Computed tomography-based virtual fracture reduction techniques in bimandibular fractures

Mandibular reconstruction after post-traumatic complex fracture: Comparison analysis between traditional and virtually planned surgery

BACKGROUND

Jaw reconstruction after complex post-traumatic fracture is still a challenge for surgeons using traditional surgery. Virtual surgical planning has proven to be a valid tool for managing these fractures. The aim of this study is to quantitatively evaluate the VSP effectiveness compared to traditional surgery in the management of complex mandibular fractures.

METHODS

30 patients with diagnosis of complex mandibular fracture were enrolled and divided in two groups: Group A (virtually planned surgery), The plate was pre-modeled and employed during the surgery; Group B (traditional surgery), the plate was shaped directly during the surgery. Virtually planned and post-operative Computer Tomography were after compared for both the groups to highlight discrepancies in mm.

RESULTS

Fracture surgical reduction was successful without intraoperative complications. In Group A, all the mean discrepancies' values were <1 mm while in Group B the values were included between 1.36 and 1.94 mm. The mean operative time was 69 min for Group A, while 106 min for Group B.

CONCLUSIONS

Fracture virtual reduction and realization of pre-modeled plate are able to guarantee a more anatomically correct reduction and a decrease in operating times. These outcomes translate into a decrease in both short and long-term complications.

Digital technology revolutionizing mandibular fracture treatment: a comparative analysis of patient-specific plates and conventional titanium plates

OBJECTIVES

The treatment of fractures prioritizes the restoration of functionality through the realignment of fractured segments. Conventional methods, such as titanium plates, have been employed for this purpose; however, certain limitations have been observed, leading to the development of patient-specific plates. Furthermore, recent advancements in digital technology in dentistry enable the creation of virtual models and simulations of surgical procedures. The aim was to assess the clinical effectiveness of patient-specific plates utilizing digital technology in treating mandibular fractures compared to conventional titanium plates.

MATERIALS AND METHODS

Twenty patients diagnosed with mandibular fractures were included and randomly assigned to either the study or control groups. The surgical procedure comprised reduction and internal fixation utilizing patient-specific plates generated through virtual surgery planning with digital models for the study group, while the control group underwent the same procedure with conventional titanium plates. Assessment criteria included the presence of malunion, infection, sensory disturbance, subjective occlusal disturbance and occlusal force in functional maximum intercuspation (MICP). Statistical analysis involved using the Chi-square test and one-way repeated measures analysis of variance.

RESULTS

All parameters showed no statistically significant differences between the study and control groups, except for the enhancement in occlusal force in functional MICP, where a statistically significant difference was observed (p = 0.000).

CONCLUSION

Using patient-specific plates using digital technology has demonstrated clinical effectiveness in treating mandibular fractures, offering advantages of time efficiency and benefits for less experienced surgeons.

CLINICAL RELEVANCE

Patient-specific plates combined with digital technology can be clinically effective in mandibular fracture treatment.

A Proof of Concept: Optimized Jawbone-Reduction Model for Mandibular Fracture Surgery

Previous research on computer-assisted jawbone reduction for mandibular fracture surgery has only focused on the relationship between fractured sections disregarding proper dental occlusion with the maxilla. To overcome malocclusion caused by overlooking dental articulation, this study aims to provide a model for jawbone reduction based on dental occlusion. After dental landmarks and fracture sectional features are extracted, the maxilla and two mandible segments are aligned first using the extracted dental landmarks. A swarm-based optimization is subsequently performed by simultaneously observing the fracture section fitting and the dental occlusion condition. The proposed method was evaluated using jawbone data of 12 subjects with simulated and real mandibular fractures. Results showed that the optimized model achieved both accurate jawbone reduction and desired dental occlusion, which may not be possible by existing methods.

Three-dimensional measurements of symmetry for the mandibular ramus

BACKGROUND

The study examines a sample of patients presenting for viscerocranial computer tomography that does not display any apparent signs of asymmetry, assesses the three-dimensional congruency of the mandibular ramus, and focuses on differences in age and gender.

