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The Value of Multislice Computed Tomography in the Diagnosis of Elbow Fractures Francisco Aparisi, MD, PhD1
Maria Pilar Aparisi, MD1
1 Hospital Universitarío La Fe y Hospital Nueve de Octubre,
Valencia, Spain
Address for correspondence Francisco Aparisi, MD, PhD, C. Dr. Sanchis Sivera, 18, 46008, Valencia, Spain (e-mail: [email protected]).
Abstract Keywords
► ► ► ► ► ►
elbow multislice CT fractures classification 3D examinations
Within the sports pathology it is vital the functional recovery of the lesions. To achieve this goal it is necessary very precise anatomical information. The elbow region is made up of three bones that together they have a complex relationship. Range of motion is wide and is thanks to the form of their components. To obtain precise information we need complex imaging techniques that allow us to avoid overlaps that show conventional radiology. Thanks to the development of CT multislices we have a high precision tool. Following the classification of the AO Foundation describes all types of fracture and provides images with 3D reconstruciton which allows you to schedule surgery the surgeon with a degree of prior information that approximates the excellence.
As a continuation of a long history of fracture classification in the AO Foundation, and the work promoted by Maurice E. Müller, the AO Classification Advisory Group and the AO Clinical Investigation and Documentation supports AO Specialties in the improvement and development of fracture classification systems. The result of this work has been a comprehensive classification of elbow fractures. The region of the elbow includes those elements belonging to the distal humerus and proximal ulna and radius. It has a complex bone anatomy and poses a difficult test for conventional radiology because overlaps make it difficult in many instances to recognize fracture traces. The introduction of tomography did not represent particular progress until the development of the multislice, which provides the possibility of multiplanar reconstruction and also allows three-dimensional (3D) evaluation that makes the anatomy of the fracture more understandable. The practice of sports is the origin of many ligamentous, osteochondral, and bone injuries that in many situations need to be evaluated with great precision to restore function. Conventional radiology is the tool’s approach and probably the magnetic resonance imaging (MRI) represents the essential tool in the near future, but currently
Issue Theme Sport Injuries of the Elbows and Fingers; Guest Editor, Mario Padrón, MD
CT multislice is the best choice to understand the anatomy.
AO/Association for the Study of Internal Fixation (ASIF) Classification of Elbow Fractures Humerus 13-A extra-articular fracture A1 apophyseal avulsion A2 metaphyseal simple A3 metaphyseal multifragmentary 13-B partial articular fracture B1 sagittal lateral condyle B2 sagittal medial condyle B3 coronal 13-C complete articular fracture C1 articular simple, metaphyseal simple C2 articular simple, metaphyseal multifragmentary C3 articular multifragmentary
Ulna and Radius 21-A extra-articular fracture A1 ulna fractured, radius intact
Copyright © 2013 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) 584-4662.
DOI http://dx.doi.org/ 10.1055/s-0033-1360664. ISSN 1089-7860.
This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.
Semin Musculoskelet Radiol 2013;17:437–445.
The Value of Multislice Computed Tomography
Aparisi
Fig. 1 Lateral condyle fracture, type A1. Multiple plane reconstructions: (a) coronal plane, (b and c) axial plane, (d) 3D volume render.
A2 radius fractured, ulna intact A3 both bones 21-B articular fracture B1 ulna fractured, radius intact B2 radius fractured, ulna intact B3 one bone articular fracture, other extra-articular 21-C articular fracture of both bones C1 simple C2 one articular simple, other articular multifragmentary C3 multifragmentary
Fracture Descriptions Distal Humerus Fracture “A classification is useful only if it considers the severity of the bone lesion and serves as a basis for treatment and for evaluation of the results.” —Maurice E. Müller Numerous fracture classification systems have been proposed in orthopedics, but only a small number of them have become widely accepted in practice. One is the Müller AO Classification of Fractures—Long Bones. Even fewer have stood the rigorous test of validation. The distal humerus was classically described as having medial and lateral structural columns that provide primary axial loadbearing stability to the humerus. The distal third of the medial column is composed of the medial epicondyle, which is notably the origin of the flexor muscles of the forearm, as well as the proximal attachment
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site of the anterior and posterior bundles of the medial collateral ligament (MCL). The distal third of the lateral column is composed of the lateral epicondyle, the proximal attachment site of the lateral collateral ligament complex. The AO-ASIF system enables more precise and reproducible classification with a potentially greater predictive benefit. It emphasizes articular and columnar involvement as well as the degree of comminution. Fractures are classified into three main types, each of which comprises three subtypes. Type A1 includes two different fractures, medial condyle and lateral condyle. Both fractures may occur together (►Figs. 1, 2, 3). Elbow stability depends on bone, ligaments, and cartilaginous elements, bone continuity solution conditions in large number of occasions problems of instability, but CT is unable to show the state of the ligaments. A separation of bone fragment > 2 mm is indicative of fracture with rupture of the periosteum that indicates potential instability. Displaced fractures need surgical treatment. Those only minimally displaced assuming there is continuity of the periosteum can be treated conservatively. Type A and B fractures are often not easy to differentiate because the partial articular extension can be difficult to recognize. There is no significant difference in prognosis. The A2 group includes extra-articular fractures involving the metaphyseal zone. This fracture is called transversal
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Aparisi
Fig. 2 Medial condyle fracture, type A1. Type A and B fractures are often difficult to differentiate because the partial articular extension can be difficult to assess. There is however no significant difference in prognosis. (a) Displaced medial epicondyle fragment in the coronal plane. (b) Tridimensional reconstruction provides information and displacement of fragment.
