less than that of the traditional titanium mesh in group B (21.83 ± 1.23 cm2; p < .05). The exposure of titanium mesh occurred in two patients in group B. The self-evaluation of facial symmetry for 23 patients showed no significant difference between group A (7.75 ± 0.71) and group B (6.68 ± 1.30; p > .05). No specific complications were reported.

Conclusion

We propose a novel method of zygomatic medial fixation of titanium mesh with a right-angled screwdriver for orbital floor and maxillary reconstruction, which has the potential to prevent the postoperative exposure of titanium mesh.

Level of Evidence

Level III (Retrospective comparative study).

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.

Accuracy of intraoperative navigation for orbital fracture repair: A retrospective morphometric analysis

In this retrospective case series, patients undergoing surgery to treat isolated orbital floor fractures were morphometrically analyzed. Cloud Compare was used to compare mesh positioning with a virtual plan, using the distance-to-nearest-neighbor method. To assess the accuracy of mesh positioning, a mesh area percentage (MAP) parameter was introduced and three distance ranges were defined as the outcome measures: the 'high-accuracy range' included MAPs at a distance of 0-1 mm from the preoperative plan; the 'intermediate-accuracy range' included MAPs at a distance of 1.1-2 mm from the preoperative plan; the 'low-accuracy range' included MAPs at a distance of >2 mm from the preoperative plan. To complete the study, morphometric analysis of the results was combined with clinical judgment ('excellent', 'good', or 'poor') of mesh positioning by two independent blind observers. In total, 73 of 137 orbital fractures met the inclusion criteria. In the 'high-accuracy range' the mean, minimum, and maximum MAP values were 64%, 22%, and 90%, respectively. In the 'intermediate-accuracy range', the mean, minimum, and maximum values were 24%, 10%, and 42%, respectively. In the 'low-accuracy range', the values were 12%, 1%, and 48%, respectively. Both observers classified 24 cases of mesh positioning as 'excellent', 34 as 'good', and 12 as 'poor'. Within the limitations of the study, it seems that virtual surgical planning and intraoperative navigation has the potential to add quality to the repair of the orbital floor and, therefore, should be taken into consideration whenever appropriate.

Technical considerations of computer-aided planning in severe orbital trauma: A retrospective study

The aim of this study was to evaluate the clinical outcomes of linear and orbital volume measurements in severe orbital trauma. Patients with severe orbital trauma that involved more than two walls and entailed a marked degree of comminution were included in this retrospective analysis. However, patients with incomplete clinical records and a simple blowout or zygmatico-orbital fractures were excluded. All the cases underwent surgical correction guided by virtual surgical planning and 3D-printed templates. The measurement protocol depended on assessing orbital dimensions, orbital volumetry, and the zygomatic bone's position in the three-dimensional planes. All patients' preoperative 3D CT scans were obtained, and DICOM files were imported into a three-dimensional image processing software. Data were then converted for 3D reconstruction in the axial, coronal, and sagittal views. A total of 18 patients with a mean age was 39.28 ± 6.28 were included in this study. The results revealed a significant difference between the pre and postoperative differences in distances in relation to the FHP (Frankfurt Horizontal Plane) (P = 0.0014) and sagittal planes (P < 0.0001). The orbital width and height of the traumatized orbit were significantly decreased from 45.26 ± 6.72 mm and 45.30 ± 2.89 mm to 39.74 ± 3.91 mm (P = 0.0022), and 40.34 ± 0.86 mm (P < 0.0001), respectively. Clinically, there was a satisfactory degree of symmetry regarding the zygomatic bones' position and orbital dimensions postoperatively. Moreover, the mean orbital volume on the traumatized side decreased significantly from 23.16 ± 1.91 cm³ preoperatively to 20.7 ± 1.96 cm³ postoperatively (P < 0.0001). These findings were associated with a low incidence of complications. Within the limitations of the study it seems that the described methodology is a relevant addition to clinical treatment options. It incorporates all the latest technology to plan virtual reconstruction surgery in the treatment of complex orbital trauma and should be adapted accordingly in cases of severe displacement and comminution.

How Accurate Are Surgeons at Calculating Orbital Volumes?

PURPOSE

Bilateral orbital volume (OV) symmetry is imperative for successful orbital reconstruction to prevent complications such as enophthalmos, diplopia, and orbital dystopia. The purpose of this study was to determine the accuracy of surgeon-led in-house OV calculation for reconstructed orbits after orbital floor fracture.

MATERIALS AND METHODS

This is a retrospective cross-sectional observational study of maxillofacial computed tomography scans for patients undergone orbital fracture repair by Emory Oral and Maxillofacial service at Grady Memorial Hospital (Atlanta, Georgia) from 2018 to 2020.The primary predictor variable was OV calculation approach (outsourced vs surgeon-led in-house approach). The primary outcome variable was OV. Secondary variables were age, gender, and race. Interobserver reliability was calculated with a 2-way mixed-effects model, intraclass correlation coefficients, 95% confidence intervals, and P values. Differences between OV (in-house and outsourced) were calculated using student t-test. Statistical significance was determined at P < .05.

RESULTS

During the study period, 172 patients sustained orbital floor fracture. Of them, 49 patients (31 male, 18 females; 98 orbits) with the mean age of 41.3 years (range, 19 to 89 years) met inclusion criteria. Subjects with incomplete medical records and inadequate computed tomography scans were excluded from the study. The racial distribution in descending order was 87.8% African American, 8.2% Caucasian, 2% Hispanic, and 2% Asian. There was excellent inter-rater reliability for calculating uninjured OV (OV-U, P < .0001) and reconstructed OV (OV-R, P < .0001). The mean OV difference of outsourced approach was 0.8 cm3and for surgeon-led in-house approach was 0.07 cm3. There was no significant difference in OV difference between outsourced and in-house approach (P = .16).

CONCLUSIONS

In conclusion, using open-source 3-dimensional imaging software is a reliable and a predictable method at calculating reconstructed OV in patients who underwent open reduction and internal fixation of orbital fractures. By having this software in our personal computers and laptops, one can easily calculate OVs in an efficient manner.

