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Scapula Fractures


  • SUMMARY
    • Scapula Fractures are uncommon fractures to the shoulder girdle caused by high energy trauma and associated with pulmonary injury, head injury, and increased injury severity scores. 
    • Diagnosis can be made with plain radiographs and CT studies are helpful for fracture characterization and surgical planning.
    • Treatment is usually nonoperative with a sling. Surgical management is indicated for intra-articular fractures, displaced scapular body/neck fractures, open fractures, and those associated with glenohumeral instability. 
  • EPIDEMIOLOGY
    • Incidence
      • rare
        • <1% of all fractures
        • 3-5% of shoulder girdle fractures
    • Demographics
      • age
        • commonly between 25-50
      • males > females
    • Location 
      • scapular body/spine = 45-50%
      • glenoid = 35%
        • glenoid neck = 25%
        • glenoid fossa/rim = 10%
        • often associated with impaction of humeral head into glenoid 
      • acromion = 8%
      • coracoid = 7%
  • ETIOLOGY
    • Pathophysiology
      • mechanism of injury
        • high-energy trauma (80-90%)
          • motor vehicle collisions
            • account for >70% of scapula fractures
        • indirect trauma through fall on outstretched hand
        • glenohumeral dislocation
          • anterior dislocation leads to anterior rim fracture
          • posterior dislocation leads to posterior rim fracture
            • seizure
            • electric shock
    • Associated injuries (in 80-95%) 
      • medical
        • thoracic injury (80%)
          • hemothorax/pneumothorax (>30%)
          • pulmonary contusion (>40%)
        • head injury (35-50%)
      • orthopaedic
        • rib fractures (53%) 
        • ipsilateral extremity injury (50%)
          • ipsilateral clavicle fractures (25%)
        • spine fracture (26-30%)
        • pelvic ring/acetabular fractures (15%)
          • scapula fracture is important predictor
        • upper extremity vascular injury (11%)
          • subclavian and axillary arteries at risk
          • higher risk with scapulothoracic dissociation
        • brachial plexus injury (5-13%)
          • 75% of brachial plexus injuries resolve
            • complete brachial plexus injuries less likely to resolve
  • ANATOMY
    • Osteology
      • scapular body
        • origin or insertion of 18 muscles 
          • function to connect scapula to thorax, spine and upper extremity
        • large triangle shape with 4 major processes 
          • scapular spine
            • osseous bridge separating supraspinatus and infraspinatus
            • spinoglenoid notch represents possible site of compression for suprascapular nerve
          • glenoid
            • represents articulating process on lateral scapula serving as socket for glenohumeral joint
            • pear-shaped and wider inferiorly from anterior to posterior
            • average 1-5º of retroversion and 15º superior tilt from scapular plane
            • fibrocartilaginous labrum deepens glenoid fossa by 50% to increase stability
          • acromion
            • articulates with clavicle to form acromioclavicular joint
            • formed by 3 ossification centers 
              • pre acromion - tip
              • meso acromion - mid
              • meta acromion - base
          • coracoid process 
            • has two secondary ossification centers that are open until around age 25 and should not be interpreted as fracture
              • angle of coracoid
              • tip of coracoid
            • muscular attachments
              • conjoint tendon
                • coracobrachialis
                • short head biceps
              • pectoralis minor
            • ligament attachments
              • coracoclavicular (CC) ligaments
                • most anterior CC ligament attachment is 25mm from tip of coracoid
              • coracoacromial ligament
    • Arthrology
      • glenohumeral joint
        • glenoid & labrum support humeral head to produce high degree of motion
        • stability provided by static and dynamic stabilizers
      • scapulothoracic joint
        • not a true joint but does represent an articulation between scapula and thorax
        • involved primarily in elevation and depression of shoulder as well as rotation and pro-/retraction
      • acromioclavicular (AC) joint
        • articulation of acromion and distal clavicle
          • supported by acromioclavicular ligaments (horizontal stability) and coracoclavicular ligaments (vertical stability)
        • 8º of rotation occurs through acromioclavicular joint
      • superior shoulder suspensory complex 
        • bone & soft tissue ring which provides connection of glenoid/scapula to axial skeleton
        • composed of 4 bony landmarks
          • distal clavicle
          • acromion
          • coracoid
          • glenoid
        • also composed of ligamentous complexes of acromioclavicular and coracoclavicular joints
    • Blood supply
      • contributions from anterior and posterior circumflex, scapular circumflex and suprascapular arteries
      • watershed area present in anterosuperior glenoid
    • Nervous system
      • scapula is intimately associated with brachial plexus
      • axillary nerve is at risk inferior to the glenoid as it runs from anterior to posterior
      • compression of suprascapular nerve at scapular notch leads to supraspinatus/infraspinatus weakness, with compression at the spinoglenoid notch leading only to infraspinatus weakness
    • Biomechanics
      • scapula contributes to glenohumeral rotation and abduction
        •  1/3 of shoulder motion is scapulothoracic, 2/3 is glenohumeral
  • CLASSIFICATION