Fig. 3 Medial and lateral condyle fractures (apophyseal), type A1. Note the epicondyle fragments in axial plane (a) and in the tridimensional reconstruction (b).
Fig. 4 Metaphyseal fracture, type A2. (a) Lucency line parallel to the physis in the coronal plane. (b) 3D reconstruction in this case adds information on alignment of the joint.
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The Value of Multislice Computed Tomography
The Value of Multislice Computed Tomography
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Fig. 5 Transversal supracondylar fracture, type A2 (a and c) coronal and sagittal planes, (b) 3D. (adapted AOS classification; Sheehan SE, Dyer GS, Sodickson AD, Patel KI, Khurana B. Traumatic elbow injuries: what the orthopedic surgeon wants to know. Radiographics 2013;33(3):869–888).1
supracondylar. This group also includes the isolated metaphyseal fractures (►Figs. 4 and 5). Radiography generally is sufficient for the initial identification and classification of distal humerus fractures. However, after a fracture of the distal humerus is identified by
radiography, CT is usually performed to ensure accurate fracture classification because of the high incidence of severe injuries that ultimately require surgery. If the fracture extends to the articular surface, the prognosis is worse because the reduction should be more correct.
Fig. 6 Supracondylar fracture type “T,” 13 C-1, AO - ASIF classification. Coronal plane (a) note the articular extension. Axial view of the humerus (b). There is minimal displacement of fragments.
Fig. 7 Condylar fracture in coronal plane, 13 B-3 AO - ASIF classification. (a) 3D reconstruction, (b) sagittal plane, (c) coronal view.
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These types of fractures are often called “T,” fracture type 13 C-1, the AO/ASIF classification (►Fig. 6). If there are more fragments, the complete reconstruction is more difficult. Fracture type 13 B-3 is a condylar fracture in the coronal plane (►Fig. 7).
If there is a single articular fracture and several metaphyseal fragments, the lesion is called 13 C-2 in the AO-ASIF classification (►Fig. 8). Using 3D reconstruction we can obtain the real number and position of the fragments.
Fig. 9 Osteochondral condylar fracture, 13 C-1 AO - ASIF classification. Coronal (a) and rendered coronal view (d). Sagittal view (c) and sagittal rendering (b). Seminars in Musculoskeletal Radiology
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Fig. 8 Single articular fracture with multiple metaphyseal fragments, 13 C-2 AO - ASIF classification. (a) Coronal plane, (b) 3D reconstruction where the spatial distribution of fragments is well demonstrated. (c) Sagittal plane.
The Value of Multislice Computed Tomography
Aparisi
Fig. 10 Multifragmented fracture of the humeral condyle, 13 C-3 AO - ASIF classification. (a) Volume rendering, (b) sagital plane, (c) axial view.
An isolated articular fracture in humerus is uncommon, but using 3D multislice examination, we can probe for the presence of a minimal articular lesion. The osteochondral lesions are included in the group 13 C. The subgroups are C-1 for isolated lesions (►Fig. 9) and C-3 in the case of multifragmented lesions. These lesions pose a serious problem in the articular prognosis (►Fig. 10).
neck fractures are classified into four groups (types I–IV) according to the morphological characteristics of the fracture and the presence or absence of associated dislocation. Treatment depends on both the fracture type and the functional range of motion.
