The First AO Classification System for Fractures of the Craniomaxillofacial Skeleton: Rationale, Methodological Background, Developmental Process, and Objectives

Evaluation of Mandibular Fractures in a German Nationwide Trauma Center Between 2015 and 2017

Introduction

This study analyses the treatment of isolated mandibular fractures between 1.1.2015 and 21.31.2017 at Dortmund General Hospital.

Materials and Methods

Patient documentation and radiological images have been assessed, and a descriptive statistical analysis has been performed.

Results

Three hundred and twenty-eight patients were identified with isolated mandibular fractures (259 male, 69 female). The male-to-female ratio is 3.75: 1. A total of 541 fracture sites have been identified (1.65 fractures/patient). Forty of these were observed in the dentoalveolar region (fracture of the alveolar process, dental injuries), and the other 501 injuries were distributed in the remaining parts of the lower jaw.A detailed analysis of the osteosynthesis implants is provided. A total of 20 serious complications were observed (6% in all primary cases, 4.5% without osseointegrated implants).

Discussion

The demographic data and the anatomical distribution of the fracture sites are comparable with international literature. Dentoalveolar injuries mostly occur in younger patients. The complication rate in this study (4.5%) is below the international data; however, we found a considerably higher rate than in the midfacial region (central midface: 0%, lateral midface: 1.43%). Despite this complication rate, the procedure can be considered safe.

Supplementary information

The online version of this article (10.1007/s12663-021-01513-4).

Craniomaxillofacial trauma in immature dogs–etiology, treatments, and outcomes

Treatment of craniomaxillofacial (CMF) trauma in dogs often requires a multidisciplinary approach and a thorough understanding of the CMF anatomical structures involved. This retrospective study aimed to utilize computed tomography (CT) studies of immature dogs evaluated for CMF trauma and to describe common fracture locations, treatment modalities, and complications, as well as the fracture healing outcomes. The medical records and CT studies of 94 dogs under 1 year of age over a 13-year period were evaluated. The skeletal location of CMF fractures, as well as the severity of displacement and fragmentation of each fracture, was recorded. Case demographic data and trauma etiology were also recorded. Animal bites accounted for the majority of trauma (71.0%). The most likely bone or region to be fractured was the maxillary bones, followed by the molar region of the mandibles. Up to 37 bones or specific regions were fractured in any given patient, with an average of 8.8 ± 3.1 fractured bones or regions per dog. Rostral mandibular trauma was associated with intra-articular fractures of the temporomandibular joint (p = 0.016). Patients sustained concomitant injuries in 32% of the cases. Muzzle therapy was the main treatment performed for most dogs (53.2%), followed by soft tissue closure (47.9%) and selective dental extractions (27.6%). Healing complications were recorded in 71.6% of the dogs, with malocclusion being the most reported complication (55.2%), and associated with dentate mandibular jaw fractures (p = 0.05). The average number of complications per dog was 2.4. No statistically significant association was found between treatment modality and healing outcome. There was a positive correlation between the severity of fracture fragmentation and displacement and a negative healing outcome (all rho >0.7). Further treatment was required in 55.6% of the dogs. Additional dental extractions were performed in 77.7% of patients. Healing complications were common in the immature CMF trauma case. Thus, the need for a comprehensive assessment of the entire CMF region during the initial visit, as well as follow-up, preferably using CT or cone beam CT, is underscored.

Titanium mesh osteosynthesis for the treatment of severely comminuted maxillofacial fractures in four dogs

INTRODUCTION

Major goals in maxillofacial fracture treatment include to restore the dental occlusion, stabilise the major skeletal supports, restore the contour of the face and achieve proper function and appearance of the face. Titanium is considered an optimal material for maxillofacial reconstruction due to its biocompatibility, high strength, minimal inflammatory reaction and minimal imaging artefact.

OBJECTIVES

To describe the clinical details, surgical technique, pre- and postoperative imaging and short- and long-term follow-up of severely comminuted maxillofacial fractures treated with titanium mesh and titanium screws in dogs.

MATERIALS AND METHODS

Retrospective short case series included four client-owned dogs with maxillofacial fractures. After appropriate medical stabilisation, preoperative CT examination of the head was obtained in all patients for evaluation of fracture configuration and surgical planning. The maxillofacial fractures were stabilised by titanium mesh osteosynthesis. Short- and long-term clinical and radiographic follow-ups were available for all dogs.