Controversies and Contemporary Management of Orbital Floor Fractures

Substantial controversy exists regarding the timing of intervention and management of patients with orbital floor fractures. Recent advances in computer-aided technology, including the use of 3-dimensional printing, intraoperative navigational imaging, and the use of novel implants, have allowed for improvement in prospective management modalities. As such, this article aims to review the indications and timing of repair, surgical approaches, materials used for repair, and contemporary adjuncts to repair. Indications for orbital floor fracture repair remain controversial as many of these fractures heal without intervention or adverse sequelae. Intraoperative navigation and imaging, as well as endoscopic guidance, can improve visualization of defects mitigating implant positioning errors, thereby reducing the need for secondary corrective procedures. Patient-specific implants may be constructed to fit the individual patient's anatomy using the preoperative CT dataset and mirroring the contralateral unaffected side and have been shown to improve pre-operative efficiency and minimize postoperative complications. With increased data, we can hope to form evidence-based indications for using particular biomaterials and the criteria for orbital defect characteristics, which may be best addressed by a specific surgical approach.

Prospective Evaluation of Two Wall Orbital Fractures Involving the Medial Orbital Wall: PSI Reconstruction versus PDS Repair—Worth the Effort?

Proper treatment of the two-wall fractured orbit is still controversial. Specifically, there is no consensus on the issue of the necessity of medial orbital wall repair. With anatomically critical structures at risk during the surgical approach, surgeons’ view on the necessity of medial orbital wall repair often is restricted and an aesthetically disturbing enophthalmos is more likely to be accepted. Therefore, treatment options range from leaving the medial wall without repair to reconstruction with autogenous tissue or alloplastic materials, which can lead to moderate to severe side effects. However, emerging technologies such as patient-specific implants (PSI) offer a reliable and anatomically correct reconstruction of the bony orbit. This study aimed to evaluate the outcome of full orbital reconstruction using PSIs compared to only orbital floor repair using PDS (bioresorbable polydioxanone) foils leaving the medial orbital wall untouched in traumatic two-wall orbital fractures. Of all patients treated at the University Hospital of Düsseldorf between 2017 and 2019 who suffered from traumatic orbital fracture, only patients with a two-wall orbital fracture involving both the orbital floor and the medial wall (n = 68) were included. Patients were treated either with a PSI (n = 35) or a PDS foil (n = 33). Primary outcome parameters were ophthalmological disturbances analyzed via clinical investigation and intra-orbital angles, volumes and implant position analyzed with radiological 3D-datasets. While a two-wall reconstruction using PSIs led to a significant improvement of the enophthalmos, the rate of postoperative enophthalmos was significantly increased in cases of only orbital floor repair with PDS foils. Radiologically, a significant reconstruction of the three-dimensional bony orbit succeeded with the simple use of PSIs leading to a significant reduction in the traumatically enlarged orbital volume. PSI also led to a significant reduction in the traumatically enlarged medial angle of the orbit. This was not the case for single-floor repair with PDS foil. The results of this study suggest that complex orbital fractures can be reconstructed at an even higher degree of accuracy with selective laser-melted PSIs than PDS foils. In order to achieve a true to original reconstruction of the bony orbit, surgical treatment of the medial orbital wall can be advocated for in the long term depending on the indication.

Surgical Navigation in Mandibular Reconstruction: Accuracy Evaluation of an Innovative Protocol

Aim: the purpose of this work is to present an innovative protocol for virtual planning and surgical navigation in post-oncological mandibular reconstruction through fibula free flap. In order to analyze its applicability, an evaluation of accuracy for the surgical protocol has been performed. Methods: 21 patients surgically treated for mandibular neoplasm have been included in the analysis. The Brainlab Vector Vision 3.0^® software for surgical navigation has been used for preoperative surgical planning and intra-operative navigation. A post-operative accuracy evaluation has been performed matching the position of mandibular landmarks between pre-operative and post-operative CT scans. Results: the maximal discrepancy observed was included between −3.4 mm and +3.2 mm, assuming negative values for under correction and positive values for overcorrection. An average grade of accuracy included between 0.06 ± 0.58 mm and 0.43 ± 0.68 mm has been observed for every mandibular landmark examined, except for mandibular angles that showed a mean discrepancy value included between 1.36 ± 1.73 mm and 1.46 ± 1.02 mm when compared to preoperative measurements. Conclusion: a satisfying level of accuracy has been observed in the protocol presented, which appears to be more versatile if compared to closed custom-made systems. The technique described may represent a valid option for selected patients, but it cannot be considered for routine activity because of the complexity of the method, the mobility of the jaw, the necessity of surgical navigator and the long surgical learning curve that is required.

Is the Mirroring Technology Reliable in the Use of Computer-Aided Design for Orbital Reconstruction? Three-Dimensional Analysis of Asymmetry in the Orbits

BACKGROUND

Reconstruction of the orbital area remains a challenge in many cases. The recently introduced mirroring technology provides surgeons with patient-specific information for accurate orbital reconstruction; its premise is that the three-dimensional anatomy of craniofacial bone is symmetric. The purpose of this study was to verify this premise of the mirroring technology by assessing three-dimensional asymmetry.

METHODS

Facial computed tomographic data of 104 patients were imported into iPlan software. Four reference points (i.e., zygomaticofrontal suture, frontomaxillary suture, infraorbital foramen, and optic canal) were set, and the three-dimensional distances from these points to the anterior nasal spine on the mirroring plane were calculated. In addition, the orbital cavity volume and the three-dimensional distances from point optic canal to the other reference points were calculated for the assessment of the orbit anatomy. Three plastic surgeons performed these processes independently.

RESULTS

No statistically significant difference was found in the three-dimensional distances between anterior nasal spine and the four reference points bilaterally. Also, no statistically significant difference in the three-dimensional distances between the point representing the optic canal and other reference points was detected bilaterally. Orbital cavity volume showed a mild asymmetry, but the discrepancy was acceptable for computer-aided design applications. For all reference points, the maximum value of the 95 percent CI was less than 1.4 mm.

CONCLUSIONS

The three-dimensional location of the orbits and the three-dimensional anatomy of the orbit were symmetric. Thus, the mirroring technology could be a reliable first step in computer-aided design, computer-assisted surgery, and navigation-assisted surgery.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

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.