Radial Head and Neck Fractures Although the AOS classification is accepted internationally, it is sometimes not enough for treatment planning of a region. Specifically, in the area of the proximal radius and proximal ulna, this classification seems insufficient. Radial head and neck fractures are the most common elbow fractures in adults, comprising 33 to 50% of elbow fractures. Multiple classification systems have been proposed, but the Mason system with the Johnston modification is the one most commonly referenced in the radiology and orthopedic literature. In the Mason-Johnston system, radial head and
Fig. 11 Radial head fracture type I. Sagittal plane. Seminars in Musculoskeletal Radiology
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Fig. 12 Type II radial head fracture in the axial plane and specific tridimensional reconstruction, as a virtual dissection (a). Radial head fracture with a significantly displaced fragment, in the sagittal and axial planes and rendered volume (b).
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The diagnosis is usually made at initial radiography, even with subtle radial head fractures indicated by the presence of elevation of the anterior and posterior fat pads that are intracapsular but extrasynovial. This radiologic sign remains useful, mainly in pediatric patients. We often read that CT scans are not necessary for diagnosis, but now facilities have multiple crowns that can obtain high-quality images that outperform conventional radiology and allow a better classification. The high accuracy of these tools even allows the radiologic “dissection” and evaluates the radial head without overlaps. Early detection and appropriate classification of radial head fractures are critical for ensuring their appropriate treatment. The recognition of a radial head fracture should prompt a focused search for associated complicating injuries. An uncommonly seen but clinically important fracture pattern is the Essex-Lopresti injury that involves a comminuted fracture of the radial head with dislocation of the distal radioulnar joint and disruption of the interosseous membrane, producing the often cited “floating radius.” The radiographic features of distal radioulnar joint dislocation can be subtle, but a radioulnar distance discrepancy > 5 mm on lateral radiographs of the injured wrist relative to the contralateral uninjured wrist is considered diagnostic.
Mason Classification of Radial Head Fractures For type I, marginal fractures, multislice CT examination allows us to obtain a good image of the radial head (►Fig. 11). The sector most frequently affected is the anterior-external. Oblique radiographs may be discovered, but the CT image is easier and provides more information. The type II classification includes radial head fracture, two fragments, with some displacement (►Fig. 12). Using electronic dissection we can better assess the extent of the fracture. Using 3D reconstruction we can assess the severity of the injury and determine if surgical reconstruction is necessary. For type III, radial head fracture comminuted, only multislice CT is able to determine the number of fragments and determine the real extension of the lesion (►Fig. 13).
Fig. 13 Type III, comminuted radial head fracture, in the sagittal (left) and coronal plane (right). CT allows to determine the number and location of fragments.
Aparisi
Fig. 14 Type IV, fracture and dislocation of the radial head. This type implies ligament rupture and needs surgical reduction. Clockwise: sagittal, coronal and rendered.
In type IV, radial fracture with luxation, the radial head loses its connection with the capitellum, implying ligament rupture and a surgical solution (►Fig. 14). Following the AO classification, there are other fractures that would not be included in the Mason classification. These radial neck fractures are type 21A2 of the AO classification (►Fig. 15).
Ulnar Fractures Coronoid Process Fracture The coronoid process makes up the anterior margin of the ulnohumeral articulation and serves to resist varus stress and prevent posterior elbow subluxation. The coronoid process also serves as the site of anterior attachment of the joint capsule, insertion of the MCL, and insertion of the brachialis muscle at its anterior aspect. Isolated coronoid process fractures are uncommon; most coronoid process fractures occur in the context of elbow dislocation and are associated with
Fig. 15 Radial neck fracture. These fractures are not included in the Mason classification. Following the AO, these would represent type 21 A2. Sagittal (left) and volume render (right). Seminars in Musculoskeletal Radiology
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The Value of Multislice Computed Tomography
The Value of Multislice Computed Tomography
Aparisi
Fig. 16 Coronoid fracture (left) and comminuted radial head fracture (right). Isolated coronoid process fractures are rare; most occur in the context of dislocation and associate comminuted proximal ulna and radial head fractures.
