Scapula Fractures

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• 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