Do Racial Differences in Orbital Volume Influence the Reconstruction of Orbital Trauma

PURPOSE

Successful orbital reconstruction relies on an accurate restoration of orbital volume (OV). The purpose of this study was to determine if the OV of African American (AA) subjects differs from that of Caucasian subjects.

METHODS

The authors implemented a retrospective observational study of successive subjects who received a maxillofacial computed tomography (CT) scan at a level I trauma center between 2017 and 2020. The primary predictor variable was race (AA/Caucasian). The primary outcome variable was orbital volume. Two independent examiners calculated OV with an open access OsiriX MD software version 10.0.5 (Pixmeo, Switzerland). Inter-rater reliability was calculated. Differences between races, genders, and sides were tested using independent samples t test with a significance of P < .05.

RESULTS

Sixty subjects (120 orbits) were included in the study. The mean age was 36.7 (SD ± 13.2) years with a range of 22 to 78 years. Gender distribution was equal with 30 male (50%) and 30 female (50%) subjects. Inter-examiner reliability was 0.973. The mean OV of AA and Caucasians was 22.38 and 23.23 cm³, respectively (P = .07). The mean OV of AA and Caucasian males was 23.92, and 24.17cm³, respectively (P = .71). The mean OV in AA and Caucasian females was 20.84 and 22.28cm³, respectively (P = .013).

CONCLUSIONS

African-American female subjects appear to have a smaller OV when compared with Caucasians which may influence orbital reconstruction. Laterality does not appear to be associated with any differences in OV.

Virtual planning and navigation for targeted excision of intraorbital space-occupying lesions: proposal of a computer-guided protocol

The purpose of this study was to present an innovative approach for the preoperative assessment and intraoperative targeted excision of masses occupying the intraorbital space based on multimodal image fusion, segmentation, virtual models, digital planning, and navigation. Nineteen patients were studied and underwent surgery using the presented workflow, in both open and endoscopic procedures. Three main scenarios were standardized for the application of computer-guided surgery: single masses of the superior-lateral compartment, single masses of the inferior-medial compartment, and multifocal masses. An operative protocol was devised, and the accuracy of the osteotomies was analysed. All patients were managed successfully by applying the same protocol. No intraoperative complications were reported. The accuracy of the osteotomies was evaluated as a surrogate endpoint for the overall precision of surgery, showing average discrepancies of <1 mm for lateral marginotomies and <0.5 mm for endoscopic osteotomies. This study outlines an operative workflow for the implementation of virtual models to excise orbital masses, enhancing in-depth preoperative understanding of the anatomical relationships within the orbital space and increasing precision in both open and endoscopic approaches.

Navigation-Assisted Resection and Fibula Free-Flap Reconstruction of an Extensive Maxillary Tumor

OBJECTIVE

Tumor resection and reconstruction as a one-step procedure requires accurate definition of the intended safety margins, precise location of osteotomy lines and reliable individual rehabilitation.In recent years, the role of image-guided surgery in the maxillofacial region has increased significantly. As this technology allows the surgeon to track the actual position of each instrument during the operation in real-time, it makes it possible to perform extensive bone structure resections and reconstructions in anatomically distorted or complex areas, such as the head and neck region, without unnecessarily damaging vital structures.The authors described a case of a 26-year-old woman presented to our Clinic with an extensive maxillary squamous cell carcinoma involving the infratemporal fossa. The patient underwent single-step navigation-guided en bloc resection of the tumor and defect reconstruction.The aim of this study is describe and discuss the unusual surgical planning and the challenging operative technique adding a new case to the currently limited scientific literature on the computer-assisted head and neck oncologic surgery.

A retrospective study to compare the treatment outcomes with and without surgical navigation for fracture of the orbital wall

PURPOSE

To evaluate the outcomes with and without aid of a computer-assisted surgical navigation system (CASNS) for treatment of unilateral orbital wall fracture (OWF).

METHODS

Patients who came to our hospital for repairing unilateral traumatic OWF from 2014 to 2017 were included in this study. The patients were divided into the navigation group who accepted orbital wall reconstruction aided by CASNS and the conventional group. We evaluated the surgical precision in the navigation group by analyzing the difference between actual postoperative computed tomography data and preoperative virtual surgical plan through color order ratios. We also compared the duration of surgery, enophthalmos correction, restoration of orbital volumes, and improvement of clinical symptoms in both groups systemically. Quantitative data were presented as mean ± SD. Significance was determined by the two-sample t-test using SPSS Version 19.0 A p < 0.05 was considered statistically significant.

RESULTS

Seventy patients with unilateral OWF were included in the study cohort. The mean difference between preoperative virtual planning and actual reconstruction outcome was (0.869 ± 0.472) mm, which means the reconstruction result could match the navigation planning accurately. The mean duration of surgery in the navigation group was shorter than it is in the control group, but not significantly. Discrepancies between the reconstructed and unaffected orbital-cavity volume and eyeball projection in the navigation group were significantly less than that in the conventional group. One patient had remnant diplopia and two patients had enophthalmos after surgery in the navigation group; two patients had postoperative diplopia and four patients had postoperative enophthalmos in the conventional group.

CONCLUSION

Compare with the conventional treatment for OWF, the use of CASNS can provide a significantly better surgical precision, greater improvements in orbital-cavity volume and eyeball projection, and better clinical results, without increasing the duration of surgery.