RESULTS

Proper dental occlusion and reconstruction of the anatomic buttresses was achieved in all cases. All dogs recovered uneventfully from the surgery and no complications were recorded on the long-term follow-up up to 43 months. Occlusion was maintained in all dogs, as well as excellent cosmesis of the midface.

CLINICAL SIGNIFICANCE

Titanium mesh osteosynthesis can achieve sufficient rigidity and lead to uncomplicated healing of severely comminuted maxillofacial fractures. This internal fixation method can be considered a valuable option to treat maxillofacial fractures in particular in cases of large bone defect and midface reconstruction.

Complications after osteosynthesis of craniofacial fractures-an analysis from the years 2015-2017

BACKGROUND

Complications mean a recurring problem in everyday clinical practice. Complication rates between 6 and 13% are described for the treatment of bony injuries to the head and neck area. This paper aims to provide a detailed analysis of the complications after osteosynthesis in facial skull fractures.

MATERIAL AND METHOD

In this retrospective study, we reviewed all patient records of injured treated in the Department of Cranial and Maxillofacial Surgery at the Dortmund General Hospital between 2015 and 2017.

RESULTS

Of the 22,031 head and neck injuries, 685 were treated with osteosynthesis. A clinically significant complication was reported in 32 patients (4.76%). The number of total complications was 63. In total, 66.7% of all complications have been identified in the paramedian mandible (44%), median mandible, mandibular angle, and in the collar area (each 12.7%). Eleven implants (in 5 patients) showed a cancellous bone impaction. Broken implants have been recognized in two cases. In 8 cases, there was a pseudarthrosis in the fracture area; in one case, there was a broken implant and pseudarthrosis in combination.

CONCLUSION

Osteosynthesis is a safe method of treating facial skull fractures, which is why we consider it the gold standard of therapy. The complication rate is well below 5%. The 3-dimensional adaptation (bending) and shortening of the osteosynthesis implants do not lead to an increase in complications.

Traumatic skull fractures in dogs and cats: A comparative analysis of neurological and computed tomographic features

BACKGROUND

Traumatic skull fractures (TSF) are relatively frequent in dogs and cats, but little information is available regarding their clinical and imaging features.

HYPOTHESIS/OBJECTIVES

To describe the neurological and computed tomographic (CT) features of a large cohort of dogs and cats with TSF.

ANIMALS

Ninety-one dogs and 95 cats with TSF identified on CT.

METHODS

Multicenter retrospective comparative study. Signalment, cause of trauma, fracture locations and characteristics, presence of neurological deficits, and 1-week survival were recorded. Fractures were classified according to the extent of fragmentation and displacement.

RESULTS

The cranial vault was affected more frequently in dogs (P = .003), whereas the face and base of the cranium more often was affected in cats (P < .001). Cats presented with multiple fractures more frequently (P < .001). All animals with TSF in the cranial vault were more likely to develop neurological signs (P = .02), especially when depressed fractures were present (95% confidence interval [CI], 1.7-8.2; P = .001). Animals with TSF located only in the facial region were less likely to have neurological signs (odds ratio with Mantel-Haenszel's method [ORMH ], 0.2; 95% CI, 0.1-0.6; P = .004). Most affected animals (84.9%) survived the first week post-trauma. Death was more likely with fractures of the cranial vault (P = .003), especially when fragmented (P = .007) and displaced (P = .004).

CONCLUSIONS AND CLINICAL IMPORTANCE

Traumatic skull fracture distribution and patterns are different between dogs and cats. Cranial vault fractures were associated with neurological deficits and worse survival. The presence of TSF alone should not be considered a negative prognostic factor because most affected animals survived the first week.

Craniomaxillofacial Trauma in Dogs-Part II: Association Between Fracture Location, Morphology and Etiology

