Snapping Scapula and Winging of the Scapula

By admin On Oct 26, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Joseph N. Chorley

Basics

Description

Snapping scapula syndrome (SSS) is a disorder of the scapulothoracic articulation resulting in crepitation that may or may not be painful. It can be the result of anatomic impediment to normal scapular motion from weakness, inflexibility, or inadequate proprioception of 1 or more of the 17 muscles that insert on the scapula. Winging scapula (WS) results from a nerve injury, usually of the long thoracic (LTN) or spinal accessory nerves (SAN). This results in profound weakness of the serratus anterior or trapezius muscles, respectively, producing functional shoulder pain and dysfunction.

Epidemiology

Incidence

SSS is relatively common.
Altered scapular position and motion has been reported in 68–100% of patients with shoulder injuries.

Prevalence

SSS:
- Relatively common
- Altered scapular position and motion has been reported in 31% of asymptomatic individuals.
WS:
- Rare
- Long thoracic nerve palsy has been reported 15/7,000 electromyelogram (EMG) patients, 1/38,500 orthopedic patients, 3/12,000 neurologic evaluations
- Spinal accessory nerve palsy prevalence is difficult to assess.

Etiology

SSS:
- Anatomic:
  - Thoracic rib disorders (fracture with prominent callus or displacement)
  - Thoracic spine disorder (costovertebral dysfunction, scoliosis, Scheuermann's kyphosis)
  - Scapular disorders (fracture with prominent callus or displacement, hooked superior medial edge, osteochondroma)
  - Soft tissue tumor (elastofibroma)
- Inadequate strength, flexibility, and proprioception:
  - Weakness (mostly in serratus anterior, middle, and lower trapezius)
  - Inflexibility (mostly in pectoralis minor, levator scapulae, and upper trapezius)
  - Abnormal firing patterns associated with repetitive motion (asymmetric strength training, throwing mechanics, swimming technique, etc.)
WS:
- Blunt trauma:
  - LTN: Sudden depression of the shoulder
  - SAN: Blow over the posterior cervical triangle
- Sports related: Archery, ballet, baseball, basketball, bowling, football, golf, gymnastics, hockey, soccer, tennis, weightlifting, wrestling
- Iatrogenic:
  - LTN: chiropractic manipulation, crutches, surgery
  - SAN: Surgery to the neck area
- Other: Postviral, exposure to toxin or drugs, muscular dystrophy

Diagnosis

History

SSS:
- Mechanical sensation, with or without pain, usually along the medial scapular border (superior ≫ inferior > middle)
- Classic anterior impingement complaints (pain with overhead activities)
- Involved in higher incident sports (baseball, swimming, tennis)
WS:
- LTN: Shoulder pain that usually is more toward the upper medial scapula. It may occur a few weeks after onset of palsy when the trapezius starts to stretch from the unopposing serratus anterior. Severe pain may occur with postviral neuritis. Burning neuralgic pain at the inferior scapular pole may occur with acute trauma.
- SAN: Stiffness, heaviness, pain, and weakness, especially with overhead activities or prolonged exertion

Physical Exam

Cervical spine evaluation, including range of motion of the cervical spine, strength, sensation, deep tendon reflexes in the upper extremity, Spurling's maneuver
Spine and shoulder inspection: Standing and forward flexed, analyzing for asymmetry and posture
Scapular position:
- SSS (may be normal scapular position with classic “teenager posture” with rounded shoulders, dynamic thoracic kyphosis, forward flexed head, and suboccipital extension)
- LTN (scapula is superior and adducted medially)
- SAN (drooping shoulder with scapula abducted laterally)
Scapular winging tests:
- LTN (entire medial scapula will protrude with shoulder forward flexion or wall push-up)
- SAN (superior medial scapula will laterally displace causing downward rotation with shoulder abduction or resisted external rotation; no winging with shoulder forward flexion)
Range of motion deficit:
- LTN (<120 degrees of forward flexion [FF] and 110 degrees of abduction)
- SAN (normal FF and <90 degrees of abduction)
Scapular motion with shoulder movement:
- Lateral scapular slide test: Patient will place the arms in the resting position (1), hands on iliac crest (2), and shoulders at 90 degrees abduction in the scapular plane (3). Distance from the inferior scapular pole to a fixed point on the midline thoracic spine (usually spinous process of T9) is measured in each position. Scapular dyskinesis is diagnosed when there is 1.5 cm difference from the opposite side.
- Scapular assistance tests: Perform the classic Neer impingement test, which is painful.
- Repeat the test with the examiner holding the superior medial scapula down (assisting serratus anterior) and gliding the inferior scapular pole medially assisting the lower trapezius), and the pain will not be provoked.
- Repeat the test with the examiner holding the medial scapula retracted, and the pain will not be provoked.
- Scapular dyskinesis classification (SSS) based on scapular prominence at rest and with lateral scapular slide test:
  - Inferior medial
  - Entire medial
  - Superior medial and superior translation
  - Slightly lower (normal in the dominant arm)