Facial Reconstruction: A Systematic Review of Current Image Acquisition and Processing Techniques

Introduction: Plastic and reconstructive surgery is based on a culmination of technological advances, diverse techniques, creative adaptations and strategic planning. 3D imaging is a modality that encompasses several of these criteria while encouraging the others. Imaging techniques used in facial imaging come in many different modalities and sub-modalities which is imperative for such a complex area of the body; there is a clear clinical need for hyper-specialized practice. However, with this complexity comes variability and thus there will always be an element of bias in the choices made for imaging techniques. Aims and Objectives: The aim of this review is to systematically analyse the imaging techniques used in facial reconstruction and produce a comprehensive summary and comparison of imaging techniques currently available, including both traditional and novel methods. Methods: The systematic search was performed on EMBASE, PubMed, Scopus, Web of Science and Cochrane reviews using keywords such as "image technique/acquisition/processing," "3-Dimensional," "Facial," and "Reconstruction." The PRISMA guidelines were used to carry out the systematic review. Studies were then subsequently collected and collated; followed by a screening and exclusion process with a final full-text review for further clarification in regard to the selection criteria. A risk of bias assessment was also carried out on each study systematically using the respective tool in relation to the study in question. Results: From the initial 6,147 studies, 75 were deemed to fulfill all selection criteria and selected for meta-analysis. The majority of papers involved the use of computer tomography, though the use of magnetic resonance and handheld scanners using sonography have become more common in the field. The studies ranged in patient population, clinical indication. Seminal papers were highlighted within the group of papers for further analysis. Conclusions: There are clearly many factors that affect the choice of image acquisition techniques and their potential at being ideal for a given role. Ultimately the surgical team's choice will guide much of the decision, but it is crucial to be aware of not just the diagnostic ability of such modalities, but their treatment possibilities as well.

Assesing Intraoperative Virtual Navigation on My Craniofacial Surgery Fellowship for Orbital Fractures Repair: Is it Useful?

ABSTRACT

Orbital fractures pose specific challenge in its surgical management. One of the greatest challenges is to obtain satisfactory restoration of normal orbital volume and globe projection following traumatic injury, due to the inability of the surgeon to gain adequate visibility and to verify proper implant position and placement during the operation. Surgical navigation is a very helpful tool when dealing with the reconstruction of such orbital fractures. During the training of the craniofacial fellowship learning to recognize the orbital floor boundaries is essential for the correct implant placement for reconstruction, their identification is a critical step, which may be assisted by intraoperative virtual navigation. Six patients were surgically treated for orbital floor fracture with intraoperative virtual navigation. The clinical evaluation showed no complications such as enophtalmos, exophtalmos or dystopia in all the patients 2 months post operatively and a correct implant/graft position.During surgery, navigation provides exact determination of transverse, cranio-caudal and postero-anterior dimensions within the orbit and precise control of the position of implants/bone grafts.This tool aids consistently on the craniofacial surgery fellow's formation, as it facilitates the identification of the bony floor boundaries and verifies the correct placement of the implants/bone grafts. It is routinely use could help to avoid implants/bone grafts misplacement not only for craniofacial surgeon's fellow, but for all the orbital surgeons.

Feasibility of virtual surgical simulation in the head and neck region for soft tissue reconstruction using free flap: a comparison of preoperative and postoperative volume measurement

In the head and neck region, preoperative evaluation of the free flap volume is challenging. The current study validated preoperative three-dimensional (3D) virtual surgical simulation for soft tissue reconstruction by assessing flap volume and evaluated fat and muscle volume changes at follow-up in 13 head and neck cancer patients undergoing anterolateral craniofacial resection. Patients received 3D virtual surgical simulation, and the volume of the planned defects was estimated by surgical simulation. Following en bloc resection of the tumor, the defect in the skull base was covered using a rectus abdominis myocutaneous flap. Following surgery, computed tomography scans were acquired at day 1 and at 6 and 12 months. Virtual planned defect was on average 227 ml (range, 154-315) and was 10% smaller than the actual flap volume in patients without skin involvement of the tumor. Between day 1 and 12 months post-surgery, the volume of fat and muscle tissue in the free flap dropped by 9% and 58%, respectively. Our results indicate that 3D virtual surgical simulation provides essential information in determining the accurate volume of the required free flap for surgical defect repair and may thus help improve surgical planning and functional and esthetic outcome.

Intraoperative Navigation and Cone Beam Computed Tomography for Restoring Orbital Dimensions: A Single-Center Experience

Background

Correction of post-traumatic orbital defects remains a challenge for the maxillofacial surgeon. We examined the added value of combined intraoperative (IO) navigation and IO cone beam computed tomography (CBCT).

Materials and Methods

A retrospective cohort study was performed in all consecutive patients requiring unilateral post-traumatic orbital surgery between January 2012 and December 2018. Patients were divided into 3 groups: IO navigation (NAV), IO-CBCT (CBCT), and IO navigation with IO-CBCT (NAV-CBCT). A detailed description of our workflow is provided. Volumetric comparison of the operated orbit to the contralateral orbit was made with Brainlab.

Results

Of the 81 cases, 22 patients were included (12 males/10 females) with a mean age of 51 years. Three patients were assigned to NAV, 6 to CBCT, and 13 to NAV-CBCT. The reconstructed orbital volume did not significantly differ from the contralateral orbital volume within the 3 groups. The mean difference between the contralateral and the operated orbit was 3.05 cm³, 3.72 cm³, and 1.47 cm³ for NAV, CBCT, and NAV-CBCT, respectively, where only NAV-CBCT showed a significant smaller volumetric difference in comparison to CBCT alone. Gender or age did not correlate with difference in orbital volume. Normal function and aesthetics was seen at 6 weeks postoperative in 0 of 3, 6of 6, and 6 of 13 patients of the NAV, CBCT, and NAV-CBCT, respectively.

Conclusion

Orbital defects can be treated effectively using IO navigation. Although our data could not demonstrate a significant added value of IO-CBCT in cases where IO navigation was used based on volumetric difference alone, the combination of IO-CBCT and IO navigation seems to give the best results considering both volumetric difference and postoperative function and aesthetics. Confirmation in a prospective, randomized trial with a larger sample size is required.

[Use of navigation in skull base surgery]

The review briefly presents the history of development of navigation systems in neurosurgery. The idea of the existing principles underlying the navigation systems used in neurosurgery is given. Currently, the basic principles of navigation are optical and electromagnetic. Studies are presented comparing the accuracy of various navigation systems. Optical navigation demonstrates greater accuracy compared to electromagnetic, but both methods demonstrate a submillimeter error in the experiment. The history of use of navigation in the surgery of the skull base is analyzed in detail, the most relevant areas of use of navigation within the surgery of the skull base are considered: craniofacial reconstruction, endoscopic endonasal surgery, surgery of common tumors of the skull base affecting the infratemporal, pterygopalatine fossa, temporomandibular joint. Indications for the use of navigation, limitations of the methodology are explained.

