Verification of clinical precision after computer-aided reconstruction in craniomaxillofacial surgery

Virtual reconstruction of orbital defects using Gaussian process morphable models

PURPOSE

The conventional method to reconstruct the bone level for orbital defects, which is based on mirroring and manual adaptation, is time-consuming and the accuracy highly depends on the expertise of the clinical engineer. The aim of this study is to propose and evaluate an automated reconstruction method utilizing a Gaussian process morphable model (GPMM).

METHODS

Sixty-five Computed Tomography (CT) scans of healthy midfaces were used to create a GPMM that can model shape variations of the orbital region. Parameter optimization was performed by evaluating several quantitative metrics inspired on the shape modeling literature, e.g. generalization and specificity. The reconstruction error was estimated by reconstructing artificial defects created in orbits from fifteen CT scans that were not included in the GPMM. The developed algorithms utilize the existing framework of Gaussian process morphable models, as implemented in the Scalismo software.

RESULTS

By evaluating the proposed quality metrics, adequate parameters are chosen for non-rigid registration and reconstruction. The resulting median reconstruction error using the GPMM was lower (0.35 ± 0.16 mm) compared to the mirroring method (0.52 ± 0.18 mm). In addition, the GPMM-based reconstruction is automated and can be applied to large bilateral defects with a median reconstruction error of 0.39 ± 0.11 mm.

CONCLUSION

The GPMM-based reconstruction proves to be less time-consuming and more accurate than reconstruction by mirroring. Further validation through clinical studies on patients with orbital defects is warranted. Nevertheless, the results underscore the potential of GPMM-based reconstruction as a promising alternative for designing patient-specific implants.

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.

Surgical Navigation and CAD-CAM-Designed PEEK Prosthesis for the Surgical Treatment of Facial Intraosseous Vascular Anomalies

Background: Intraosseous vascular anomalies in the facial skeleton present significant diagnostic and therapeutic challenges due to complex anatomy. These anomalies represent about 0.5-1% of bony neoplastic and tumor-like lesions, usually presenting as a firm, painless mass. Most described intraosseous vascular malformations are venous malformations (VMs) and, more rarely, arteriovenous malformations. Objectives: The objectives of this work are to show our experience, protocol and the applications of computer planning, virtual surgery, CAD-CAM design, surgical navigation, and computer-assisted navigated piezoelectric surgery in the treatment of facial intraosseous vascular anomalies and to evaluate the advantages and disadvantages. Methods: Three females and one male with periorbital intraosseous vascular anomalies were treated using en-block resection and immediate reconstruction with a custom-made PEEK prosthesis. One lesion was in the supraorbital rim and orbital roof, one in the frontal bone and orbital roof, and two in the zygomatic region. We accomplished the resection and reconstruction of the lesion using virtual planning, CAD-CAM design, surgical navigation and piezoelectric device navigation. Results: There were no complications related to the surgery assisted with navigation. With an accuracy of less than 1 mm, the procedure may be carried out in accordance with the surgical plan. The surgeon's degree of uncertainty during deep osteotomies and in locations with low visibility was decreased by the use of the navigated piezoelectric device. Conclusions: Resection and reconstruction of facial intraosseous vascular anomalies benefit from this new surgical strategy using CAD-CAM technologies, computer-assisted navigated piezoelectric surgery, and surgical navigation.

Does facial asymmetry vary between subjects of different age groups? A 3D stereophotogrammetry analysis

This study was aimed to assess whether facial asymmetry increases with age and to examine potential gender differences using 3D stereophotogrammetry. A prospective cross-sectional study was performed. 3D photographs were acquired from 600 control subjects, 300 male, 300 female, and were stratified into 15 different age groups ranging from 0 to 70+. The 3D photographs were postprocessed and mirrored. The original and mirrored faces were surface-based matched using an iterative closest point algorithm. The primary outcome variable, facial asymmetry, was evaluated by calculating the absolute mean distance between the original and mirrored images. The primary predictor was age. Pearson's correlation was used to assess the correlation between facial asymmetry and age. The average overall facial asymmetry was 0.72 mm (SD 0.72 mm; range 0.25 - 3.04 mm). Mean facial asymmetry increased significantly with age, from 0.45 mm in the age group of 0-4 years to 0.98 mm in the age group of 70+ (p<0.001). Facial asymmetry was positively correlated with age (Pearson's r = 0.55; p<0.001). Male subjects were significantly more asymmetric compared to females, 0.77 mm and 0.67 mm, respectively (p<0.001). This study indicates that facial asymmetry significantly increases with age and is significantly larger in males than in females.

