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Introduction
  • A dysfunction involving the stabilizing muscles of the scapula resulting in imbalance and abnormal motion of the scapula
  • Types of scapular winging
    • defined by the direction of the superomedial corner of the scapula
    • medial scapular winging  
      • etiology
        • dysfunction of the serratus anterior (long thoracic nerve  
          • weak protraction of the scapula
          • excessive medializing scapular retraction (rhomboid major and minor) and elevation (trapezius)
      • epidemiology
        • young athletic patient
        • more common than lateral
    • lateral scapular winging  
      • etiology
        • dysfunction of the trapezius (cranial nerve XI - spinal accessory nerve)
          • weak superior and medializing force on the scapula
          • excessive lateralizing scapular protraction (serratus anterior, pectoralis major and minor)
      • epidemiology
        • usually iatrogenic (history of neck surgery)
Anatomy
  • Scapulothoracic articulation
    • not a true joint
    • attached to thorax via ligaments at the acromioclavicular (AC) joint
    • suction mechanism created by serratus anterior and subscapularis holds scapula closely to thorax
    • allows scapular movement against the posterior rib cage
      • contributes to glenohumeral joint positioning and mechanics
  • Stabilizing muscles
    • scapula serves as attachment site for 17 muscles
      • function to stabilize scapula to the thorax, provide power to the upper limb and synchronize glenohumeral motion
    • serratus anterior  
      • originates from ribs 1-8 and inserts on anteromedial border of scapula
        • total 7-10 slips
      • primary motion is scapular protraction (anterior and lateral motion)
      • innervated by long thoracic nerve
        • ventral rami of C5, C6, C7
      • blood supply
        • superiorly: long thoracic artery
        • inferiorly: thoracodorsal artery branches
      • three parts with different functions
        • upper: downward rotation (glenoid down), stabilizes superior scapula
        • middle: scapular protraction
        • lower: upward rotation and abduction
    • trapezius  
      • originates from medial third superior nuchal line, external occipital protuberance, nuchal ligament and C7-T12 spinous processes
      • inserts on lateral third clavicle, acromion and scapular spine
      • primary motion is upward rotation and elevation of the scapula
      • innervated by spinal accessory nerve
        • cranial nerve XI
      • three parts with different functions
        • upper: upward rotation and elevation
        • middle: scapular retraction and adduction
        • lower: downward rotation and depression 
    • rhomboid major and rhomboid minor  
      • rhomboid major originates from T2-T5 spinous processes and inserts onto medial scapular border, just below insertion of rhomboid minor
      • rhomboid minor originates from C7 and T1 spinous processes and inserts onto medial scapular border, near base of scapular spine
      • primary motion is scapular retraction
      • innervated by dorsal scapular nerve
    • levator scapulae 
      • originates from C1-C4 transverse processes and inserts onto medial border of scapula at the level of the scapular spine
      • primary motion is elevation of the scapula and downward rotation to tilt the glenoid cavity inferiorly
      • innervated by C3-C4 cervical plexus with contributions from dorsal scapular nerve
  • Nerves 
    • long thoracic nerve 
      • arises from ventral rami of C5, C6 and C7
      • anatomic variations
        • C4 contribution in 13%
        • absence of C7 contribution in 8%
      • travels posterior to the axillary vessels and brachial plexus
      • runs superficially to the serratus anterior, giving branches to each slip
      • crow's foot
        • point where the long thoracic nerve intersects the most dominant and inferior serratus branch of the thoracodorsal artery
    • spinal accessory nerve (cranial nerve XI)
      • spinal and cranial portions join to form the accessory trunk
      • accessory trunk traverses the jugular foramen, crosses laterally over the internal jugular vein to innervate the sternocleidomastoid
      • enters posterior triangle of the neck to innervate the trapezius
Medial Scapular Winging
  •  Pathophysiology
    • deficit in serratus anterior function due to injury to the muscle itself or to the long thoracic nerve   
    • mechanical
      • traumatic avulsion of the serratus anterior
      • displaced fractures of the inferior pole of the scapula
    • neurologic
