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Claire K Sandstrom1, Stephen A Kennedy2, Joel A Gross1 University of Washington School of Medicine – Harborview Medical Center 1 Department of Radiology, Section of Emergency & Trauma Radiology 2 Department of Orthopaedics & Sports Medicine ARRS 2015 Toronto, Canada No relevant financial disclosures for any of the authors After reviewing this educational exhibit, you will be able to: Describe the surgical considerations for: ◦ Clavicle fractures, depending on location (lateral, middle, medial) ◦ Acromioclavicular joint separation ◦ Sternoclavicular joint dislocation Recognize imaging signs of clinically significant injuries: ◦ Complex shoulder injury – Floating Shoulder ◦ Complex shoulder girdle injury – Scapulothoracic Dissociation Target Audience: Emergency and Musculoskeletal Radiologists, including physicians-in-training The clavicle is the sole osseous linkage between the torso and upper extremity, via its sternoclavicular and acromioclavicular articulations The clavicle shape varies between patients but is generally S-shaped S-shaped clavicle as seen from above on 3D volume rendered reconstruction Muscular attachments of the clavicle and direction of muscular tension (white arrows on lateral clavicle; black arrows on medial clavicle). SCM = sternocleidomastoid acromion SCM acromioclavicular joint humerus head shaft trapezius deltoid pectoralis major sternoclavicular joint manubrium Unlike other bones, true orthogonal XR projections of the clavicle are not achievable Clavicle radiographic evaluation includes a horizontal AP XR and an apical oblique XR with 15-40o (usually 25-30o) of cephalic angulation superior 1. Sternoclavicular joint 3 1 Radiographic Anatomy 6 2 (SCJ) 4 2. Clavicular head AP Clavicle XR inferior 5 1 2 anterosuperior 3 6 4. Conoid tubercle 5. Deltoid tubercle 6. Acromioclavicular joint (ACJ) 4 Apical Oblique Clavicle XR 3. Shaft posteroinferior Dedicated evaluation of the ACJ includes the bilateral joints in upright position simultaneously “Stress views” can also be obtained with weights in each hand Stress views may be helpful in confirming the diagnosis of an AC separation when the diagnosis is unclear from the physical examination or to confirm a type III dislocation when surgery is being considered, but are uncomfortable for the patient and may not change management, so are not routinely performed Abnormal alignment may actually improve on the stress views due to active muscular contraction. Regardless of when it is seen, abnormal alignment confirms injury Other specialized views of the clavicle include: ◦ Zanca view • 10-15o cephalic inclination @ ⅓–½ kVp of normal shoulder XR for visualization of the ACJ and distal clavicle • This view is not usually needed or obtained in the ED setting Zanca Clavicle XR AP Clavicle XR ◦ Serendipity view • 40o cephalic inclination for visualization of the SCJ and medial clavicle. This region is better seen on CT Serendipity Clavicle XR AP Clavicle XR Although other classification systems exist, the Allman system1 is used most frequently and divides the clavicle into thirds. Fracture frequency, demographics, and complications differ by location 15-20% of clavicle fractures2,3 GROUP II Lateral GROUP III rare – <5%2,3 Medial usually heal well most likely to displace and go on to nonunion (Distal) (Proximal) most common in elderly osteoporotic population2 GROUP I Mid Shaft most common in elderly osteoporotic adults2 (Middle) most common location of clavicle fracture - 75-80%2,3 most common in children and young adults2 We will discuss each of these fracture groups separately 1. 2. 3. Allman FL. J Bone Joint Surg Am. 1967;49:774-84 Nordqvist A, Petersson C. Clin Orthop Relat Res 1994; 300:127-32 O'Neill BJ, et al. Int Orthop 2011; 35:909-14 GROUP I Traditionally treated conservatively More recent reports describe 15-20% rate of nonunion and impaired upper limb function when certain fractures are treated non-operatively1-6 A 2007 multicenter RCT2 of completely displaced fractures without osseous contact showed operative fixation: ◦ rates of nonunion thought to be ~1% Exceptions requiring immediate surgery • open fractures • compromised “tented” skin (Fig below) • vascular or neurologic injury ◦ improved functional and symptomatic scores compared with closed reduction However, there is a trend toward primary repair of more clavicle fractures ◦ reduced time to union and rate of nonunion ◦ decreased malunion 24yo man with mildly comminuted, displaced mid clavicular shaft fx with skin tenting (arrow) ◦ increased patient satisfaction with appearance of shoulder Apical Oblique Clavicle XR 1. 