2.2 Fracture Classifi Cation 2.2.1 Principles Of Müller AO .

2 Principles of trauma care1142.2 Fracture classification2.2Fracture classification2.2.1Principles of Müller AO/OTA Classification of Fractures—Long Bones2.2.2Describing fracture n terminology1212.2.5Further reading121Techniques and Principles for the Operating RoomPorteous, Bäuerle115

Author James Kellam2.2 Fracture classificationFracture classifications have multiple purposes. They should facilitatecommunication among physicians and be useful for documentationand research. For clinical relevance, they should have a value toguide physicians in their planning and management of fractures.They should also inform both physicians and patients of theprognosis for the injury. The basis for all clinical activity, be itassessment and treatment, investigation and evaluation, or learningand teaching, must be sound data which is properly assembled,clearly expressed, and readily accessible. Numerous classificationsystems have been proposed in orthopaedics but only a smallnumber of them are widely accepted in practice, such as theMüller AO/OTA Classification of fractures. Even fewer have stoodthe rigorous task of evaluation.2.2.1 Principles of Müller AO/OTA Classification of Fractures—Long BonesOverall structure and attributesAny classification system should be suitable for the acquisition,storage, and retrieval of data. The Müller system presents a waynot only to document fractures but also to understand them inbiomechanical and biological terms. The system is based on a welldefined terminology which allows the surgeon to consistentlydescribe the fracture in as much detail as is required for the clinicalsituation. The description is the key to the classification and thisthen forms the basis for the alphanumeric code which makes itsuitable for computerization, documentation, and research. Thefirst aim of the surgeon is to identify what Müller has referred toas the “essence of the fracture.” This is the attribute that gives thefracture its particular identity and enables it to be assigned to oneparticular type.Classification is an ongoing process which depends on theinformation available to the surgeon at any given time. Thisprocess of classification is known as the diagnostic method. To makea diagnosis, information concerning the anatomical location andmorphological characteristics of the fracture is obtained. This consistsof a description of the location (ie, which bone is fractured andwhich part of the bone is affected?), followed by a fracturetype (ie, how many fragments are involved?), and finally themorphological characteristics of a fracture (ie, what does the fracturelook like?). This process provides useful clinical information forthe physician to determine treatment. Only when all informationconcerning the fracture is collected may the classification processbe considered complete.Fracture localization: bones and segmentsEach major long bone (humerus, radius and ulna, femur, andtibia and fibula) is named and then numbered (Fig 2.2-1). It shouldbe noted that the two-paired bones, that is the radius and ulna,and the tibia and fibula, are regarded as one entity or group. Eachlong bone consists of three segments. There are two end segments(proximal and distal) and these are joined by a middle portionknown as the diaphysis or shaft. The end segment consists of themetaphysis and articular surface. The extent of the end segmentsis defined as a square whose sides are the same length as the widest part of the epiphysis of the segment in question. Each of thesegments in the bones is also numbered (Fig 2.2-2). There is a finalsegment, the malleolar segment, which is an exception to therule. The pattern of these ankle fractures is determined by therelationship between the bones of the ankle mortise and theirassociated ligaments. The rule of defining the end segment cannotbe applied. The Weber classification is universally accepted forthis segment.To assign each fracture to a segment, the center of the fracturemust be determined. For a simple fracture, where there are onlytwo bone fragments, this is apparent. It is the midpoint of anoblique or spiral fracture, and in a transverse fracture it is obvious.115

2 Principles of trauma care2.2 Fracture classification .&"." 8gVc dbVm aad[VX Va WdcZh .'"*&"*'" &&"&" jbZgjh &*"&)"&*" 8aVk XjaV&)" HXVejaV &'"*" He cZ &("*(" '&"'" GVY jh jacV &" ''" '(" " EZak h VXZiVWjajb (&" '"," VcY ('"(" ;Zbjg eViZaaV ((" ()" )&")'")("))"-" ;ddiFig 2.2-1 Müller AO/OTA Classification for numbering the anatomical location of a fracture in three bone segments (proximal 1, diaphyseal 2,distal 3).116Techniques and Principles for the Operating RoomPorteous, BäuerleA wedge fracture has a center which is the broadest portion of thewedge or the mid portion of the fragmented area when reduced.For complex fractures, where there are many bone fragments, thecenter may well have to be determined after reduction whenthe full extent of fragmentation is determined. This may meanthat the surgeon can only give a final classification after surgicaltreatment. A displaced articular fracture will always be classifiedin an end segment regardless of its diaphyseal extension, since thearticular injury is the most important for treatment and prognosis.

