REVIEW ARTICLE

Clavicle and acromioclavicular joint injuries: a reviewof imaging, treatment, and complications

Yulia Melenevsky & Corrie M. Yablon &

Arun Ramappa & Mary G. Hochman

Received: 15 December 2009 /Revised: 4 May 2010 /Accepted: 11 May 2010 /Published online: 6 June 2010# ISS 2010

Abstract Fractures of the clavicle account for 2.6–5% ofall fractures. Clavicular fractures have traditionally beentreated conservatively, however, there has recently beenincreased interest in surgical repair of displaced clavicularfractures, with resultant lower rates of nonunion andmalunion. Treatment of acromioclavicular (AC) separationhas traditionally been conservative, with surgery reservedfor patients with chronic pain or significant dislocation andacute soft tissue injury. It is important for the radiologist tobecome familiar with the surgical techniques used to fixatethese fractures as well as the post-operative appearance andpotential complications.

Keywords Clavicle fractures .

Clavicle and acromioclavicular joint imaging .

Acromioclavicular reconstruction

Introduction

Fractures of the clavicle account for 2.6–5% of all fractures[1–3]. Clavicular fractures have traditionally been treatedconservatively, with initial reported rates of nonunion aslow as 1% [4, 5]. However, recent literature has shown thatthe outcome of nonoperative treatment is not as good aspreviously thought. Nonunion of displaced clavicular

fractures can result in orthopedic, neurovascular, andcosmetic complications [6]. Recent studies demonstratelower rates of nonunion with surgery compared tononoperative treatment [7]. Furthermore, patients nowadaysexpect improved cosmetic outcomes and earlier resumptionof preoperative activity levels, leading surgeons to focus onprimary surgical repair of displaced clavicular fractures.Treatment of acromioclavicular (AC) separation has alsotraditionally tended to be conservative, however, there is arole for surgery in patients with chronic pain, significantdislocation, and acute soft tissue injury, or type IIIseparations in high performance athletes [8].

This article will focus on the more common clavicularinjuries, including midshaft clavicular fractures, distalclavicular fractures, and AC separation. Each of theseinjuries has its own classification system and rationale fortreatment. It is important for the radiologist to becomefamiliar with the techniques developed to fixate thesefractures. Some of the surgical anchors and fixation devicesare radiolucent on radiography, and thus the postsurgicalappearance can be subtly altered from the preoperativeappearance. In addition, there are multiple potentialpostsurgical complications of which one needs to becognizant. It is important to understand the surgicalconsiderations when these injuries are corrected, as thisallows an appreciation for the expected postoperativeappearance and potential postoperative complications.

Imaging of clavicular fractures

Radiography is usually the first-line imaging modality usedto evaluate patients with uncomplicated clavicular andacromioclavicular joint injury. Clavicular anterior-posterior(AP) and apical oblique views (15–25° cephalic tilt) are

Y. Melenevsky :C. M. Yablon (*) :M. G. HochmanDepartment of Radiology, Beth Israel Deaconess Medical Center,Boston, MA, USAe-mail: cyablon@bidmc.harvard.edu

A. RamappaDepartment of Orthopedic Surgery,Beth Israel Deaconess Medical Center,Boston, MA, USA

Skeletal Radiol (2011) 40:831–842DOI 10.1007/s00256-010-0968-3

used to evaluate clavicular fractures. Computed tomography(CT) is not routinely used for the evaluation of simple,nondisplaced clavicle fractures. However, thin section CT hasbecome the standard of care to evaluate suspected subtlemedial clavicle fractures in younger patients with open physesor for sternoclavicular dislocation [9]. Multidetector CT(MDCT) with sagittal and coronal reformatted images orthree-dimensional volume renderings (3DVR) can beextremely helpful for the preoperative evaluation ofsuspected nonunion or displaced clavicle fractures. MDCTcan assess the degree of displacement of the fracturefragments and the proximity of the fragments to adjacentvessels and to the brachial plexus (Figs. 1, 2).

