Canadian Residents’ Corner / Coin canadien des residents en radiologie Case of the Month #177: Bipolar Clavicular Dislocation: Radiologic Evaluation of a Rare Traumatic Injury Michael P. Loreto, MD, MSc * , Dawn Pearce, MD Department of Medical Imaging, University of Toronto and St Michael’s Hospital, Toronto, Ontario, Canada Clinical Presentation A 42-year-old female pedestrian who was struck by a car sustained multiple traumatic injuries, including a closed head injury, T5 transverse process fracture, iliac crest fracture, multiple rib fractures, and injury to her right clavicle. There was no surgical intervention at the time of the injury, and the patient recovered reasonably well but presented 6 months later with ongoing problems related to her clavicular injury, including pain, decreased range of motion, and cosmetic dissatisfaction. Delayed surgical correction of the clavicular injury was elected, and a computed tomography (CT) of the clavicles with 3-dimensional (3D) reconstruction was obtained for preoperative planning purposes. Diagnosis Bipolar clavicular dislocation. Radiologic Findings A frontal chest radiograph performed at the time of injury demonstrates dislocation of both the sternoclavicular and acromioclavicular joints on the right side as well as multiple right-sided anterior rib fractures (Figure 1). Six months later, a CT was performed, including 3D reconstructed images for the purpose of preoperative planning. Axial CT images at the level of the clavicle demonstrate posterior dislocation of the acromioclavicular joint and anterior dislocation of the ster- noclavicular joint (Figure 2). The 3D reconstructed images further demonstrate both the anterior dislocation of the right sternoclavicular joint, with slight overriding of the clavicular head over the sternum, and posterior dislocation of the right clavicle at the acromioclavicular joint (Figure 3). Discussion Clavicular injuries are common, and it has been estimated that 10% of all joint dislocations involve the clavicle [1]. Despite this, bipolar clavicular injuries are exceptionally rare. As the name suggests, these injuries either involve dislocations at both the acromioclavicular and sternocla- vicular joints, or a fracture at one end and a dislocation at the other. The injury was first described by Porral [2] in 1831, as ‘‘double luxation de la clavicule.’’ A review of the literature revealed that there have only been 16 published case reports since 1924 [3e14]. Of note, all of these case reports were published in the orthopaedic surgical literature, with no publications in the radiologic literature. In addition, there has only been a single report to take advantage of 3D CT imaging to evaluate this injury [11]. Figure 1. Frontal chest radiograph, demonstrating dislocation of both the sternoclavicular and acromioclavicular joints on the right side as well as multiple right-sided anterior rib fractures. *Address for correspondence: Michael P. Loreto, MD, MSc, 250 Wellington Street West, Suite 940, Toronto, Ontario M5V 3P6, Canada. E-mail address: [email protected](M. P. Loreto). 0846-5371/$ - see front matter Ó 2012 Canadian Association of Radiologists. All rights reserved. doi:10.1016/j.carj.2010.09.009 Canadian Association of Radiologists Journal 63 (2012) 156e158 www.carjonline.org
Transcript
Canadian Association of Radiologists Journal 63 (2012) 156e158www.carjonline.org
Canadian Residents’ Corner / Coin canadien des r�esidents en radiologie
Case of the Month #177: Bipolar Clavicular Dislocation:Radiologic Evaluation of a Rare Traumatic Injury
Michael P. Loreto, MD, MSc*, Dawn Pearce, MD
Department of Medical Imaging, University of Toronto and St Michael’s Hospital, Toronto, Ontario, Canada
Clinical Presentation
A 42-year-old female pedestrian who was struck by a carsustained multiple traumatic injuries, including a closed headinjury, T5 transverse process fracture, iliac crest fracture,multiple rib fractures, and injury to her right clavicle. Therewas no surgical intervention at the time of the injury, and thepatient recovered reasonably well but presented 6 monthslater with ongoing problems related to her clavicular injury,including pain, decreased range of motion, and cosmeticdissatisfaction. Delayed surgical correction of the clavicularinjury was elected, and a computed tomography (CT) of theclavicles with 3-dimensional (3D) reconstruction wasobtained for preoperative planning purposes.
Diagnosis
Bipolar clavicular dislocation.
Radiologic Findings
A frontal chest radiograph performed at the time of injurydemonstrates dislocation of both the sternoclavicular andacromioclavicular joints on the right side as well as multipleright-sided anterior rib fractures (Figure 1). Six months later,a CT was performed, including 3D reconstructed images forthe purpose of preoperative planning. Axial CT images at thelevel of the clavicle demonstrate posterior dislocation of theacromioclavicular joint and anterior dislocation of the ster-noclavicular joint (Figure 2). The 3D reconstructed imagesfurther demonstrate both the anterior dislocation of the rightsternoclavicular joint, with slight overriding of the clavicularhead over the sternum, and posterior dislocation of the rightclavicle at the acromioclavicular joint (Figure 3).
