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The floating shoulder

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The floating shoulder is defined as ipsilateral fractures of the midshaft of the clavicle and the neck of the glenoid. This rare injury can be difficult to manage without a thorough understanding of the complex anatomy of the shoulder girdle.
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    VOL. 88-B, No. 11, NOVEMBER 20061419    ASPECTS OF CURRENT MANAGEMENT  The floating shoulder  B. D. Owens, T. P. Goss   From Keller Army Hospital, West Point, New York, USA    B. D. Owens, MD, Orthopaedic SurgeonKeller Army Hospital, West Point, New York 10996, USA.    T. P. Goss, MD, Professor of Orthopaedic SurgeryUniversity of Massachusetts Medical School, 55 Lake Avenue North, Worcester, Massachusetts 01655, USA.Correspondence should be sent to Dr B. D. Owens; e-mail: b.owens@us.army.mil ©2006 British Editorial Society of Bone and Joint Surgerydoi:10.1302/0301-620X.88B11. 17997 $2.00 J Bone Joint Surg [Br] 2006;88-B:1419-24.  The floating shoulder is defined as ipsilateral fractures of the midshaft of the clavicle and the neck of the glenoid. This rare injury can be difficult to manage without a thorough understanding of the complex anatomy of the shoulder girdle. Surgical intervention needs to be considered for all of these injuries. While acceptable results can be expected with non-operative management of minimally-displaced fractures, displacement at one or both sites is best managed with surgical reduction and fixation.   The ‘floating shoulder’ is a rare injury consist-ing of ipsilateral fractures of the clavicle andglenoid neck. It was first described by Ganzand Noesberger in 1975.   1   Subsequently, Goss   2   expanded on their definition by describing it asa ‘double disruption’ of the superior shouldersuspensory complex. An understanding of theanatomy and biomechanics of the superiorshoulder suspensory complex is essential tosuccessful treatment. We review the currentstate of knowledge of the diagnosis, manage-ment and outcome of this injury.  Anatomy and biomechanics   The superior shoulder suspensory complex is,essentially, a bone and soft-tissue ring securedto the trunk by superior and inferior bonystruts (Fig. 1) from which the upper extremityis suspended. The ring is composed of theglenoid process, coracoid process, coracocla-vicular ligament, distal clavicle, acromioclavic-ular joint, and acromial process. The superiorstrut is the middle third of the clavicle, whilethe inferior strut is the junction of the most lat-eral portion of the scapular body and the mostmedial portion of the glenoid neck. The com-plex can be subdivided into three units: 1) theclavicular-acromioclavicular joint-acromial strut;2) the three-process-scapular body junction;and 3) the clavicular-coracoclavicular ligamen-tous-coracoid (C-4) linkage (Fig. 2). Secondarysupport is provided by the coracoacromialligament. The superior shoulder suspensory complexis extremely important biomechanically. Eachof its components has its own individual func-tions, it serves as a point of attachment for avariety of musculotendinous and ligamentousstructures, it allows limited, but significantmovement to occur through the coracoclavicu-lar ligament and the acromioclavicular articu-lation, and it maintains a normal, stablerelationship between the upper extremity andthe axial skeleton. It should be appreciatedthat the clavicle is the only bony connectionbetween the upper extremity and the axialskeleton. The scapula is ‘hung’ or suspendedfrom the clavicle by the coracoclavicular liga-ments and the acromioclavicular joint.The double disruption concept allows one tounderstand a variety of troublesome injuries of the shoulder, which have previously beendescribed in isolation, but which may be unitedby a single biomechanical theory. It also has apredictive value for rarely encountered inju-ries.   2   When the complex is disrupted in twoplaces (a double disruption), the integrity of the superior shoulder suspensory complex isbreached and a potentially unstable anatom-ical situation is created. If significant displace-ment occurs at either or both sites, there maybe problems with healing, such as delayedunion, malunion, and nonunion, as well asadverse long-term functional difficulties, suchas subacromial impingement, weakness anddiscomfort due to muscle fatigue, neurovascu-lar compromise from a drooping shoulder, anddegenerative joint disease, depending on thenature of the particular injury.   3   The floating shoulder is one such double dis-ruption. Williams et al   4   conducted a cadaverstudy to determine the stability afforded byspecific structures. Using a model with ipsilat-eral glenoid neck and clavicular fractures, theyfound that instability of the glenoid segmentoccurred only if the coracoacromial and    1420B. D. OWENS, T. P. GOSSTHE JOURNAL OF BONE AND JOINT SURGERY   acromioclavicular ligaments were divided. They concludedthat the floating shoulder only becomes unstable whenthere is an associated disruption of these ligaments. Thestudy by Williams et al   4   is the only cadaver study of floatingshoulder injuries and the interpretation of its results is con-troversial.  