Falling on the Elbow: As Hard as Love

Transcription

1 Falling on the Elbow: As Hard as Love Poster No.: C-2538 Congress: ECR 2012 Type: Educational Exhibit Authors: E. Alvarado Burgos, Y. M. López-Álvarez, L. García, N. I Sedora-Roman, S. Baussan, M. Rivera, S. Vale, J. Vidal ; 1 2 San Juan, PR/US, Bayamon, PR/US Keywords: Trauma, Education, Plain radiographic studies, CT-High Resolution, CT, Musculoskeletal joint, Musculoskeletal bone DOI: /ecr2012/C-2538 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 42

2 Learning objectives 1. To review the relevant anatomy of the elbow. 2. Discuss the anatomical and radiological descriptors and terminology in the reporting of elbow trauma. 3. Review the complementary role of plain films and Multi-Detector Computed Tomography (MDCT), with the use of Multi-Planar Reconstruction (MPR), in the diagnosis and management of selected patients with elbow trauma. 4.Review classifications for injuries at supracondylar area, capitellum, radial head, coronoid process, olecranon process, lateral condyle, and multiple sites proposed by Gartland, Bryan and Morrey, Mason Johnston, Morrey, Mayo Clinic, Rutherford, and Monteggia, respectively. Background INTRODUCTION AND EPIDEMIOLOGY The radiologist plays a crucial role in evaluation of patients with elbow trauma because management of elbow dislocations and fractures is based on clinical examination and interpretation of imaging studies. Missed fractures can lead to malunion, pain, instability, recurrent elbow dislocation, and/ or limited motion [20]. This not only causes increase in patient morbidity but also accounts for many of radiology malpractice suits involving misdiagnosis in the United States [20]. Elbow dislocations represent 11-28% of all elbow injuries, with an annual incidence of 6-8 cases per 100,000 people [7]. Approximately 40% of elbow dislocations occur during sports. The mean age of an individual sustaining this injury is 30 years. There is male predominance with 2 to 2.5 times that of females [1]. Elbow fractures account for approximately 7% of all adult fractures; of these, approximately 30% involve the distal humerus [23]. Page 2 of 42

3 CLINICAL PRESENTATION After trauma, most patients with injury involving the elbow region will present with: Regional pain Point tenderness Swelling Inability to bear weight Ecchymosis Limited range of motion CONTRAINTS OF THE ELBOW JOINT Primary static constraints: Ulno-humeral articulation Anterior bundle of the Medial Collateral Ligament (MCL) Lateral Collateral Ligament (LCL) Secondary static constraints: Radio-capitellar articulation Common flexor tendon Common extensor tendon Capsule Dynamic stabilizers: muscles that cross the elbow joint (e.g. biceps) Muscular flexor and extensor origins represent secondary stabilizers of the elbow. If they are intact, they provide adequate stability to allow ligamentous healing after elbow dislocation [1]. BIOMECHANICS Weight bearing: 43% distribution of the weight is distributed across the ulno-humeral joint and 57% across the radio-capitellar joint [2]. Page 3 of 42

4 Force: When the elbow is flexed at 90 degrees, force is concentrated at the olecranon; when extended, the force is concentrated at the coronoid [2]. Movement: The elbow is a hinge joint with a normal range of flexion/extension motion of 0 to 140 degrees [2]. AMERICAN COLLEGE OF RADIOLOGY (ACR) APPROPRIATENESS CRITERIA Acute elbow pain is not included in the ACR appropriateness criteria. However, at our institution, acute trauma to the elbow is usually evaluated with AP and lateral x-rays. MDCT has been useful for controversial cases in which the x-ray does not provide enough information for the orthopedist, or when a hidden fracture is suspected. ACR appropriateness criteria does include chronic elbow pain for which x-ray has a rating of 9 (most appropriate) for initial evaluation. Elbow MRI without contrast has a rating of 9 in chronic elbow pain with suspected: Biceps tendon tear Collateral ligament tear Occult injury Unstable osteochondral injury Nerve abnormality IMAGING A. RADIOGRAPHS Best imaging tool: AP, Lateral and Oblique views External rotation view preferred for radio-capitellar joint. Internal rotation view is used to assess the humeral ulnar joint. B. STRESS RADIOGRAPHS: Provide an indirect measure of valgus laxity, not used at our institution. Limitations: In the setting of acute injury, pain inhibits full valgus or varus load to the elbow joint. Page 4 of 42