2. 3. 4. 5. 6. McKee MD, Wild LM, Schemitsch EH. JBJS 2003; 85A:790-797. Canadian Orthopaedic Trauma Society. JBJS 2007; 89A:1-10 McKee MD, et al. JBJS 2006; 88A:35-40 Zlowodzki M, et al. J Orthop Trauma 2005; 19:504-7 Virtanen KJ, et al. Acta Orthop 2012; 83:65-73 Hill JM, et al. JBJS 1997; 79B:537-539 GROUP I Fractures for which internal fixation may now be considered: ◦ completely displaced fractures ◦ initial clavicular shortening ≥ 2 cm ◦ comminuted z-shaped fracture What is a “completely displaced fracture”? ◦ translation of one full clavicular shaft width (100%) – superior, anterior, etc. i.e. inferior cortical edge of the medial fragment is superior to the superior cortical edge of the lateral fragment (fig below) ◦ no osseous contact 46yo man with bilateral clavicular midshaft fractures. Right AP Clavicle XR Left AP Clavicle XR The right fracture is completely displaced – the medial inferior cortex (black arrow) is displaced above the superior cortex (white arrow) of the lateral fragment. This underwent surgical fixation (below) Post-op AP Clavicle XR The left fracture was mildly displaced – the medial inferior cortex (black arrow) is still below the superior cortex (white arrow) of the lateral fragment. This was treated conservatively GROUP I Fractures for which internal fixation may now be considered: How is “clavicular shortening” measured? ◦ completely displaced fractures ◦ difficult for both radiologists and orthopedic surgeons, and interrater reliability is poor1,2 ◦ initial clavicular shortening ≥ 2 cm Options include: ◦ comminuted z-shaped fracture ◦ unilateral view measuring amount of osseous overlap (Fig to left)3 AP Clavicle XR ◦ symmetric bilateral views measuring clavicle length difference (Fig below) ◦ 3D CT (but unnecessary radiation and expense in most cases) ◦ clinically with measuring tape (on skin) 2 cm 34yo man with borderline shortening when measuring the amount of osseous overlap. The distance between the superior cortices of the medial (white arrow) and lateral (black arrow) bone fragments is approximated (double-ended yellow arrow). After discussion, the patient underwent ORIF. 1. 2. 3. Jones GL, et al. Am J Sports Med 2014; 42:1176-81 Silva SR, et al. J Pediatr Orthop 2013; 33:e19-e22 Hill JM, McGuire MH, Crosby LA. JBJS 1997; 79B:537-9 15yo boy with 3 cm of left shortening when comparing length of bilateral clavicles Bilateral Upright Clavicle XR GROUP I Fractures for which internal fixation may now be considered: ◦ completely displaced fractures ◦ initial clavicular shortening ≥ 2 cm What is a “z-shaped fracture”? ◦ Segmental fracture of the middle third with the segmental fragment rotated vertically ◦ comminuted z-shaped fracture 43yo man with more displaced and comminuted z-shaped clavicle fracture, which was repaired with cortical plate 16yo man with z-shaped clavicle fracture, which was repaired with cortical plate AP Clavicle XR AP Clavicle XR Post-op AP Clavicle XR Post-op AP Clavicle XR GROUP II What is the “lateral clavicle”? Several different definitions exist in the literature: ◦ Fractures occurring lateral to both components of coracoclavicular ligament (CCL) ◦ Fractures of the lateral ⅓ of the clavicle ◦ Fractures of the lateral ⅕ of the clavicle - lateral to a vertical line from middle of corocoid base (usually marked by conoid tuberosity) Is this a lateral clavicle fracture? AP Clavicle XR If you use the 1st or 3rd definitions above (lateral to CCL or lateral ⅕), then the answer is no However, it does involve the lateral third – we will therefore describe this as a lateral clavicle fracture For this discussion, we will use the most common definition, which is the lateral 1/3, encompassing the bone just medial to the CCL Lateral clavicular fractures are less common than midshaft fractures However, lateral fractures are associated with higher rate of nonunion than with midshaft fractures, likely due to associated ligamentous injuries. The risk of nonunion is greatest when the fracture has no osseous contact and with advancing age1 1. Robinson CM, et al. JBJS 2004; 86A:1359-65 GROUP II Most fractures (75%) are between the CCL and ACJ, and the ligaments remain intact; these fractures can be treated nonoperatively AP Clavicle XR 30yo woman with transverse fracture lateral to the conoid tubercle with intact CCL, treated nonoperatively Apical Oblique Clavicle XR 86yo woman with oblique fracture lateral to the conoid tubercle with intact CCL, treated nonoperatively Some lateral clavicular fractures extend into the ACJ; these can usually be managed conservatively with good results AP Clavicle XR 37yo woman with oblique nondisplaced fracture extending into an otherwise intactappearing ACJ, treated nonoperatively 1. 