    • Classification is based on the location of the fracture and includes 
      • scapular body fractures 
        • usually described based on anatomic location
      • scapular neck fractures 
        • look for associated AC joint separation or clavicle fracture
          • if occuring together, known as "floating shoulder" 
      • glenoid fractures
        • Ideberg classification with Goss modification (below)
          • low inter- and intra-observer reliability and questionable association with management
        • AO-OTA classification
          • more reliable in diagnosis than Ideberg classification
      • acromial fractures
        • Kuhn classification
      • coracoid fractures
        • Ogawa classification - based on fracture proximity to CC ligaments
        • Eyres classification
      • scapulothoracic dissociation 
      • Ogawa Coracoid Fracture Classification
      • Type I
      • Fracture occurs proximal to the coracoclavicular ligament
      • Type II
      • Fracture occurs towards the tip of the coracoid
      • Kuhn Acromial Fracture Classification
      • Type I
      • Nondisplaced or minimally displaced
      • Type II
      • Displaced but does not compromise the subacromial space
      • Type III
      • Displaced and compromises the subacromial space
      • Ideberg Classification of Glenoid Fracture 
      • Type Ia
      • Anterior rim fracture
      • Type Ib
      • Posterior rim fracture
      • Type II
      • Fracture line through glenoid fossa exiting scapula inferiorly
      • Type III
      • Fracture line through glenoid fossa exiting scapula superiorly
      • Type IV
      • Fracture line through glenoid fossa exiting scapula medially through body
      • Type Va
      • Combination of types II and IV
      • Type Vb
      • Combination of types III and IV
      • Type Vc
      • Combination of types II, III, and IV
      • Type VI
      • Severe comminution
      •  
      • AO Classification for Glenoid Fractures
      • Fracture type
      • Subtype
      • Qualification
      •  
      • 14F0: Extra-articular
      • Glenoid neck
      •  
      • 14F1: Simple, intra-articular
      • 1.1: anterior glenoid rim
      • 1.2: posterior glenoid rim
      • 1.3: transverse/short oblique
      • f: infraequitorial, single quadrant
      • r: supraequatorial, 2 quadrants
      • t: infraequitorial, 2 quadrants
      • i: infraequitorial
      • e: equitorial
      • p: supraequitorial 
      • 14F2: Multifragmentary
      • 2.1: >= 3 articular fragments
      • 2.2: central fracture-dislocation
      •  
      • 14B: Extension into body
      • 1: exits body at <=2 points
      • 2: exits body at >=3 points
      •  
      •  
  • PRESENTATION
    • History
      • traumatic direct blow to shoulder or fall on outstretched arm
      • scapula fracture may be missed or diagnosed late in presence of other distracting, traumatic injuries
    • Symptoms
      • diffuse, severe shoulder pain
      • systemic symptoms
        • shortness of breath
        • chest wall pain
    • Physical exam
      • inspection
        • tenderness to palpation
          • shoulder diffusely
            • inaccurate in determining specific location of fracture
          • clavicle
          • spine
          • rib cage
        • evaluate for abnormal shoulder contour compared to contralateral site
        • look for open wounds or abrasions
        • soft tissue swelling may be significant
      • motion
        • acute active range of motion testing not recommended
          • likely to cause unnecessary pain
        • gentle passive range of motion can be useful in noting any blocks to motion
      • neurovascular
        • check motor and sensory function of nerves at risk
          • axillary
          • radial
          • median
          • ulnar
        • confirm symmetry of extremity pulses to contralateral side
  • IMAGING
    • Radiographs
      • recommended views
        • true AP, grashey AP, scapular Y and axillary lateral view 
        • AP chest radiograph
          • evaluate for pneumothorax 
          • evaluate for widening of space between medial scapular border and spine
            • >1 cm indicates possible scapulothoracic dissociation
      • measurements
        • intra-articular step-off
        • lateral border offset (medialization) 
        • glenopolar angle (measured on grashey AP) 
          • angle connecting superior/inferior scapula and lateral border of scapula
          • normal considered 30-45º
        • scapular angulation 
          • best seen on scapular Y radiograph
    • CT
      • indications
        • intra-articular fracture 
        • significant displacement >1cm
        • may also help detect other thoracic/spine injuries
      • views
        • three-dimensional reconstruction better demonstrates fracture patterns 
        • coronal and axial views useful to evaluate displacement, intra-articular step-off and medialization of glenoid
        • sagittal view useful to evaluate anterior-posterior displacement and angulation
    • MRI
      • indications
        • not regularly obtained but may be useful in some cases to evaluate the superior shoulder suspensory complex for ligamentous injury
  • DIFFERENTIAL
    • Os Acromiale 
      • unfused secondary ossification centers (meso- and meta-acromion)
        • associated with impingement and rotator cuff symptoms and may be detected incidentally with trauma
  • TREATMENT
    • Nonoperative
      • sling for 2-3 weeks, followed by early motion 
        • scapular body fractures
          • indications 
            • indicated for vast majority of scapula fractures
            • 90% are minimally displaced and acceptably aligned 
          • outcomes
            • progressive deformity/displacement is possible during first 3 weeks