      • traction nerve injury
        • > 50% of the cases
        • repetitive stretch injury is most common
          • gradual onset of weakness and winging
          • increased risk with head tilted away during overhead arm activity, repetitive throwing, prolonged abduction
          • weight lifters, volleyball players
        • can be acute injury with immediate winging in cases of high-energy trauma (motorcycle accident)
      • compressive nerve injury
        • acute
          • blunt trauma to the chest wall, head or neck (contact sports, motor vehicle accidents)
          • sudden depression of the shoulder girdle (fall)
        • chronic
          • sites of compression
            • scalene muscles
            • subcoracoid between coracoid and 1st or 2nd rib (carrying heavy objects on shoulder)
            • inflamed bursae (subcoracoid, subscapular, accessory and supracoracoid)
            • anteroinferior scapular border
      • direct nerve injury
        • iatrogenic
          • 10% of patients had prior surgery
          • radical mastectomy / axillary lymph node dissection
          • thoracic surgery
          • chest tube placement for pneumothorax
        • penetrating injury to chest wall
      • neuralgic amyotrophy (brachial neuritis) 
        • presents with isolated unilateral palsy of the long thoracic nerve in 22%
        • consider in patients without clear traumatic onset and with antecedent immunological insult and/or inflammatory response
  • Presentation
    • vague, nonspecific shoulder girdle pain and fatigue
      • base of neck, scapula and deltoid
    • muscle spasms
    • weakness when lifting away from body and overhead activity
    • discomfort sitting against a chair
    • may have neurologic symptoms due to traction on brachial plexus
    • subjective shoulder instability
      • failure of the scapula to provide a stable platform for rotation of the glenohumeral joint 
  • Evaluation
    • physical examination 
      • superior medial scapula elevates and protrudes posteriorly and medially  
        • worsened by forward arm flexion
      • abduction often limited to 90° or less
      • weakness of forward arm flexion and abduction
      • wasting of anterior scalene triangle 
        • due to atrophy of the sternocleidomastoid muscle
      • scapular stabilization
        • manual stabilization of the scapula often improves pain and increases flexion and abduction
    • diagnostic studies
      • electromyography
        • helps assess involvement of long thoracic nerve versus a mechanical cause of winging (serratus anterior avulsion)
  • Treatment
    • nonoperative
      • observation, physical therapy and activity modification
        • indications
          • observe for a minimum of 6 months, ideally 18 months to 2 years
            • wait for nerve to recover
        • technique
          • physical therapy for serratus anterior strengthening, stretching
          • avoid painful or heavy lifting activities
          • bracing with a modified thoracolumbar brace can be considered
            • poor compliance and little benefit
        • outcomes
          • majority of patients will spontaneously resolve with full return of shoulder function and resolution of winging by 2 years
    • operative
      • early repair of serratus anterior avulsion
        • indications
          • mechanical disruption of the serratus anterior muscle (avulsion) and/or its insertion (inferior pole scapula fractures) with symptomatic winging should undergo surgical repair acutely
      • neurolysis of the long thoracic nerve
        • indications
          • failure to improve with conservative treatment, at least 6 months
          • electromyography with signs of nerve compression (distal latency, dennervation)
        • technique
          • supraclavicular decompression as the nerve traverses the scalene muscles
        • outcomes
          • excellent improvement in pain and resolution of winging in patients who failed nonoperative management (98%)
          • better improvement in shoulder strength (flexion and abduction) compared to muscle transfers
      • muscle transfer: split pectoralis major transfer 
        • indications
          • failure to improve with conservative treatment, for 1-2 years
          • pain relief and improved shoulder function with manual scapular stabilization
        • technique
          • split pectoralis major transfer (sternal head) 
            • with or without augmentation with a fascia lata or hamstring graft
            • most effective
          • other transfers
            • pectoralis minor transfer