Magnetic resonance imaging (MRI), with its three-dimensional imaging capability and superior soft tissuecontrast, can be extremely useful for imaging suspectedneurovascular complications, pseudoaneurysm formation,impingement of fracture fragments on the brachial plexusand adjacent vessels, and hematoma formation (Fig. 3).MRI is also extremely helpful to delineate concomitantligamentous injury with distal clavicular fractures and aid infurther subtyping these injuries.

Classification of clavicle fractures

There are myriad classification schemes used to describeclavicle fractures. Allman initially divided clavicle fracturesby anatomic location into thirds: type I involves the middlethird of the clavicle; type II, the distal clavicle; and type III,the proximal clavicle [10]. Although in common use, theAllman classification does not take into account thepresence of comminution or displacement of fracturefragments. The Neer modification of the Allman classifica-tion further subdivides distal clavicle fractures (type II)based on the integrity of the coracoclavicular (CC)ligaments and the acromioclavicular (AC) joint. Craigsubsequently modified the Neer and Allman system, furtherrefining the classification to include medial fractures,degree of comminution, displacement, and joint involve-ment [11]. The Allman classification, incorporating theNeer modification, is commonly used. In 1998, Robinsoncreated the newer Edinburgh classification, and this systemis gaining popularity because of its useful prognosticinformation as to fracture healing. This scheme subdividesclavicular fractures on the basis of anatomical location,comminution, and displacement of the fracture [12]. Inclinical practice, orthopedic surgeons and radiologistsusually place less emphasis on trying to classify the fracturethan on making the clinical determination of the location ofthe clavicle fracture, the degree of comminution anddisplacement, the relationship of the fracture to the ACjoint and CC ligaments, and the integrity of the ligaments.

Medial clavicular fractures

Medial clavicular fractures occur uncommonly and com-prise 2–3% of all clavicle fractures [2]. Most medialclavicle fractures are nondisplaced and do not involve thesternoclavicular joint. These fractures are usually managednonoperatively. However, posterior fractures or dislocationshave the potential to displace into the superior mediastinum

Fig. 1 A 20-year-old male who fell while snowboarding andpresented with a foreshortened limb. a Frontal radiograph demon-strates 6 cm overriding of the medial and lateral clavicle fracturefragments. b Standard sagittal reformat of multidetector CT demon-strates a posteriorly displaced distal clavicle fracture fragmentimpinging on the subclavian vessels (black arrow). c 3D volumerendering (VR) MDCT demonstrates a markedly distracted, displacedmidshaft clavicle fracture with overriding of the fragments and aposteriorly displaced fragment (white arrow) abutting the first rib. Acomminuted fracture fragment (black arrow) is wedged perpendicu-larly between the proximal and distal comminuted fracture fragmentand required surgical reduction. 3DVR most effectively demonstratesthis fracture configuration

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with resultant great vessel, airway, and neurologic injury.Medial clavicular fractures may be radiographically occult,and CT commonly helps to identify the fracture andevaluate for neurovascular or airway compromise (Fig. 4).If reduction is required, closed reduction is preferable toopen reduction, due to potential for implant migration.Internal fixation methods including plates, interosseoussutures, and Kirschner wires have been described [12].

Midshaft clavicular fractures

Midshaft clavicular fractures account for 69–82% of allclavicular fractures and occur more frequently in childrenand young adults [1, 2]. These injuries have been shown toresult from falls, a direct blow incurred in sports, or motorvehicle accidents. Although midshaft clavicle fractures havetraditionally been treated nonoperatively with presumptivegood outcomes, it has now been shown that conservativelytreated displaced midshaft clavicular fractures can result innonunion rates as high as 15% [6, 13, 14]. This discrepancyis explained in part by the inclusion of pediatric patients inearlier studies, with pediatric patients having superioroutcomes to adults. Criteria for outcome assessment amongthe studies differed, which affected the reported rates ofnonunion. There is also debate in the literature as to whetherdisplaced midshaft clavicle fractures should be treatedinitially or after conservative treatment has failed [12, 15].