*Address for correspondence: Michael P. Loreto, MD, MSc, 250
Wellington Street West, Suite 940, Toronto, Ontario M5V 3P6, Canada.
0846-5371/$ - see front matter � 2012 Canadian Association of Radiologists. A
doi:10.1016/j.carj.2010.09.009
Discussion
Clavicular injuries are common, and it has been estimatedthat 10% of all joint dislocations involve the clavicle [1].Despite this, bipolar clavicular injuries are exceptionallyrare. As the name suggests, these injuries either involvedislocations at both the acromioclavicular and sternocla-vicular joints, or a fracture at one end and a dislocation at theother. The injury was first described by Porral [2] in 1831, as‘‘double luxation de la clavicule.’’ A review of the literaturerevealed that there have only been 16 published case reportssince 1924 [3e14]. Of note, all of these case reports werepublished in the orthopaedic surgical literature, with nopublications in the radiologic literature. In addition, there hasonly been a single report to take advantage of 3D CTimaging to evaluate this injury [11].
Figure 1. Frontal chest radiograph, demonstrating dislocation of both the
sternoclavicular and acromioclavicular joints on the right side as well as
Figure 2. Axial computed tomographic images at the level of the clavicle,
demonstrating posterior dislocation of the acromioclavicular joint (upper
panel) and anterior dislocation of the sternoclavicular joint (lower panel).
Figure 3. Computed tomography bilateral clavicles with 3-dimensional
reconstruction visualized in the coronal (upper panel), axial (middle panel),
and oblique (lower panel) planes. There is anterior dislocation of the right
sternoclavicular joint, with slight overriding of the clavicular head over the
sternum. There is also a posterior dislocation of the right clavicle at the AC
joint. This figure is available in colour online at http://carjonline.org/.
157Radiologic evaluation of bipolar clavicular dislocation / Canadian Association of Radiologists Journal 63 (2012) 156e158
Bipolar clavicular dislocationhas alternativelybeendescribedas a ‘‘traumatic floating clavicle’’ and ‘‘panclavicular disloca-tion’’ [4,5,13].With reference to the former descriptor, this injuryis not to be confused with a ‘‘floating shoulder’’ (ipsilateralfractures of the midshaft of the clavicle and the glenoid neck).The simultaneous dislocation of both ends of the clavicle iscommonly the result of a major trauma, such as a violent blow tothe lateral aspect of the shoulder or heavy compression of theshoulders in combination with torsion of the trunk.
Rockwood classified acromioclavicular injuries into 6separate types of lesion, with bipolar dislocation representinga rare subtype of a class IV injury in which there is posteriordisplacement of the distal clavicle into or through thesubstance of the adjacent trapezius muscle [15]. The mosttypical pattern of injury that has been observed has been ananteromedial dislocation of the sternoclavicular joint anda posterosuperior dislocation of the acromioclavicular joint,however, other patterns of displacement have been observed.Clavicular dislocation in the horizontal plane only and, muchmore infrequently, anterosuperior dislocation of the medialend of the clavicle with posteroinferior dislocation of theacromioclavicular joint have also been observed [1,4,7,16].
In terms of management, there remains no consensusopinion because of the small number of cases that have beenseen. Historically, a conservative nonsurgical approach hasbeen adopted for the elderly, older lesions, in multitraumapatients with more profound injuries, and in subjects who aregenerally poor surgical candidates. Conversely, operativetreatment has been pursued in younger patients with relativelyfresh lesions and active adults in whom stable external reduc-tion cannot be achieved, and residual deformity, functionallimitation, or restriction are not accepted by the patient.
The full extent of the injury is often not appreciated on plainradiographs, and cross-sectional CT images are much better
for diagnosing the injury. Although the injury can be seen onstandard planar CT images for the purposes of diagnosis,orthopaedic surgeons at our institution often find 3D recon-structed CT images helpful in planning their operativeapproach. In our case, the patient ultimately elected to pursuesurgical correction because of ongoing pain and limitedfunctionality of the right shoulder, as well as ongoing dissat-isfaction with the deformity associated with the sternocla-vicular dislocation. A preoperative CTwith 3D reconstructedimages was performed, and the patient underwent openreduction and internal fixation of the sternoclavicular joint,with placement of a hook plate and cancellous screws. Inreducing the sternoclavicular joint, the acromioclavicular jointreduced indirectly and did not require fixation. Six monthsafter the initial surgery, the hardware was removed, with thesternoclavicular joint remaining stable in reduced position.
In summary, bipolar clavicular dislocation is a very raretype of traumatic injury in which there typically is simulta-neous posterior dislocation of the acromioclavicular joint andanterior dislocation of the sternoclavicular joint. There haveonly been a handful of case reports published in the pastseveral decades, and, to the best of our knowledge, this is thefirst such report in the radiologic literature. Cross-sectionalimaging (CT) best depicts the injury, and the orthopaedicsurgeons at our institution found 3D reconstructed CTimages to be particularly useful for their operative planning.