Treatment of craniomaxillofacial (CMF) trauma in dogs requires a thorough understanding of the CMF skeletal structures involved. The human medical literature has several examples of CMF trauma and fracture classification, including the classically described Le Fort fractures. The recent classification schemes require large studies using computed tomography (CT). In the veterinary medical literature, such studies are lacking. The aims of part II of this retrospective study were to use a large number of CT studies of dogs evaluated for CMF trauma to determine whether specific fracture locations in the CMF region occur concurrently, and whether trauma etiology influences fracture morphology. This information may then be used to form a fracture classification scheme in the future. The medical records and CT studies of 165 dogs over a 10-year period were evaluated. The skeletal location of CMF fractures as well as the severity of displacement and fragmentation of each fracture was recorded. Dogs' demographic data and trauma etiology were also recorded. Fractured portions of the mandible tended to occur with fractures of adjacent bones, with the major exception of symphyseal separation, which occurred simultaneously with fractures of the cribriform plate. Fractures of the maxillary bone were accompanied by many concurrent fractures affecting the majority of the midface, skull base, and cranial vault. When the zygomatic bone was fractured, the other bones comprising the orbit also tended to fracture. Fractures of the relatively superficially located frontal and nasal bones were often accompanied by fractures of the skull base. Fracture etiology influenced fracture morphology such that vehicular trauma resulted in a relatively higher number of severely displaced and comminuted fractures than did other trauma etiologies. This study provides examples of fractures that, when found, should prompt veterinarians to look for additional injuries in specific locations. In addition, it further highlights the need for thorough CT evaluation of the entire CMF region, even when clinically apparent fractures appear relatively superficial.

Craniomaxillofacial Trauma in Dogs-Part I: Fracture Location, Morphology and Etiology

Treatment of craniomaxillofacial (CMF) trauma in dogs often requires a multidisciplinary approach and a thorough understanding of the CMF skeletal structures involved. The aim of this retrospective study was to use a large number of CT studies of dogs evaluated for CMF trauma and to describe fracture location and morphology in relation to demographic data and trauma etiology. The medical records and CT studies of 165 dogs over a 10-year period were evaluated. The skeletal location of CMF fractures as well as the severity of displacement and fragmentation of each fracture was recorded. Patient demographic data and trauma etiology were also recorded. Animal bites accounted for the majority of trauma (50%), followed by unknown trauma (15%), vehicular accidents (13%), and blunt force trauma (13%). Small dogs, <10 kg, and juveniles accounted for the majority of patients (41.8 and 25.5%, respectively). The most likely bone or region to be fractured was the maxillary bone, followed by the premolar and molar regions of the mandible. Up to 37 bones or regions were fractured in any given patient, with an average of 8.2 fractured bones or regions per dog. The most commonly fractured location varied according to trauma etiology. Specifically, vehicular accidents tended to result in more locations with a higher probability of fracture than other trauma types. A major conclusion from this study is that every bone of the CMF region was fractured in at least one case and many cases had a large number of fractured regions. Thus, the need for comprehensive assessment of the entire CMF region, preferably using CT, is underscored.

The Comprehensive AO CMF Classification System for Mandibular Fractures: A Multicenter Validation Study

The AO CMF has recently launched the first comprehensive classification system for craniomaxillofacial (CMF) fractures. The AO CMF classification system uses a hierarchical framework with three levels of growing complexity (levels 1, 2, and 3). Level 1 of the system identifies the presence of fractures in four anatomic areas (mandible, midface, skull base, and cranial vault). Level 2 variables describe the location of the fractures within those defined areas. Level 3 variables describe details of fracture morphology such as fragmentation, displacement, and dislocation. This multiplanar radiographic image-based AO CMF trauma classification system is constantly evolving and beginning to enter worldwide application. A validation of the system is mandatory prior to a reliable communication and data processing in clinical and research environments. This interobserver reliability and accuracy study is aiming to validate the three current modules of the AO CMF classification system for mandible trauma in adults. To assess the performance of the system at the different precision levels, it focuses on the fracture location within the mandibular regions and condylar process subregions as core components giving only secondary attention to morphologic variables. A total of 15 subjects individually assigned the location and features of mandibular fractures in 200 CT scans using the AO CMF classification system. The results of these ratings were then statistically evaluated for interobserver reliability by Fleiss' kappa and accuracy by percentage agreement with an experienced reference assessor. The scores were used to determine if the variables of levels 2 and 3 were appropriate tools for valid classification. Interobserver reliability and accuracy were compared by hierarchy of variables (level 2 vs. level 3), by anatomical region and subregion, and by assessor experience level using Kruskal-Wallis and Wilcoxon's rank-sum tests. The AO CMF classification system was determined to be reliable and accurate for classifying mandibular fractures for most levels 2 and 3 variables. Level 2 variables had significantly higher interobserver reliability than level 3 variables (median kappa: 0.69 vs. 0.59, p  < 0.001) as well as higher accuracy (median agreement: 94 vs. 91%, p  < 0.001). Accuracy was adequate for most variables, but lower reliability was observed for condylar head fractures, fragmentation of condylar neck fractures, displacement types and direction of the condylar process overall, as well as the condylar neck and base fractures. Assessors with more clinical experience demonstrated higher reliability (median kappa high experience 0.66 vs. medium 0.59 vs. low 0.48, p  < 0.001). Assessors with experience using the classification software also had higher reliability than their less experienced counterparts (median kappa: 0.76 vs. 0.57, p  < 0.001). At present, the AO CMF classification system for mandibular fractures is suited for both clinical and research settings for level 2 variables. Accuracy and reliability decrease for level 3 variables specifically concerning fractures and displacement of condylar process fractures. This will require further investigation into why these fractures were characterized unreliably, which would guide modifications of the system and future instructions for its usage.