comminuted proximal ulna fractures and radial head fractures (►Fig. 16). Coronoid process fractures were classically defined within the Regan and Morrey classification system, according to the percentage of the process fractured in the horizontal (shear) plane. However, the clinical utility of this system has been called into question because it fails to emphasize the importance of the sagittal fracture plane. It has been shown that 50% of the coronoid process surface area is needed to maintain posterior and varus elbow stability. Fractures of the anteromedial facet are a commonly seen coronoid process fracture pattern, often with associated injuries of the MCL (which inserts on the sublime tubercle of the medial coronoid base) that lead to the development of varus and posteromedial rotatory instability (PLRI). O’Driscoll et al introduced a more comprehensive classification system that emphasizes the importance of the anteromedial facet that has been widely adopted by the orthopedic community. In the O’Driscoll system, coronoid process fractures are classified into three main types, each of which comprises several more specific subtypes. Type I transverse coronoid tip fractures can be treated conservatively if stability is maintained; however, the risk of
Fig. 17 Type I coronoid process fracture, in the sagittal (left) and axial planes (right). The risk of instability increases with the increasing size of fracture fragment.
instability increases with the increasing size of fracture fragments (►Fig. 17). Type II fractures involve the anteromedial facet, with subtypes varying according to the degree of involvement of the sublime tubercle and the location of the fracture along the facet. The anteromedial facet of the coronoid process is evaluated because it confers stability during varus stress and is in close proximity to the ulnar attachment site of the anterior bundle of the MCL, which resists valgus stress. Type III fractures involve the base of the coronoid process, with disruption of > 50% of the coronoid body. Types II and III nearly always require surgical repair for maintenance of elbow stability, and the surgical approach varies by fracture type. Tiny coronoid process tip fractures are often described as avulsion fractures, but such descriptions are erroneous because there is no anatomical structure that inserts directly onto the coronoid tip. These fractures most commonly occur as a complication of subluxation or dislocation, predominantly during axial and posteromedial rotatory loading, and they may herald additional occult damage to bone or soft tissue (e.g., lateral collateral ligament complex injuries). The severity and extent of small coronoid tip fractures therefore cannot be adequately evaluated with radiography alone, and a
Fig. 18 Olecranon fracture type II, without displacement of fragment. Best seen in the sagittal plane (sagittal view on left, volume rendering on the right).
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radiographic finding of a seemingly tiny coronoid tip fracture should prompt additional imaging.
Olecranon Fractures The olecranon, which forms the posteroinferior margin of the ulnohumeral articulation, functions as a buttress preventing anterior dislocation of the elbow. The olecranon also provides an insertion point for the triceps tendon. The anterior margin of the olecranon merges with the posterior margin of the coronoid process to form the semilunar notch, the locus of ulnohumeral articulation with the trochlea. By convention, fractures involving the semilunar notch are considered olecranon fractures. Multiple systems have been proposed for classifying olecranon fractures, and no single system has achieved predominance. In evaluating olecranon fractures, emphasis should be placed on describing the degree of displacement and presence of comminution because those are the key determinants of the treatment approach. Patients with nondisplaced fractures < 2 mm wide, with no increase in displacement > 90 degrees of flexion or during active extension, can usually undergo a trial of conservative therapy (►Fig. 18). Displacement of fracture fragments (with a gap > 2 mm), increased displacement during elbow flexion or extension, and the presence of comminution are surgical indications (►Fig. 19). The presence of comminution should be specifically emphasized because it is an indication for the use of a plate instead of a tension band-wire construct for fixation.
Horne and Tanzer Classification of Olecranon Fractures This classification is described as follows: type I, transverse intra-articular, proximal third of olecranon articular surface or oblique extra-articular, involving the tip of the olecranon; type II, oblique or transverse, involving middle third of greater sigmoid notch; and type III, involving distal third of the greater sigmoid notch with or without coronoid fracture. Radiography is generally sufficient for initial and postreduction evaluations, but CT is often performed in cases in which surgical repair is indicated. MR imaging is occasionally used in ambiguous cases or when the presence of stress fractures is suspected. MR imaging allows excellent evaluation of the triceps tendon and is often indicated in cases of avulsion-type fracture .With appropriate treatment, the outcomes of olecranon fractures are generally good, with chronic anterior instability only rarely encountered. Multislice CT has given us the best tool for the detailed evaluation of the bone anatomy of joints. The elbow region confirms this assumption and currently represents an essential tool for the treatment when the goal is the complete functional recovery of the joint, a circumstance that is essential to practice sports.
Reference 1 Sheehan SE, Dyer GS, Sodickson AD, Patel KI, Khurana B. Traumatic
elbow injuries: what the orthopedic surgeon wants to know. Radiographics 2013;33(3):869–888
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Fig. 19 Olecranon fracture type II. Displaced fracture. Sagittal view (left) and sagittal rendering (right).