Facial Transplantation for an Irreparable Central and Lower Face Injury: A Modernized Approach to a Classic Challenge

BACKGROUND

Facial transplantation introduced a paradigm shift in the reconstruction of extensive facial defects. Although the feasibility of the procedure is well established, new challenges face the field in its second decade.

METHODS

The authors' team has successfully treated patients with extensive thermal and ballistic facial injuries with allotransplantation. The authors further validate facial transplantation as a reconstructive solution for irreparable facial injuries. Following informed consent and institutional review board approval, a partial face and double jaw transplantation was performed in a 25-year-old man who sustained ballistic facial trauma. Extensive team preparations, thorough patient evaluation, preoperative diagnostic imaging, three-dimensional printing technology, intraoperative surgical navigation, and the use of dual induction immunosuppression contributed to the success of the procedure.

RESULTS

The procedure was performed on January 5 and 6, 2018, and lasted nearly 25 hours. The patient underwent hyoid and genioglossus advancement for floor-of-mouth dehiscence, and palate wound dehiscence repair on postoperative day 11. Open reduction and internal fixation of left mandibular nonunion were performed on postoperative day 108. Nearly 1 year postoperatively, the patient demonstrates excellent aesthetic outcomes, intelligible speech, and is tolerating an oral diet. He remains free from acute rejection.

CONCLUSIONS

The authors validate facial transplantation as the modern answer to the classic reconstructive challenge imposed by extensive facial defects resulting from ballistic injury. Relying on a multidisciplinary collaborative approach, coupled with innovative emerging technologies and immunosuppression protocols, can overcome significant challenges in facial transplantation and reinforce its position as the highest rung on the reconstructive ladder.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Implant-oriented navigation in orbital reconstruction part II: preclinical cadaver study

In orbital reconstruction, the acquired position of an orbital implant can be evaluated with the aid of intraoperative navigation. Feedback of the navigation system is only obtained after positioning of the implant: the implant's position is not tracked in real time during positioning. The surgeon has to interpret the navigation feedback and translate it to desired adjustments of the implant's position. In a previous study, a real-time implant-oriented navigation approach was introduced and the system's accuracy was evaluated. In this study, this real-time navigation approach was compared to a marker-based navigation approach in a preclinical set-up. Ten cadavers (20 orbital defects) were reconstructed twice, by two surgeons (total: 80 reconstructions). Implant positioning was significantly improved in the real-time implant-oriented approach in terms of roll (2.0° vs. 3.2°, P=0.03), yaw (2.2° vs. 3.4°, P=0.01) and translation (1.3mm vs. 1.8mm, P=0.005). Duration of the real-time navigation procedure was reduced (median 4.5 min vs. 7.5 min). Subjective appreciation of the navigation technique was higher for real-time implant-oriented navigation (mean 7.5 vs. 9.0). Real-time implant-oriented navigation feedback provides real-time, intuitive feedback to the surgeon, which leads to improved implant positioning and shortens duration of the navigation procedure.

Orbital floor symmetry after maxillectomy and orbital floor reconstruction with individual titanium mesh using computer-assisted navigation

PURPOSE

The present study aimed to evaluate the symmetry of the orbital floor after maxillectomy and orbital floor reconstruction with individual titanium mesh using a computer-assisted navigation system.

PATIENTS AND METHODS

Nineteen patients who underwent orbital floor reconstruction with individual titanium mesh were included in this study. Postoperative computed tomography scans recorded after three-dimensional (3D) reconstruction were used to evaluate the symmetry of the orbital floor, including orbital floor height, orbital floor eminence, globe projection, orbital volume, and surface deviation.

RESULTS

The average orbital floor height of the reconstructed and the unaffected side was 37.7 ± 2.3 and 37.8 ± 2.7 mm, respectively (P = .47). The average orbital floor eminence of the reconstructed and the unaffected side was 40.1 ± 5.5 and 39.6 ± 5.3 mm, respectively (P = .17). The average globe projection of the reconstructed and the unaffected side was 15.5 ± 3.2 and 15.3 ± 3.0 mm, respectively (P = .27). The average orbital volume of the reconstructed and the unaffected side was 25.9 ± 4.4 and 26.3 ± 4.4 cm³, respectively (P = .29). Repeatability between the reconstructed and the unaffected side was 88.3% ± 2.6% at within 1 mm and 98.6% ± 0.9% at within 2 mm. The average of maximum deviation was 2.4 ± 0.2 mm.

CONCLUSION

Individual titanium mesh is one of the best techniques for orbital floor reconstruction, as it can be placed precisely and helps achieve desirable esthetic outcomes through virtual surgical planning and using a computer-assisted navigation system.

Applications of three-dimensional printing in orbital diseases and disorders

PURPOSE OF REVIEW

To comprehensively review the applications of advanced three-dimensional printing technology in the management of orbital abnormalities.

RECENT FINDINGS

Three-dimensional printing has added value in the preoperative planning and manufacturing of patient-specific implants and surgical guides in the reconstruction of orbital trauma, congenital defects and tumor resection. In view of the costs and time, it is reserved as strategy for large and complex craniofacial cases, in particular those including the bony contour. There is anecdotal evidence of a benefit of three-dimensional printing in the manufacturing of prostheses for the exenterated and anophthalmic socket, and in the fabrication of patient-specific boluses, applicators and shielding devices for orbital radiation therapy. In addition, three-dimensional printed healthy and diseased orbits as phantom tangible models may augment the teaching and learning process of orbital surgery.

SUMMARY

Three-dimensional printing allows precision treatment tailored to the unique orbital anatomy of the patient. Advancement in technology and further research are required to support its wider use in orbital clinical practice.

Intraoperative Image-Guided Navigation in Craniofacial Surgery: Review and Grading of the Current Literature

INTRODUCTION

Image-guided navigation has existed for nearly 3 decades, but its adoption to craniofacial surgery has been slow. A systematic review of the literature was performed to assess the current status of navigation in craniofacial surgery.

METHODS

A Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) systematic review of the Medline and Web of Science databases was performed using a series of search terms related to Image-Guided Navigation and Craniofacial Surgery. Titles were then filtered for relevance and abstracts were reviewed for content. Single case reports were excluded as were animal, cadaver, and virtual data. Studies were categorized based on the type of study performed and graded using the Jadad scale and the Newcastle-Ottawa scales, when appropriate.