5 In the immature athlete, caution should be taken to avoid inadvertent displacement of the medial epicondylar apophysis by excessive valgus load to the already injured growth plate. C. CT SCAN Determines position of comminuted fragments and complex dislocation patterns. Primarily aimed at supporting the planning of an operation [7]. D. Ultrasound Not routinely used at our institution. Permits direct guidance for regional injections [4]. Provides a non-invasive modality of assessing the integrity of regional tendon attachments [4]. E. MR Imaging Limited role in the acute setting. More useful in the evaluation of muscles, tendons, and ligaments as well as in the case of chronic instability and continued pain in spite of normal radiographs. Imaging findings OR Procedure details OSSEUS ARTICULATION The elbow joint consists of an articulation between three bones: Humerus (H), Ulna (U), and Radius (R). The humerus provides the proximal articular surface of the elbow comprising the trochlea and capitellum. The trochlea articulates with the proximal ulna, at the trochlear notch, providing flexion and extension. The capitellum articulates with the radial head, providing rotation[9]. OSSIFICATION CENTERS The capitellum is the first ossification center to appear, and usually is well formed by the age of 1 in both boys and girls. The radial head then follows at about 3 years of age. The medial epicondyle often appears at 5 years of age. The olecranon is next, which appears Page 5 of 42

6 between 8 and 10 years of age. That is followed by the trochlea, and finally the lateral epicondyle. A useful mnemonic is CRITOE, used as an acronym (Fig.1 & 2): Capitellum Radial head Internal (medial) epicondyle Trochlea Olecranon External (lateral) epicondyle LIGAMENTS Radial (lateral) collateral ligament complex (Fig. 3) Composed of the lateral ulnar collateral ligament (red), radial collateral ligament (RCL) proper (blue), and the annular ligament (green). The radial collateral ligament proper attaches to the annular ligament. Injury to the RCL is usually due to varus stress, subluxation or dislocation. The lateral ulnar collateral ligament is the primary stabilizer against varus stress; disruption can lead to posterolateral rotatory instability of the elbow [15]. Ulnar (medial) collateral ligament complex (Fig. 3) Consists of 3 bands. The anterior band (red) is the dominant structure and the primary stabilizer against valgus stress on the elbow. It courses anteriorly from the anteroinferior surface of the epicondyle and attaches to the medial edge of the coronoid process. The posterior band (blue) is smaller and has a fan-like configuration. It extends from behind the medial epicondyle and courses slightly posteriorly to attach onto the medial aspect of the olecranon. The transverse band (green) is less clinically relevant and often difficult to identify in imaging studies [15]. ALIGNMENT The alignment can be assessed radiographically with the anterior humeral line, the radiocapitellar line, and the Baumann angle (Fig. 4 & 5). Page 6 of 42

7 Anterior humeral line - a line along the anterior surface of the humerus on the lateral view normally intersects the middle third of the capitellum. Radio-capitellar line - a line through the mid-diaphysis of the proximal radius should bisect the capitellum; this line is maintained in all radiographic views. Baumann (humeral-capitellar) angle -angle between the long axis of the humeral shaft and the physeal line of the lateral condyle; the normal range for this angle is about 9 to 26 degrees. A decrease in the Baumann angle is a sign that a fracture is in varus. JOINT EFFUSION: FAT PAD Normally, on a lateral view of the elbow flexed at 90 degrees, a fat pad is seen on the anterior aspect of the coronoid fossa at the distal humerus, representing normal fat located in the joint capsule. On the posterior aspect, no fat pad is seen since the posterior fat pad is located within the deep olecranon fossa of the humerus. Distention of the joint will cause the anterior fat pad to become elevated in a sail-like configuration and the posterior fat pad to become visible on a true lateral x-ray, described as a positive fat pad sign (Fig. 6). Any elbow joint distention either hemorrhagic, inflammatory or traumatic gives rise to a positive fat pad sign. A visible fat pad sign without the demonstration of a fracture should be regarded as an occult fracture in the setting of trauma. These patients are treated as having a non-displaced fracture with 2 weeks splinting. Displacement of the anterior fat pad alone however can occur due to minimal joint effusion and is less specific for fracture. If a positive fat pad sign is not present in a child, significant intra-articular injury is unlikely. CLASSIFICATION OF DISLOCATIONS SIMPLE ELBOW DISLOCATIONS Simple elbow dislocations have soft tissue injury and no fractures. Anterior Posterior Direct posterior* Posterolateral* Page 7 of 42

