Abstract
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.
Keywords: craniomaxillofacial fractures, classification system, case collection, clinical documentation system
Fractures of the craniomaxillofacial skeleton occur in an endless array of different patterns. To design a standardized classification system to categorize fractures in a way that is meaningful, validated and clinically relevant is a challenging long-term project that requires an iterative development process.
A key prerequisite in the development of a classification system is to establish a reproducible visual language and coding to ensure referral to identical fracture entities across medical disciplines.1
The new AO classification system for fractures of the craniomaxillofacial (CMF) skeleton in adults is organized in several anatomic modules in a precision-level hierarchy relating to the rendition of topographical details and fracture morphology.
The introduction of precision levels offers versatility and staged procedures during the developmental phase, the validation process and the finalization of a classification proposal.
Three precision levels enable to refine the documentation of fractures according to their complexity:
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, and internal orbit. The endocranial surface of the skull base is divided in 9 regions: a central part further subdivided into 3 components (cribriform plate and ethmoido-sphenoidal planum, sellar/parasellar compartment, clivus) adjoined by two lateral parts each encompassing an anterior, middle and posterior component. The regions of the exocranial skull base and the cranial vault are defined according to common anatomical nomenclature into paired and non-paired bones: frontal, parietal, temporal, sphenoid and occipital.
Level-3 is based on an even more refined topographic assessment and focuses on the morphology – fragmentation, displacement, and bone defects – within the specified subregions, parts and components.
Objective
The purpose of this paper is to present an electronic case collection complementing the series of tutorial papers2 3 4 5 6 7 8 about the AOCMF classification system preceding in this issue of the Journal. The electronic cases demonstrate 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).9
The electronic case collection is intended to serve as a guide in getting started and familiar with all the nuances of the AOCMF classification system. A total of 94 case examples listed in two tables (Tables 1 and 2) provides a fast overview to select appropriate fracture patterns for a first orientation or comparison in reference to injuries in the own clinical setting. The case examples are grouped according to the sequence of the preceding tutorial papers, which accounts for the anatomical regions/ subregions and the 3 precision levels. The tables list the documentation ID used for documentation within the integrated database in AOCOIAC and indicate case examples simultaneously published in the tutorial papers.
Table 1. Case examples of mandibular fractures.
| AOCOIAC ID | Description | Collection ID |
|---|---|---|
| Level 2 case examples 2 | ||
| CMTR-91–003 | Body fracture traversing anterior transition zone | 1 |
| CMTR-91–004 | Body region fracture | 2 |
| CMTR-91–005 | Angle fracture in posterior transition zone | 3 |
| CMTR-91–007 | Fracture fully within posterior transition zone | 4 |
| CMTR-91–008 | Horizontal angle / ramus fracture | 5 |
| CMTR-91–010 | Vertical angle / ramus fracture | 6 |
| CMTR-91–011 | Isolated coronoid fracture | 7 |
| CMTR-91–012 | Condylar process fracture | 8 |
| CMTR-91–014 | Double fracture of the mandible (a) | 9 |
| CMTR-91–016 | Double fracture of the mandible (b) | 10 |
| CMTR-91–017 | Multifragmented fracture within right ascending ramus with condylar 2 process involvement | 11 |
| CMTR-91–018 | Triple mandibular fracture (a) | 12 |
| CMTR-91–019 | Triple mandibular fracture (b) | 13 |
| CMTR-91–020 | Triple mandibular fracture (c) | 14 |
| CMTR-91–021 | Multiple mandible fractures | 15 |
| CMTR-91–022 | Mandibular fracture within the posterior transitional zone | 16 |