Copyright of Seminars in Musculoskeletal Radiology is the property of Thieme Medical Publishing Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
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The Value of Multislice Computed Tomography in the Diagnosis of Elbow Fractures Francisco Aparisi, MD, PhD1
Maria Pilar Aparisi, MD1
1 Hospital Universitarío La Fe y Hospital Nueve de Octubre,
Valencia, Spain
Address for correspondence Francisco Aparisi, MD, PhD, C. Dr. Sanchis Sivera, 18, 46008, Valencia, Spain (e-mail: [email protected]).
Abstract Keywords
► ► ► ► ► ►
elbow multislice CT fractures classification 3D examinations
Within the sports pathology it is vital the functional recovery of the lesions. To achieve this goal it is necessary very precise anatomical information. The elbow region is made up of three bones that together they have a complex relationship. Range of motion is wide and is thanks to the form of their components. To obtain precise information we need complex imaging techniques that allow us to avoid overlaps that show conventional radiology. Thanks to the development of CT multislices we have a high precision tool. Following the classification of the AO Foundation describes all types of fracture and provides images with 3D reconstruciton which allows you to schedule surgery the surgeon with a degree of prior information that approximates the excellence.
As a continuation of a long history of fracture classification in the AO Foundation, and the work promoted by Maurice E. Müller, the AO Classification Advisory Group and the AO Clinical Investigation and Documentation supports AO Specialties in the improvement and development of fracture classification systems. The result of this work has been a comprehensive classification of elbow fractures. The region of the elbow includes those elements belonging to the distal humerus and proximal ulna and radius. It has a complex bone anatomy and poses a difficult test for conventional radiology because overlaps make it difficult in many instances to recognize fracture traces. The introduction of tomography did not represent particular progress until the development of the multislice, which provides the possibility of multiplanar reconstruction and also allows three-dimensional (3D) evaluation that makes the anatomy of the fracture more understandable. The practice of sports is the origin of many ligamentous, osteochondral, and bone injuries that in many situations need to be evaluated with great precision to restore function. Conventional radiology is the tool’s approach and probably the magnetic resonance imaging (MRI) represents the essential tool in the near future, but currently
Issue Theme Sport Injuries of the Elbows and Fingers; Guest Editor, Mario Padrón, MD
CT multislice is the best choice to understand the anatomy.
AO/Association for the Study of Internal Fixation (ASIF) Classification of Elbow Fractures Humerus 13-A extra-articular fracture A1 apophyseal avulsion A2 metaphyseal simple A3 metaphyseal multifragmentary 13-B partial articular fracture B1 sagittal lateral condyle B2 sagittal medial condyle B3 coronal 13-C complete articular fracture C1 articular simple, metaphyseal simple C2 articular simple, metaphyseal multifragmentary C3 articular multifragmentary
Ulna and Radius 21-A extra-articular fracture A1 ulna fractured, radius intact
Copyright © 2013 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) 584-4662.
DOI http://dx.doi.org/ 10.1055/s-0033-1360664. ISSN 1089-7860.
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Semin Musculoskelet Radiol 2013;17:437–445.
The Value of Multislice Computed Tomography
Aparisi
Fig. 1 Lateral condyle fracture, type A1. Multiple plane reconstructions: (a) coronal plane, (b and c) axial plane, (d) 3D volume render.
A2 radius fractured, ulna intact A3 both bones 21-B articular fracture B1 ulna fractured, radius intact B2 radius fractured, ulna intact B3 one bone articular fracture, other extra-articular 21-C articular fracture of both bones C1 simple C2 one articular simple, other articular multifragmentary C3 multifragmentary
Fracture Descriptions Distal Humerus Fracture “A classification is useful only if it considers the severity of the bone lesion and serves as a basis for treatment and for evaluation of the results.” —Maurice E. Müller Numerous fracture classification systems have been proposed in orthopedics, but only a small number of them have become widely accepted in practice. One is the Müller AO Classification of Fractures—Long Bones. Even fewer have stood the rigorous test of validation. The distal humerus was classically described as having medial and lateral structural columns that provide primary axial loadbearing stability to the humerus. The distal third of the medial column is composed of the medial epicondyle, which is notably the origin of the flexor muscles of the forearm, as well as the proximal attachment
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site of the anterior and posterior bundles of the medial collateral ligament (MCL). The distal third of the lateral column is composed of the lateral epicondyle, the proximal attachment site of the lateral collateral ligament complex. The AO-ASIF system enables more precise and reproducible classification with a potentially greater predictive benefit. It emphasizes articular and columnar involvement as well as the degree of comminution. Fractures are classified into three main types, each of which comprises three subtypes. Type A1 includes two different fractures, medial condyle and lateral condyle. Both fractures may occur together (►Figs. 1, 2, 3). Elbow stability depends on bone, ligaments, and cartilaginous elements, bone continuity solution conditions in large number of occasions problems of instability, but CT is unable to show the state of the ligaments. A separation of bone fragment > 2 mm is indicative of fracture with rupture of the periosteum that indicates potential instability. Displaced fractures need surgical treatment. Those only minimally displaced assuming there is continuity of the periosteum can be treated conservatively. Type A and B fractures are often not easy to differentiate because the partial articular extension can be difficult to recognize. There is no significant difference in prognosis. The A2 group includes extra-articular fractures involving the metaphyseal zone. This fracture is called transversal
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Aparisi
Fig. 2 Medial condyle fracture, type A1. Type A and B fractures are often difficult to differentiate because the partial articular extension can be difficult to assess. There is however no significant difference in prognosis. (a) Displaced medial epicondyle fragment in the coronal plane. (b) Tridimensional reconstruction provides information and displacement of fragment.