METHODS

This cross-sectional cohort study screened viscerocranial CT data of patients without deformation or developmental anomalies. Segmentations were obtained from the left and right sides and superimposed according to the best-fit alignment. Comparisons were made to evaluate three-dimensional congruency and compared between subgroups according to age and gender.

RESULTS

Two hundred and sixty-eight patients were screened, and one hundred patients met the inclusion criteria. There were no statistical differences between the left and right sides of the mandibular ramus. Also, there were no differences between the subgroups. The overall root mean square was 0.75 ± 0.15 mm, and the mean absolute distance from the mean was 0.54 ± 0.10 mm.

CONCLUSION

The mean difference was less than one millimetre, far below the two-millimetre distance described in the literature that defines relative symmetry. Our study population displays a high degree of three-dimensional congruency. Our findings help to understand that there is sufficient three-dimensional congruency of the mandibular ramus, thus contributing to facilitating CAD-CAM-based procedures based on symmetry for this specific anatomic structure.

An automatic reduction method of 3D bone fragments based on a novel section contour point descriptor

Comminuted fractures are orthopedic traumas with greater surgical difficulty. In clinical treatment, a great challenge is precise reduction of multiple broken bone fragments; Another great challenge is personalized and precise internal fixation after reduction. For these two issues, we designed an automated method framework for precise reduction and internal fixation of comminuted fractures. First, the Gaussian mixture model (GMM) is used to distinguish section points and noise points in a broken bone model; Second, ellipse fitting is carried out to achieve section points matching and a descriptor is proposed to describe the section features; Then, the Convolution Auto-Encoder (CAE) and genetic algorithm are used to extract feature vectors; Finally, after broken bone models registration, internal fixed plate can be reconstructed. Three verification experiments for comminuted bone fracture show this method has high accuracy and good efficiency. It can provide support for minimally invasive treatment for comminuted fractures.

Classification of unusual fracture patterns of the mandible: A retrospective study

The aim of this study is to devise and summarize a classification of fracture patterns involving multiple anatomical sites of the mandible. A retrospective study was conducted by reviewing clinical case records, imaging records, and the surgical management of patients presenting with mandibular fracture. Demographic data were collected and causes of the fractures were studied. Following radiological evaluations based on the courses of fracture lines, these fractures were categorized into three components: horizontal (H), vertical (V), and sagittal (S). In case of horizontal components, the mandibular canal was used as a reference. For vertical components, the fracture lines were classified according to where they terminated. With sagittal components, the direction of the bicortical split at the base of mandible was used as a reference. Out of a total of 893 mandibular trauma patients, 30 unusual fractures were identified (21 in males and nine in females), which do not fit into existing classifications. These were mainly due to road traffic accidents. Horizontal components of fractures were classified as H-I, H-II, and H-III, and vertical components as V-I, V-II, and V-III. For sagittal components, two types were identified - S-I and S-II - resulting in a bicortical split of the mandible. This classification is proposed to help understanding the complex fractures and to allow standardized communication among clinicians. Moreover, it is designed in such a way that aids in the choice of fixation technique. Further studies are needed to establish standardized treatment algorithms for efficient management of these unusual fractures.

Mandibular fracture repair techniques in cats: a dentist's perspective

PRACTICAL RELEVANCE

Feline head trauma injuries are common in general practice, often resulting in mandibular fracture. An understanding of the recent advances in the field of mandibular fracture repair will facilitate evidence-based decision-making in clinical practice.

CLINICAL CHALLENGES

Feline maxillofacial and oral anatomy brings unique challenges in comparison with dogs. It has been commonplace to adapt techniques and equipment that are better suited to other body regions or are species-inappropriate for use in feline maxillofacial surgery, and this has traditionally resulted in high morbidity.