8 Posteromedial Divergent *Account for 80-90% of the simple dislocations [7]. The articular relationship is disrupted by way of soft tissue injury, which begins laterally and extends medially involving both the anterior and posterior soft tissue envelope. It has been described in 3 stages [9]: (1) the LCL complex is partially or completely torn (posterolateral subluxation) (2) anterior and posterior soft tissue is torn (posterolateral dislocation) (3) the MCL complex is torn (true dislocation). With each progressive stage of soft tissue injury, the elbow experiences increasing instability, from posterolateral subluxation to frank dislocation. As long as the anterior band of the MCL is left intact, the joint can be reduced and stability can be attained through reduction of the bony articulations, despite the significant soft tissue injury [9]. Simple dislocations usually may be managed with closed reduction and early range of motion, with minimal sequelae [16]. Treated generally with a reduction maneuver, followed by immobilization of 2 weeks maximum. Surgery is only clearly indicated when the elbow becomes stable with less than 60 degrees of flexion, if no anatomical reduction is possible or if there are neurovascular injuries [7]. COMPLEX ELBOW DISLOCATIONS Complex elbow dislocations have both bone and soft tissue injuries. Four common patterns have been described: (1) Posterior elbow dislocation with fracture of the radial head (2) Posterior elbow dislocation with fracture of the radial head and coronoid process (the "terrible triad") Page 8 of 42

9 (3) Anterior elbow dislocation with fracture of the olecranon (4) Posterior elbow dislocation with fracture of the proximal ulna (one of the Monteggia fracture types)[3] When a dislocation is not associated with a fracture, early mobilization after closed reduction is associated with a low risk of redislocation[3]. However, when one of the osseous or articular component structures that contribute to stability of the elbow is disrupted, the risk of recurrent or chronic instability and arthrosis is increased [3]. MONTEGGIA FRACUTURE-DISLOCATION Monteggia fracture-dislocation is one of the complex types and it is composed of a fracture of the proximal ulna and a dislocation of the radial head [15]. Bado classified four types depending on the direction of the dislocation of the radial head and the angulation of the ulnar fracture [21]. Type I: anterior dislocation with posterior apex angulation (Fig. 7,8 & 9) Type II: posterior dislocation and posterior apex angulation (Fig. 10 & 11) Type III: lateral dislocation with proximal ulnar fracture (Fig. 12) Type IV: radial head dislocation and fracture of both proximal radius and ulna Predominance of type II fractures is found in adults. In children, type I fractures are more common and type II injuries are rare [22]. RADIAL HEAD Radial head fractures are the most common type of elbow fractures in adults [6, 15]. Imaging features that affect patient prognosis include the degree of comminution, angulation, and depression of the radial head fracture. MDCT may be useful in evaluating the articular congruity of the radial head, especially after reduction [15]. MRI is very sensitive for the detection of occult fractures, either in the marrow or physis [15], although not routinely used for this purpose at our institution. Marrow edema or bone contusions are low in signal intensity on T1W images. Page 9 of 42

10 Fractures are evident as hypointense lines within the marrow if there is trabecular compression and discontinuity of hypointense cortical bone. Radial head fractures can be classified by the Mason Johnston classification system [15]. Type I: non-displaced fractures (Fig. 13) Type II: minimally displaced fractures with depression, angulation, and impaction Type III: comminuted and displaced (Fig. 14) Type IV: associated with dislocation of the elbow. The Essex-Lopresti injury consists of a fracture of the radial head, rupture of the interosseous membrane and disruption of the distal radioulnar joint. The greatest challenge with this injury pattern is its diagnosis. It is frequently missed given the fact that the attention is usually focused on the elbow joint [24]. HUMERAL CONDYLE TRANSCONDYLAR AND INTERCONDYLAR Humeral condyle fractures include the transcondylar and intercondylar types. Transcondylar fractures differ from supracondylar fractures in that they occur within the joint capsule. There are two types, classified into flexion and extension types on the basis of the position of elbow during impact. Fracture line extends through the condyles proximal to the articular surface. Treatment of non-displaced fractures is with splinting or percutaneous pinning. Displaced fracture will require open reduction and internal fixation. Intercondylar fractures are T or Y shaped with varying amounts of displacement between condyles and humerus. This fracture is due to blunt force trauma received from the olecranon impact to the articular surface splitting the humerus (Fig. 16). Preferred studies include AP and lateral radiographs. MDCT may be useful for detecting hidden fractures of the proximal ulna. Treatment is with open reduction and internal fixation. ULNAR CORONOID PROCESS Page 10 of 42

11 Fractures of the coronoid process are often seen as part of the complex elbow fracture group, associated to radial head fracture and elbow dislocation, leading to instability of the ulno-humeral joint. Regan and Morrey proposed a classification according to the findings on lateral radiographs: Type I: involve the tip (Fig. 17) Type II: involve < 50% of the height of the coronoid process. Type III: involve > 50% of the height of the coronoid process. Management of Type I and II fractures require non-operative treatment, closed reduction and splinting in a degree of flexion for < 3 weeks. Surgical treatment of Type III coronoid fractures enables a concentric reduction of the elbow, stability and early motion. TERRIBLE TRIAD Posterior elbow dislocation with fracture of the radial head and coronoid process [9] (Fig. 18). It is characterized by joint stiffness and is prone to acute redislocation [25] as well as to chronic instability and post-traumatic arthrosis [26,27]. OLECRANON PROCESS OF THE ULNA Approximately 10% of adult elbow fractures consist of fractures of the olecranon process of the ulna due to its exposed position, where most direct injuries occur. Olecranon fractures are caused by direct blows at 90 of flexion. Ossification centers of the olecranon generally appear by 9 to 10 years of age, and fuse with the proximal ulna by 14 years of age, which decreases the occurrence of olecranon fractures in children. Persistence of the physis into adulthood may occur and can be confused with a fracture; clues to this condition include a family tendency and the presence of persitent physis bilaterally. Loss of motion is rarely a significant problem in patients with isolated olecranon fractures, since they exhibit little or no displacement. Page 11 of 42