Diagnosis   A high index of suspicion for complex injury patterns isnecessary when assessing patients with injuries of the shoul-der girdle. Ipsilateral midshaft clavicle and glenoid neckfractures can usually be diagnosed radiologically with rou-tine shoulder views (a true anteroposterior (AP) of theshoulder with the arm in neutral rotation, a true axillaryview of the glenohumeral joint, a true lateral scapular view,and if necessary weight-bearing films). Routine CT scansand three-dimensional reconstructions can help to definethe exact nature of the bony injury. Both plain films andscans should be examined for changes suggestive of liga-mentous disruption. McAdams et al,   5   found that CT scanswere no better than plain films in the evaluation of glenoidneck fractures but did help in the identification of associ-ated injuries to the superior shoulder suspensory complex.Associated injuries to adjacent and distant bony and soft-tissue structures are often present and may affect the out-come accordingly.   6,7   These injuries are often the result of high-energy trauma, and concomitant ipsilateral upperextremity, shoulder girdle and thoracic injuries are com-mon. It is often these injuries and their recovery that influ-ence the overall outcome from the floating shoulder injury.  Surgical indications   A floating shoulder represents a double disruption of thesuperior shoulder suspensory complex. In isolation, eachfracture is generally minimally-displaced and can be man-aged non-operatively. In combination, however, each dis-ruption can make the other unstable, for example, theglenoid neck fracture may increase the displacement of theclavicular fracture site and vice versa   . The resultant insta-bility will be greater if there is additional disruption of theclavicular-acromioclavicular joint-acromial strut or coraco-acromial ligament, or if the C-4 linkage is violated (Fig. 3).Hardegger, Simpson and Weber   8   felt that these injuriesrepresented a “functional imbalance” owing to the “alteredglenohumeral-acromial relationships”. By changing therelationships between anatomic structures, muscular forcesare altered, resulting in functional difficulty. Hardegger etal   8   and Butters   9   recommended surgery in these cases.Reduction and stabilisation of the clavicular fracture byscrew/plate fixation is advisable if the displacement isunacceptable. It reduces the risk of nonunion, alleviatestension on the brachial plexus, restores normal anatomicalrelationships, and ensures the restoration of normal shoul-der function.   10,11   The fracture of the glenoid neck will oftenreduce and stabilise as a result. However, if significant dis-placement persists, it should be reduced and fixed.   12,13   Additional injuries of the clavicular-acromioclavicularjoint-acromial strut may also require operative treatment,whereas associated injuries of the coracoacromial ligamentand the C-4 linkage will usually heal satisfactorily if thefracture sites of the glenoid neck and clavicle are treatedappropriately.The amount of displacement that is acceptable at thefracture sites of the glenoid neck and clavicle is controver-sial. Fractures of the clavicle have traditionally been treatednon-operatively, unless their displacement is severe.   14   Recent reports, however, have suggested that displacement Fig. 1bDiagram of the superior shoulder suspensory complex showing a) ananteroposterior view of the bony soft-tissue ring and the superior andinferior bony struts and b) a lateral view of the bony soft-tissue ring (from Goss TP.  Fractures of the scapula. In: Rockwood CA, Matsen FA, WirthMA, Lippitt SB, eds. The shoulder  . Third ed. Philadelphia: Saunders,2004:413 (reproduced with permission)).Fig. 1a    THE FLOATING SHOULDER1421VOL. 88-B, No. 11, NOVEMBER 2006   previously thought acceptable can result in nonunion ormalunion and a poor outcome.   15-19   Wick et al   18   found thatshortening of 2 cm or more of a middle-third fracture of theclavicle is a risk factor for nonunion. McKee et al   16   reported a series of 15 patients with middle third clavicularmalunions treated successfully by surgery. These injurieshad united in a shortened position (mean 2.9 cm) resultingin pain, weakness, and neurological symptoms.   