AIMS

This review presents an overview of the diagnosis of, and decison-making for, maxillofacial trauma in cats, specifically with reference to the feline mandible. The challenges associated with the management of these injuries are presented. Techniques for repair that can be employed in general practice, as well as more advanced surgical options, are discussed, as well as the indications for invasive vs non-invasive management. Underutilised methods involving composite dental materials and their versatility for the repair of mandibular fractures in cats, and miniplates for caudal mandibular fractures in cats, are specifically covered, as well as other recent advances in the field, including three-dimensional printing and custom-printed implants.

EVIDENCE BASE

Management of feline facial fractures is an often neglected topic, with very few published studies choosing to focus on head trauma outcomes in cats. Where available, however, this review draws on the published literature, as well as the authors' own clinical experience.

Computer-assisted preoperative planning of bone fracture fixation surgery: A state-of-the-art review

Background: Bone fracture fixation surgery is one of the most commonly performed surgical procedures in the orthopedic field. However, fracture healing complications occur frequently, and the choice of the most optimal surgical approach often remains challenging. In the last years, computational tools have been developed with the aim to assist preoperative planning procedures of bone fracture fixation surgery. Objectives: The aims of this review are 1) to provide a comprehensive overview of the state-of-the-art in computer-assisted preoperative planning of bone fracture fixation surgery, 2) to assess the clinical feasibility of the existing virtual planning approaches, and 3) to assess their clinical efficacy in terms of clinical outcomes as compared to conventional planning methods. Methods: A literature search was performed in the MEDLINE-PubMed, Ovid-EMBASE, Ovid-EMCARE, Web of Science, and Cochrane libraries to identify articles reporting on the clinical use of computer-assisted preoperative planning of bone fracture fixation. Results: 79 articles were included to provide an overview of the state-of-the art in virtual planning. While patient-specific geometrical model construction, virtual bone fracture reduction, and virtual fixation planning are routinely applied in virtual planning, biomechanical analysis is rarely included in the planning framework. 21 of the included studies were used to assess the feasibility and efficacy of computer-assisted planning methods. The reported total mean planning duration ranged from 22 to 258 min in different studies. Computer-assisted planning resulted in reduced operation time (Standardized Mean Difference (SMD): -2.19; 95% Confidence Interval (CI): -2.87, -1.50), less blood loss (SMD: -1.99; 95% CI: -2.75, -1.24), decreased frequency of fluoroscopy (SMD: -2.18; 95% CI: -2.74, -1.61), shortened fracture healing times (SMD: -0.51; 95% CI: -0.97, -0.05) and less postoperative complications (Risk Ratio (RR): 0.64, 95% CI: 0.46, 0.90). No significant differences were found in hospitalization duration. Some studies reported improvements in reduction quality and functional outcomes but these results were not pooled for meta-analysis, since the reported outcome measures were too heterogeneous. Conclusion: Current computer-assisted planning approaches are feasible to be used in clinical practice and have been shown to improve clinical outcomes. Including biomechanical analysis into the framework has the potential to further improve clinical outcome.

Primary reconstruction of combined orbital and zygomatic complex fractures with patient-specific milled titanium implants - A retrospective study

The aim of this retrospective study was to compare mid-facial symmetry and clinical outcomes between patients treated with patient-specific and standard implants in primary fracture reconstructions of combined orbital and zygomaticomaxillary complex fractures. Patients who underwent primary reconstruction of orbital and zygomaticomaxillary complex fractures during the study period were identified and background and clinical variables and computed tomography images were collected from patient records. Zygomaticomaxillary complex dislocation and orbital volume were measured from pre- and postoperative images and compared between groups. Out of 165 primary orbital reconstructions, eight patients treated with patient-specific and 12 patients treated with standard implants were identified with mean follow-up time of was 110 days and 121 days, respectively. Postoperative orbital volume difference was similar between groups (0.2 ml for patient-specific vs 0.3 ml for standard implants, p = 0.942) despite larger preoperative difference in patient-specific implant group (2.1 ml vs 1,5 ml, p = 0.428), although no statistical differences were obtained in symmetricity or accuracy between the reconstruction groups. Within the limitations of the study it seems that patient-specific implants are a viable option for primary reconstructions of combined zygomaticomaxillary complex and orbital fractures, because with patient-specific implants at least as symmetrical results as with standard implants can be obtained in a single surgery.