Fig. 3 Medial and lateral condyle fractures (apophyseal), type A1. Note the epicondyle fragments in axial plane (a) and in the tridimensional reconstruction (b).
Fig. 4 Metaphyseal fracture, type A2. (a) Lucency line parallel to the physis in the coronal plane. (b) 3D reconstruction in this case adds information on alignment of the joint.
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The Value of Multislice Computed Tomography
The Value of Multislice Computed Tomography
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Fig. 5 Transversal supracondylar fracture, type A2 (a and c) coronal and sagittal planes, (b) 3D. (adapted AOS classification; Sheehan SE, Dyer GS, Sodickson AD, Patel KI, Khurana B. Traumatic elbow injuries: what the orthopedic surgeon wants to know. Radiographics 2013;33(3):869–888).1
supracondylar. This group also includes the isolated metaphyseal fractures (►Figs. 4 and 5). Radiography generally is sufficient for the initial identification and classification of distal humerus fractures. However, after a fracture of the distal humerus is identified by
radiography, CT is usually performed to ensure accurate fracture classification because of the high incidence of severe injuries that ultimately require surgery. If the fracture extends to the articular surface, the prognosis is worse because the reduction should be more correct.
Fig. 6 Supracondylar fracture type “T,” 13 C-1, AO - ASIF classification. Coronal plane (a) note the articular extension. Axial view of the humerus (b). There is minimal displacement of fragments.
Fig. 7 Condylar fracture in coronal plane, 13 B-3 AO - ASIF classification. (a) 3D reconstruction, (b) sagittal plane, (c) coronal view.
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These types of fractures are often called “T,” fracture type 13 C-1, the AO/ASIF classification (►Fig. 6). If there are more fragments, the complete reconstruction is more difficult. Fracture type 13 B-3 is a condylar fracture in the coronal plane (►Fig. 7).
If there is a single articular fracture and several metaphyseal fragments, the lesion is called 13 C-2 in the AO-ASIF classification (►Fig. 8). Using 3D reconstruction we can obtain the real number and position of the fragments.
Fig. 9 Osteochondral condylar fracture, 13 C-1 AO - ASIF classification. Coronal (a) and rendered coronal view (d). Sagittal view (c) and sagittal rendering (b). Seminars in Musculoskeletal Radiology
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Fig. 8 Single articular fracture with multiple metaphyseal fragments, 13 C-2 AO - ASIF classification. (a) Coronal plane, (b) 3D reconstruction where the spatial distribution of fragments is well demonstrated. (c) Sagittal plane.
The Value of Multislice Computed Tomography
Aparisi
Fig. 10 Multifragmented fracture of the humeral condyle, 13 C-3 AO - ASIF classification. (a) Volume rendering, (b) sagital plane, (c) axial view.
An isolated articular fracture in humerus is uncommon, but using 3D multislice examination, we can probe for the presence of a minimal articular lesion. The osteochondral lesions are included in the group 13 C. The subgroups are C-1 for isolated lesions (►Fig. 9) and C-3 in the case of multifragmented lesions. These lesions pose a serious problem in the articular prognosis (►Fig. 10).
neck fractures are classified into four groups (types I–IV) according to the morphological characteristics of the fracture and the presence or absence of associated dislocation. Treatment depends on both the fracture type and the functional range of motion.