12 Mayo classification is based on three variables: displacement, stability, and comminution [13]. Type 1: non-displaced Type 2: displaced, but the ulno-humeral joint is stable Type 3: displaced and unstable ulno-humeral joint (Fig. 19) Each fracture type is subdivided into non-comminuted and comminuted fractures. Patella cubiti, an accessory ossicle embedded in the distal triceps, may be present and can be mistaken for a fracture. Management of non-displaced fractures (less than 2mm) (Mayo 1A and 1B) can be treated non-operatively with immobilization in a long arm cast. A radiograph should be obtained after cast application to ensure that displacement of the fracture has not occurred [13]. Displaced fractures require operative treatment. Tension band wire fixation is by far the most common technique used for the treatment of non-comminuted fractures. Plate fixation has been used principally for the management of comminuted olecranon fractures in which tension band wire fixation is not appropriate. BICEPS/TRICEPS/BRACHIAL ARTERY BICEPS The distal biceps tendon is the most commonly injured tendon in the elbow [15]. Radiographs may exhibit irregularity of the radial tuberosity in chronic biceps tendon injuries, obliteration of the supinator fat stripe, or, rarely, acute avulsion fractures [15]. MR imaging is ideally suited to evaluate injuries of the biceps tendon. T2-weighted, gradient-echo, or short tau inversion recovery (STIR) images are best for showing the high signal abnormality of hemorrhage as well as the inflammation and fluid seen against the normal low signal intensity of the tendon [15]. Page 12 of 42

13 TRICEPS Radiography is useful in evaluating triceps injury, since up to 80% of patients will have avulsion fractures of the olecranon [15]. Inflammation in the muscle or tendon is evident as an irregular area of increased signal intensity on fluid-sensitive MR images [15]. Complete disruption results in areas of high signal intensity separating the low-intensity tendon fragments [15]. The triceps tendon normally has striations of increased signal that insinuate between the distal tendon fibers and should not be mistaken for tears [15]. BRACHIAL ARTERY Brachial artery injury has been reported with posterior dislocations of the elbow [1] and supracondylar fractures in pediatrics. At our institution, this is commonly evaluated with CT angiography. SUPRACONDYLAR Supracondylar fractures are the most common elbow fractures in children[12].typically occur in children 3 to 10 years of age and are more common in males [12]. Extension-type supracondylar fracture account for approximately 95% and are caused by a fall on outstretched hand with hyperextension of the elbow. In this type of fracture, the capitellum is posterior to the anterior humeral line. Flexion-type supracondylar fracture may occur by a direct blow to the elbow with the elbow flexed [12]. The posterior cortex fails first and the resulting fracture has anterolateral displacement of the distal fragment. The fracture line courses from below, upward and forward. Soft tissue swelling and damage are usually much less than in the extension type and neurovascular complications are rare. Ulnar nerve palsy occurs in some cases as the sharp spike of proximal fragments injures the nerve. Posterolateral fracture displacement is correlated with median nerve and vascular compromise. Posteromedial fracture displacement is strongly correlated with radial nerve injury [28]. Gartland types of supracondylar fractures: Page 13 of 42