RESULTS

A total of 2030 titles were returned by our search criteria. Of these, 518 abstracts were reviewed, 208 full papers were evaluated, and 104 manuscripts were ultimately included in the study. A single randomized controlled trial was identified (Jadad score 3), and 12 studies were identified as being case control or case cohort studies (Average Newcastle-Ottawa score 6.8) The most common application of intraoperative surgical navigation cited was orbital surgery (n = 36), followed by maxillary surgery (n = 19). Higher quality studies more commonly pertained to the orbit (6/13), and consistently show improved results.

CONCLUSION

Image guided surgical navigation improves outcomes in orbital reconstruction. Although image guided navigation has promise in many aspects of craniofacial surgery, current literature is lacking and future studies addressing this paucity of data are needed before universal adoption can be recommended.

A Novel Noninvasive Patient-Specific Navigation Method for Orbital Reconstructive Surgery: A Phantom Study Using Patient Data

BACKGROUND

The correction of orbital deformities is an ongoing challenge in maxillofacial surgery. Computer-assisted navigation can improve surgical outcomes. However, conventional registration methods for navigation are not appropriate for orbital reconstructive surgery. This study proposes an accurate, noninvasive, patient-specific navigation method and demonstrates its feasibility.

METHODS

A noninvasive, patient-specific registration frame based on the external auditory canals and upper front teeth was designed using software developed in-house. A three-dimensional craniofacial model was segmented from patient computed tomographic data for the registration frame. A customized craniofacial phantom was also made using this three-dimensional model, with 20 embedded target points on the orbital model and 21 landmark points on the reference standard model. The proposed method was compared with two conventional registration methods: the dental splint-based method and the invasive marker frame-based method. Twenty trials were conducted for evaluation. Target registration error and surface registration error were computed to measure accuracy.

RESULTS

The proposed method showed a target registration error of 1.05 ± 0.52 mm, with greater accuracy than conventional methods (dental splint, 2.10 ± 0.63 mm; invasive marker frame, 1.22 ± 0.46 mm). The proposed method yielded the best results for surface registration error, with 0.38 mm of deviation (dental splint, 0.82 mm; invasive marker frame, 0.60 mm).

CONCLUSION

The proposed noninvasive patient-specific registration method demonstrated superior results for both target registration error and surface registration error compared with other conventional registration methods for computer-assisted navigation in orbital reconstructive surgery.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Three-dimensional orbital wall modeling using paranasal sinus segmentation

PURPOSE

Three-dimensional orbital wall modeling is a time-consuming process because of the presence of pseudoforamina. We developed an automated three-dimensional modeling software to characterize the orbital wall, and evaluated it using data from fracture patients.

METHODS

We first characterized the air and face regions using multiphase segmentation; the sinuses were segmented by applying morphological operations to air regions. Pseudoforamina of the orbital wall were offset with the segmented sinuses. Finally, the three-dimensional facial bone model, with orbital wall, was reconstructed from the segmented images.

RESULTS

Ten computed tomography data sets were used to evaluate the proposed method. Results were compared with those obtained using the active contour model and manual segmentation. The process took 31.7 ± 8.0 s, which was 30-60 times faster than other methods. The average distances between surfaces obtained with the proposed method and those obtained with manual segmentation (normal side: 0.20 ± 0.06 mm; fractured side: 0.28 ± 0.10 mm) were approximately half those obtained using the active contour model.

CONCLUSIONS

Three-dimensional orbital wall models, which were very similar to the manually segmented models, were archived within 1 min using the developed software, regardless of fracture presence. The proposed method might improve the safety and accuracy of surgical procedures.

A simple method to estimate the linear length of the orbital floor in complex orbital surgery

BACKGROUND

The orbital floor (OrF) and infraorbital rim (IOR) repair in cases of complete destruction is challenging mainly due to the fact that the defect length cannot be measured. The aim of the current study is to develop a method of calculating the Orf length by using the gender and the lengths of the medial, superior and lateral orbital walls (OrW) of the same orbit.

MATERIAL AND METHODS

Ninety-seven (59 male and 38 female) European adult dry skulls were classified according to age: 20-39, 40-59 and 60 years and above. The length of each OrW was measured by using the direct distance between the optic foramen and a landmark in each orbital rim.

RESULTS

A side asymmetry was detected for the lengths of the inferior, superior and medial OrW. Although a gender dimorphism was detected, no correlation with the age was found. Using the Stepwise multiple regression analysis two formulas were developed, one for the right and one for the left OrF with coefficient of determination R² 0.43 and 0.57, respectively.

CONCLUSIONS

The proposed formulas represent a simple, applicable and individualized method to calculate the OrF linear length in cases of complete destruction of the IOR and OrF, with accuracy and without the use of expertise material. Such data may improve the surgery planning of orbital floor fractures and complex orbital reconstructions.

Predictors of enophthalmos among adult patients with pure orbital blowout fractures

The aim of this study was to determine the predictors of post-traumatic enophthalmos (PE) in relation to the internal orbital changes following pure orbital blowout fractures. The design was a 10-year retrospective cross-sectional study analysing 629 medical records and computed tomography (CT) data of patients with orbital fractures from January 2008 to January 2017. Demographic, etiology, co-morbidity and clinical characteristics were obtained from the medical records. Assessment of the PE, fracture site and size, intraorbital structures and muscle change were performed using the Digital Imaging and Communications in Medicine (DICOM) viewer software, OsiriX v5.8.2. Of the 629 patients with orbital fractures, 87 were pure orbital blowout fractures. Demographic pattern showed that males outnumbered females in the series, with male: female ratio of 5.7:1. The mean age was 37.2 ± 14.7 and the main etiology was motor vehicle accident. Orbital floor fracture was the most common fracture location (67.8%). The involvement of the posterior ledge and inferior orbital fissure showed statistical significant difference with PE (Fisher's exact test, p = 0.03). Binary logistic regression showed that after controlling for age, patients with fracture size of more than 150 mm2 had three times the odds of sustaining a PE, (adjusted odds ratio (AOR) = 3.01 (95% CI 1.17-7.92). Fracture size larger than 150 mm2 was a radiological predictor of PE. Additional research investigating further on the role of concurrent fracture of the posterior ledge and inferior orbital fissure is advocated.