| CMTR-91–023 | Condylar process fracture on edentulous mandible | 17 |
| CMTR-91–025 | Mandibular body fracture | 18 |
| CMTR-91–002 | Anterior transition zone determination in edentulous mandible | 19 - Tutorial |
| CMTR-91–013 | Nonconfined fracture over symphysis and body | 20 - Tutorial |
| CMTR-91–015 | Double fracture of the mandible (c) | 21 - Tutorial |
| Level 3 case examples (excl. condylar process) 3 | ||
| CMTR-91–051 | Alvelolar process fracture | 22 |
| CMTR-91–052 | Alvelolar process fracture region 42–45 | 23 |
| CMTR-91–053 | Double fracture with basal wedge fracture within anterior transition 1 zone (on the right) and angle fracture on the left | 24 |
| CMTR-91–054 | Multifragmented mandibular body region | 25 |
| CMTR-91–055 | Major fragmentation confined to the symphyseal region | 26 |
| CMTR-91–056 | Major fragmentation extending between the lateral symphysis and the 1 anterior body region | 27 |
| CMTR-91–057 | Body fracture with major fragmentation | 28 |
| CMTR-91–024 | Major fragmented fracture body and symphysis | 29 |
| CMTR-91–058 | Multiple fractures of an edentulous mandible | 30 |
| CMTR-91–059 | Bilateral body fracture in a severely atrophic mandible | 31 |
| CMTR-91–060 | Fragmented angle-ramus fracture | 32 |
| CMTR-91–061 | Long reaching sagittal fracture from angle/ramus to symphysis plus 1 bilateral condylar head fractures | 33 |
| CMTR-91–001 | Symphysis fracture of grade 0 fragmentation | 34 - Tutorial |
| CMTR-91–026 | Two fracture lines in conjunction with alveolar process fracture | 35 - Tutorial |
| CMTR-91–027 | Body fracture of grade 2 fragmentation extending into the symphysis | 36 - Tutorial |
| Level 3 Condylar Process 4 | ||
| CMTR-91–102 | Unilateral condylar base fracture with lateral override/ramus 3 shortening | 37 |
| CMTR-91–104 | Bilateral condylar process neck and head fractures | 38 |
| CMTR-91–106 | Borderline condylar head fracture | 39 |
| CMTR-91–107 | Atypical condylar head and neck fracture | 40 |
| CMTR-91–108 | Non-fragmented neck fracture | 41 |
| CMTR-91–109 | Neck fracture and sagittal symphysis-to-angle/ramus fracture in 1 edentulous mandible | 42 |
| CMTR-91–101 | Unilateral condylar base fractures with lateral override | 43 - Tutorial |
| CMTR-91–103 | Condylar neck fracture | 44 - Tutorial |
| CMTR-91–105 | Bilateral condylar head fractures | 45 - Tutorial |
Abbreviations: AOCOIAC, AO COmprehensive Injury Automatic Classifier9; Tutorial, case presented in the respective tutorial article.
Table 2. Case examples of midface, cranio-facial skull base and cranial vault fractures.
| AOCOIAC ID | Description | Collection ID |
|---|---|---|
| Level 2 Midface 5 | ||
| CMTR-92–004 | Zygoma fracture | 46 |
| CMTR-92–005 | Zygoma and nose fractures with ICM involvement | 47 |
| CMTR-92–006 | Isolated fracture of the zygomatic arch | 48 |
| CMTR-92–007 | Fracture on the zygomatic arch | 49 |
| CMTR-92–008 | Fracture of the anterior maxillary sinus wall (ICM) | 50 |
| CMTR-92–009 | Le Fort I fracture (LCM) and nasal bone involvement | 51 |
| CMTR-92–010 | Naso-orbito-ethmoid (NOE) fracture | 52 |
| CMTR-92–011 | Complex fracture pattern of the central and lateral midface | 53 |
| CMTR-92–012 | Le Fort I fracture pattern with bilateral zygoma fractures | 54 |
| CMTR-92–013 | Displaced zygoma fracture | 55 |
| CMTR-92–001 | Fracture of the upper central midface | 56 - Tutorial |
| CMTR-92–002 | Bilateral Le Fort I fracture associated with nasal bones and zygoma fracture on the left side | 57 - Tutorial |
| CMTR-92–003 | Zygoma fracture on the left side | 58 - Tutorial |
| Level 3 Midface 6 | ||
| CMTR-92–107 | Undisplaced midface fracture: bilateral Le Fort I, unilateral Le II Fort 7 II right, and zygoma left - as component of a panfacial fracture | 59 |
| CMTR-92–108 | Zygoma minimally displaced with multifragmentation of ZMC and ZSS | 60 |
| CMTR-92–109 | Le Fort I Type 1, 2 and 3 fracture combination, bilateral NOE and frontal sinus fractures | 61 |
| CMTR-92–110 | Panfacial fracture - retrosdiplaced Le Fort I, II, III midface fracture, parasagittal palatal fracture and triple mandibular fracture: symphyseal fracture and bilateral condylar base fracture | 62 |