Fig. 4 a Frontal radiograph demonstrates sternoclavicular dislocationwith disruption of the sternoclavicular joint and proximal elevation of themedial clavicle. b Axial CT centered on the sternoclavicular jointsdemonstrates marked posterior displacement of the left clavicle withrespect to the sternum. There is mild impingement on the arch vessels andbrachiocephalic vein (arrow). The patient was managed conservatively.(Images courtesy of Dr. Jim S. Wu, Boston, MA)

Fig. 3 A 52-year-old male who sustained a displaced left midshaftclavicle fracture after falling off a bicycle. He was managedconservatively initially. Four months later he presented with decreasedstrength and weakness in his left C8 and T1 distributions suggestive ofbrachial plexus neuropathy. MR of the torso demonstrates callus withhematoma formation (black arrow) at the left midshaft claviclefracture site causing impingement of the brachial plexus withconcomitant edema of the brachial plexus distal to the site ofimpingement (white arrow)

Fig. 2 A 28-year-old female hit by a snowplow who sustained neartotal left forequarter amputation. a Frontal chest radiograph demon-strates a large soft tissue defect and markedly distracted comminutedfractures of the clavicular midshaft and scapula. (Incidental note ismade of right mainstem bronchial intubation with associated left lungatelectasis. The endotracheal tube was pulled back). b 3D VR MDCTdemonstrates the markedly comminuted midshaft clavicle and scapularfractures. These images aided in the preoperative planning ofreconstruction of the clavicle and scapula with plate and screw fixation

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Nonoperative management

Mid-shaft clavicular fractures, either nondisplaced or dis-placed, have commonly been treated conservatively withclosed reduction with a sling or a figure-of-eight brace [1,2, 5–7, 13, 14]. It has traditionally been thought thatradiographic nonunion or malunion had little effect onfunctional outcome [16]. However, recent studies haveshown a high nonunion and malunion rate if displacedmidshaft fractures are treated conservatively [6, 7, 13]. Arecent study examined “patient-based outcomes” afterclavicular fractures and demonstrated 31% of patientsreporting unsatisfactory results after nonoperative treatmentincluding weakness, numbness, paresthesias of the handand forearm with elevation of the limb, and “droopy”shoulder [7, 14]. A meta-analysis of recent studies showeda 15.1% rate of nonunion of displaced midshaft clavicularfractures treated conservatively compared with 2.2% afterplate fixation [7, 15].

Operative management

Several types of fixation plates have been used in thetreatment of midshaft clavicle fractures. Dynamic compres-sion plates are most commonly applied to the anterosuperiorsurface of the clavicle with a minimum of three screws in theproximal and distal fracture fragments. Care is taken to restorethe original length and rotation of the clavicle, as well as thepreoperative distance between the AC and sternoclavicularjoints. Precontoured “anatomic” plates are favored rather thanstraight compression plates as the precontoured plates arefound to produce less soft tissue irritation [17]. Antero-inferior plating has also been described with good functionaland cosmetic results and reduced hardware-related skinirritation [18, 19] (Fig. 5).

Intramedullary nailing or pinning is an alternative toplating that has the potential benefit of less soft tissuestripping at the fracture site, better cosmetic appearancewith a smaller skin incision, easier hardware removal,and less weakness at the fracture site after hardwareremoval. However, intramedullary nailing may provideless rotational stability compared to plating. Severalother fixation methods have been described to repairmidshaft clavicle fractures, including Kirschner wires,Knowles pins, Steinmann pins, elastic nails, and cancellousscrews [20–25] (Fig. 6).

Complications

Both nonoperative and operative management can result inpain and tenderness at the fracture site, limited range ofmotion, and malunion or nonunion of the fracture.Radiographic characteristics of malunion in the clavicle

include shortening in the medial-lateral dimension withinferior displacement of the distal fracture fragment. Thereis commonly some clavicular length discrepancy betweenthe affected and normal side [6] (Fig. 7). Nonunion isdefined as the lack of radiographic healing with absence ofosseous bridging at the fracture site and clinical evidence ofpain and motion at the fracture site at 24 weeks [2]. Thereare two types of nonunion: hypertrophic nonunion, wherethere is sclerosis with abundant callus formation associatedwith good blood supply, and atrophic nonunion, wherethere is absence of callus and demineralization associatedwith poor blood supply. Hypertrophic nonunion occursmore frequently where there is abnormal motion at thefracture site, either secondary to absence of fixation or toinadequate fixation. Atrophic nonunion occurs morefrequently in the case of segmental fractures, where