Clinical Application of Digital Joint Guide in the Fracture of the Condyle Neck

PURPOSE

The purpose of this study is to use a digital guide plate for joint positioning to assist the reduction of condylar neck fractures and evaluate the accuracy of the reduction after surgery.

MATERIALS AND METHODS

In this study, 20 patients were selected from January 2016 to October 2020, and the reduction of the mandibular condyle neck fracture was designed virtual and digital based on the computed tomography data of the patients, based on the position of the condyle in the articular socket, the height of the ascending mandibular ramus, and the joints. The average value of the anterior space and the posterior space of the joint is these indicators, the position of the condyle is reconstructed, and the fracture reduction finger guide plate is designed. During the operation, the digital guide plate is used to assist the reduction of the condyle neck fracture. The postoperative follow-up was 4 to 12 months to check the accuracy of the reduction.

RESULTS

A total of 20 patients, all fractures achieved complete bone healing, the patients' mouth opening was normal, no obvious complications were found, and none of the patients had facial paralysis. In the postoperative evaluation and preoperative virtual design plan, the chromatographic error was within 2 mm, and the magnetic resonance of the temporomandibular joint showed no displacement of the articular disc.

CONCLUSION

The digital joint guide can reduce the fracture of the condyle neck while ensuring the position of the condyle in the joint socket, which is beneficial to reduce the occurrence of subsequent temporomandibular joint complications.

Virtual surgical planning is a useful tool in the surgical management of mandibular condylar fractures

PURPOSE

The aim of this study is to evaluate the application value of virtual surgical planning in the management of mandibular condylar fractures and to provide a reliable reference.

METHODS

This was a prospective randomized controlled study and recruited 50 patients requiring surgical treatment for their mandibular condylar fractures. The inclusion criteria were patients (1) diagnosed with a condylar fracture by two clinically experienced doctors and required surgical treatment; (2) have given consent for the surgical treatment; and (3) had no contraindications to the surgery. Patients were excluded from this study if: (1) they were diagnosed with a non-dislocated or only slightly dislocated condylar fracture; (2) the comminuted condylar fracture was too severe to be treated with internal reduction and fixation; or (3) patients could not complete follow-up for 3 months. There were 33 male and 17 female patients with 33 unilateral condylar fractures and 17 bilateral condylar fractures included. The 50 patients were randomly (random number) divided into control group (25 patients with 35 sides of condylar fractures) and experimental group (25 patients with 32 sides of condylar fractures). Virtual surgical planning was used in the experimental group, but only clinical experience was used in the control group. The patients were followed up for 1, 3, 6 and 12 months after operation. Variables including the rate of perfect reduction by radiological analysis, the average distance of deviation between preoperative and postoperative CT measurements using Geomagic software and postoperative clinical examinations (e.g., mouth opening, occlusion) were investigated for outcome measurement. SPSS 19 was adopted for data analysis.

RESULTS

The average operation time was 180.60 min in the experimental group and 223.2 min in the control group. One week postoperatively, CT images showed that the anatomic reduction rate was 90.63% (29/32) in the experimental group and 68.57% (24/35) in the control group, revealing significant difference (X² = 4.919, p = 0.027). Geomagic comparative analysis revealed that the average distance of deviation was also much smaller in the experimental group than that in the control group (0.639 mm vs. 0.995 mm; t = 3.824, p < 0.001).

CONCLUSION

These findings suggest that virtual surgical planning can assist surgeons in surgical procedures, reduce operative time, and improve the anatomic reduction rate & accuracy, and thus of value in the diagnosis and treatment of condylar fractures.