| CMTR-92–111 | Complex zygomatic fracture | 63 |
| CMTR-92–112 | Pancraniofacial fracture | 64 |
| CMTR-92–113 | Central craniocfacial - asymmetric bilateral NOE fracture in combination with frontal sinus fracture | 65 |
| CMTR-92–114 | Midface fracture: atypical Le Fort I and II combined with palate, atypical zygoma left and involvement of greater sphenoid wing left | 66 |
| CMTR-92–101 | Asymmetric Le Fort Level midface fracture | 67 - Tutorial |
| CMTR-92–102 | Zygoma Fracture left with dorsocranial displacement and antral impaction | 68 - Tutorial |
| CMTR-92–103 | Panfacial fracture including lower central midface fracture analogous to Hemi Le Fort I fracture | 69 - Tutorial |
| CMTR-92–104 | Naso-orbito-ethmoidal fracture bilateral (Example 1) | 70 - Tutorial |
| CMTR-92–105 | Naso-orbito-ethmoidal fracture (Example 2) | 71 - Tutorial |
| CMTR-92–106 | Lateral cranio-orbito-facial injury: fronto-spheno-zygomatico-orbital fracture | 72 - Tutorial |
| Level 3 Orbit 7 | ||
| CMTR-92–204 | Orbital floor fracture | 73 |
| CMTR-92–205 | NOE fracture | 74 |
| CMTR-92–206 | Orbital floor fracture | 75 |
| CMTR-92–207 | Zygoma fracture on the right side with inferior rim involvement | 76 |
| CMTR-92–208 | Zygoma fracture on the left side with inferior rim involvement | 77 |
| CMTR-92–209 | Four wall orbital fracture with complete bilateral disintegration | 78 |
| CMTR-92–210 | Fracture of the medial orbital wall in the anterior and middle section | 79 |
| CMTR-92–211 | NOE fracture on the right side with displacement | 80 |
| CMTR-92–212 | Isolated medial orbital wall fracture | 81 |
| CMTR-92–213 | Bilateral fractures of the orbital roof | 82 |
| CMTR-92–201 | Orbital floor fracture with intraorbital buttress involvement | 83 - Tutorial |
| CMTR-92–202 | Isolated medial orbital wall fracture with apex involvement | 84 - Tutorial |
| CMTR-92–203 | Zygoma fracture on the right side | 85 - Tutorial |
| Level 2 and 3 Skull Base and Cranial Vault 8 | ||
| CMTR-93–94–004 | Frontal cranial vault with right and central skull base fractures | 86 |
| CMTR-93–94–005 | Linear fracture involving the cranial vault and middle fossa skull base | 87 |
| CMTR-93–94–006 | Multiple, depressed and multifragmentary frontal cranial vault fractures with anterior skull base involvement | 88 |
| CMTR-93–94–007 | Anterior skull base fracture | 89 |
| CMTR-93–94–008 | Bilateral cranial vault fractures with extension into the anterior and middle skull base | 90 |
| CMTR-93–94–009 | Parietal cranial vault fracture with depression into the brain | 91 |
| CMTR-93–94–001 | Multiple cranial vault fractures | 92 - Tutorial |
| CMTR-93–94–002 | Single skull base fracture extending into the temporal cranial vault | 93 - Tutorial |
| CMTR-93–94–003 | Right occipital and temporal cranial vault fracture extending into the right middle fossa skull base | 94 - Tutorial |
Abbreviations: AOCOIAC, AO COmprehensive Injury Automatic Classifier9; Tutorial, case presented in the respective tutorial paper.
Access to Additional Electronic Content
Each fracture case example is available electronically from a Website of AOCMF (www.aocmf.org/classification) for viewing and editing by use of the new CMF fracture module of AOCOIAC software.9 A freeware copy of AOCOIAC (Version 4.0) and its user manuals can be obtained at the following Website: www.aofoundation.org/aocoiac.
Note and Disclaimer
While the developers thrived to make AOCOIAC 4.0 software as user-friendly and applicable as possible, they cannot guarantee it is problem-free and will work adequately on all computers. The user manuals should be read carefully before installation and use. The AO Foundation cannot take responsibility for any damages or inconveniences that may occur by using the available most current software version. For use of the AOCOIAC software, its manuals and all case examples, the AO Foundation terms, conditions, and disclaimers apply (https://www.aofoundation.org/Structure/the-ao-foundation/Pages/legal.aspx).
References
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