Insights into Orbital Symmetry: A Comprehensive Retrospective Study of 372 Computed Tomography Scans

Background: The operation planning and production of individualized implants with the help of AI-based software after orbital fractures have become increasingly important in recent years. This retrospective study aimed to investigate the healthy orbitae of 372 patients from CT images in the bone and soft tissue windows using the Disior™ Bonelogic™ CMF Orbital software. (version 2.1.28). Methods: We analyzed the variables orbital volume, length, and area as a function of age and gender and compared bone and soft tissue windows. Results: For all variables, the intraclass correlation showed excellent agreement between the bone and soft tissue windows (p < 0.001). All variables showed higher values when calculated based on bone fenestration with, on average, 1 mL more volume, 0.35 mm more length, and 0.71 cm2 more area (p < 0.001). Across all age groups, men displayed higher values than women with, on average, 8.1 mL larger volume, a 4.78 mm longer orbit, and an 8.5 cm2 larger orbital area (p < 0.001). There was also a non-significant trend in all variables and both sexes toward growth with increasing age. Conclusions: These results mean that, due to the symmetry of the orbits in both the bone and soft tissue windows, the healthy orbit can be mirrored for surgical planning in the event of a fracture.

Accuracy of Orbital Shape Reconstruction-Comparative Analysis of Errors in Implant Shape Versus Implant Positioning: A Cadaveric Study

INTRODUCTION

Orbital blowout fractures are commonly reconstructed with implants shaped to repair orbital cavity defects, restore ocular position and projection, and correct diplopia. Orbital implant shaping has traditionally been performed manually by surgeons, with more recent use of computer-assisted design (CAD). Accuracy of implant placement is also key to reconstruction. This study compares the placement accuracy of orbital implants, testing the hypothesis that CAD-shaped implants indexed to patient anatomy will better restore orbit geometry compared with manually shaped implants and manually placed implants.

METHODS

The placement accuracy of orbital implants was assessed within a cadaveric blowout fracture model (3 skulls, 6 orbits) via 3-dimensional CT analysis. Defects were repaired with 4 different techniques: manually placed-manually shaped composite (titanium-reinforced porous polyethylene), manually placed CAD composite, indexed placed CAD composite, and indexed placed CAD titanium mesh.

RESULTS

Implant placement accuracy differed significantly with the implant preparation method ( P =0.01). Indexing significantly improved the placement accuracy ( P =0.002). Indexed placed titanium mesh CAD implants (1.42±0.33 mm) were positioned significantly closer to the intact surface versus manually placed-manually shaped composite implants (2.12±0.39 mm).

DISCUSSION

Computer-assisted design implants indexed to patient geometry yielded average errors below the acceptable threshold (2 mm) for enophthalmos and diplopia. This study highlights the importance of adequately indexing CAD-designed implants to patient geometry to ensure accurate orbital reconstructions.

Modeling Methods in Craniofacial Virtual Surgical Planning

Despite the widespread use of virtual surgical planning (VSP), few papers describe the modeling methods used to generate the digital simulations that underpin VSP. This paper aims to review the modeling methods that are currently available for use in VSP and the implications of their use in clinical practice. A literature review was undertaken of the two broad categories of modeling techniques; contour-based planning-namely mirroring from the contralateral side, templating from a normative database, and extrapolation from surrounding landmarks-and occlusal-based planning (OBP). The indications for each modeling method were discussed, including mandibular/maxillary reconstruction, pediatric craniofacial surgery, and orthognathic, as well as the limitations to the accuracy of modeling types. Unilateral defects of the upper/midface, wherein contour accuracy is paramount, are best reconstructed using mirroring methods, whereas bilateral defects-or cases with asymmetry due to craniofacial dysmorphology-are most suited to normative-data-based methods. Cases involving resection of the alveolar margin, in which functional occlusion is the primary outcome are best managed with OBP. Similarly, orthognathic surgery typically uses OBP, although complex cases involving asymmetry, such as clefts, may benefit from a combination of OBP and normative data methods. The choice of modeling methods is, therefore, largely driven by the defect type and the goals of reconstruction.

Increased Reliability in Medial Canthal Tendon Reposition in Nasoorbitoethmoidal Fractures with Computer-assisted Surgery and Surgical Navigation

Avulsion of the medial canthal tendon secondary to nasoorbitoethmoidal fractures leads to severe aesthetic and functional impairments. The tendon should be repositioned at the posterior lacrimal crest. Owing to the complexity of nasoorbitoethmoidal fractures, accurate location of this point during surgery can be challenging. With the aid of computer-assisted planning and surgical navigation, the point at which the medial canthal tendon should be repositioned can be easily and precisely located. We have developed an innovative navigation-assisted technique that increases the reliability and safety of internal canthus repositioning. We performed a case series of three consecutive patients who underwent medial canthal tendon repositioning using computer-assisted planning and surgical navigation. We believe that this innovation provides a new and useful application of computer-assisted planning and surgical navigation in craniomaxillofacial surgery.