Short-Segment Drilling Guides for the Management Comminuted Mandibular Fractures

ABSTRACT

Treatment of a severely comminuted mandibular fracture is challenging. This technical note describes a novel office-based workflow, combining virtual surgery planning with short-segment drilling guides. The authors reduced the comminuted mandibular fractures via virtual surgery planning. Then, the reconstructed mandible model was printed using an in-house 3D printer. Next, the reconstruction plate was preformed according to the shape of the mandibular model surface, and the position of the screw hole in the mandibular surface was determined. Finally, hand-made short-segment drilling guides for screw position transfer were fabricated with temporary resin. During the operation, the authors reset the guides for the drill to make screw holes as planned. After the hole was drilled, the pre-bent plate was applied to the mandible. The fracture was expected to be reduced, when tightening the screws. In our workflow, by using short and simple operative procedures, the authors were able to achieve precise reduction and reduce the operation time.

Analyzing the Fitting of Novel Preformed Osteosynthesis Plates for the Reduction and Fixation of Mandibular Fractures

Purpose: The known preformed osteosynthesis plates for the midface are helpful tools for a precise and fast fixation of repositioned fractures. The purpose of the current study is to analyze the precision of newly developed prototypes of preformed osteosynthesis plates for the mandible. Methods: Four newly designed preformed osteosynthesis plates, generated by a statistical shape model based on 115 CT scans, were virtually analyzed. The used plates were designed for symphyseal, parasymphyseal, angle, and condyle fractures. Each type of plate has three different sizes. For analysis, the shortest distance between the plate and the bone surface was measured, and the sum of the plate-to-bone distances over the whole surface was calculated. Results: A distance between plate and bone of less than 1.5 mm was defined as sufficient fitting. The plate for symphyseal fractures showed good fitting in 90% of the cases for size M, and in 84% for size L. For parasymphyseal fractures, size S fits in 80%, size M in 68%, and size L in 65% of the cases. Angle fractures with their specific plate show good fitting for size S in 53%, size M in 60%, and size L in 47%. The preformed plate for the condyle part fits for size S in 75%, for size M in 85%, and for size L in 74% of the cases. Conclusion: The newly developed mandible plates show sufficient clinical fitting to ensure adequate fracture reduction and fixation.

Computer-Aided Surgical Simulation in Severe Atrophic Mandibular Fractures: A New Method for Guided Reduction and Temporary Stabilization Before Fixation

In severe atrophic mandibular fractures, the absence of stable occlusion, as well as poor bone volume at the fracture site, constitutes a lack of references during surgery to achieve accurate fracture reduction. Unsuccessful reduction and stabilization can lead to several complications, such as fracture misalignments, malunion, and facial asymmetry. An alternative to avoid the aforementioned issues is fracture reduction based on virtual surgical planning (VSP) technology. However, there is little information regarding VSP protocols for the management of mandible fractures. Herein, a new technique with low cost is reported in which VSP and computer-aided manufacturing of a positioning guide were applied in a 72-year-old female patient with bilateral fractures in her atrophic mandible in the body region. The positioning guide was used during fracture reduction on the inferior surface of the mandible as per the virtual reduction. A 3-dimensional mandible model was also printed, facilitating the prebent 2.4-mm reconstructive plate. The surgical procedure was performed with no complications, resulting in the accurate fit of both the bent plate and the guide. A postoperative computed tomography scan showed good condylar position, fracture reduction, and hardware adaptation. A follow-up approximately 2 years later showed that she was successfully rehabilitated with the dental prosthesis. Therefore, VSP is a valuable tool for attaining a predictable result in the treatment of severe atrophic mandibular fracture, with a reduced operative duration, acceptable precision of fracture reduction, and low cost.

The Impact of 3D Technology in Optimizing Midface Fracture Treatment-Focus on the Zygomatic Bone

PURPOSE

In the context of the ongoing development and expanding availability of 3-dimensional (3D) printing, there is increasing interest in designing simplified workflows that would encourage more medical practitioners to include 3D printing in their current practice. The purpose of this study is to present our experience regarding the use of 3D printing in the preoperative planning and management of acute midface trauma, an area less explored by existing studies.

METHODS

We performed a retrospective case series study including admitted patients who underwent surgical repair of midface fractures, in which 3D-printed stereolithic models were used preoperatively for shaping the osteosynthesis material. We recorded standard information about the patients, imaging method used, and type of midface fracture. We also logged the details and durations of each main step in the preoperative 3D printing workflow and documented the durations and outcomes of each surgical procedure.