14 Gartland Type I o Nondisplaced or minimally displaced (<2 mm) fracture. It is associated with an intact anterior humeral line. There may or may not be evidence of osseous injury; the posterior fat-pad sign may be the only evidence of the fracture. o Management: Long arm cast with the elbow in approximately 60 to 90 of flexion for approximately three weeks. It is recommended that follow-up radiographs be performed at one to two weeks to identify any fracture displacement. Gartland Type II (Fig. 15) o Displaced (>2 mm), and the posterior cortex is intact, but hinged. On a true lateral radiograph of the elbow, the anterior humeral line does not go through the middle third of the capitellum. With common usage of the classification, any rotational deformity noted on an anteroposterior radiograph would qualify the fracture as a type III. o Management: Toddlers (less than three years old) have some remodeling potential so the surgeon may accept non-operative treatment. A child who is eight to ten years old has only 10% of growth of the distal part of the humerus remaining, so an adequate reduction is essential to prevent malunion. Gartland Type III (Fig. 20) o Displaced supracondylar fracture with no meaningful cortical contact. There is usually extension in the sagittal plane and rotation in the frontal and/ or transverse planes. The periosteum is extensively torn, and soft-tissue and neurovascular injuries often accompany this fracture. A potential pitfall is to underappreciate the extent of loss of normal alignment in fractures with comminution and collapse of the medial column. Involvement of the medial column in this way signifies malrotation in the frontal plane and thus defines the injury as type III. o Management: Requires reduction closed or open, if necessary. Stabilization is maintained with either two lateral pins or medial lateral cross pin technique. Gartland Type IV o Characterized by an incompetent periosteal hinge circumferentially and defined by instability in both flexion and extension. The instability pattern may be due to the initial injury, or it may occur iatrogenically during attempted reduction. SALTER HARRIS Page 14 of 42

15 Fractures involving the physes are described in patterns by the Salter-Harris classification. In general, there are five types of Salter-Harris fractures as described below: I: Epiphyseal plate damage only by separation, epiphyses and metaphysis intact (Fig. 21) II: Same as I, but with metaphyseal fracture (Fig. 22 & 23) III: Same as I, but with epiphyseal fracture IV: Fracture of plate, epiphysis, and metaphysis V: Crush fracture of the epiphyseal plate, poor prognosis LATERAL HUMERAL CONDYLE FRACTURES Usually occur as a fall on an outstretched hand and a fragment is displaced posteroinferiorly because of traction by forearm extensors. Posterior fat pad is displaced. X-ray usually underestimates the degree of displacement, which is best visualized in oblique views. These are seen usually in children and are a Salter-Harris type IV. They present as a lateral metaphyseal flake and possibly with disruption of the radio-capitellar line. Theyincid ence of nonunion resulting from this type of fracture has lead it to be the second most common operative elbow fracture in children. The Rutherford classification is used to evaluate the stability of lateral condyle fractures [18]. Rutherford type I - the fracture line does not extend to the articular surface Rutherford type II - the fracture line does extend to the articular surface Rutherford type III - the fractured fragment is displaced (Fig. 24) MEDIAL EPICONDYLE FRACTURES Medial epicondyle fractures are more common in children than adults. The flexor-pronator muscles of the forearm and the ulnar collateral ligament may cause traction during valgus stress (Fig. 25, 26 & 27). Types of injuries in this anatomic region include: Avulsion: also known as "little Leaguer's elbow" and may present as fragmentation and hypertrophy if chronic. Best visualized in AP view Page 15 of 42

16 inferiorly displaced. It is extra-articular so there is no joint effusion, however, if present may represent entrapment versus Salter-Harris type IV. Avulsion with entrapment: entrapment between trochlea and coronoid process of ulna. It is important to recognize ossification centers according to patient's age. Avulsion associated to elbow dislocation: location is variable. Entrapment suspected when there is limited range of motion. Salter-Harris type IV: suspected when there is a joint effusion, a metaphyseal flake, or joint instability with lack or decreased of mobility on physical exam. Images for this section: Fig. 1: AP and lateral views of an 11 y/o boy showing the predicted order of appearance of ossification centers (1, 3, 5, 7, 9, 11 years). Page 16 of 42

17 Fig. 2: Elbow radiographs of patients at different ages showing the progression of appearance of ossifications centers. (a) 2 year old patient AP view showing ossification of the capitellum. (b) 5 year old patient AP view showing ossification of the capitellum and radial head. (c) 5 year old patient AP view showing ossification of the capitellum, radial head, and medial epicondyle. (d) 8 year old patient AP view showing ossification of the capitellum, radial head, medial epicondyle, and trochlea. (e) Lateral view of same patient as in (d) showing ossification of the olecranon process. (f) 11 year old AP view showing ossification of the previously mentioned centers, and the lateral epicondyle which is the last one to ossify. Page 17 of 42

18 Fig. 3: (a) Ulnar (medial) collateral ligament complex: Anterior bundle (red), transverse ligament (green), Posterior bundle (blue) (b) Radial (lateral) collateral ligament complex: Lateral (ulnar) collateral ligament (red), Radial Collateral Ligament (blue), Annular ligament (green), Accessory Collateral Ligament (yellow) Page 18 of 42

19 Fig. 4: (a) Anterior humeral line (b) Baumann angle Page 19 of 42

20 Fig. 5: Radiocapitellar line Fig. 9: 3-dimensional volume rendering (a) and sagittal multiplanar reconstruction in maximum intensity projection (b) of a MDCT showing changes of a Monteggia Type I fracture-dislocation including anterior dislocation of the radial head (yellow asterisk) and proximal ulnar diaphyseal fracture with anterior apex angulation (blue arrow). Page 20 of 42