Fig. 6 A 21-year-old male with a midshaft clavicular fracture fixatedwith a Hagie pin. Postoperative radiograph shows near anatomicalignment of initially angulated fracture fragments

Fig. 5 Midshaft clavicle fractures with different types of fixationplates. a A 44-year-old male with displaced midshaft clavicle fracturetransfixed by anterior reconstruction plate. b A 23-year-old male withanatomic reduction of midshaft fracture and fixation with a precon-toured plate to the superior aspect of the clavicle. Three proximal andfour distal cortical screws transfix the proximal and distal fracturefragments. Additionally, a lag screw transfixes the fracture fragmentsin the antero-posterior direction

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there is loss of bone apposition to promote healing(Fig. 8). Subclavian vessel compression, thrombosis, andpseudoaneurysm as well as brachial plexus injury canoccur secondary to posteriorly displaced fracture fragmentand hypertrophic callus formation at the fracture site afterconservative management [26] (Fig. 9).

Postoperative complications include hardware loosening,with the possible consequence of subsequent migration,hardware failure or breakage, wound dehiscence, andinfection (Fig. 10). Hardware-related irritation can necessi-tate removal of the hardware [6, 7, 20, 27]. Delayed unionand nonunion remain infrequent complications of surgicalmanagement. Clavicle re-fracture following plate removalhas been described [27]. There have been reports ofoccasional intramedullary nail migration [20]. Hardwareloosening can be manifested by radiolucency surroundingthe implant caused by abnormal motion (Fig. 11). Postop-erative radiographs should always be evaluated for signs ofinfection, manifesting as abnormal widening between boneand hardware, erosion of bone, periosteal reaction, and softtissue swelling [27] (Fig. 12).

Distal clavicular fractures

Approximately 28% of clavicular fractures occur at thedistal aspect of the clavicle [2]. The mechanism rangesfrom simple falls to trauma involving a direct blow to theshoulder. The Neer modification of the Allman classificationhas commonly been used to describe distal clavicularfractures. The classification system categorizes fracturesbased on their relationship to the coracoclavicular (CC)

ligaments. Neer type I fractures occur between theconoid and trapezoid ligaments; the CC ligaments remainintact and the fracture is stable. Neer type II fracturesoccur proximal to the CC ligaments, resulting indisplacement of the proximal fracture fragment. Withtype IIa fractures, both CC ligaments remain attached;with type IIB fractures one or both CC ligaments aretorn. Neer type III occur lateral to the CC ligaments butextend into the AC joint [28]. The determination tointervene operatively is made on the basis of whether thefracture is stable or unstable, whether the CC ligamentsare torn, and whether the AC joint is involved. It has beenshown that type II distal clavicular fractures occurringproximal to the CC ligaments heal with approximately a30% rate of nonunion if treated conservatively [29].

Nonoperative management

Type I and III fractures are nondisplaced and stable.These are treated conservatively with a sling. The typeIII fracture may predispose to osteolysis and arthritis asthis injury involves the AC joint. The distal clavicle canbe resected once the fracture heals if the area remainssymptomatic [29].

Operative management

Surgical fixation of type II displaced distal claviclefractures has been advocated due to the reported high rateof nonunion and delayed union after conservative manage-ment [12, 28–30]. Surgical treatment, however, remainssomewhat controversial because the largest published serieshave not reported significant symptoms or functionallimitation if these fractures are left untreated. Thisdiscrepancy is explained in part by the fact that no largeprospective studies have been done. Comparison among thestudies is difficult because the published studies have haddiffering initial treatments and differing reported outcomeson the basis of reported radiographic union, patient