RESULTS

We identified 29 cases of midface fractures that benefited of a preoperative stereolithic model. From the 2 main methods of obtaining the virtual model, mirroring and virtual fracture reduction, the longest duration was recorded in a case in which the later method was used. The longest stereolithic model printing time was found in a complex midface fracture case. All the prebent osteosynthesis material was used intraoperatively and fitted the reduced fracture sites, also serving as an intraoperative guide for correct fracture reduction. The particularities, benefits, as well as the possible challenges associated with the application of 3D printing in acute trauma cases are discussed.

CONCLUSIONS

Our 3D printing protocol was applicable and rendered favorable outcomes in the acute midface trauma setting. Proper understanding of the steps involved in achieving the stereolithic model is key for the adaptation of 3D printing to the current management of acute midface trauma.

Key points in surgical management of mandibular condylar fractures

Mandibular condylar fractures are among the most common facial fractures and some of the most difficult to manage. Opinions about the management of mandibular condylar fractures differ among surgeons. With the implementation of new technology, an increased understanding of fracture management, and better functional and morphological outcomes reported in the literature, open reduction and internal fixation is becoming many surgeons' preferred choice for the treatment of condylar fractures. Because surgical treatment of such fractures is complex, certain factors must be considered to achieve satisfactory outcomes. In this article, we summarise six key points in the management of mandibular condylar fractures: virtual evaluation of condylar fracture, a suitable surgical approach, good reduction, stable internal fixation, repair of the articular disc, and restoration of the mandibular arch width. We believe that these points will help to improve the prognosis of mandibular condyle fractures.

The Influence of the Gonial Angle on the Initial Biomechanical Stability of the Plate Osteosynthesis in Polyurethane Mandibles With Angle Fractures

The aim of the present study was to examine the biomechanical stability of the mandibular angle fractures (MAF) fixated with standard titanium miniplates in polyurethane models with different gonial angles (GA). Three custom molds were prepared for 3-dimensional printed mandibles with low, normal and high GA. Twenty polyurethane replicas were cast per group and standard MAFs were created on each sample. Fractures were stabilized with 1 4-hole standard titanium miniplate inserted over the superior alveolar border. Half of the samples were subjected to molar loading and the other half to the incisal loading up until 150 N force magnitude. The load-displacement curves and the horizontal moment arms were recorded and analyzed. The samples with high GA demonstrated greater displacement than those with normal and low GA during molar loading (P < 0.05 for both). After correcting for the effects of the moment arm, the incisal loading also resulted in higher mean displacement in the high GA group than the others (P < 0.05 for both) and the normal GA samples showed higher displacement after 100 N level compared to those in low GA (P < 0.05). Within the limits of this in vitro study, it can be concluded that the MAFs of the polyurethane mandibles with high GA fixated with 1 standard monocortical plate are more likely to demonstrate higher displacement values under the effects of the molar and incisal loadings than do the mandibles with normal and low GA.

The risk of tooth root injuries using cortical screws for intermaxillary fixation and osteosynthesis plates - A retrospective analysis

Intermaxillary fixation (IMF) and osteosynthesis plates (OP) are widely used for the non-surgical and surgical treatment of mandible and condyle fractures. The aim of this retrospective study was to analyze the frequency of tooth root injuries by IMF and OP screws. Electronic patient reports (2004-2013) were screened for patients treated with either IMF screws and/or OP in the Department of Oral- and Maxillofacial Surgery, University Medical Center Mainz, Germany. The frequency and the position of endangered and injured teeth were analyzed by orthopantomogram (OPTG) and cone beam computer tomography (CBCT). Next, possible predictive factors for tooth root injuries, namely interdental- and crestal distance, screw length and distance between tooth root and screw were evaluated. Further, the accuracy of OPTG vs. CBCT concerning the diagnosis of tooth root injuries was analyzed. Three-hundred sixty-six patients were included and 3388 teeth were defined as endangered by IMF- and OP screws. Overall, 16 injured teeth (0.5%) in 13 patients (3.55%) were detected. Nine injuries (56.3%) were caused by IMF- and seven injuries (43.8%) by OP screws. Three teeth were non-vital, one tooth had to be extracted. No correlation between the predictive factors crestal distance, screw length and tooth root injuries was found. If tooth injury occurred, a significant correlation between the interdental distance and the distance between tooth root and screw was found (κ = 0.48; p < 0,0001). Comparison between OPTG vs. CBCT demonstrated that many of the injuries that were seen in the OPTG (n = 230) could not be verified in the CBCT scans (n = 16) (κ = 0.12). To conclude, screws for IMF and OP can be considered as a safe procedure concerning the risk of tooth root injuries.