A novel approach to skull-base and orbital osteotomies through virtual planning and navigation

OBJECTIVE

Computer-assisted planning of osteotomy lines, coupled with navigation-guided performance of planned osteotomies, is a highly innovative approach to skull-base and orbital surgery. The aim of this pilot study is to provide an assessment of the accuracy of this novel approach in guiding the correct positioning of osteotomy lines in frontal, temporal, and orbital regions, defining the agreement between the spatial position of the planned and performed osteotomies.

METHODS

Fifteen patients with orbital, frontal sinus, and lateral skull-base diseases underwent virtual surgical planning. Osteotomies to access the orbit, frontal sinus, and lateral skull base were planned on computer tomography-based three-dimensional models. The planned osteotomies were reproduced on the operating field using a navigation system. The positions of the performed and planned osteotomies were compared. The results were described as the mean positional difference between planned and performed osteotomies and as Lin's concordance coefficient, and Bland-Altman limits of agreement were also defined.

RESULTS

The overall mean difference was 0.719 mm (95% confidence interval [CI]: 0.472 to 0.965 mm). Overall, Lin's concordance coefficient was 0.997 (95% CI: 0.996 to 0.998), and overall Bland-Altman limits of agreement ranged from -1.407 to 2.844 mm. The smallest mean difference (0.587 mm, 95% CI: 0.244 to 0.931 mm) was calculated in the orbit group, whereas the highest mean difference (0.904 mm, 95% CI: 0.428 to 1.379 mm) was described in the lateral skull-base group.

CONCLUSION

This study's results support the use of this novel planning and navigation protocol for guiding osteotomy in anterior and lateral skull-base surgery, providing a clinical validation of this technique.

LEVEL OF EVIDENCE

4 Laryngoscope, 00:1-9, 2018 Laryngoscope, 129:823-831, 2019.

Low-cost, self-made CAD/CAM-guiding system for mandibular reconstruction

Facial symmetry, as well as function, remains the big challenge for surgeons who attempt mandibular reconstruction. Nowadays several studies recommend the use of computer aided surgery (CAS) and CAD/CAM technology to guide mandibular segmental osteotomies and reconstruction using free fibula flap. Although these systems have radically changed the way of doing mandibular reconstructive surgery, they are expensive and require extended periods of time for prototypation. This may be an important limitation in case of malignant neoplasms which require short-term treatment. The aim of our study is to investigate the reliability and efficiency of a protocol to obtain cutting guides produced in a "homemade" way. This study includes four consecutive patients who underwent a segmental mandibulectomy and fibula osteo-cutaneous free flap reconstruction for oral squamous cell carcinoma between January and September 2016. The CAD/CAM system algorithm proposed was based on the use of free open source software for digital planning and 3D layer plastic deposition printer. A cost of about 3 Euro for each case was estimated. An average mean distance between 3D preoperative and postoperative mesh points of 1.631 mm and a standard deviation of 5.496 mm has been demonstrated by 3D volume overlay analysis. Overlapping results with much shorter prototyping time was required with the in-house procedure described as compared to the available commercial system. In conclusion, we expect that this technique will reduce operative time and cost however further study and large series are needed to confirm our results and better define the applicability in everyday surgical practice.

Should Virtual Mirroring Be Used in the Preoperative Planning of an Orbital Reconstruction?

PURPOSE

Mirroring has been used as a diagnostic tool in orbital wall fractures for many years, but limited research is available proving the assumed symmetry of orbits. The purpose of this study was to evaluate volume and contour differences between orbital cavities in healthy humans.

MATERIALS AND METHODS

In this cross-sectional study, the left and right orbital cavities of a consecutive sample of patients' computed tomograms were measured. Inclusion criteria were patients with no sign of orbital or sinus pathology or fracture. Outcome variables were differences in volume and contour. Descriptive statistics and Student paired t test were used for data analysis of orbital volume and distance maps were used for analysis of orbital contour.

RESULTS

The sample was composed of 100 patients with a mean age of 57; 50% were men. The total mean orbital volume was 27.53 ± 3.11 mL. Mean difference between cavities was 0.44 ± 0.31 mL or 1.59% (standard deviation [SD], 1.10%). The orbital contour showed high similarity, with an absolute mean left-versus-right difference of 0.82 mm (SD, 0.23 mm).

CONCLUSION

The authors hypothesize that the measured differences between right and left orbital volumes and contours are clinically minor. In consequence, the use of mirroring tools as part of preoperative planning in orbital reconstruction is legitimate with the aim of simulating the pre-traumatized anatomy.

The use of 3D-printed titanium mesh tray in treating complex comminuted mandibular fractures: A case report

RATIONALE

Precise bony reduction and reconstruction of optimal contour in treating comminuted mandibular fractures is very difficult using traditional techniques and devices. The aim of this report is to introduce our experiences in using virtual surgery and three-dimensional (3D) printing technique in treating this clinical challenge.

PATIENT CONCERNS

A 26-year-old man presented with severe trauma in the maxillofacial area due to fall from height.

DIAGNOSIS

Computed tomography images revealed middle face fractures and comminuted mandibular fracture including bilateral condyles.

INTERVENTIONS AND OUTCOMES

The computed tomography data was used to construct the 3D cranio-maxillofacial models; then the displaced bone fragments were virtually reduced. On the basis of the finalized model, a customized titanium mesh tray was designed and fabricated using selective laser melting technology. During the surgery, a submandibular approach was adopted to repair the mandibular fracture. The reduction and fixation were performed according to preoperative plan, the bone defects in the mental area were reconstructed with iliac bone graft. The 3D-printed mesh tray served as an intraoperative template and carrier of bone graft. The healing process was uneventful, and the patient was satisfied with the mandible contour.

LESSONS

Virtual surgical planning combined with 3D printing technology enables surgeon to visualize the reduction process preoperatively and guide intraoperative reduction, making the reduction less time consuming and more precise. 3D-printed titanium mesh tray can provide more satisfactory esthetic outcomes in treating complex comminuted mandibular fractures.