              • recommend serial weekly radiographs during this time
              • those associated with multiple underlying rib fractures or superior shoulder suspensory complex disruptions are more likely to displace
            • union at 6-8 weeks in most cases
            • most recover near-normal function
              • attributed to shoulder's capability for compensatory motion
            • poorer outcomes noted in patients with glenopolar angle <20º
        • scapular neck fractures
          • indications
            • translation <1 cm
            • angulation <40º
            • glenopolar angle >20º
            • no additional injury to superior shoulder suspensory complex
          • outcomes
            • true outcomes not well established
              • some reports of unsatisfactory results in ~30% of cases treated nonoperatively, while others note equivalent outcomes to surgical fixation
        • intra-articular glenoid fractures
          • indications
            • <4 mm step-off and less than 25% glenoid involvement 
          • outcomes
            • with small fractures and minimal intra-articular step-off, nonoperative management results in excellent functional outcomes 
            • risk of instability exists in rim fractures with larger degree of articular surface involvement
        • acromion fractures
          • indications
            • displacement <1 cm and no additional injury to superior shoulder suspensory complex
          • outcomes
            • good outcomes with Kuhn type I and II fractures which do not compromise subacromial space
        • coracoid fractures
          • indications
            • displacement <1 cm and no additional injury to superior shoulder suspensory complex
            • coracoid tip fractures distal to insertion of coracoclavicular (CC) ligaments, even if displacement is >1 cm (Ogawa II)
          • outcomes
            • good results and motion with both type I and II fractures meeting indications
    • Operative
      • open reduction internal fixation
        • indications (most are relative) 
          • open fracture
          • scapular body fractures
            • medialization of lateral border > 20 mm
            • glenopolar angle < 20-22º
            • angulation > 40º
            • combination of medialization >15 mm and angulation >35º
          • scapular neck fracture
            • angulation > 40º
            • translation > 1 cm
            • glenopolar angle < 20-22º
            • "double disruption" of the superior shoulder suspensory complex (floating shoulder) 
              • indicates unstable nature of bony/ligamentous ring
          • intra-articular glenoid fracture
            • > 20-25% anterior or posterior glenoid involvement with subluxation of humerus
              • can cause persistent glenohumeral instability 
            • articular step-off > 4 mm 
          • acromion fracture
            • displacement > 1cm
            • painful nonunion
            • subacromial impingement
            • double disruption of superior shoulder suspensory complex
          • coracoid fracture
            • displacement > 1 cm 
            • painful nonunion
            • ipsilateral scapula fracture requiring fixation
            • Ogawa type I coracoid fracture extending into scapular body
            • double disruption of superior shoulder suspensory complex
        • techniques
          • screw(s)
            • percutaneous vs. open
          • plate(s) + screws(s)
          • arthroscopic-assisted
            • suture anchor repair vs. percutaneous screw fixation
              • useful in anterior/posterior glenoid rim fractures
        • outcomes
          • scapular body fractures
            • most return to having near-normal strength and symmetric range of motion
          • scapular neck fractures
            • good shoulder function and high union rates
            • complication rates up to 15%
          • intra-articular glenoid fractures
            • good to excellent subjective outcomes (pain, strength, and motion) in 80-95% of patients
            • higher rate of poor outcomes with concomitant chest and neurologic trauma
          • coracoid/acromion fractures
            • good outcomes in >85% of cases
              • high rates of union and full range of motion
            • some risk exists for requiring hardware removal
  • TECHNIQUES
    • Nonoperative (immobilization)
      • noninvasive but can lead to stiffness
      • technique
        • sling immobilization for 2-3 weeks
    • Open Reduction Internal Fixation (ORIF) 
      • scapular body/neck fractures
        • approaches
          • straight posterior overlying glenohumeral joint 
            • indicated in isolated displaced fractures
              • scapular neck
              • lateral scapular border
            • less extensile than Judet approach
          • Judet approach 
            • indicated if multiple scapular borders need to be accessed
            • incision courses along spine of scapula and angles down vertebral scapula border in "L" shape
            • utilizes internervous plane between infraspinatus (suprascapular nerve) and teres minor (axillary nerve)  
        • technique
          • can use 2.7 mm or 3.5 mm plates
          • locking plate technology may be advantageous given thin scapular bone, especially along vertebral border
          • reconstruction plates can be contoured around scapular spine and superomedial angle of scapula 
        • complications
          • neurovascular injury
          • malunion
          • hardware failure
      • intra-articular glenoid fractures
        • approaches
          • deltopectoral approach
            • utilizes intermuscular plane between deltoid (axillary n.) and pectoralis major (medial/lateral pectoral n.)