Do Radiologists and Surgeons Speak the Same Language? A Retrospective Review of Facial Trauma

OBJECTIVE

The objective of the present study is to examine the concordance of facial fracture classifications in patients with trauma who underwent surgery and to assess the epidemiologic findings associated with facial trauma.

MATERIALS AND METHODS

Patients with trauma who underwent facial CT examination and inpatient operative intervention during a 1-year period were retrospectively analyzed. Patient demographic characteristics, the mechanism of injury, the radiology report, the surgical diagnosis, and clinical indications were reviewed. Fractures were documented according to bone type and were classified into the following subtypes: LeFort 1, LeFort 2, LeFort 3, naso-orbital-ethmoidal, zygomaticomaxillary complex (ZMC), orbital, and mandibular. Concordance between the radiology and surgery reports was assessed.

RESULTS

A total of 115,000 visits to the emergency department resulted in 9000 trauma activations and 3326 facial CT examinations. One hundred fifty-six patients (4.7%) underwent facial surgical intervention, and 133 cases met criteria for inclusion in the study. The mean injury severity score was 10.2 (range, 1-75). The three most frequently noted injury mechanisms were as follows: assault (77 cases [57.9%]), a traffic accident (21 cases [15.8%]), and a fall (20 cases [15%]). The three most frequently noted facial bone fractures were as follows: mandible (100 cases [75.2%]), maxilla (53 cases [39.8%]), and orbit (53 cases [39.8%]). The five descriptors most frequently found in the radiology and surgery reports were the mandibular angle (25 cases), the orbital floor (25 cases), the mandibular parasymphysis (22 cases), the mandibular body (21 cases), and ZMC fractures (19 cases). A classification was not specified in 31 of the radiologic impressions (22.5%), with 28 of 31 radiologists expecting the surgeon to read the full report. The descriptors used in the radiology and surgery reports matched in 73 cases (54.9%) and differed in 51 cases (38.3%). No classifications were used by one or both specialties in nine cases (6.8%).

CONCLUSION

For 38.3% of patients needing facial surgery, descriptors used in the radiologic and surgery reports differed. Speaking a common language can potentially improve communication between the radiology and surgery services and can help expedite management of cases requiring surgery.

The Comprehensive AOCMF Classification System: Orbital Fractures - Level 3 Tutorial

The AOCMF Classification Group developed a hierarchical three-level craniomaxillofacial classification system with increasing level of complexity and details. Within the midface (level 1 code 92), the level 2 system describes the location of the fractures within defined regions in the central and lateral midface including the internal orbit. This tutorial outlines the level 3 detailed classification system for fractures of the orbit. It depicts the orbital fractures according to the subregions defined as orbital rims, anterior orbital walls, midorbit, and apex. The system allows documentation of the involvement of specific orbital structures such as inferior orbital fissure, internal orbital buttress, the greater wing of sphenoid, lacrimal bone, superior orbital fissure, and optic canal. The classification system is presented along with rules for fracture location and coding, a series of case examples with clinical imaging and a general discussion on the design of this classification.

The Comprehensive AOCMF Classification System: Midface Fractures - Level 3 Tutorial

This tutorial outlines the details of the AOCMF image-based classification system for fractures of the midface at the precision level 3. The topography of the different midface regions (central midface-upper central midface, intermediate central midface, lower central midface-incorporating the naso-orbito-ethmoid region; lateral midface-zygoma and zygomatic arch, palate) is subdivided in much greater detail than in level 2 going beyond the Le Fort fracture types and its analogs. The level 3 midface classification system is presented along with guidelines to precisely delineate the fracture patterns in these specific subregions. It is easy to plot common fracture entities, such as nasal and naso-orbito-ethmoid, and their variants due to the refined structural layout of the subregions. As a key attribute, this focused approach permits to document the occurrence of fragmentation (i.e., single vs. multiple fracture lines), displacement, and bone loss. Moreover, the preinjury dental state and the degree of alveolar atrophy in edentulous maxillary regions can be recorded. On the basis of these individual features, tooth injuries, periodontal trauma, and fracture involvement of the alveolar process can be assessed. Coding rules are given to set up a distinctive formula for typical midface fractures and their combinations. The instructions and illustrations are elucidated by a series of radiographic imaging examples. A critical appraisal of the design of this level 3 midface classification is made.