2. Neer CS. J Trauma. 1963:99-110 Jackson WF, et al. J Trauma 2006; 61:222-5 GROUP II AP Clavicle XR Fractures most likely to displace (and therefore heal poorly) are: ◦ near the conoid tubercle with associated rupture1 or avulsion2 of the CCL ◦ just medial to the conoid tubercle of the CCL In both cases, the lateral fragment is pulled inferiorly, while unopposed forces on the medial fragment result in wide fracture displacement (see next slide) ◦ Surgery may be considered – may require specialized fixation due to problems of bone quality and comminution, including fixation to the coracoid (e.g. suture button) or the acromion (hook plate) 28yo man with clavicle fracture lateral to the conoid tubercle. Although the tubercle (arrow) is spared, the CCL is disrupted, inferred by elevation of the medial clavicular fragment (and widening between the conoid tubercle and coracoid process) 1. 2. Neer CS. J Trauma. 1963:99-110 Jackson WF, et al. J Trauma 2006; 61:222-5 25 yo man with comminuted fracture of the lateral clavicle, including an inferior fragment containing the CCL attachment sites. This was treated with a plate and screws and suture button fixation from the plate to the coracoid – note the metallic button (arrow) on the undersurface of the coracoid. This prevents pull-out of the screws from the distal comminuted fragments AP Clavicle XR Post-op AP Clavicle XR GROUP II Displacing forces shown below result in a higher rate of nonunion for lateral fractures than for midshaft fractures Requirements for Displacement: 1 Distal fracture medial to conoid tubercle, OR Fracture at or lateral to conoid tubercle, AND Avulsion of conoid tubercle or widening between conoid tubercle and coracoid = conoid ligament torn (example shown) Trapezius AC T L Displacing Forces: 1. 4 1. Pectoralis major 3 Trapezius muscle pulls medial fragment superior and posterior; muscle may become entrapped 2. Weight of arm pulls lateral fragment down Bahk MS, et al.3. J Bone Joint Surg Am. 2009;91:2492-2510 Pectoralis muscle pulls humerus & therefore lateral fragment medial 4. Scapula acting via AC and trapezoid (TL) ligaments rotates lateral fragment up to 40o 2 Arm 1. Neer CS. Clin Orthop Relat Res 1968; 58:43-50 2. Neer CS. J Trauma 1963:99-110 GROUP III Uncommon fractures of the medial ⅓ of the clavicle, usually treated nonoperatively unless open1 Described as transverse, oblique, comminuted, or avulsive, and can be intraarticular or extraarticular Radiographically subtle due to overlapping structures, these fractures are best visualized and characterized on CT1 Cor CT AP CXR (cropped) 58yo man with trauma to left shoulder. Initial CXR shows asymmetric positioning of the clavicles, suspicious for clavicle dislocation. However, subsequent CT images show displaced, extraarticular, oblique fracture of the medial left clavicle. The shaft fragment is displaced inferior and anterior relative to the clavicular head, accounting for the XR appearance 1. Throckmorton T, Kuhn JE. J Shoulder Elbow Surg 2007; 16:49-54 Ax CT GROUP III Medial clavicular fractures are a marker of high-energy trauma and occur in a trauma population with high mortality Presence of a medial clavicular fracture should prompt CT to look for coexisting injuries, including hemothorax/pneumothorax, pulmonary contusions, ARDS, rib fractures, facial and head injuries, cervical spine injuries1 Coronal CT AP Clavicle XR 15yo boy s/p MVC with right pulmonary contusions and segmental clavicle fx involving the midshaft (black arrow) and medial clavicle (yellow arrow) AP CXR 1. Throckmorton T, Kuhn JE. J Shoulder Elbow Surg 2007; 16:49-54 Fracture location Middle third fracture Important factors affecting treatment decisions completely displaced (>100%) ≥2 cm shortening z-shaped fragment skin tenting, open