21 Fig. 8: AP (a) and lateral (b) elbow radiographs of an adult patient showing a comminuted displaced proximal ulnar diaphyseal fracture (blue arrow) with anterior apex angulation and associated anterior dislocation of the radial head. Fig. 7: Lateral cross-table (a) and AP (b) radiographs of the elbow in a patient who suffered trauma showing proximal ulnar oblique fracture (blue arrow) with mild anterolateral apex angulation and anterior radial head dislocation (yellow asterisk). Note multiple radiopaque debris in soft tissues (yellow arrow) with soft tissue swelling. Patient was unable to flex elbow. Page 21 of 42

22 Fig. 6: Lateral radiographs of the elbow showing displacement of the anterior (blue arrow) and posterior (yelllow arrow) fat pads (positive fat pad sign) shown as a lucency within the soft tissues. This finding is consistent with fluid within the joint (e.g. effusion or hemarthrosis). (a) 9 year old patient with displacement of the anterior and posterior fat pads. Note that there are unossified structures in this patient which is normal for age. No fractures or dislocations are noted. (b) 13 year old patient with displacement of the anterior and posterior fat pads. Note that the anterior fat pad has the shape of a sail (blue arrow), known as the sail sign. (c) 47 year old showing displacement of the posterior fat pad. There was no evidence of fractures or dislocations in the AP or lateral views. (d) Sagittal multiplanar reconstruction CT scan of an adult patient showing how the anterior fat pad is displaced superiorly from the coronoid fossa in a sail-like configuration by joint fluid. Page 22 of 42

23 Fig. 10: AP (a) and lateral (b) elbow radiographs showing a comminuted fracture of the proximal ulna (blue arrow) with posterior apex angulation and posterior dislocation of the radial head (yellow asterisk). These findings are consistent with a Type II Monteggia fracture-dislocation. Page 23 of 42

24 Fig. 11: AP (a) and lateral (b) elbow radiographs showing a comminuted fracture of the proximal ulna (blue arrow) with posterior apex angulation and posterior dislocation of the radial head (yellow asterisk). These findings are consistent with a Type II Monteggia fracture-dislocation. Page 24 of 42

25 Fig. 13: AP (a) and lateral (b) views of the elbow in an adult patient showing a radial head anteriorly displaced fracture (yellow arrow). Notice that the lateral view is not flexed at 90 degrees and there is no displacement of the fat pads, even though there is an intra-articular fracture. Axial (c) and sagittal multiplanar reconstruction (d) show better anatomic detail of the fracture line (yellow arrow) and rules out other osseous injuries in the remainder of the elbow structures. Note the lucent line in the radial epiphysis with preservation of the radiocapitellar relationship. Page 25 of 42

26 Fig. 14: AP (a) and lateral (b) views of the elbow showing an impacted anteromedially displaced comminuted fracture of the radial head. Sagittal maximum intensity projection of multiplanar reconstruction of an MDCT (c) show osseous fragments anterior to the distal humerus. In addition, there was an incomplete fracture of the capitellum. However, notice that there is no elbow dislocation in this case. Findings are consistent with a Mason Type III radial head fracture. 3-dimensional volumetric reconstruction (d) provides the relationship between capitellum and radial head and degree of impaction in a practical basis. Dislocation of the elbow joint would have made this a radial head fracture Mason Type IV. Page 26 of 42

27 Fig. 12: AP (a) and lateral (b) elbow radiographs showing a comminuted fracture of the proximal ulna with anterior displacement and lateral apex angulation (blue arrow). There is associated lateral radial head dislocation (yellow asterisk). Findings are consistent with a Monteggia Type III Fracture-Dislocation. Page 27 of 42

28 Fig. 15: AP (a) and lateral (b) radiographs of a pediatric patient after elbow trauma showing a lucent line through the distal humerus (blue arrow) and disruption of the anterior humeral line consistent with a posteriorly displaced supracondylar fracture Gartland Type II. Notice the intact posterior cortex and the displacement of the posterior fat pad in a true lateral radiograph (yellow arrow). Page 28 of 42

29 Fig. 16: AP radiograph of an adult patient showing a comminuted displaced intercondylar fracture (yellow arrow) with surrounding soft tissue swelling. The degree of comminution and displacement may be underestimated in a radiograph. Coronal multiplanar reconstruction (b) and axial (c) views of an MDCT show the intercondylar fracture which has a transcondylar component and extends to the articular surface (blue arrowhead). The degree of comminution is much more than expected by the radiograph. 3-dimensional volumetric reconstruction from a posterior approach (d) shows the fracture fragments displaced peripherally. The olecranon process is intact. Page 29 of 42