            • rhomboid transfer
        • outcomes
          • predictor of successful surgery is symptom relief and improved function with preoperative manual scapular stabilization
          • often have persistent shoulder abduction weakness
          • complications
            • failure of pectoralis muscle transfer attachment at scapula
            • unsatisfactory cosmesis (breast asymmetry in women)
            • infection
            • adhesive capsulitis
      • nerve transfer
        • developing area in the microsurgical field
        • technique
          • lateral branch of the thoracodorsal nerve to the long thoracic nerve
          • medial pectoral nerve with sural nerve graft to the long thoracic nerve
        • outcomes
          • shown to successfully reinnervate the long thoracic nerve
          • benefit of preserving proper muscle biomechanics
      • scapulothoracic fusion
        • indications
          • scapular winging from diffuse neuromuscular disorders
          • failed muscle transfer surgery
          • often not the first surgical treatment of choice
          • primary goal is pain relief
        • technique
          • fusion of the anterior scapula to the posterior rib cage, with wire cables and/or plates and screws
        • outcomes
          • limited increase in shoulder motion
            • ~20° gain of abduction
          • recent studies show high satisfaction levels in 82% of patients at 5-year follow up
          • complications
            • nonunion
            • pleural effusion
            • adhesive capsulitis
            • symptomatic hardware requiring removal
Lateral Scapular Winging
  • Pathophysiology
    • deficit in trapezius function due to injury to the spinal accessory nerve (CN XI) 
    • neurologic
      • iatrogenic 
        • most common
        • vulnerable in the posterior triangle of the neck
          • cervical lymph node biopsy
          • radical neck dissection
      • traumatic
        • traction injury
          • sudden lateral flexion of the neck (motor vehicle or motorcycle accidents)
        • blunt trauma
          • deep tissue massage
        • penetrating injury to the neck
  • Presentation
    • similar to medial scapular winging
    • vague, nonspecific shoulder girdle pain and fatigue
    • muscle spasms
    • weakness with overhead activity
    • discomfort sitting against a chair
    • may have neurologic symptoms from traction on the brachial plexus
    • subjective shoulder instability
      • failure of the scapula to provide a stable platform for rotation of the glenohumeral joint
    • shoulder impingement
      • inferior translation of the coracoacromial arch as scapula depresses secondary to loss of trapezius
  • Evaluation
    • physical examination
      • superior medial scapula drops downward and protrudes posterior and lateral
        • worsened by arm abduction and resisted external rotation
      • shoulder girdle appears depressed or drooping
      • asymmetry or visible atrophy of the ipsilateral trapezius
      • weakness of forward arm flexion and abduction
      • scapular stabilization
        • manual stabilization of the scapula often improves pain
    • diagnostic studies
      • electromyography
        • helps distinguish isolated spinal accessory nerve injury from other more extensive neurologic injuries
  • Treatment
    • nonoperative
      • observation, physical therapy and activity modification
        • indications
          • the role of conservative management is controversial given that most injuries are iatrogenic direct nerve injuries and warrant surgical intervention
          • elderly and sedentary patients and those without an identifiable injury should be initially treated conservatively
        • outcomes
          • predictors of a poor outcome with conservative management include inability to raise the arm above the shoulder at presentation and dominant extremity involvement
    • operative
      • exploration of the spinal accessory nerve, neurolysis, repair
        • indications
          • identifiable nerve injury diagnosed early
        • technique
          • should be performed within 20 months of injury
      • muscle transfer: Eden-Lange transfer  
        • indications
          • nerve injury diagnosed late (> 20 months from injury)
        • technique
          • transfer of the levator scapulae and rhomboid muscles from the medial border of the scapula to the lateral border, to effectively reconstruct the trapezius
      • scapulothoracic fusion
        • see above under Medial Scapular Winging
 

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