Author James Kellam2.2.2 Describing fracture morphologyEnd segment fractures (metaphyseal and articular)The questions are:The description of the morphology of a fracture is determined bya set of precisely defined rules. Following these rules allows thesurgeon to classify a fracture according to its type, group, andsubgroup. For all fractures the surgeon classifies the fracture byanswering a well described set of questions. Müller and colleaguesrefined this process into a binary-type questioning. This meansthat there is either a yes/no or either/or answer. Different rulesapply to fractures in the middle segments of long bones (diaphyseal)and fractures in the end segments (articular or metaphyseal)Diaphyseal fracturesThe questions are:1. Which bone? Humerus, radius and ulna, femur or tibia(Fig 2.2-1)2. Which segment? Proximal end segment, middle segment(diaphysis), or distal end segment (Fig 2.2-1)3. Which type? (Fig 2.2-2)A. A simple fracture in which there are only two pieces ofboneB. A wedge fracture—there are more than two pieces of bonebut once reduced the main fragments will have somecontactC. Complex—three or more fragments. No contact betweenmain fragments after reduction4. Which group? (Fig 2.2-3)1. Spiral fractures2. Oblique fractures3. Transverse fractures1. Which bone?—Humerus, radius and ulna, femur, or tibia(Fig 2.2-1)2. Which segment—proximal or distal end segment(Fig 2.2-1)3. Which type? (Fig 2.2-2)A. Extraarticular—no involvement of articular surfaceB. Partial articular—part of the articular surface is involvedleaving the other part attached to the diaphysisC. Complete articular—articular surface involved. Metaphysealfracture completely separates articular component fromdiaphysis4. Which group? (Fig 2.2-4)A. Extraarticular fractures:1. Simple fracture with two pieces of bone2. Wedge fracture3. Multifragmentary fractureB. Partial articular fractures:1. Split2. Depression3. Split depressionC. Total articular fractures:1. Simple articular fracture with a simple metaphysealfracture2. Simple articular fracture with a complex metaphysealfracture3. Complex articular fracture with a complex metaphysealfracture117

2 Principles of trauma care2.2 Fracture classificationSegmentTypeABCExtraarticularPartial articularComplete articular1 ProximalNo involvement of displaced fracturesextending into the articular surfacePart of the articular component isinvolved, leaving the other part attachedto the meta-/diaphysisArticular surface involved, metaphysealfracture completely separates articularcomponent from the diaphysis2 DiaphysealSimpleOne fracture line, cortical contactbetween fragments exceeds 90% afterreductionWedgeComplexThree or more fragments, main fragmentshave contact after reductionThree or more fragments, main fragmentshave no contact after reductionPartial articularComplete articular3 DistalExtraarticularNo involvement of displaced fracturesextending into the articular surfacePart of the articular component isinvolved, leaving the other part attachedto the meta-/diaphysisFig 2.2-2 Definitions of fracture types for long-bone fractures in adults according to Müller AO/OTA Classification.118Techniques and Principles for the Operating RoomPorteous, BäuerleArticular surface involved, metaphysealfracture completely separates articularcomponent from the diaphysis

Author James eBWedgeCComplexFig 2.2-3 Classification of fractures of the diaphysis into the three fracture groups according to Müller AO/OTA Classification.119

2 Principles of trauma care2.2 Fracture DepressionSplit-depressionSimple articular,simple metaphysealSimple articular,complex metaphysealComplex articular,complex metaphysealAExtraarticularBPartial articularCArticularFig 2.2-4120Classification of fractures of the diaphysis into the three fracture groups according to Müller AO/OTA Classification.Techniques and Principles for the Operating RoomPorteous, Bäuerle