The Comprehensive AOCMF Classification System: Midface Fractures - Level 2 Tutorial

The AOCMF Classification Group developed a hierarchical three-level craniomaxillofacial classification system with increasing level of complexity and details. The highest level 1 system distinguish four major anatomical units including the mandible (code 91), midface (code 92), skull base (code 93), and cranial vault (code 94). This tutorial presents the level 2 system for the midface unit that concentrates on the location of the fractures within defined regions in the central (upper, intermediate, and lower) and lateral (zygoma, pterygoid) midface, as well as the internal orbit and palate. The level 2 midface fracture location outlines the topographic boundaries of the anatomical regions. The common nasoorbitoethmoidal and zygoma en bloc fracture patterns, as well as the time-honored Le Fort classification are taken into account. This tutorial is organized in a sequence of sections dealing with the description of the classification system with illustrations of the topographical cranial midface regions along with rules for fracture location and coding, a series of case examples with clinical imaging and a general discussion on the design of this classification. Individual fracture mapping in these regions regarding severity, fragmentation, displacement of the fragment or bone defect is addressed in a more detailed level 3 system in the subsequent articles.

The Comprehensive AOCMF Classification System: Condylar Process Fractures - Level 3 Tutorial

This tutorial outlines the detailed system for fractures of the condylar process at the precision level 3 and is organized in a sequence of sections dealing with the description of the classification system within topographical subdivisions along with rules for fracture coding and a series of case examples with clinical imaging. Basically, the condylar process comprises three fracture levels and is subdivided into the head region, the condylar neck, and the condylar base. Fractures of the condylar head show typical fracture lines either within the lateral pole zone, which may lead to loss of vertical height, or medially to the pole zone, with the latter ones usually not compromising the vertical condyle to fossa relation. In condylar head fractures, the morphology is further described by the presence of minor or major fragmentation, the vertical apposition of fragments at the plane of the head fracture, the displacement of the condylar head with regard to the fossa including a potential distortion of the condylar head congruency resulting in dystopic condyle to fossa relations and the presence or absence of a loss of vertical ramus height. A specific vertical fracture pattern extending from the head to the neck or base subregion is considered. Fractures of the condylar neck and base can be differentiated according to a newly introduced one-third to two-thirds rule with regard to the proportion of the fracture line above and below the level of the sigmoid notch, which is presented in the classification article, and are basically subdivided according to the presence or absence of displacement or dislocation. In both condylar neck and base fractures, the classification is again based on the above mentioned parameters such as fragmentation, displacement of the condylar head with regard to the fossa, including dystopic condyle to fossa relations and loss of vertical ramus height, that is, according to the measurement of the condylar process. In addition, the classification assesses a sideward displacement including the respective displacement sector at the neck or base fracture site as well as the angulation of the superior main fragment and also considers a potential displacement of the caudal fragment with regard to the fossa, which may occur in fractures affecting additional fracture locations in the mandible. The design of this classification is discussed along with a review of existing classification systems. The condylar process for fracture location was defined according to the level 2 system presented in a previous tutorial in this special issue.

The Comprehensive AOCMF Classification System: Mandible Fractures- Level 2 Tutorial

This tutorial outlines the details of the AOCMF image-based classification system for fractures of the mandible at the precision level 2 allowing description of their topographical distribution. A short introduction about the anatomy is made. Mandibular fractures are classified by the anatomic regions involved. For this purpose, the mandible is delineated into an array of nine regions identified by letters: the symphysis/parasymphysis region anteriorly, two body regions on each lateral side, combined angle and ascending ramus regions, and finally the condylar and coronoid processes. A precise definition of the demarcation lines between these regions is given for the unambiguous allocation of fractures. Four transition zones allow an accurate topographic assignment if fractures end up in or run across the borders of anatomic regions. These zones are defined between angle/ramus and body, and between body and symphysis/parasymphysis. A fracture is classified as "confined" as long as it is located within a region, in contrast to a fracture being "nonconfined" when it extents to an adjoining region. Illustrations and case examples of mandible fractures are presented to become familiar with the classification procedure in daily routine.