Effect of the number and distribution of fiducial markers on the accuracy of robot-guided implant surgery in edentulous mandibular arches: An in vitro study

OBJECTIVES

Robot-guided implant placement based on the screw marker-assisted registration technique has been applied in dentistry. This study aimed to identify the optimal number and distribution of fiducial markers for robot-guided implant placement in edentulous mandibular phantoms.

METHODS

Four implants were digitally planned and placed in edentulous mandibular phantoms under robotic guidance. Different numbers of fiducial markers (3, 4, 5, or 6) and distribution patterns (dispersed or localized) were used to register the robotic system. Platform, apex, and angular deviations were measured between the planned and actual implant positions using different numbers and distributions of fiducial markers.

RESULTS

Inserting six fiducial markers resulted in optimal implant position accuracy at the platform (0.53 ± 0.19 mm) and apex (0.59 ± 0.2 mm) deviations. However, the angular deviation did not differ significantly between different numbers of fiducial markers. Furthermore, the implant position accuracy did not differ significantly between the dispersed and localized distributions of fiducial markers.

CONCLUSION

In robot-guided implant placement for edentulous mandibular arches, the insertion of six fiducial markers significantly increases the implant placement accuracy.

CLINICAL SIGNIFICANCE

The findings of this in vitro study may serve as a reference for clinicians to determine the optimal placement of fiducial markers and to facilitate the clinical application of robot-guided systems for implant placement in edentulous patients. Further clinical studies are necessary to confirm these findings.

Three-dimensional Quantitative Standards for Assessing Outcomes of Facial Lipotransfer: A Review

BACKGROUND

Reliable quantitative data are required to address the unpredictability of facial autologous fat grafting (AFG). Facial evaluation by 3D scanning technology is getting popular. However, this process lacks unified standards and the reliability assessments. This study aimed to summarize a set of standards to improve the 3D quantified reliability of AFG outcomes.

METHODS

A systematic review was used to collect the differences in and limitations of 3D assessments and analyze the effect of the quantification process on the AFG outcomes. Healthy subjects undergoing only one facial structural AFG and 3D assessments were included. The revealed specific issues guided the subsequent narrative review that involves 3D measurement and fat volume retention rate (FVRR) analysis. Criteria were formulated based on the narrative review.

RESULTS

The systematic review revealed the quantitative process to be operator-dependent. The intra-group FVRR in the postoperative 11+ month group varied significantly (P=.03). The review identified a set of 3D measurement standards, including two optimal software products, two necessary steps for preprocessing, and four testing criteria. We proposed a new calculation formula and parameter and recommended a segmental area analysis for assessing the outcomes of full-face fat grafting.

CONCLUSIONS

As far as the 3D evaluation of AFG outcomes is concerned, this is the first study to comprehensively analyze the process and set quantitative criteria. These standards would not only guide future research more reliably, but also provide fresh insight into the review of the past research. 3D measurement standards also apply to all face-related studies requiring 3D registration.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

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.

Accuracy of virtual planning and intraoperative navigation in zygomaticomaxillary complex fractures: A systematic review

OBJECTIVE

This systematic review aims to investigate the effect of virtual planning on the treatment of zygomaticomaxillary complex (ZMC) traumatology followed by intraoperative navigation. Furthermore, clinical outcomes following intraoperative navigation surgery or conventional surgery will be compared.

MATERIALS AND METHODS

A systematic literature search was conducted in PubMed, Embase, Web-of-Science, and Cochrane on January 1st, 2022. Inclusion criteria were articles using preoperative three-dimensional (3D) virtual planning combined with intraoperative navigation or comparing these 3D methods with conventional methods. Furthermore, at least one of the following outcomes needed to be included in the article: technical accuracy of the procedure, preoperative planning time, operative time, number of fixation points, patient satisfaction, complications, or total costs of the intervention.

RESULTS

Following the screening of 4478 articles, 17 were included. Five articles appeared to indicate a significantly better technical linear accuracy, one article reported better accuracy for rotation and two articles showed better accuracy in restoring orbital volume when using navigation. Nine articles investigated operative time with varying results. Seven articles calculated the additional costs, of which three concluded no extra cost while the others indicated high additional costs or questionable cost-effectiveness.

CONCLUSION

Virtual planning and intraoperative navigation technologies have the potential to assist maxillofacial trauma surgeons in reducing ZMC fractures significantly more accurately and restoring the facial contour in a less invasive manner at an acceptable cost.

REGISTRATION

The protocol for this systematic review (CRD42020216717) was registered in the International Prospective Register of Systematic Reviews (PROSPERO).