16   Hill,McGuire and Crosby   20   found that an initial fracture short-ening of 2 cm or more was the only significant risk factorfor nonunion in a series of 52 middle-third fractures of theclavicle. Based upon this recent data, operative fixation hasbeen recommended for middle-third fractures that areshortened by 2 cm or more. Middle third fractures in whichthe fragments either lack cortical apposition and/or arecomminuted may also have a poor outcome. The preciseamount of displacement and comminution needed has notbeen determined. Nordqvist, Peterssen and Redlund- Johnell   21   reported the long-term outcome of 225 conserva-tively-treated middle-third fractures of the clavicle andfound an increased rate of malunion, nonunion, and poorerfunctional results in displaced fractures and comminuted Fig. 2aThe three components of the superior shoulder suspensory complexshowing a) the clavicular-acromioclavicular joint-acromial strut, b) theclavicular-coracoclavicular ligamentous-coracoid (C-4) linkage and c) thethree process-scapular body junction (from Goss TP.  Fractures of thescapula. In: Rockwood CA, Matsen FA, Wirth MA, Lippitt SB, eds. The shoulder  . Third ed. Philadelphia: Saunders, 2004:413 (reproduced withpermission)).Fig. 2cFig. 2b    1422B. D. OWENS, T. P. GOSSTHE JOURNAL OF BONE AND JOINT SURGERY   fractures, compared with those that maintained corticalapposition. In a prospective analysis of 581 conservatively-treated middle third fractures, Robinson et al   17   noted anincreased risk of nonunion in those that either lacked corti-cal apposition or were comminuted. Zlowodzki et al   19   per-formed a meta-analysis of studies of middle-third fracturesof the clavicle and concluded that both displacement (rela-tive risk (RR) = 2.3) and comminution (RR = 1.4) resultedin an increased risk of nonunion. Based upon this data, sur-gery should be considered for middle-third fractures of theclavicle that lack any cortical apposition and/or are severelycomminuted. In a floating shoulder, the further destabilis-ing effect of a fracture of the glenoid neck makes operativefixation imperative.Other indications for operative fixation include openfractures requiring surgical irrigation and debridement,fractures compromising the overlying skin (an impendingopen fracture), and middle-third fractures in patients withmultiple injuries in order to facilitate their care and rehabil-itation.   22   Fractures of the glenoid neck can be classified in twoways. The first describes the position of the fracture in rela-tion to the coracoid process.   23   Fractures medial to the cora-coid process are surgical neck fractures (the most commoninjury pattern), while fractures lateral to the coracoid pro-cess are anatomical neck fractures. The latter are highlyunstable, as there is no attachment of the glenoid fragmentto the clavicular-acromioclavicular joint-acromial strut viathe C-4 linkage, and often require surgical management.   8,24   The second method is based upon the degree of displace-ment at the fracture site.   23   Type I fractures according to thesystem of Goss   23   are insignificantly displaced and consti-tute more than 90% of cases. Their management is non-operative, and a good to excellent functional result can beexpected. Type II fractures are significantly displaced, asdefined by translational displacement of the glenoid frag-ment by 1 cm or more and/or angulatory displacement of the fragment of 40˚ or more in either the coronal or sagittalplane.   23   These injuries, whether involving the surgical oranatomical neck, should at least be considered for openreduction and stabilisation.  Surgical technique   Operations on the floating shoulder require wide access tothe entire shoulder girdle. The patient is placed in the lat-eral decubitis position or in the ‘deck chair’ position. Caremust be taken to allow adequate exposure of the scapulaand clavicle. The shoulder girdle and whole upper limb areprepped and draped. Alternatively, if the surgeon prefers, astaged procedure can be performed using separate posi-tions, sterile preparations, and exposures.The order of fixation is debatable and remains at the dis-cretion of the surgeon. Initial fixation of the clavicle mayallow indirect reduction of the glenoid segment and obviatethe need for a posterior procedure. If significant displace-ment persists, however, the fracture of the glenoid must also abc Fig. 3Radiographs and CT scan showing a double disruption of the superiorshoulder suspensory complex resulting in a floating shoulder. a) a pre-operative anteroposterior view showing a fracture of the glenoid neckwith medial translation (white arrow) and a severely-displaced fracture of the middle-third of the clavicle (black arrow), b) a pre-operative axial CTimage showing the fracture of the glenoid neck to be complete (largewhite arrow), with the glenoid fragment and the entire superior shouldersuspensory complex rendered particularly unstable by an associated frac-ture of the coracoid process (small white arrow), and c) a post-operativeanteroposterior radiograph showing anatomical reduction and stabilisa-tion of the fracture of the clavicle. The fracture of the glenoid neck wasmanaged non-operatively, although a strong case could have been madefor internal fixation in light of its persistent medial displacement (the gle-noid fragment remained unstable due to the fractured coracoid process;a double disruption of the superior shoulder suspensory complex was stillpresent) (from Goss TP.  