Fig. 8 A 52-year-old male with atrophic nonunion of a displacedcomminuted midshaft clavicle fracture after conservative treatment,8 months after the initial injury. Frontal radiograph demonstratesnonunion of the midshaft fracture with wide distraction of the fracturefragments, elevation of the proximal fracture fragment, eburnation ofthe fracture ends, without evidence of callus or osseous bridging

Fig. 7 Malunion. a Initial radiograph at the time of injurydemonstrates a displaced midshaft clavicle fracture with overridingof the fracture fragments and elevation of the proximal fracturefragment. b Six months later after conservative management, there isbulky callus formation with medial-lateral shortening of the clavicle, alarge residual step-off and deformity at the fracture site, with elevationof the proximal fracture fragment

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satisfaction, and patients’ functional expectations followingsurgery [28, 29]. The decision to intervene surgicallyremains to be made on the basis of the patient’s age,preoperative function, and postoperative expectations.

Many surgical fixation techniques have been describedincluding clavicular plates, hook plates, Kirschner (K)wires, coracoclavicular screws, coracoclavicular ligamentreconstruction, Knowles pin fixation, tension band wiring,and transacromial K-wiring. These methods require opendissection and the removal of hardware before the patientcan resume mobilization [29, 31–36]. Clavicular plateshave been developed that use either bicortical screws in thedistal fracture fragment or locking screw technology [37](Fig. 13). Plate fixation may be augmented by cerclagewiring (Fig. 14). The clavicular hook plate system isdesigned to fixate fractures with distal fragments that aretoo small to be fixated with the two or three bicorticalscrews. The plate is affixed to the superior aspect of the

Fig. 9 A 47-year-old male whodeveloped a pseudoaneurysm ofthe subclavian artery secondaryto a midshaft clavicle fracturethat was initially treated conser-vatively. a Displaced midshaftclavicular fracture with overrid-ing fracture fragments. b MRangiogram demonstrates a largepseudoaneurysm (white arrow)arising from the right subclavianartery. The patient presented18 months after the initial injurywith a pulsatile mass and a rightulnar nerve palsy. c Digitalsubtraction angiographic spotview confirms the presence of aright subclavian artery pseudoa-neurysm (black arrow)

Fig. 10 An 18-year-old male with midshaft clavicle fracture with abent plate. a Immediate postoperative radiograph obtained post platefixation of a comminuted midshaft clavicular fracture with areconstruction plate and cortical screws. b Radiograph obtained atthe 2 week follow-up visit demonstrates interval apical deformity ofthe plate with apex deformity of the fracture. The large butterflyfracture fragment is inferiorly displaced. The skin was visibly tented.One week after this radiograph was obtained, the patient presentedwith wound dehiscence

Fig. 11 Nonunion in a 40-year-old male with a right midshaftclavicular fracture fixated with a 3 mm Rockwood pin. Despiteextensive callus formation, the fracture line remains visible withpseudarthrosis, hypertrophic callus formation, and nonunion. There isextensive lucency around the pin indicating loosening and motion atthe fracture site. Clinically there were no signs of infection in thispatient

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clavicle, and the hook passes below the acromion into atunnel created in the subacromial space behind theacromioclavicular joint. There is the potential for hookmigration into the acromion, and hardware removal isrecommended within 6 months after surgery [35] (Fig. 15).

K-wire fixation was initially used by Neer, but thistechnique has fallen out of favor due to wire breakage andmigration [28, 33]. Use of coracoclavicular screws can beless invasive and has been associated with high healing rates,but a second procedure for removal is required as range ofmotion can be limited, and hardware failure and migrationremain a potential concern [31, 32]. Reconstruction of the

coracoclavicular ligaments to create a coracoclavicular slingabout the coracoid and clavicle can be performed withDacron or Mersiline tape, polydioxanone sutures, wire, orcable [29, 37, 38].

Complications

Complications of surgical treatment of distal clavicularfractures are similar to those of midshaft clavicle fractures,including hardware-related complications, loosening andinfection, delayed union and nonunion. Unique compli-cations with the hook plate include hook migration,loosening, and osteolysis around the hook, warrantinghardware removal [34, 35] (Fig. 16). Fractures may occurmedial to the hook plate if the plate is removed too soon[33]. K-wire migration, breakage, and infection have beenseen occasionally [33]. The CC reconstruction can fail;either the graft material can rupture or the hardware canbreak (Fig. 17). Osteoarthritis of the acromioclavicularjoint remains a persistent potential complication offractures of the distal clavicle if the fracture involved theAC joint at the time of initial injury.