Clinical Analysis and CT 3D-Mediated Precise Internal Fixation in Maxillofacial Fracture

BACKGROUND/PURPOSE

To retrospectively analyze the epidemiological features, clinical diagnosis, and treatment of 610 patients with maxillofacial fractures, while providing a reference for the prevention and optimized treatment of maxillofacial fractures.

METHODS

Data of patients with maxillofacial fractures who were treated and followed up at the Second People's Hospital of Kashi Prefecture from June 2012 to April 2018 were summarized. The epidemiological features, clinical manifestations, fracture sites, treatment methods, and results were analyzed.

RESULTS

The highest incidence was in the age range of 20 to 49 years. The main cause of fracture was traffic injury. Mandibular fractures accounted for 37.77%, zygoma and zygomatic arch fractures for 37.00%, and maxillary fractures for 21.19%. Atypical zygomatic arch fractures were more common in the maxilla, followed by Le Fort I and II fractures. Closed fractures accounted for 85.97%. Many (73.39%) patients were treated with computed tomography 3-dimensional (3D)-mediated precision modified incision internal fixation with satisfactory results.

CONCLUSIONS

There is a high incidence of maxillofacial fractures among young men, especially in summer, with the most common injuries being traffic-related injuries. The most common site is the mandible, followed by the zygomatic arch, zygomatic complex, and maxilla. Computed tomography 3D-mediated precision modified incision internal fixation can achieve satisfactory results.

[Frequency and management of complex facial fractures-an oral and maxillofacial surgical assessment]

INTRODUCTION

The treatment of facial fractures is an integral part of the oral and maxillofacial surgical treatment spectrum. In the case of complex fractures that involve multiple levels of the facial skeleton associated with severe concomitant injuries, an individual and interdisciplinary treatment approach is needed, which requires the infrastructure of a national trauma center.

OBJECTIVE

The aim of this study was to analyze the incidence and management of patients with complex facial fractures and considering the concomitant injury pattern.

MATERIAL AND METHODS

A retrospective analysis of patients with complex facial fractures during the years 2009-2015 admitted to the emergency surgical department of a national trauma center was carried out. The identification of appropriate patient cases was based on the International Statistical Classification of Diseases and Related Health Problems (ICD) coding of electronic patient data. Only patients with at least a combination of mandibular and midfacial fractures (2-level fractures) were considered. Patients with mainly dentoalveolar fractures and simple nasal bone fractures were not included. The evaluation of the electronic medical records included the etiology, fracture pattern, associated severe injuries on the basis of the injury severity score (ISS), treatment regimen as well as the length of the hospital stay.

RESULTS

In the 7‑year study period, 3382 patients were identified with facial fractures. Of these, 128 patients (3.78%) presented with a complex fracture pattern with a combination of mandibular fractures and fractures of the midface. The majority of these patients (n = 92) had less severe concomitant injuries (ISS ≤ 16), while 36 patients showed severe concomitant injuries (ISS > 16). The incidence of a 3-level fracture involving the mandible, midface and anterior skull base was only 0.47% and could be detected in 16 patients, of which 10 were classified as polytrauma (ISS > 16).