30 Fig. 17: Lateral (a) radiograph of an adult patient after elbow trauma showing a faint lucent line (blue arrow) in the tip of the coronoid process representing a nondisplaced fracture. The patient was not able to flex the elbow and lateral view is inadequate for which a CT scan was recommended for further characterization. MDCT sagittal multiplanar reconstruction (b) shows the coronoid tip nondisplaced fracture (blue arrow) visualized in the radiograph. No other fractures were noted in this case. This is a Type I coronoid fracture. Page 30 of 42

31 Fig. 18: Sagittal MDCT multiplanar reconstructions through the ulna (a) and proximal radius (b) show anterior posterior ulnar dislocation (blue arrow), fracture of the coronoid process (yellow arrow) and radial head fracture (blue arrowhead) consistent with a terrible triad. 3-dimensional volume rendering reconstructions from medial (c) and lateral (d) aspects show these findings in more detailed basis. Notice that the trochlea is impacted in the coronoid process and the capitellum in the proximal radius. This fracture may have comorbidity after repair and adequate identification is important. Page 31 of 42

32 Fig. 19: AP (a) and lateral (b) radiographs of an adult patient with a comminuted fracture of the olecranon and associated anterolateral radial head dislocation (blue asterisk). Sagittal multiplanar reconstruction (c) and 3-dimensional volume rendering reconstruction (d) of MDCT show that the distal humerus is intact and the fracture line involves the base of the coronoid and extends to the proximal ulnar shaft. There are no fractures in the radial head. This would be classified as a Type IIIB olecranon fracture under the Mayo Classification. Page 32 of 42

33 Fig. 20: Radiographs and MDCT correlation of a patient with distal humeral fracture. AP (a) and lateral (b) radiographs show comminuted posteromedially displaced intraarticular fracture. Note that there is disruption of the medial column. The radiocapitellar line, however, is preserved. MDCT coronal multiplanar reconstruction (c) shows further detail of the degree of comminution and displacement. 3-D volumetric reconstruction shows anatomic relation between fragments and the intact radius and ulna. This type of images are helpful for surgical planning. Page 33 of 42

34 Fig. 25: AP (a) and lateral (b) radiographs of a 15 year old avulsion fracture of the medial epicondyle with approximately 6 mm of medial displacement of the fracture fragment (blue arrow). There is no evidence of dislocations. Page 34 of 42

35 Fig. 26: AP radiograph (a) of an adult patient who suffered elbow trauma showing no evidence of fractures or dislocations. The joint spaces are preserved. Patient was unable to flex the elbow and a true lateral view was not available. Patient continued with pain and there was considerable clinical suspicion of a hidden fracture and a CT was performed. Axial (a) and coronal multiplanar reconstruction (c) MDCT of the elbow shows a small avulsion minimally displaced fracture of the medial epicondyle (blue arrow). Joint effusion was present on the CT scan. Page 35 of 42

36 Fig. 21: Lateral radiograph (a) of the elbow in an 11 year old patient showing separation of the proximal radial physis indicative of displaced Salter Harris Type I fracture (blue arrow). Coronal (b) and sagittal (c) multiplanar reconstructions MDCT show displacement of the radial head from the growth plate and gas within the physeal plate (blue arrow). This type of physeal plate fracture may be subtle and is not always as obvious as in this case. Page 36 of 42

37 Fig. 22: AP (a) and lateral (b) radiographs of a 7 y/o male with Salter Harris type II fracture of left elbow involving the physis and metaphysis. The AP view shows an irregularity of the metaphysis (blue arrow). Notice absence of posterior fat pad displacement on lateral view. Fracture better characterized on coronal multiplanar MDCT reconstruction (c) where mild comminution and minimal displacement is better noticed. No intra-articular fragments are noted. Page 37 of 42

38 Fig. 24: AP (a) and lateral (b) radiographs of an adult patient showing a comminuted laterally displaced fracture of the lateral humeral condyle extending to the articular surface (blue arrow) with intact radial head (blue asterisk). Note on the lateral view that there is a posterior dislocation of the radius and ulna (yellow arrow). Displacement and articular extension makes this a Rutherford Type III lateral condyle fracture. Fig. 23: AP (a) and lateral oblique (b) radiographs of the elbow in a 6 year old patient showing a fracture of the lateral distal humeral physis (yellow arrow) extending proximally towards the metaphysis consistent with a Salter Harris Type II fracture. Notice the absence of several ossification centers, as is expected for this age. Page 38 of 42

39 Fig. 27: AP (a) and lateral (b) elbow radiographs of an adult patient showing the avulsed capitellum displaced anteriorly with associated soft tissue swelling. No other osseous abnormalities were noted. Page 39 of 42