Radial Head and Neck Fractures Although the AOS classification is accepted internationally, it is sometimes not enough for treatment planning of a region. Specifically, in the area of the proximal radius and proximal ulna, this classification seems insufficient. Radial head and neck fractures are the most common elbow fractures in adults, comprising 33 to 50% of elbow fractures. Multiple classification systems have been proposed, but the Mason system with the Johnston modification is the one most commonly referenced in the radiology and orthopedic literature. In the Mason-Johnston system, radial head and
Fig. 11 Radial head fracture type I. Sagittal plane. Seminars in Musculoskeletal Radiology
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Fig. 12 Type II radial head fracture in the axial plane and specific tridimensional reconstruction, as a virtual dissection (a). Radial head fracture with a significantly displaced fragment, in the sagittal and axial planes and rendered volume (b).
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The diagnosis is usually made at initial radiography, even with subtle radial head fractures indicated by the presence of elevation of the anterior and posterior fat pads that are intracapsular but extrasynovial. This radiologic sign remains useful, mainly in pediatric patients. We often read that CT scans are not necessary for diagnosis, but now facilities have multiple crowns that can obtain high-quality images that outperform conventional radiology and allow a better classification. The high accuracy of these tools even allows the radiologic “dissection” and evaluates the radial head without overlaps. Early detection and appropriate classification of radial head fractures are critical for ensuring their appropriate treatment. The recognition of a radial head fracture should prompt a focused search for associated complicating injuries. An uncommonly seen but clinically important fracture pattern is the Essex-Lopresti injury that involves a comminuted fracture of the radial head with dislocation of the distal radioulnar joint and disruption of the interosseous membrane, producing the often cited “floating radius.” The radiographic features of distal radioulnar joint dislocation can be subtle, but a radioulnar distance discrepancy > 5 mm on lateral radiographs of the injured wrist relative to the contralateral uninjured wrist is considered diagnostic.
Mason Classification of Radial Head Fractures For type I, marginal fractures, multislice CT examination allows us to obtain a good image of the radial head (►Fig. 11). The sector most frequently affected is the anterior-external. Oblique radiographs may be discovered, but the CT image is easier and provides more information. The type II classification includes radial head fracture, two fragments, with some displacement (►Fig. 12). Using electronic dissection we can better assess the extent of the fracture. Using 3D reconstruction we can assess the severity of the injury and determine if surgical reconstruction is necessary. For type III, radial head fracture comminuted, only multislice CT is able to determine the number of fragments and determine the real extension of the lesion (►Fig. 13).
Fig. 13 Type III, comminuted radial head fracture, in the sagittal (left) and coronal plane (right). CT allows to determine the number and location of fragments.
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Fig. 14 Type IV, fracture and dislocation of the radial head. This type implies ligament rupture and needs surgical reduction. Clockwise: sagittal, coronal and rendered.
In type IV, radial fracture with luxation, the radial head loses its connection with the capitellum, implying ligament rupture and a surgical solution (►Fig. 14). Following the AO classification, there are other fractures that would not be included in the Mason classification. These radial neck fractures are type 21A2 of the AO classification (►Fig. 15).
Ulnar Fractures Coronoid Process Fracture The coronoid process makes up the anterior margin of the ulnohumeral articulation and serves to resist varus stress and prevent posterior elbow subluxation. The coronoid process also serves as the site of anterior attachment of the joint capsule, insertion of the MCL, and insertion of the brachialis muscle at its anterior aspect. Isolated coronoid process fractures are uncommon; most coronoid process fractures occur in the context of elbow dislocation and are associated with
Fig. 15 Radial neck fracture. These fractures are not included in the Mason classification. Following the AO, these would represent type 21 A2. Sagittal (left) and volume render (right). Seminars in Musculoskeletal Radiology
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The Value of Multislice Computed Tomography
The Value of Multislice Computed Tomography
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Fig. 16 Coronoid fracture (left) and comminuted radial head fracture (right). Isolated coronoid process fractures are rare; most occur in the context of dislocation and associate comminuted proximal ulna and radial head fractures.