injury Lateral third fracture fracture at, medial to, or lateral to conoid tubercle displaced medial fragment (>100%) CCL avulsion Medial third fracture fracture description + additional injuries The acromioclavicular joint (ACJ) at the distal end of the clavicle has a synoviumlined joint capsule stabilized by superior, inferior, anterior, and posterior acromioclavicular (AC) capsular ligaments ◦ The superior AC capsular ligament is the most important component and is reinforced by fibers of the deltoid and trapezius muscles ◦ The AC ligaments primarily prevent anterior and posterior displacement The coracoclavicular ligament (CCL) is composed of the fan-shaped conoid ligament medially and the quadrilateral-shaped trapezoid ligament laterally ◦ The CCL primarily resists vertical displacement The deltoid and trapezius muscular aponeuroses converge over the ACJ to form the deltotrapezial fascia ACJ alignment is best assessed on a Zanca view, but the AP view is usually sufficient in the ED Normal ACJ alignment is maintained by the: • ACJ capsule and AC ligaments • conoid and trapezoid components of the CCL • coracoacromial ligament • deltotrapezial fascia (aponeurosis) (DTF) Diagram of normal measurements for ACJ alignment1 Deltotrapezial fascia Trapezius m. . ACJ capsule + AC ligaments Deltoid m. Conoid Ligament Trapezoid Ligament CCL Coracoacromial Ligament Diagram of ACJ structures Normal ACJ alignment on XR1: • 5-8 mm ACJ and <2-3 mm contralateral asymmetry • Inferior cortex of distal clavicle aligns with that of acromion • 10-13 mm CC interval and <5 mm contralateral asymmetry 1. Eschler A, et al. Arch Orthop Trauma Surg. 2014;134:1193-8 ACJ separations are described according to the modified Rockwood classification1 Six types of injury exist, based on integrity of the AC ligaments, CCL, and DTF and on the ultimate location of the distal clavicle ◦ Type VI injury (dislocation of clavicle inferior to the coracoid process) is extremely rare and will not be discussed further, though important because it is treated surgically Modified Rockwood Classification Upward displacement of clavicle * Pathology Treatment I 0% (radiographically occult) AC ligament sprain with intact AC capsule Non-operative II 0-50% AC ligament tear, normal or sprain of CCL Non-operative III 50-100% AC ligament and CCL torn, DTF intact – distal clavicular subluxation is reducible Often non-operative, consider ORIF IV 50-100% + posteriorly displaced on axillary AC ligament and CCL torn, DTF torn with distal clavicle button-holed posteriorly through trapezius Surgical V 100-300% AC ligament and CCL torn, DTF torn with distal clavicle button-holed superiorly through trapezius Surgical * Originally described as % of CC interval. However, without prior knowledge of the patient’s normal CC interval, % of the width of the clavicle is an adequate approximation 1. Rockwood CA, Young DC. Disorders of the acromioclavicular joint. In: Rockwood CA, Matsen FAI, eds. The Shoulder. Philadelphia: WB Saunders; 1990. p. 413-76 II Upward displacement of clavicle Pathology Treatment 0-50% AC ligament tear, normal or sprain of CCL Non-operative Rockwood Type II injury results from tear of the AC ligament but other structures are intact Only the ACJ is wide and/or minimally vertically offset Potential mimics include distal clavicular osteolysis or surgical resection of the distal clavicle (Mumford procedure) – look for truncated appearance of the clavicle + widening of AC joint interval without vertical offset 52yo woman with type II ACJ separation, slight vertical offset of the ACJ without significant widening AP Clavicle XR Diagram of grade II ACJ separation 54yo man with type II ACJ separation, widening of the ACJ without vertical offset AP Clavicle XR III Upward displacement of clavicle Pathology Treatment 50-100% AC ligament and CCL torn, DTF intact – distal clavicular subluxation is reducible Often non-operative, consider ORIF Tears of both the AC ligaments and CCL give rise to the Rockwood Type III injury; DTF remains intact AC and CC intervals are both wide This injury is readily reducible with upward force applied to the elbow This injury may be treated operatively or non-operatively, depending on surgeon and patient factors. Most often, conservative management is offered with surgery for failure of nonoperative treatment Diagram of grade III ACJ separation 42yo