Outcome and Quality of Life after Individual Computer-AssistedReconstruction of the Midface

Often, midfacial defects are not only relevant regarding functional aspects but also esthetics of such congenital or acquired deformities impair significantly the patients' quality of life. Reconstructions of the midface do not only include replacing lost or non-developed tissue but moreover to achieve predictable results with regard to esthetics as well as function for the individual patient. Digital planning modalities including different surface and volume data in combination with modern additive manufacturing techniques for biomodel and implant production and intraoperative support by using real and virtual 3D volume data for navigation and intraoperative imaging, but also securing the outcome based on postoperative analysis have been implemented in modern midface reconstruction and represent new standards for medical care. The objective of this paper is to describe modern options of patient-specific midfacial reconstruction with integration of computer-assisted planning and production techniques.

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.

Advances in the Resection and Reconstruction of Midfacial Tumors Through Computer Assisted Surgery

Curatively intended oncologic surgery is based on a residual-free tumor excision. Since decades, the surgeon’s goal of R0-resection has led to radical resections in the anatomical region of the midface because of the three-dimensionally complex anatomy where aesthetically and functionally crucial structures are in close relation. In some cases, this implied aggressive overtreatment with loss of the eye globe. In contrast, undertreatment followed by repeated re-resections can also not be an option. Therefore, the evaluation of the true three-dimensional tumor extent and the intraoperative availability of this information seem critical for a precise, yet substance-sparing tumor removal. Computer assisted surgery (CAS) can provide the framework in this context. The present study evaluated the beneficial use of CAS in the treatment of midfacial tumors with special regard to tumor resection and reconstruction. Therefore, 60 patients diagnosed with a malignancy of the upper jaw has been treated, 31 with the use of CAS and 29 conventionally. Comparison of the two groups showed a higher rate of residual-free resections in cases of CAS application. Furthermore, we demonstrate the use of navigated specimen taking called tumor mapping. This procedure enables the transparent, yet precise documentation of three-dimensional tumor borders which paves the way to a more feasible interdisciplinary exchange leading e.g. to a much more focused radiation therapy. Moreover, we evaluated the possibilities of primary midface reconstructions seizing CAS, especially in cases of infiltrated orbital floors. These cases needed reduction of intra-orbital volume due to the tissue loss after resection which could be precisely achieved by CAS. These benefits of CAS in midface reconstruction found expression in positive changes in quality of life. The present work was able to demonstrate that the area of oncological surgery of the midface is a prime example of interface optimization based on the sensible use of computer assistance. The fact that the system makes the patient transparent for the surgeon and the procedure controllable facilitates a more precise and safer treatment oriented to a better outcome.

Virtual reconstruction of orbital floor defects using a statistical shape model

PURPOSE

The current standard in reconstructing defects of the orbital floor, by using the concept of mirroring, is time-consuming and ignores the natural asymmetry of the skull. By using a statistical shape model (SSM), the reconstruction can be automatized and improved in accuracy. The present study aims to show the possibilities of the virtual reconstruction of artificial defects of the orbital floor using an SSM and its potentials for clinical implementation.

METHODS

Based on 131 unaffected CT scans of the midface, an SSM was created which contained the shape variability of the orbital floor. Nineteen midface CT scans, that were not included in the SSM, were manually segmented to establish ground truth (control group). Then artificial defects of larger and smaller sizes were created and reconstructed using SSM (Group I) and the gold standard of mirroring (Group II). Eventually, a comparison to the surface of the manual segmentation (control group) was performed.

RESULTS

The proposed method of reconstruction using an SSM leads to more precise reconstruction results, compared with the conventional method of mirroring. Whereas mirroring led to the reconstruction errors of 0.7 mm for small defects and 0.73 mm for large defects, reconstruction using SSM led to deviations of 0.26 mm (small defect) and, respectively, 0.34 mm (large defect).

CONCLUSIONS

The presented approach is an effective and accurate method for reconstructing the orbital floor. In connection with modern computer-aided design and manufacturing, individual patient-specific implants could be produced according to SSM-based reconstructions and could replace current methods using manual bending techniques. By acknowledging the natural asymmetry of the human skull, the SSM-based approach achieves higher accuracy in reconstructing injured orbits.

The Volume Difference Along the External Surface of the Zygomatic Bone: A Novel Method of Measuring Zygomatic Bone Asymmetry

ABSTRACT

This study introduced the volume difference along the external surface (VDAES) of the zygomatic bone as a novel approach to assess zygomatic bone asymmetry and was the first to describe a distinctive, 4-step method of measuring it. VDAES has a potential to be used as an objective tool to evaluate dislocation and can assist surgeons in predicting risks of long-term cosmetic complications in patients with zygomaticomaxillary complex fractures. After having measured 100 healthy study participants, the observed median VDAES was 1.48 cm3 for all study participants, 2.02 cm3 for males, and 1.09 cm3 for females, with the gender difference being significant (P = 0.003). Additional studies are needed to test the hypothesis of whether VDAES is more relevant than conventional methods of clinically evaluating zygomatic bone asymmetry.