References
[1] Cook F, Horowitz M. Bipolar clavicular dislocation. Report of a case.
J Bone Joint Surg 1987;69:145e7.
[2] Porral A. Observation d’une double luxation de la clavicule droite.
[10] Caranfil R. Bipolar luxation of the clavicle. A case report. Acta Orthop
Belg 1999;65:102e4.
[11] ScapinelliR.Bipolardislocationof the clavicle: 3DCTimaging anddelayed
surgical correction of a case. Arch Orthop Trauma Surg 2004;124:421e4.[12] Pang KP, Yung SW, Lee TS, et al. Bipolar clavicular injury. Med J
Malaysia 2003;58:621e4.
[13] Dieme C, Bousso A, Sane A, et al. Bipolar dislocation of the clavicle or
floating clavicle. A report of 3 cases. Chir Main 2007;26:113e6.[14] Lee HJ, Lee JS, Ko YB. Bipolar clavicular dislocation: a case report.
J Korean Fracture Soc 2008;21:316e9.
[15] Buckholz RW, Heckman JD. Rockwood and Green’s fracture in adults.
5th ed. Philadelphia: Lippincott Williams & Wilkins; 2001. 1210e44.
[16] Sanders JO, Lyons FA, Rockwood Jr CA. Management of dislocations
of both ends of the clavicle. J Bone Joint Surg 1990;72-A:399e402.
Book Review / Critiques de livres
Book Review: BodyMR Imaging at 3 Tesla. Kamel Ihab R,Merkle Elmar M, editors. Body MR Imaging at 3 Tesla.New York: Cambridge University Press; 2011. 224 pages,Hardcover, USD$99.00. ISBN: 978-0-521194-86-0
With the recent growth in the volume of magnetic reso-nance (MR) imaging studies performed at 3 Tesla (3T) due toincreased availability of this technology, this text would bea welcome addition to the bookshelf of any radiologist whois currently performing body imaging at 3T or indeed anyradiologist who is considering it. The 14 chapters (224 pagesin total) are well laid out, the content of each chapter isconcise, and the text within each section is clearly written.The first chapter on ‘‘Basic Considerations About Artifactsand Safety’’ is an obvious place to start and covers the topicin detail. A chapter on ‘‘Novel Acquisition Techniques ThatAre Facilitated by 3T’’ follows, which again is clearly pre-sented. It covers practical explanations of the mostcommonly used imaging sequences and how they differ at 3Tcompared with 1.5T. The remaining chapters are dividedamong breast, cardiac, and abdominopelvic imaging, withindividual chapters about the liver, pancreas, adrenal glands,bowel, kidneys, prostate, and the female pelvis. Each sectioncovers the individual topic with clarity and detail.
There is some repetition within the various chapters, mostof the chapters start out with caveats regarding field homo-geneity, specific absorption rate, as well as discussionregarding the relative benefits of the increased signal-to-noiseratio achievable at the 3T.However, this is to be expected giventhe subject matter. There is also some overlap in content.Combining the chapters on ‘‘MR Imaging of the Pancreas’’and ‘‘Magnetic Resonance Cholangiopancreatography’’ couldhave avoided duplication in these sections, which are strangelyseparated by the chapter on adrenal imaging.
Images are generally good quality and plentiful, with clearimage legends. There also are numerous graphs and tablesthat aid in the understanding of the often complex conceptsof MR physics when imaging at 3T compared with 1.5T. Thedecision to place the colour plates in the middle of chapter 13is somewhat confusing. It is a pity that the colour imageswere not placed at their respective locations within the maintext instead of the grey-scale images, thus obviating the needfor colour plates at all. Alternatively, they could have beenplaced as an appendix at the end of the book, before theIndex. This, however, is a minor grievance. Within theircontributing chapters, most authors acknowledge that thebenefits of MR imaging at 3T over 1.5T are largely unproven,a fact also acknowledged in the preface, and this is to bewelcomed. When discussing the benefits of imaging at 3Tover 1.5T, the authors have included appropriate and up-to-date references.
Ultimately, the book succeeds in what the editors andindividual chapter authors set out to achieve. Witha paucity of textbooks that discuss imaging at 3T, it isa welcome addition and fills a gap in the market. Retailingat USD$99 (Kindle edition is USD$74.26), this bookwould be an excellent starting point for any radiologistwho is planning to perform body imaging at 3T. Indeed, itmay inspire more research to further elucidate moreclearly where the benefits of imaging at 3T lie and thusmaximize the exciting potential of body MR imaging athigher field strengths.
Darra T. Murphy, MB, BCh, BAO, MRCPI, FFR (RCSI)Vancouver General Hospital