The Comprehensive AOCMF Classification System: Classification and Documentation within AOCOIAC Software

The AOCMF Classification Group developed a hierarchical three-level craniomaxillofacial (CMF) fracture classification system. The fundamental level 1 distinguishes four major anatomical units including the mandible (code 91), midface (code 92), skull base (code 93) and cranial vault (code 94); level 2 relates to the location of the fractures within defined topographical regions within each units; level 3 relates to fracture morphology in these regions regarding fragmentation, displacement, and bone defects, as well as the involvement of specific anatomical structures. The resulting CMF classification system has been implemented into AO comprehensive injury automatic classifier (AOCOIAC) software allowing for fracture classification as well as clinical documentation of individual cases including a selected sample of diagnostic images. This tutorial highlights the main features of the software. In addition, a series of illustrative case examples is made available electronically for viewing and editing.

The Comprehensive AOCMF Classification System: Radiological Issues and Systematic Approach

The AOCMF Classification Group developed a hierarchical three-level craniomaxillofacial (CMF) classification system with increasing level of complexity and details. The basic level 1 system differentiates fracture location in the mandible (code 91), midface (code 92), skull base (code 93), and cranial vault (code 94); the levels 2 and 3 focus on defining fracture location and morphology within more detailed regions and subregions. Correct imaging acquisition, systematic analysis, and interpretation according to the anatomic and surgical relevant structures in the CMF regions are essential for an accurate, reproducible, and comprehensive diagnosis of CMF fractures using that system. Basic principles for radiographic diagnosis are based on conventional plain films, multidetector computed tomography, and magnetic resonance imaging. In this tutorial, the radiological issues according to each level of the classification are described.

The Comprehensive AOCMF Classification: Skull Base and Cranial Vault Fractures - Level 2 and 3 Tutorial

The AOCMF Classification Group developed a hierarchical three-level craniomaxillofacial classification system with increasing level of complexity and details. The highest level 1 system distinguish four major anatomical units, including the mandible (code 91), midface (code 92), skull base (code 93), and cranial vault (code 94). This tutorial presents the level 2 and more detailed level 3 systems for the skull base and cranial vault units. The level 2 system describes fracture location outlining the topographic boundaries of the anatomic regions, considering in particular the endocranial and exocranial skull base surfaces. The endocranial skull base is divided into nine regions; a central skull base adjoining a left and right side are divided into the anterior, middle, and posterior skull base. The exocranial skull base surface and cranial vault are divided in regions defined by the names of the bones involved: frontal, parietal, temporal, sphenoid, and occipital bones. The level 3 system allows assessing fracture morphology described by the presence of fracture fragmentation, displacement, and bone loss. A documentation of associated intracranial diagnostic features is proposed. This tutorial is organized in a sequence of sections dealing with the description of the classification system with illustrations of the topographical skull base and cranial vault regions along with rules for fracture location and coding, a series of case examples with clinical imaging and a general discussion on the design of this classification.

The Comprehensive AOCMF Classification System: Fracture Case Collection, Diagnostic Imaging Work Up, AOCOIAC Iconography and Coding

The AO classification system for fractures in the adult craniomaxillofacial (CMF) skeleton is organized in anatomic modules in a 3 precision-level hierarchy with account for an increasing complexity and details. Level-1 is most elementary and identifies no more than the presence of fractures in 4 separate anatomical units: the mandible (code 91), midface (92), skull base (93) and cranial vault (94). Level-2 relates the detailed topographic location of the fractures within defined regions of the mandible, central and lateral midface, internal orbit, endo- and exocranial skull base, and the cranial vault. Level-3 is based on an even more refined topographic assessment and focuses on the morphology - fragmentation, displacement, and bone defects - within specified subregions. An electronic fracture case collection complements the preceding tutorial papers, which explain the features and options of the AOCMF classification system in this issue of the Journal. The electronic case collection demonstrates a range of representative osseous CMF injuries on the basis of diagnostic images, narrative descriptions of the fracture diagnosis and their classification using the icons for illustration and coding of a dedicated software AOCOIAC (AO Comprehensive Injury Automatic Classifier). Ninety four case examples are listed in two tables for a fast overview of the electronic content. Each case can serve as a guide to getting started with the new AOCMF classification system using AOCOIAC software and to employ it in the own clinical practice.