Thickness accuracy of virtually designed patient-specific implants for large neurocranial defects

The combination of computer‐aided design (CAD) techniques based on computed tomography (CT) data to generate patient‐specific implants is in use for decades. However, persisting disadvantages are complicated design procedures and rigid reconstruction protocols, for example, for tailored implants mimicking the patient‐specific thickness distribution of missing cranial bone. In this study we used two different approaches, CAD‐ versus thin‐plate spline (TPS)‐based implants, to reconstruct extensive unilateral and bilateral cranial defects in three clinical cases. We used CT data of three complete human crania that were virtually damaged according to the missing regions in the clinical cases. In total, we carried out 132 virtual reconstructions and quantified accuracy from the original to the generated implant and deviations in the resulting implant thickness as root‐mean‐square error (RMSE). Reconstructions using TPS showed an RMSE of 0.08–0.18 mm in relation to geometric accuracy. CAD‐based implants showed an RMSE of 0.50–1.25 mm. RMSE in relation to implant thickness was between 0.63 and 0.70 mm (TPS) while values for CAD‐based implants were significantly higher (0.63–1.67 mm). While both approaches provide implants showing a high accuracy, the TPS‐based approach additionally provides implants that accurately reproduce the patient‐specific thickness distribution of the affected cranial region.

Fifteen-Year Review of the American Board of Plastic Surgery Maintenance of Certification Tracer Data: Clinical Practice Patterns and Evidence-Based Medicine in Zygomatico-Orbital Fractures

BACKGROUND

From 2005 to 2020, the American Board of Plastic Surgery collected data on 20 common plastic surgery operations as part of the Maintenance of Certification process. These data allow the authors to examine national trends in zygomatico-orbital fracture repair over a 15-year period.

METHODS

Tracer data for zygomatico-orbital fracture repair were reviewed in cohorts from 2005 to 2013 and 2014 to 2020. Results were categorized based on their presence in evidence-based medicine articles published during this period. Differences between years were assessed using the t test or chi-square test as appropriate.

RESULTS

Four hundred thirty patients were included as of March of 2020. Average age was 37 years (range, 6 to 85 years), and 76 percent were male. Operations took place on average 10 days from injury. There were significant decreases in the use of subciliary (31.9 percent versus 10.0 percent; p < 0.001), gingival buccal (84.3 percent versus 56.4 percent; p < 0.001), and lateral brow (45.2 percent versus 22.3 percent; p < 0.001) incisions, with an increase in lower lid external incisions (15.2 percent versus 30.9 percent; p < 0.001); 2.7 percent of patients had a complication requiring readmission and 4.5 percent required reoperation. The incidence of postoperative diplopia was 7.7 percent, and the infection rate was 1.7 percent.

CONCLUSIONS

This article reviews the American Board of Plastic Surgery tracer data for zygomatico-orbital fracture repair. The Maintenance of Certification tracer data provide a national database with longer follow-up and more specific information than comparable databases. Analysis of these data over time enables the authors to describe practice trends and gives surgeons the opportunity to compare their outcomes to national norms.

Does the choice of the reference model affect the results of 3D-3D superimposition procedure? A comparison of different protocols for personal identification

In literature, 3D-3D superimposition has been widely recognized as a valid method for personal identification. However, very little information is available about possible variability due to differences in protocols of registration of 3D models and calculation of RMS (root mean square) point-to-point distance. Frontal sinuses from 50 CT scans were segmented twice through the ITK-SNAP software and grouped in two samples (1 and 2). Maximum breadth, height and volume were measured. 3D models belonging to the same subject were then superimposed one on each other in 50 matches. In addition, superimposition of 50 random mismatches was performed. For each superimposition, the procedure was repeated four times choosing different reference models both for registration and calculation of RMS. Differences in RMS value among protocols of registration and RMS calculation were assessed through paired Student's t-test (p < 0.05). Possible correlations between differences in RMS among groups and differences in frontal sinus size between the superimposed models were analysed through calculation of Pearson's correlation coefficient (p < 0.05). Results showed that RMS calculation did not yield significant differences according to which 3D model is used as reference; on the other hand, RMS values from registration procedure significantly differ according to which model is chosen as reference, but only in the mismatch group (p < 0.001). Differences in RMS value according to RMS calculation are dependent upon all the three measurements, whereas differences according to registration protocols were significantly related only with the breadth of frontal sinuses but only in mismatches (p < 0.001). In no case, superimpositions of RMS values were found between matches and mismatches. This article for the first time proves that the protocol of registration and calculation of RMS significantly influences the results of 3D-3D superimposition only in case of mismatches.