man with type III ACJ separation. Upright clavicle radiographs show ~100% vertical offset of left ACJ and widening of CC interval. However, supine radiographs show only minimal widening of ACJ, confirming reducibility Upright Supine IV Upward displacement of clavicle Pathology Treatment 50-100% + posteriorly displaced on axillary AC ligament and CCL torn, DTF torn with distal clavicle button-holed posteriorly through trapezius Surgical If DTF is also torn, the distal clavicle may become entrapped within the fascial defect or within the trapezius muscle In Rockwood Type IV injuries, the clavicle is displaced posteriorly into a subcutaneous position, which might be visible on axillary radiographs as posterior displacement of at least 100% of the clavicle width1 This injury is not reducible with upward force applied to the elbow This injury is treated operatively Diagram of grade IV ACJ separation 66yo man hit by truck with grade IV ACJ separation. The clavicle is vertically offset 100% on the AP view, which can be seen with grade III or even grade IV injuries. However, on the axillary view, the clavicle (black arrows) is also posteriorly displaced relative to the acromion (white arrows), indicating grade IV injury AP XR Axillary XR 1. Cho CH, et al. J Shoulder Elbow Surg 2014; 23:665-70 IV Upward displacement of clavicle Pathology Treatment 50-100% + posteriorly displaced on axillary AC ligament and CCL torn, DTF torn with distal clavicle button-holed posteriorly through trapezius Surgical However, it is important to recognize that the distal clavicle can project posterior relative to the acromion even when there is no ACJ separation (see example below)1 AP Shoulder XR Axillary Shoulder XR 63yo woman with mild ACJ degeneration but normal alignment on AP view. However, the distal clavicle (black arrows) artifactually projects posterior to the acromion (white arrows) on the axillary view Reliable differentiation of types III and IV therefore requires correlation of the radiographic and physical exam findings. CT can also be helpful for problem solving 1. Rahm S, et al. J Orthop Trauma 2013; 27: 622-626. V Upward displacement of clavicle Pathology Treatment 100-300% AC ligament and CCL torn, DTF torn with distal clavicle button-holed superiorly through trapezius Surgical The distal clavicle may also displace superiorly through the torn DTF. This results in more marked elevation of the clavicle, between 100-300% This injury is also not reducible with upward force applied to the elbow This injury is treated operatively The possibility of a type V injury should be raised for those injuries with the clavicle displaced more than 100% above the acromion, realizing that there is a grey zone between type III and type V injuries around 100% displacement 52yo man with type V ACJ separation. Clavicle radiograph at right shows more than 200% vertical offset of left ACJ and widening of CC interval. Soft tissue gas was related to left rib fractures, not an open injury. The patient was treated operatively with CCL reconstruction (osseous tunnels indicated by arrows on left image) Post-op AP Clavicle XR AP Clavicle XR Diagram of grade V ACJ separation Pediatric pseudodislocation is characterized by the appearance of ACJ dislocation and CCL tear Instead of the CCL tearing, however, the intact ligaments are attached to a periosteal sleeve arising from the distal clavicle.1 The diaphysis herniates superiorly through the periosteal defect while the epiphysis, periosteal sleeve, and CCL remain in place The periosteal sleeve regenerates new bone, and these children often do well with nonoperative management 15yo boy with widened ACJ and CC interval related to football injury. A bone fragment lies underneath the distal clavicle, which represented a small cortical fragment attached to the periosteal sleeve and epiphysis avulsed by the CCL AP Clavicle XR 17yo girl with ACJ separation following MVC. Radiographs show widening of the ACJ and CC interval. At surgery, type V ACJ separation was diagnosed due to additional DTF disruption. However, the CCL was actually intact but was attached to an avulsed periosteal sleeve (without associated radiographic finding) AP Clavicle XR 1. Falstie-Jensen S, Mikkelsen P. JBJS. 1982;64B:368-369 Components of the SSSC The superior suspensory shoulder complex (SSSC) is an osseoligamentous ring formed by acromion process, acromioclavicular joint capsule, distal clavicle, coracoclavicular ligaments, coracoid process, and glenoid process1 Multiple injuries to the SSSC potentially destabilize the arm relative to the shoulder girdle and are important to recognize. They result in a “floating shoulder”2 Originally identified when scapular neck and ipsilateral clavicular shaft fractures coexist,3-4 the floating shoulder can also result from grade III or higher ACJ separations and unstable distal clavicle fractures2 One or more of the sites of disruption in a floating shoulder may be surgically repaired ACJ Coracoid Osseoligamentous ring of the SSSC 1. 