Scapular Winging - Shoulder & Elbow

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