Evaluation of facial asymmetry by stereophotogrammetry in individuals with unilateral maxillary impacted canine

PURPOSE

The aim of this study is to compare the symmetry of the facial and dentoalveolar structures of patients with unilateral impacted maxillary canine teeth with a control group of individuals without impacted teeth using three-dimensional face scans.

METHODS

The study included 28 patients (10 females, 18 males) with unilateral impacted maxillary canine teeth and 28 patients (15 females, 13 males) without any impacted maxillary canine between 12 and 25 years of age. The 3dMDface™ (3dMD Inc., Atlanta, GA, USA) imaging system was used to obtain 3D face images. 3dMD Vultus® (3dMD Inc., Atlanta, GA, USA) software was used for the measurements.

RESULTS

According to the study findings, there were differences in linear measurements and volume measurements between the right and left sides of the face in patients with an impacted canine. However, these differences were not statistically significant. In patients with an impacted canine, surface differences between the right and left halves of the face were not found to be statistically different from the control group.

CONCLUSION

There was no difference in the amount of facial asymmetry between patients with unilateral maxillary impacted canine and patients with normal tooth alignment in the control group.

Reproducibility of 3D scanning in the periorbital region

The reproducibility of scanning in the periorbital region with 3D technology to enable objective evaluations of surgical treatment in the periorbital region was assessed. Facial 3D-scans of 15 volunteers were captured at different time points with a handheld Artec Space Spider structured light scanner. Two scans were made with a one minute interval and repeated after 1 year; for both a natural head position and with the head in a fixation-device. On assessing the area between the eyelashes and eyebrows, the medians of the average deviations between the various cross-sections of the one minute interval 3D-scans ranged from 0.17 to 0.21 mm at baseline, and from 0.10 to 0.11 mm when the minute-interval scanning was repeated one year later. The systematic differences when scanning in a natural head position and fixated position were comparable. The reproducibility of the 3D processing was excellent (intraclass correlation coefficient > 0.9). The repeated scanning deviations (baseline versus one year data) were well within the accepted clinical threshold of 1 mm. Scanning with a hand-held 3D-scanning device (Artec Space Spider) is a promising tool to assess changes in the periorbital region following surgical treatment since the median deviations are well below the clinically accepted 1 mm measuring error, for both the natural head and fixated positions.

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.

Reliability of orbital volume measurements based on computed tomography segmentation: Validation of different algorithms in orbital trauma patients

PURPOSE

To compare the most common methods of segmentation for evaluation of the bony orbit in orbital trauma patients.

MATERIALS AND METHODS

Computed tomography scans (before and after treatment) from 15 patients with unilateral blowout fractures and who underwent orbital reconstructions were randomly selected for this study. Orbital volume measurements, volume difference measurements, prolapsed soft tissue volumes, and bony defect areas were made using manual, semi-automated, and automated segmentation methods.

RESULTS

Volume difference values between intact and damaged orbits after surgery using the manual mode were 0.5 ± 0.3 cm³, 0.5 ± 0.4 cm³ applying semi-automated method, and 0.76 ± 0.5 cm³, determined by automated segmentation (р = 0.216); the mean volumes (MVs) for prolapsed tissues were 3.0 ± 1.9 cm³, 3.0 ± 2.3 cm³, and 2.8 ± 3.9 cm³ (p = 0.152); and orbital wall defect areas were 4.7 ± 2.8 cm², 4.75 ± 3.1 cm², and 4.9 ± 3.3 cm² (p = 0.674), respectively.

CONCLUSIONS

The analyzed segmentation methods had the same accuracy in evaluation of volume differences between two orbits of the same patient, defect areas, and prolapsed soft tissue volumes but not in absolute values of the orbital volume due to the existing diversity in determination of anterior closing. The automated method is recommended for common clinical cases, as it is less time-consuming with high precision and reproducibility.

Virtual Surgical Planning for Successful Second-Stage Mandibular Defect Reconstruction Using Vascularized Iliac Crest Bone Flap: A Valid and Reliable Method

PURPOSE

Second-stage reconstruction of mandibular defects faces problems of anatomic disorder and bone displacement due to tumor resection. As a newer technique, virtual surgical planning (VSP) may help to increase the accuracy and efficiency of the complicated reconstruction. This study aims to evaluate the application of VSP and splint-guided surgery in second-stage mandibular reconstruction using vascularized iliac crest bone flap.