Fractures of the scapula: diagnosis and treat-ment. In: Iannotti JP, Williams GR Jr eds. Disorders of the shoulder: diag- nosis and management  . Philadelphia: Lippincott Williams & Wilkins,1999:624 (reproduced with permission)).    THE FLOATING SHOULDER1423VOL. 88-B, No. 11, NOVEMBER 2006   be addressed.   23   Conversely, fixation of the displacedglenoid segment may be deemed more important and canbe carried out first, followed by open reduction and internalfixation of the fracture of the clavicle if necessary.The clavicle is approached through an incision directlyover its subcutaneous border. Care must be taken to iden-tify and protect the adjacent neurovascular structures. Thefracture site is exposed subperiosteally both proximally anddistally then reduced and stabilised using a standard plateand screws. Intramedullary devices, precontoured plates,and locking plates may be preferred in certain situations,such as severe comminution, osteoporotic bone, or surgeonpreference.The glenoid neck is approached posteriorly. The poste-rior deltoid is either split in the line of its fibres or detachedat its srcin and retracted distally. The interval betweeninfraspinatus and teres minor is developed to expose theposteroinferior glenoid neck and lateral border of the scap-ula. A superior approach can be added to control the freeglenoid fragment. Once a satisfactory reduction has beenachieved, temporary fixation can be achieved by passingK-wires through the glenoid fragment into adjacent bonystructures (for example, through the glenoid fragment andinto the scapular body, or through the acromial process intothe glenoid fragment). Definitive fixation is generallyachieved by means of a contoured 3.5 mm reconstructionplate applied along the lateral border of the scapula and theposterior aspect of the glenoid process. Additional fixationcan be provided by K-wires or lag screws. The K-wires pro-viding temporary fixation can be retained or used for theplacement of 3.5 mm cannulated lag screws.   25,26   In somecases, comminution of the scapular body and spine may beso severe, or the size of the glenoid fragment so small, as topreclude plate fixation. Under these circumstances, it mayonly be possible to fix the reduced glenoid fragment to theadjacent intact bony structures, such as the acromial pro-cess or the distal clavicle with K-wires or lagged screws.  Published results   Leung and Lam   27   described 15 patients with a mean fol-low-up of 25 months, in which 14 fractures healed with agood or excellent functional result. Herscovici et al   10   described nine patients with ipsilateral fractures of the clav-icle and glenoid neck who were followed up for a mean of 48.5 months. Seven were treated with plate fixation of thefracture of the clavicle and achieved an excellent result.Two were treated conservatively and had a decreased rangeof movement as well as drooping of the involved shoulder.The authors strongly recommended open reduction andinternal fixation of the clavicle to prevent malunion of theglenoid neck.Rikli, Regazzoni and Renner   28   expanded this concept,stating that a fracture of the glenoid neck with either anassociated fracture of the clavicle or a disruption of theacromioclavicular joint or sternoclavicular (SC) jointresults in an “unstable shoulder girdle”. They reviewed 12patients in whom the clavicular injury was surgically stabi-lised and reported mostly excellent results.Hashiguchi and Ito   29   reported excellent results in fivepatients with ipsilateral fractures of the clavicle and glenoidneck, for whom only fixation of the clavicle was performed.Van Noort et al   30   reported a multicentre study of 35patients with ipsilateral fractures of the clavicle and glenoidneck treated both operatively and non-operatively, with Table I. Published results of floating shoulder injuries TreatmentNumber of floating shouldersConservativeFixation of the clavicleFixation of the clavicle and glenoidOutcome Herscovici et al 10  9 21 good, 1 poor, 77 excellentLeung and Lam 27 1515Mean Rowe = 84Rikli et al 28 1211 1Mean Constant = 96% age-matched normsRamos et al 33 131311 excellent, 1 good, 1 fair (Herscovici score 10 )Edwards et al 32 2020Mean Rowe = 95Mean Constant = 96Low and Lam 34  4 4Rowe 70 to 100van Noort et al 30 3528Mean Constant = 76 7Mean Constant = 71Oh et al 35 11 3Mean Rowe = 77 5Mean Rowe = 88 3Mean Rowe = 90Hagino et al 36  1 1“acceptable”Hashiguchi and Ito 29  5 5Mean UCLA = 34.2/35Labler et al 7 17 8Mean Constant = 90 6Mean Constant = 66 (includes 2 patients with brachial plexus palsies) 3Mean Constant = 93Egol et al 31 1912Mean American Society of Elbow and Shoulder surgery (ASES) score = 80.27Mean ASES = 88.7
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