            • indicated in fractures involving anterior glenoid with inferior extension (Ideberg II)
              • in cases of medial/inferior fracture extension into scapular body, posterior approach may be necessary
            • can be extended proximally to clavicle in cases where superior glenoid fracture extends to coracoid
          • posterior approach (detailed above)
            • displaced posterior glenoid rim fractures with intra-articular involvement
            • intra-articular glenoid fractures with inferior or medial extension into body not accessible anteriorly
          • lateral midaxial approach
            • incision just caudal to axilla in order to access inferior glenoid fractures
              • easier ability to instrument along inferior scapular neck
        • techniques
          • percutaneous fixation
            • if hardware is inserted percutaneously, arthroscopic assistance may be beneficial to ensure articular reduction
              • suture anchors can be used to advance labrum in cases of small bony defects
              • screw fixation can be used to fixate larger bony rim fragments 
                • minifragment fixation recommended in most cases
          • open fixation
            • inferior glenoid fractures may be fixed with plate/screw(s) in buttress fashion
        • complications
          • post-traumatic arthritis
          • subscapularis failure
            • if anterior approach requires subscapularis take-down
          • recurrent glenohumeral instability
      • acromion fractures 
        • approach
          • vertically based posterior incision centered over the scapular spine and posterior acromion
          • dissection taken down to deltoid and trapezius muscles and reflected off the scapular spine and posterior acromion
        • technique
          • proximal acromial fracture
            • 2.7 or 3.5 mm lag screws placed perpendicular to fracture site if possible
            • 2.4 or 2.7 mm reconstruction plate placed to neutralize fracture 
          • distal acromial fracture
            • bone is very thin in this area
              • plate fixation may be difficult to obtain, although 2.0mm mini-fragment plate can function well
            • tension band technique can be considered
        • complications
          • hardware irritation/failure
      • coracoid fractures
        • approach
          • deltopectoral approach (detailed above)
            • retractor placed at base of coracoid to visualize fracture
        • technique
          • can carefully remove portion of the coracoacromial ligament and pectoralis minor attachment to better visualize the fracture bed
          • provisionally pin the coracoid with 1-2 Kirschner wires
          • fixation achieved with 1-2 bicortical 2.7 or 3.5 mm screws +/- washers 
          • may also place quarter tubular buttress plate if needed 
            • increased risk of requiring hardware removal
          • rarely, in Ogawa type II fractures requiring intervention, suture anchor can be placed in fracture bed and tip can be captured using a suture lasso technique
        • complications
          • neurovascular injury
          • hardware irritation
  • COMPLICATIONS
    • Post-traumatic glenohumeral arthritis 
      • risk factors
        • intra-articular glenoid fracture with residual step-off/displacement
      • treatment
        • conservative management
          • NSAIDs, therapy, injections
        • shoulder arthroplasty (total vs. reverse)
    • Malunion
      • risk factors
        • higher degree of angulation, translation or medialization
        • more likely with nonoperative management
          • questionable effect on shoulder function
      • treatment
        • typically nonoperative depending on location of fracture and degree of deformity
        • If deformity involves glenoid, may be correctable with reverse total shoulder arthroplasty
    • Recurrent glenohumeral instability
      • risk factors
        • younger patients
        • larger degree of bone loss (anterior or posterior) 
      • treatment
        • bony fixation (open or percutaneous)
        • arthroscopic vs. open suture anchor repair with labral advancement
          • more useful for smaller bony fragments which are not able to be fixated otherwise
    • Neurovascular injury
      • risk factors
        • scapulothoracic dissociation
        • iatrogenic injury during surgical dissection
          • deltopectoral approach
            • musculocutaneous n.
            • axillary n.
          • posterior/judet approach
            • axillary n.
            • suprascapular n.
            • circumflex scapular v.
            • posterior humeral circumflex v. 
      • treatment
        • nerve injury after scapulothoracic dissociation
          • EMG 3-6 weeks after injury to assess extent of injury and degree of recovery
        • iatrogenic neurovascular injury
          • direct repair if possible 

 

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