METHODS

Between October 2016 and February 2018, 5 patients (3 men and 2 women) with mandibular defects of duration between 8 months and 8 years underwent VSP-aided secondary reconstruction in the School and Hospital of Stomatology of Wuhan University (Wuhan, China). Virtual surgical planning was performed and serial guiding splints were printed to replicate the design into the actual operation. The linear and 3-dimensional deviations after surgery were analyzed. Patient complications and feedback were recorded during follow up.

RESULTS

All 5 patients underwent successful reconstruction using vascularized iliac crest bone flap. No serious donor sites or recipient site complications were observed after 10- to 28-month follow-up. In comparison with the presurgery designs, the linear deviations in coronal plane were 2.7 ± 0.4 mm (range, -2.2 to 3.9 mm) in measurements from the condylar head to the condylar head and 0.70 ± 0.6 mm (range, -0.1 to 1.7 mm) from the gonial angle to the gonial angle, and that in sagittal plane was 2.4 ± 0.88 mm (range, -3 to 4.4 mm) from the anterior inferior mandibular border to the center point on the condylar head to the condylar head line. The whole 3-dimensional deviation was 1.2 ± 1.7 mm in all patients.

CONCLUSION

Well-designed splints can assist in precise mandibular reconstruction with high efficiency and accuracy, and thus are a reliable method for complicated second-stage mandibular reconstruction. However, to achieve a better outcome, a satisfactory design is required to adapt the complicated and varied defect.

Validation of a low-cost portable 3-dimensional face scanner

Purpose

The goal of this study was to assess the accuracy and reliability of a low-cost portable scanner (Scanify) for imaging facial casts compared to a previously validated portable digital stereophotogrammetry device (Vectra H1). This in vitro study was performed using 2 facial casts obtained by recording impressions of the authors, at King's College London Academic Centre of Reconstructive Science.

Materials and Methods

The casts were marked with anthropometric landmarks, then digitised using Scanify and Vectra H1. Computed tomography (CT) scans of the same casts were performed to verify the validation of Vectra H1. The 3-dimensional (3D) images acquired with each device were compared using linear measurements and 3D surface analysis software.

Results

Overall, 91% of the linear Scanify measurements were within 1 mm of the corresponding reference values. The mean overall surface difference between the Scanify and Vectra images was <0.3 mm. Significant differences were detected in depth measurements. Merging multiple Scanify images produced significantly greater registration error.

Conclusion

Scanify is a very low-cost device that could have clinical applications for facial imaging if imaging errors could be corrected by a future software update or hardware revision.

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.

Natural variation of the zygomaticomaxillary complex symmetry in normal individuals

OBJECTIVE

The study aim was to investigate variations in the symmetry of the zygomaticomaxillary complex (ZMC) in normal individuals.

METHOD

Computed tomography datasets of 200 individuals without facial fractures were analyzed using a validated three-dimensional analysis technique. The absolute average distance (AD) and 90th percentile distance (NPD) were calculated, representing respectively the overall and maximum symmetry between bilateral ZMCs.

RESULTS

The mean AD and NPD of the total study group was 0.9 ± 0.3 mm (95% CI 0.3-2.3) and 1.7 ± 0.5 mm (95% CI 0.5-3.9), respectively. The mean AD and NPD in males were 1.0 ± 0.3 mm (95% CI 0.28-2.34) and 1.9 ± 0.5 mm (95% CI 0.5-3.9) versus 0.8 ± 0.3 mm (95% CI 0.4-1.7) and 1.6 ± 0.5 mm (95% CI 0.8-2.9), respectively, for females. A statistically significant difference between male and female was found for both AD and NPD (p < 0.01). The male population <40 years had a mean AD and NPD of 1.0 ± 0.3 mm and 1.8 ± 0.5 mm, which was not statistically significant when compared with males >40 years.

CONCLUSION

The naturally occurring anatomic variation in ZMC symmetry described in this study is proposed as a benchmark for evaluating the amount of preoperative displacement and postoperative reduction of ZMC in trauma cases.

Clinical outcomes for minimally invasive primary and secondary orbital reconstruction using an advanced synergistic combination of navigation and endoscopy

BACKGROUND

Sequelae of inadequate orbital reconstruction include enophthalmos, hypoglobus, and diplopia. Accuracy of orbital reconstruction is largely subjective and especially difficult to achieve because of anatomic distortion in secondary or late reconstruction and in extensive injury. We combined computer navigation and endoscopy to perform accurate, aesthetic, and safe minimal-access primary and secondary orbital reconstruction.

METHODS

From 2013 to 2014, 24 patients underwent unilateral primary and secondary or late minimally invasive orbital reconstruction with mainly Medpor and/or titanium mesh by navigation and endoscopic assistance through transantral, transconjunctival, or upper blepharoplasty approaches. Mean follow-up was 13.8 months (range, 6.2 months to 2.8 years).