Acromioclavicular joint separation

Approximately 9% of shoulder girdle injuries involve damageto the acromioclavicular joint [16]. The mechanism of most

Fig. 15 Radiograph of the right shoulder demonstrates an AO hookplate transfixing a healed distal clavicle fracture. The plate is affixedto the superior margin of the clavicle and the hook passes beneath theacromion

Fig. 14 A 42-year-old female with distal clavicular fracture. Inaddition to the superior plate and screws, a cerclage wire has beenplaced about the distal fragments of this comminuted fracture

Fig. 13 A 28-year-old male with comminuted distal clavicularfracture. a Preoperative radiograph demonstrates an intact AC jointand disrupted coracoclavicular ligaments with marked retraction of theproximal fracture fragment. b Postoperative radiograph demonstratesnear anatomic alignment of the fracture fragments with plate andscrew fixation and restoration of the CC distance

Fig. 12 Osteomyelitis in a 52-year-old male with midshaft clavicularfracture with plate fixation. The proximal fracture fragment issuperiorly displaced with respect to the distal fragment. The fractureremains ununited and there is fragmentation and erosive change at thefracture site, particularly at the proximal aspect of the distal claviclefragment. The lateral aspect of the plate has become dislodged fromthe distal fracture fragment, and the two lateral screws have backedout of the bone. There is lucency subjacent to the screws and thecortex is eroded (arrow), consistent with osteomyelitis. The patientpresented with pain, deformity, and discharge from a sinus tract;cultures grew Staphylococus aureus

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AC separations is trauma, caused either by a direct blow tothe top of the shoulder with the arm in the adducted positionor by a fall on an outstretched hand; these injuries tend tooccur in younger, more physically active patients [8].

Classification of acromioclavicular joint separation

Tossy originally classified AC separations into three types:in type I the AC ligaments are sprained; in type II the ACligaments are torn but the CC ligaments remain intact; intype III both AC and CC ligaments are torn [39]. The Tossyclassification was expanded by Rockwood to include threeadditional types of injuries; this classification is nowcommonly used to describe acromioclavicular joint separa-tion [40]. Type IV injury occurs when the clavicle isdislocated posteriorly. Type V AC injury is an exaggeratedtype III injury where the AC and CC ligaments are torn anddeltotrapezial fascia are also torn, causing the scapula todroop inferiorly. Type VI AC injury occurs when theclavicle dislocates inferiorly to the coracoid.

Imaging of acromioclavicular joint separation

In patients with suspected acromioclavicular injuries,simultaneous bilateral AP views are obtained providing areference for the normal AC and CC distances in theuninjured shoulder. Lateral and axial views are beneficial inthe diagnosis of posterior dislocation of the clavicle.Bilateral Zanca views (the beam is directed 10° cephaladtoward the AC joint) and cross-arm adduction AP viewscan also be performed. It is generally accepted thatacromioclavicular joint distances greater than 6–7 mm andcoracoclavicular distances greater than 11–13 mm arepathologic. Weighted views of the AC joint may unmaskthe difference between type II and III injuries. Traditionally,these have been performed by comparing views of the ACjoint performed with and without a 10 pound weight affixedto the patient’s ipsilateral wrist. However these views are

controversial and are falling into disfavor because they areuncomfortable for the patient and frequently add no newinformation to the clinical examination [41].

There has been growing interest in using MRI todelineate AC and CC ligamentous disruption and thedegree of concomitant soft tissue injury with AC jointseparations [42, 43]. MRI can be very useful in classifyingthe types of AC joint injury preferentially to radiography asthe coracoclavicular ligaments can be directly visualized onMRI, whereas their integrity is only inferred on radiogra-phy. MRI is also useful to characterize postoperativechanges and to distinguish degenerative changes from acuteinjury. A specialized coronal plane of imaging parallel tothe anterior acromion has been described [43] (Fig. 18).