40 Conclusion The radiologist plays an important role in finding and describing direct or indirect signs of traumatic injuries to the elbow region. Knowledge of the anatomy of the elbow as it varies between children and adults due to various ossification centers that ossify at a predicted order and age range is necessary for adequate interpretation. Some kinds of fractures are more common in adults and others more common in children. MDCT plays an important role in evaluation of traumatic injuries in cases where a hidden fracture is suspected and for the orthopedic surgery planning. AP and Lateral Radiographs, are ideal for preliminary evaluation of suspected elbow fractures. CT and MRI images are ideal to evaluate in depth neurologic and vascular damage when surgery is indicated. Personal Information Enrique Alvarado Burgos, Yania Lopez Alvarez; Luis Garcia, Neda I. Sedora Roman, Stephanie Baussan, Melisa Rivera, Stephanie Vale, Jorge Vidal; Department of Diagnostic Radiology. University of Puerto Rico, Medical Sciences Campus, San Juan Puerto Rico. References 1. Kuhn M, Ross G. Acute elbow dislocations. Orthop Clin N Am 2008; 39: Bryce C, Armstrong A. Anatomy and biomechanics of the elbow. Orthop Clin N Am 2008; 39: Ring D, Jupiter J. Current concepts review - fracture-dislocation of the elbow. J Bone Joint Surg Am. 1998;80: Potter H, Schachar J, Jawetz S. Imaging of the elbow. Oper Tech Orthop 2009; 19: Page 40 of 42

41 Athwal G, Faber K, Rosenblatt Y. Current recommendations for the treatment of radial head fractures. Orthop Clin N Am 2008; 39: Jungbluth P, Hakimi M, Linhart W, et al. Current concepts: simple and complex elbow dislocations - acute and definite treatment. Eur J Trauma Emerg Surg 2008; 34: Patel B, Reed M, Patel S. Gender-specific pattern differences of the ossification centers in the pediatric elbow. Pediatr Radiol 2009; 39: Ilyas A, Jupiter. The pathoanatomy of elbow fracture-dislocations: A road map to treatment. J Musculoskel Med 2008; 25: Elbow Fractures. Wheeless' Textbook of Orthopaedics. [online resource] 11. ACR Appropriateness Criteria chronic elbow pain. American College of Radiology - Medical Specialty Society (revised 2005). 5 pages. [NGC Update Pending] NGC: Wade M. Pediatric Supracondylar fractures and pediatric physeal elbow fractures. Orthop Clin N Am 2008; 39: Steinmann S, Veillete C. Olecranon fractures. Orthop Clin N Am 2008; 39: Krikler S, Mauffrey C, Newman S. Olecranon fractures. Injury 2009; 40: Bancroft L, Berquist T, Peterson J, et al. Imaging of elbow pathology. Applied Radiology 2007; 36(7): Mehlhoff T, Noble P, Bennett J, Tullos H. Simple dislocation of the elbow in the adult: results after closed treatment. J Bone Joint Surg. 1988;70A: Regan W, Morrey B. Fractures of the coronoid process of the ulna. J Bone Joint Surg [Am]1989,71-A: Rutherford A. Fractures of the lateral humeral condyle in children. J Bone Joint Surg Am 1985;67: Gaffney J, Mallo G, Stanat S. Use of the Gartland Classification System for treatment of supracondylar humerus fractures. Orthopedics 2010; 33(1): Hopgood B, Kozin S, McGinley J, et al. Nondisplaced elbow fractures: a commonly occurring and difficult diagnosis. Am J Emerg Med 2006; 24: Bado J. The Monteggia lesion. Clin Orthop 1967;50:71-86 Page 41 of 42

42 22. Konrad G, Kreuz P, Kundel K, et al. Monteggia fractures in adults: Long-term results and prognostic factors. J Bone Joint Surg [Br] 2007; 89 (3): Athwal G, Faber K, Whitcomb J. Distal humerus fractures. Orthop Clin N Am 2008; 39: Pretell J, Rodriguez J, Vidal C. Unusual pattern of Essex-Lopresti injury with negative plain radiographs of the wrist: a case report and literature review. Hand Surg 2010; 15(1): Josefsson, P. O.; Gentz, C. E; Johnell, O.; and Wendeberg, B.: Dislocations of the elbow and intra-articular fractures. Clin. Orthop., 246: , Cobb, T. K., and Morrey, B. E: Use of distraction arthroplasty in unstable fracture dislocations of the elbow. Clin. Orthop., 312: , Regan, W., and Morrey, B. E: Fractures of the coronoid process of the ulna. J. Bone and Joint Surg., 11-A: , Oct Lyons ST, Quinn M, Stanitski CL. Neurovascular injuries in type III humeral supracondylar fractures in children. Clin Orthop Relat Res Jul;(376):62-7. Page 42 of 42