2. 3. 4. Lambert S, et al. Injury 2013; 44:1507-13 Goss TP. J Orthop Trauma 1993; 7:99-106 van Noort A, van der Werken C. Injury 2006; 37:218-27 Herscovici D, et al. JBJS 1992; 74B:362-4 26yo man with floating shoulder resulting from comminuted scapular fracture traversing the glenoid neck and acromial process combined with grade III ACJ separation. Due to extensive neurologic and other injuries resulting from being hit by a train, this injury was treated conservatively despite being unstable Grashey Shoulder XR 25yo man with floating shoulder resulting from moderately displaced mid clavicular shaft fracture and glenoid neck fracture. He underwent surgical fixation of the clavicular shaft only, with successful conservative treatment of the scapular neck AP Shoulder XR Post-op AP Clavicle XR While the osseous anatomy of the sternoclavicular joint (SCJ) is not intrinsically stable, SCJ dislocation is rare due to strong ligaments supported by a dynamic muscular envelope SCM sternal clavicular head head . 6 5 3 1 The anterior & posterior joint capsule (sternoclavicular ligaments) (1) plays primary stabilizing role 2 4 7 ◦ disruption of anterosuperior/posterior capsular thickening or “ligament” allows superior translation of joint1 Secondary stabilizing roles played by the interclavicular (2) and costoclavicular (rhomboid) (3) ligaments and the dynamic muscular envelope ◦ subclavius muscle (4) acts as extrinsic shock-absorber for the clavicle and SCJ ◦ sternocleidomastoid (SCM) and pectoralis major form an muscular aponeurosis anterior to SCJ ◦ sternohyoid (5) and sternothyroid (6) muscles lie directly behind the SCJ An intraarticular disc (7) separates the clavicular head from the manubrium and can be torn or crushed 1. Robinson CM, et al. JBJS 2008; 90B:685-96 2. Lee JT, et al. JBJS. 2014;96A:e166 Injury can range from minimal sprain of the supporting ligaments without laxity to rupture of the sternoclavicular ligaments only, resulting in subluxation and mild deformity, and finally to complete rupture of the sternoclavicular and costoclavicular ligaments resulting in anterior or posterior dislocation ◦ Anterior dislocation is more common, often from an indirect force directed against the lateral clavicle * AP CXR (cropped) 3D Volume-rendered CT 42yo pedestrian hit by car with anterior left SCJ dislocation. AP CXR shows asymmetric position of the clavicular heads (yellow dashed outlines). Volume rendered CT shows normal right SCJ (arrow) and anteriorly dislocated left clavicle (*) Though SCJ dislocation may be detected on AP or serendipity radiographs of the joint, CT is the mainstay of diagnosis 1. Robinson CM, et al. JBJS 2008; 90B:685-96 Posterior dislocations are much less common but are associated with more complications, the most worrisome of which is vascular or aerodigestive tract injury from the clavicular head. CT should be performed in these patients AP Clavicle XR Surgical indications include: ◦ failure of closed reduction of anterior dislocation ◦ neurovascular compromise ◦ open fracture-dislocation ◦ closed reduction of posterior dislocation is only performed in the OR with cardiothoracic surgery available in case of complications 29yo man with posterior right SCJ dislocation. AP radiograph shows asymmetric position of the clavicular heads (yellow dashed outlines). On apical oblique view, the right clavicular head moves more inferior relative to the left, suggesting posterior dislocation. This is easily confirmed on axial MIP CT. Slight anteroposterior tracheal narrowing is an artifact of the MIP reconstruction – no airway or other soft tissue injury was identified Apical Oblique Clavicle XR Axial 3D MIP CT 1. Robinson CM, et al. JBJS 2008; 90B:685-96 Asymmetric widening or superior subluxation