Initial management

Type I and II AC separations are treated conservatively [8,44]. Type IV through VI AC separations are treatedoperatively due to the significant morbidity associated withjoint dislocation and severe soft tissue injury [8, 45–49].Initial treatment of acute type III AC separations is usuallyconservative although some authors do advocate surgeryfor acute injuries in high performance throwing athletes.Patients with persistent pain or disability after conservativetreatment for type III separations may be candidates forsurgery [8, 46, 50].

Operative management

As of March 2010, there have been at least 17 publishedtechniques for repairing the AC joint. These involvevarious methods for stabilization of the AC joint, distal

Fig. 17 a A 34-year-old female with distal clavicle fracture nonunionrepaired with cortical screw through the distal fracture fragments and aDall-Miles cable about the coracoid process and the distal clavicle. bThe same patient presented 1 year later with pain. Frontal radiographdemonstrates a fractured cable indicating loss of the CC reconstruction

Fig. 16 A 25-year-old male with distal clavicular fracture with hookplate fixation. AP image demonstrates a hook plate with corticalscrews and a screw transfixing the proximal and distal fracturefragments. There is focal lucency around the hook within theacromion (black arrow) denoting loosening of the hook plate

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clavicle resection, CA ligament transfer, and CC ligamentreconstruction [8]. It is beyond the scope of this paper todescribe all of these techniques, but we will describe thosemore commonly used.

Initially, primary AC joint fixation was performed usingK-wires, however this is no longer commonly done owingto known complications of K-wire migration describedabove. Currently, AC joint repair involves reducing the ACjoint and reconstructing the coracoclavicular ligament.Many of these techniques are similar to the methodsemployed in distal clavicle fracture repair. Hook plate

Fig. 20 A 48-year-old male with AC joint reconstruction. Postoper-ative radiograph of bilateral AC joints shows the normal right ACjoint and the postoperative left AC joint with evidence of distalclavicle resection and normalization of the coracoclavicular distance.Parallel tunnels in the distal clavicle are created to reproduce conoidand trapezoid ligaments. A tibialis graft has been passed underneaththe base of the coracoid process and secured in the clavicular tunnels

Fig. 18 Normal MR coracocla-vicular ligamentous anatomyand common types of AC jointinjury. a PD coronal imagedemonstrates intact conoid(white arrow) and trapezoid(black arrow) ligaments. bRadiograph of type II AC jointseparation demonstrates intactAC and CC intervals. c PDcoronal MR of a type II ACjoint separation with abnormalsignal, fluid, and edema at theAC joint (white arrow) withoutwidening of the AC joint. dRadiograph of type III AC jointseparation demonstrates disrup-ted AC and CC ligaments withelevation of the clavicle. e PDcoronal MR shows a type III ACseparation with disruption of theAC joint, fluid, and edema andelevation of the clavicle (blackarrow). f T2FS MR shows atype V AC separation, withdisruption of the CC ligaments(small white arrow), wideningof the AC joint, fluid, andedema. In addition, the clavicleis displaced superiorly into thetrapezius (large white arrow)with resultant partial tear of thetrapezius

Fig. 19 A 19-year-old male with acromioclavicular joint dislocationtreated with a hook plate. Postoperative radiograph shows near-anatomic reduction of the AC joint and normalization of coracocla-vicular distance achieved with an AO hook plate. A CC reconstructionwas performed with tibialis allograft, passed beneath the coracoidprocess and secured in a clavicular tunnel (black arrow)

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fixation of the AC joint is becoming more commonplace,either alone or in combination with ligament reconstruction[51, 52]. As with distal clavicle repair, hook plates cannotbe left in permanently and must be removed after initialhealing (Fig. 19).