Surgical Navigation: A Systematic Review of Indications, Treatments, and Outcomes in Oral and Maxillofacial Surgery

PURPOSE

This systematic review investigates the most common indications, treatments, and outcomes of surgical navigation (SN) published from 2010 to 2015. The evolution of SN and its application in oral and maxillofacial surgery have rapidly developed over recent years, and therapeutic indications are discussed.

MATERIALS AND METHODS

A systematic search in relevant electronic databases, journals, and bibliographies of the included articles was carried out. Clinical studies with 5 or more patients published between 2010 and 2015 were included. Traumatology, orthognathic surgery, cancer and reconstruction surgery, skull-base surgery, and foreign body removal were the areas of interests.

RESULTS

The search generated 13 articles dealing with traumatology; 5, 6, 2, and 0 studies were found that dealt with the topics of orthognathic surgery, cancer and reconstruction surgery, skull-base surgery, and foreign body removal, respectively. The average technical system accuracy and intraoperative precision reported were less than 1 mm and 1 to 2 mm, respectively. In general, SN is reported to be a useful tool for surgical planning, execution, evaluation, and research. The largest numbers of studies and patients were identified in the field of traumatology. Treatment of complex orbital fractures was considerably improved by the use of SN compared with traditionally treated control groups.

CONCLUSIONS

SN seems to be a very promising addition to the surgical toolkit. Planning details of the surgical procedure in a 3-dimensional virtual environment and execution with real-time guidance can significantly improve precision. Among factors to be considered are the financial investments necessary and the learning curve.

Interactive navigation-guided ophthalmic plastic surgery: assessment of optical versus electromagnetic modes and role of dynamic reference frame location using navigation-enabled human skulls

AIM

The aim of this study was to assess the anatomical accuracy of navigation technology in localizing defined anatomic landmarks within the orbit with respect to type of technology (optical versus electromagnetic systems) and position of the dynamic reference marker on the skull (vertex, temporal, parietal, and mastoid) using in vitro navigation-enabled human skulls. The role of this model as a possible learning tool for anatomicoradiological correlations was also assessed.

METHODS

Computed tomography (CT) scans were performed on three cadaveric human skulls using the standard image-guidance acquisition protocols. Thirty-five anatomical landmarks were identified for stereotactic navigation using the image-guided StealthStation S7™ in both electromagnetic and optical modes. Three outcome measures studied were accuracy of anatomical localization and its repeatability, comparisons between the electromagnetic and optical modes in assessing radiological accuracy, and the efficacy of dynamic reference frame (DRF) at different locations on the skull.

RESULTS

The geometric localization of all the identified anatomical landmarks could be achieved accurately. The Cohen's kappa agreements between the surgeons were found to be perfect (kappa =0.941) at all predetermined points. There was no difference in anatomical localization between the optical and electromagnetic modes (P≤0.001). Precision for radiological identification did not differ with various positions of the DRF. Skulls with intact anatomical details and careful CT image acquisitions were found to be stereotactically useful.

CONCLUSION

Accuracy of anatomic localization within the orbit with navigation technology is equal with optical and electromagnetic system. The location of DRF does not affect the accuracy. Navigation-enabled skull models can be potentially useful as teaching tools for achieving the accurate radiological orientation of orbital and periorbital structures.

Orbital Osteoblastoma: Technical Innovations in Resection and Reconstruction Using Virtual Surgery Simulation

Osteoblastoma is a benign tumor of bone, representing less than 1% of bone tumors. Craniomaxillofacial localizations account for up to 15% of the total and frequently involve the posterior mandible. Endo-orbital localization is very rare, with most occurring in young patients. Very few of these tumors become malignant. Orbital localization requires radical removal of the tumor followed by careful surgical reconstruction of the orbit to avoid subsequent aesthetic or functional problems. Here, we present a clinical case of this condition and describe a surgical protocol that uses and integrates state-of-the art technologies to achieve orbital reconstruction.

Orbital reconstruction

PURPOSE OF REVIEW

Post-traumatic orbital reconstruction is a complex issue that involves both the soft tissue and bony injury. The current literature focuses primarily on bony reconstruction, with fewer investigators evaluating soft-tissue injuries. This article will review recent advances in orbital reconstruction, including presurgical planning software, intra-operative navigation, patient-specific implants, and intra-operative imaging.

RECENT FINDINGS

Traditional techniques for diagnosis and orbital injuries continue to be refined; however, advances in computer-aided surgery are allowing surgeons to significantly improve the anatomic accuracy of orbital reconstruction.

SUMMARY

While not all surgeons currently have access to computer-aided applications for orbital reconstruction, these techniques will continue to be refined, resulting in lower cost and greater access.

Quantitative Assessment of Orbital Implant Position--A Proof of Concept

Introduction

In orbital reconstruction, the optimal location of a predefined implant can be planned preoperatively. Surgical results can be assessed intraoperatively or postoperatively. A novel method for quantifying orbital implant position is introduced. The method measures predictability of implant placement: transformation parameters between planned and resulting implant position are quantified.

Methods

The method was tested on 3 human specimen heads. Computed Tomography scans were acquired at baseline with intact orbits (t0), after creation of the defect (t1) and postoperatively after reconstruction of the defect using a preformed implant (t2). Prior to reconstruction, the optimal implant position was planned on the t0 and t1 scans. Postoperatively, the planned and realized implant position were compared. The t0 and t2 scans were fused using iPlan software and the resulting implant was segmented in the fused t2 scan. An implant reference frame was created (Orbital Implant Positioning Frame); the planned implant was transformed to the reference position using an Iterative Closest Point approach. The segmentation of the resulting implant was also registered on the reference position, yielding rotational (pitch, yaw, roll) as well as translational parameters of implant position.

Results

Measurement with the Orbital Implant Positioning Frame proved feasible on all three specimen. The positional outcome provided more thorough and accurate insight in resulting implant position than could be gathered from distance measurements alone. Observer-related errors were abolished from the process, since the method is largely automatic.

Conclusion

A novel method of quantifying surgical outcome in orbital reconstructive surgery was presented. The presented Orbital Implant Positioning Frame assessed all parameters involved in implant displacement. The method proved to be viable on three human specimen heads. Clinically, the method could provide direct feedback intraoperatively and could improve postoperative evaluation of orbital reconstructive surgery.