Scapular Winging - Shoulder & Elbow

summary
- Scapular winging is a dysfunction involving the stabilizing muscles of the scapula resulting in imbalance and abnormal motion of the scapula.
- Diagnosis is made clinically with the presence of excessive medializing scapular retraction (medial winging) or excessive lateralizing scapular protraction (lateral winging).
- Treatment is generally observation, physical therapy and activity modification or operative depending on etiology of winging and presence of identifiable neurological lesion.

Epidemiology
- Anatomic location
  - 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
    
    inferior 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