The classic Weaver-Dunn technique deserves specialmention as this method involved the resection of the distalaspect of the clavicle and the transfer of the acromial end ofthe coracoacromial (CA) ligament to the medullarycavity of the distal aspect of the clavicle [53]. It is nolonger commonly performed. The modified Weaver-Dunntechnique involves stabilizing the clavicle to the coracoidduring ligament healing with preservation of the AC joint,thereby reducing the risk of symptomatic arthritis. How-ever, the CA ligament is sacrificed in the procedure. Thismay predispose to anterosuperior instability if the patientshould suffer a rotator cuff tear in the future, because thestabilizing force of the coracoacromial ligament is lost[54, 55].

At our institution the CA ligament is spared. The CCligament is reconstructed using a hamstring tendonautograft or an allograft. Parallel tunnels in the distal

clavicle are created to reproduce the conoid andtrapezoid ligament attachments. The tendon graft ispassed underneath the base of the coracoid process andsecured in the clavicular tunnels. Studies have foundthese constructs to be biomechanically superior to CAligament transfer [56, 57] (Fig. 20). Postoperatively it isnormal to see a widened AC interval consistent with thedistal clavicular resection; however, the plane of the clavicleis nearly aligned with the acromion process.

The newest technique to have been developed is theTightRope system, which secures the coracoid to theclavicle by means of a double metallic button withFiberWire suture. This method does not require tendongraft to be incorporated into clavicular tunnels [8].

Alternatively, a variety of fixation devices can be used toachieve coracoclavicular stabilization, including coracocla-vicular screws, suture loops, and synthetic loops betweenthe coracoid process and clavicle. These devices may becombined with ligament reconstruction techniques [58–61].Patients with persistent pain and arthritis following lowgrade injury (type I or II AC separations with intactcoracoclavicular ligaments) may benefit from open orarthroscopic distal clavicular resection without ligamentousreconstruction (Mumford procedure) [52].

Fig. 23 Postoperative radiograph obtained approximately 1 year aftercoracoclavicular ligament reconstruction demonstrates heterotopicossification of the reconstructed coracoclavicular ligament graft. Inaddition, there is loss of reduction, with disruption of the normal ACinterval. The patient was asymptomatic

Fig. 22 A 55-year-old male with post-AC joint reconstruction whoexperienced repeated falls and presented with pain. The radiographdemonstrates evidence of prior modified Weaver Dunn procedure,with distal clavicular resection, and parallel radiolucent tunnels in thedistal clavicle for graft attachment sites. There has been loss ofanatomical reduction with proximal retraction of the clavicle, lack ofalignment of the distal clavicle and acromion, and widening of thecoracoclavicular interval

Fig. 21 A 38-year-old malewith infected AC joint recon-struction. a PD coronal MRdemonstrates a fractured screwin the clavicular tunnel (whitearrow) with abnormal signal inthe coracoid process and distalclavicle. b T1FS postcontrastcoronal MR shows attenuationof the CC graft (white arrow)with a large amount ofenhancement consistent withinfection. Cultures subsequentlygrew Mycobacterium fortuitum

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Complications

Wound infection and dehiscence are occasionally seenpostoperatively as are hardware migration and failure(Fig. 21). Complete or partial loss of the surgicalreduction is encountered more commonly (Fig. 22).Fracture of the clavicle and coracoid process can also beseen and heterotopic ossification can occur about thetendon graft site [8] (Fig. 23). Patients may eventuallydevelop osteoarthritis of the AC joint or distal clavicleosteolysis whether they receive conservative or surgicaltreatment.

Summary

Nonoperative treatment of displaced midshaft and distalclavicular fractures can result in nonunion or malunion,patient dissatisfaction, and potential orthopedic, neuro-logic, and cosmetic complications. These factors havecompelled surgeons to examine surgical repair of mid-shaft and distal clavicular fractures, in an effort to restorepreoperative baseline function and improve cosmesis.While surgical treatment of type III AC separationremains controversial, surgical fixation occurs regularlyin active, highly functioning patients and in someathletes. Familiarity with the multiple surgical techniquesemployed in treating midshaft and distal clavicularfractures as well as AC separations allows improvedpostoperative assessment by the radiologist. Knowledgeof potential postoperative complications may facilitatetimely intervention by the surgeon and improve patientcare and postsurgical outcomes.

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