of the sternoclavicular joint without anteroposterior malalignment is worth mentioning, as it directs attention to a joint that may be sprained or have some pre-existing inflammatory or degenerative process, although this can usually be treated conservatively 51yo woman with asymmetric widening of the left SCJ without anteroposterior displacement after MVC. This was treated conservatively Coronal CT 25yo man isolated superior dislocation of the right SCJ without anteroposterior displacement. CXR shows slight asymmetry of the medial clavicles Coronal CT CXR (cropped) The medial clavicular epiphysis is the last to appear (around 18yo) and to fuse (between 23-30yo, usually around 25yo) Many “dislocations” in those <25yo are not dislocations but actually physeal injuries 16yo girl with Salter-Harris type 1 injury of the medial clavicle during a basketball game. Clinically and radiographically (not shown), the injury mimics a posterior SCJ dislocation, but CT (axial MIP reconstruction shown) confirms that both clavicular epiphyses (black arrows) are in normal position, with right-sided physeal disruption and posterior metaphyseal (M) displacement. She also had mediastinal hematoma (*) ascribed to venous bleeding and a small pseudoaneurysm of the brachiocephalic vein (yellow arrow) on coronal CT reformation * M Axial MIP CT Coronal CT 1. Bishop JY, Flatow EL. Clin Orthop Relat Res. 2005;432:41-48 Scapulothoracic dissociation is a rare but severe injury of the osseous and/or muscular shoulder girdle and potentially involving the subclavian / axillary vascular structures and/or brachial plexus.1 It is not specifically a clavicular injury, although the clavicle or surrounding articulations are often affected, and the clavicular injury may be the first imaging clue to this important diagnosis Focused neurovascular exam is required to prompt appropriate work-up, including: ◦ Emergent CT angiogram for evaluation of suspected vascular injuries (see Fig) ◦ MR neurogram obtained after a delay of several days for suspected brachial plexus injury, which if complete will often render the arm functionless with a poor long-term prognosis 20yo man with scapulothoracic dissociation from motorcycle crash. CT angiogram (3D volume rendered reconstruction shown to right) confirmed complete occlusion of the left axillary artery with distal reconstitution 3D Volume Rendered CT angiogram 1. Brucker PU, Gruen GS, Kaufmann RA. Injury. 2005;36:1147-55 The scapula is usually lateralized from the ribs relative to the normal side Quantified with scapular index ◦ ratio of distances bilaterally from medial border of scapula to spinous process The 20yo male motorcyclist with left scapulothoracic dissociation (with CTA shown on previous slide). At presentation, suspicious radiographic findings included increased scapular index (A/B), comminuted left scapular fracture (S), increased soft tissue density in the left axillary & supraclavicular regions (*), and left apical capping (arrows) ◦ ≥1.4 is considered abnormal ◦ prone to error (beware asymmetric arm positioning, spine fractures, or scapular fractures) * S ◦ should not definitively rule in or exclude this diagnosis1 Distracted fractures of the clavicle or separations of the ACJ or SCJ often present Secondary signs from chest wall hematoma accompanying the vascular injury * Scapular index = A / B ◦ asymmetric increased axillary density ◦ ipsilateral apical capping 1. Brucker PU, Gruen GS, Kaufmann RA. Injury. 2005;36:1147-55 Thank you for viewing this Education Exhibit on Clavicle Trauma Fractures of the middle third of the clavicle that demonstrate >2 cm of shortening, >100% translation without osseous contact, and/or segmental comminution may be considered for surgical repair Fractures of the lateral third of clavicle, including at the level of or just medial to the coracoclavicular ligaments, have higher rates of nonunion and therefore may also be repaired surgically The modified Rockwood classification is used to describe the degree and direction of displacement in AC separation, and injuries of grade IV or V (or extremely rare grade VI) are repaired surgically Associated injuries are common in medial clavicular fractures and sternoclavicular joint injuries, and additional imaging with CT is recommended, particularly if displacement is posterior Author Contact Info: Claire Sandstrom - [email protected]