CONCLUSION

The incidence of complex fractures of the facial skeleton was comparatively low with almost 4%. More than one in four patients with complex injury patterns of the facial skeleton exhibited severe concomitant life-threatening injuries, necessitating an interdisciplinary management with the specialized infrastructure of a nationwide trauma center.

Computerized anatomy of the distal radius and its relevance to volar plating, research, and teaching

Distal radius fractures are common and fracture patterns and fixation can be complex. Computerized anatomy evaluation (CAE) might offer non-invasive and enhanced anatomy assessment that might help with implant selection and placement and screw length determination. Our goal was to test the accuracy of two CAE methods for anatomical volar plate positioning and screw lengths measurement of the distal radius. We included 56 high-resolution peripheral quantitative computed tomography scans of intact, human distal radii. Plates were placed manually onto 3D printed models (method 1), which was compared with automated computerized plate placement onto the 3D computer models (method 2). Subsequently, screw lengths were determined digitally for both methods. Screw lengths evaluations were compared via Bland-Altman plots. Both CAE methods resulted in identical volar plate selection and in anatomical plate positioning. For screw length the concordance correlation coefficient was ≥0.91, the location shift ≤0.22 mm, and the scale shift ≤0.16. The differences were smaller than ±1 mm in all samples. Both CAE methods allow for comparable plate positioning and subsequent screw length measurement in distal radius volar plating. Both can be used as a non-invasive teaching environment for volar plate fixation. Method 2 even offers fully computerized assessments. Future studies could compare our models to other anatomical areas, post-operative volar plate positioning, and model performance in actual distal radius fracture instead of intact radii. Clin. Anat. 32:361-368, 2019. © 2018 The Authors. Clinical Anatomy published by Wiley Periodicals, Inc. on behalf of American Association of Clinical Anatomists.

Radiological Society of North America (RSNA) 3D printing Special Interest Group (SIG): guidelines for medical 3D printing and appropriateness for clinical scenarios

Medical three-dimensional (3D) printing has expanded dramatically over the past three decades with growth in both facility adoption and the variety of medical applications. Consideration for each step required to create accurate 3D printed models from medical imaging data impacts patient care and management. In this paper, a writing group representing the Radiological Society of North America Special Interest Group on 3D Printing (SIG) provides recommendations that have been vetted and voted on by the SIG active membership. This body of work includes appropriate clinical use of anatomic models 3D printed for diagnostic use in the care of patients with specific medical conditions. The recommendations provide guidance for approaches and tools in medical 3D printing, from image acquisition, segmentation of the desired anatomy intended for 3D printing, creation of a 3D-printable model, and post-processing of 3D printed anatomic models for patient care.

The accuracy of ultrashort echo time MRI sequences for medical additive manufacturing

OBJECTIVES

Additively manufactured bone models, implants and drill guides are becoming increasingly popular amongst maxillofacial surgeons and dentists. To date, such constructs are commonly manufactured using CT technology that induces ionizing radiation. Recently, ultrashort echo time (UTE) MRI sequences have been developed that allow radiation-free imaging of facial bones. The aim of the present study was to assess the feasibility of UTE MRI sequences for medical additive manufacturing (AM).

METHODS

Three morphologically different dry human mandibles were scanned using a CT and MRI scanner. Additionally, optical scans of all three mandibles were made to acquire a "gold standard". All CT and MRI scans were converted into Standard Tessellation Language (STL) models and geometrically compared with the gold standard. To quantify the accuracy of the AM process, the CT, MRI and gold-standard STL models of one of the mandibles were additively manufactured, optically scanned and compared with the original gold-standard STL model.

RESULTS

Geometric differences between all three CT-derived STL models and the gold standard were <1.0 mm. All three MRI-derived STL models generally presented deviations <1.5 mm in the symphyseal and mandibular area. The AM process introduced minor deviations of <0.5 mm.

CONCLUSIONS

This study demonstrates that MRI using UTE sequences is a feasible alternative to CT in generating STL models of the mandible and would therefore be suitable for surgical planning and AM. Further in vivo studies are necessary to assess the usability of UTE MRI sequences in clinical settings.