comminuted proximal ulna fractures and radial head fractures (►Fig. 16). Coronoid process fractures were classically defined within the Regan and Morrey classification system, according to the percentage of the process fractured in the horizontal (shear) plane. However, the clinical utility of this system has been called into question because it fails to emphasize the importance of the sagittal fracture plane. It has been shown that 50% of the coronoid process surface area is needed to maintain posterior and varus elbow stability. Fractures of the anteromedial facet are a commonly seen coronoid process fracture pattern, often with associated injuries of the MCL (which inserts on the sublime tubercle of the medial coronoid base) that lead to the development of varus and posteromedial rotatory instability (PLRI). O’Driscoll et al introduced a more comprehensive classification system that emphasizes the importance of the anteromedial facet that has been widely adopted by the orthopedic community. In the O’Driscoll system, coronoid process fractures are classified into three main types, each of which comprises several more specific subtypes. Type I transverse coronoid tip fractures can be treated conservatively if stability is maintained; however, the risk of
Fig. 17 Type I coronoid process fracture, in the sagittal (left) and axial planes (right). The risk of instability increases with the increasing size of fracture fragment.
instability increases with the increasing size of fracture fragments (►Fig. 17). Type II fractures involve the anteromedial facet, with subtypes varying according to the degree of involvement of the sublime tubercle and the location of the fracture along the facet. The anteromedial facet of the coronoid process is evaluated because it confers stability during varus stress and is in close proximity to the ulnar attachment site of the anterior bundle of the MCL, which resists valgus stress. Type III fractures involve the base of the coronoid process, with disruption of > 50% of the coronoid body. Types II and III nearly always require surgical repair for maintenance of elbow stability, and the surgical approach varies by fracture type. Tiny coronoid process tip fractures are often described as avulsion fractures, but such descriptions are erroneous because there is no anatomical structure that inserts directly onto the coronoid tip. These fractures most commonly occur as a complication of subluxation or dislocation, predominantly during axial and posteromedial rotatory loading, and they may herald additional occult damage to bone or soft tissue (e.g., lateral collateral ligament complex injuries). The severity and extent of small coronoid tip fractures therefore cannot be adequately evaluated with radiography alone, and a
Fig. 18 Olecranon fracture type II, without displacement of fragment. Best seen in the sagittal plane (sagittal view on left, volume rendering on the right).
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radiographic finding of a seemingly tiny coronoid tip fracture should prompt additional imaging.
Olecranon Fractures The olecranon, which forms the posteroinferior margin of the ulnohumeral articulation, functions as a buttress preventing anterior dislocation of the elbow. The olecranon also provides an insertion point for the triceps tendon. The anterior margin of the olecranon merges with the posterior margin of the coronoid process to form the semilunar notch, the locus of ulnohumeral articulation with the trochlea. By convention, fractures involving the semilunar notch are considered olecranon fractures. Multiple systems have been proposed for classifying olecranon fractures, and no single system has achieved predominance. In evaluating olecranon fractures, emphasis should be placed on describing the degree of displacement and presence of comminution because those are the key determinants of the treatment approach. Patients with nondisplaced fractures < 2 mm wide, with no increase in displacement > 90 degrees of flexion or during active extension, can usually undergo a trial of conservative therapy (►Fig. 18). Displacement of fracture fragments (with a gap > 2 mm), increased displacement during elbow flexion or extension, and the presence of comminution are surgical indications (►Fig. 19). The presence of comminution should be specifically emphasized because it is an indication for the use of a plate instead of a tension band-wire construct for fixation.
Horne and Tanzer Classification of Olecranon Fractures This classification is described as follows: type I, transverse intra-articular, proximal third of olecranon articular surface or oblique extra-articular, involving the tip of the olecranon; type II, oblique or transverse, involving middle third of greater sigmoid notch; and type III, involving distal third of the greater sigmoid notch with or without coronoid fracture. Radiography is generally sufficient for initial and postreduction evaluations, but CT is often performed in cases in which surgical repair is indicated. MR imaging is occasionally used in ambiguous cases or when the presence of stress fractures is suspected. MR imaging allows excellent evaluation of the triceps tendon and is often indicated in cases of avulsion-type fracture .With appropriate treatment, the outcomes of olecranon fractures are generally good, with chronic anterior instability only rarely encountered. Multislice CT has given us the best tool for the detailed evaluation of the bone anatomy of joints. The elbow region confirms this assumption and currently represents an essential tool for the treatment when the goal is the complete functional recovery of the joint, a circumstance that is essential to practice sports.
Reference 1 Sheehan SE, Dyer GS, Sodickson AD, Patel KI, Khurana B. Traumatic
elbow injuries: what the orthopedic surgeon wants to know. Radiographics 2013;33(3):869–888
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Fig. 19 Olecranon fracture type II. Displaced fracture. Sagittal view (left) and sagittal rendering (right).
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Copyright of Seminars in Musculoskeletal Radiology is the property of Thieme Medical Publishing Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