RESULTS

All orbital fractures were successfully reduced. Average enophthalmos among patients who underwent early reconstruction, late reconstruction, and multiorbital wall repair improved (p < .001) to 0.2 mm from 1.6, 2.6, and 2.6 mm, respectively. Hypoglobus and diplopia resolved in all. In early reconstruction patients, mean interorbital volume difference improved from 1.72 ± 0.87 to 0.53 ± 0.83 ml (P = .03). For late reconstruction patients, this difference improved from 3.41 ± 1.23 to 0.56 ± 0.96 ml (p < .001). There were no major complications during follow-up, and all were satisfied with their final appearance and function.

CONCLUSION

Navigation sharpens reconstructive accuracy and avoids injury to vital structures. Combined with endoscopic assistance for minimal-access reconstruction of wide-ranging orbital defects from primary to secondary or late cases and to extensive multiwall fractures, navigation facilitates minimal cosmetic incision and synergistic endoscope use and clearly optimizes aesthetic and functional outcomes, all with enhanced safety and unparalleled intraoperative visualization.

Secondary reconstruction of maxillofacial trauma

PURPOSE OF REVIEW

Craniomaxillofacial trauma is one of the most complex clinical conditions in contemporary maxillofacial surgery. Vital structures and possible functional and esthetic sequelae are important considerations following this type of trauma and intervention. Despite the best efforts of the primary surgery, there are a group of patients that will have poor outcomes requiring secondary reconstruction to restore form and function. The purpose of this study is to review current concepts on secondary reconstruction to the maxillofacial complex.

RECENT FINDINGS

The evaluation of a posttraumatic patient for a secondary reconstruction must include an assessment of the different subunits of the upper face, middle face, and lower face. Virtual surgical planning and surgical guides represent the most important innovations in secondary reconstruction over the past few years. Intraoperative navigational surgery/computed-assisted navigation is used in complex cases. Facial asymmetry can be corrected or significantly improved by segmentation of the computerized tomography dataset and mirroring of the unaffected side by means of virtual surgical planning. Navigational surgery/computed-assisted navigation allows for a more precise surgical correction when secondary reconstruction involves the replacement of extensive anatomical areas. The use of technology can result in custom-made replacements and prebent plates, which are more stable and resistant to fracture because of metal fatigue.

SUMMARY

Careful perioperative evaluation is the key to positive outcomes of secondary reconstruction after trauma. The advent of technological tools has played a capital role in helping the surgical team perform a given treatment plan in a more precise and predictable manner.

Systematic analysis on the efficacy of bone enhancement methods used for success in dental implants

Bone grafting is beneficial in enhancing bones that are lost due to trauma or natural or pathologic process. Autogenous bone, allogenic bone, xenogeneic bone, bone substitutes, and alloplasts can also be used for this purpose. Bone quantity should be adequate for the placement of implants, which necessitate the use of bone grafts before implant placement.

OBJECTIVE

This review analyses the different bone graft materials that are used for grafting around implants and evaluate if these grafts yield successful implant osseointegration over a period of time.

MATERIALS AND METHODS

The MEDLINE-PubMed database was searched from September 2016 to 10 years previously. Several journals were hand searched and from cross-references. The primary outcome measure that was analyzed was the survival rate of dental implants in the grafted sites at 6 months-1 year, and the secondary outcomes were success rates of dental implants over a period of 3-5 years' follow-up.

RESULTS

The search yielded 213 articles. Ultimately, 31 studies meeting the eligibility criteria were selected. The analysis shows that autologous bone grafts can be preferred over allografts and xenografts for grafting implant sites, which showed less complication and high success rate.

CONCLUSION

Based on the available data in the current existing studies with a follow-up period of at least 3-5 years, it can be summarized that the autologous bone grafts can be preferred over allografts and xenografts for grafting implant sites since they are stable for at least 3-5 years.

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.

Proceedings of the American Association of Oral and Maxillofacial Surgeons 2015 Research Summit

The Fifth Biennial Research Summit of the American Association of Oral and Maxillofacial Surgeons and its Committee on Research Planning and Technology Assessment was held in Rosemont, Illinois on May 6 and 7, 2015. The goal of the symposium is to provide a forum for the most recent clinical and scientific advances to be brought to the specialty. The proceedings of the events of that summit are presented in this report.

Surgical approach to isolated bilateral orbital floor fractures

Isolated bilateral orbital floor fractures are uncommon and are rarely described in the scientific literature. They are usually seen in association with naso-ethmoidal fractures, zygomatic fractures, or fractures of the middle third. We report our experience in the management of a patient presenting bilateral isolated orbital floor fracture. The difficulties in management of these fractures are due to the lack of an uninjured contralateral side for intraoperative comparison.