Diagnostic Tests & Interpretation

Imaging

Radiographs of the cervical spine, shoulder, chest, and ribs will usually be normal.
CT scans and MRI are rarely necessary unless concern about bone or soft tissue masses. Isolated left thoracic scoliosis should be evaluated with cervical spine MRI secondary to its association with congenital anomalies (syringomyelia, Arnold-Chiari malformations).

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Diagnostic Procedures/Surgery

Electromyography (EMG) is the only definitive diagnostic test for nerve dysfunction and muscle paralysis associated with WS. Abnormalities such as resting denervation potentials, decreased motor unit recruitment, and polyphasic motor unit potential with volitional activities. Electromyography does not correlate with clinical improvement and cannot be used to predict extent of recovery.

Differential Diagnosis

Cervical discogenic neuropathy
Thoracic outlet syndrome
Rotator cuff tear
Glenohumeral instability
Suprascapular nerve entrapment
Primary neuromuscular disease
Neurofibromatosis
Primary pulmonary pathology

Treatment

ED Treatment

Acute injury may result in WS, but the symptoms of pain and nerve dysfunction may not present for a few weeks.
Avoiding painful activities, especially overhead activities, is important.
Brief sling immobilization may be necessary for pain control.

Medication

Analgesic medications may be necessary for acute injuries and severe pain, like with postviral neuritis.
Subacromial bursa steroid injection and oral anti-inflammatories may be used with SSS in order to decrease pain while physical therapy is retraining normal muscle firing patterns.

Additional Treatment

General Measures

SSS (treat the etiology):
- Anatomic lesions (fracture callus, fracture displacement, mass lesion): Assessment for surgical consultation, depending on their contribution to the pain and dysfunction.
- Thoracic dysfunction: Thoracic scoliosis and Scheuermann's kyphosis may require bracing and surgery. Segmental thoracic dysfunction (resulting in malalignment) may benefit from manual manipulation followed by stabilization rehabilitation.
- Scapular dyskinesis: Requires an astute clinician to direct the subtle relationships that need to be restored. Outlined below are the most common components of most scapular dyskinesis:
  - Release the muscular and capsular restrictions:
    - Glenohumeral posterior capsule tightness with decrease internal rotation can be improved using the side lying “sleeper stretch.”
    - Pectoralis minor muscular shortening can be improved with the patient supine with a towel roll under thoracic spine and a steady posteriorly directed force on the anterior shoulder.
  - Improve muscular strength and scapular force couples:
    - Early rehabilitation will include closed chain exercises like low, middle, and high rows, and advancing to “scapular clocks,” “wall washes,” and “punches.”
    - When a stable scapular base is achieved, open chained exercises can be incorporated (classic rotator cuff with increasing abduction, scapular 4 directions against manual resistance).
    - “Pushups with a plus” are effective in strengthening serratus anterior and plyometrics, and proprioceptive neuromuscular facilitation will complete most of this phase of rehab.
    - Return to activity: Correcting technique, overload, and other problems in the kinetic chain are important as return to activity is considered. Incorporating the new biomechanics into often-entrenched biomechanics takes time and an astute team, including the coach, patient, therapist, and clinician.
WS:
- LTN: 75% will respond to conservative management, but will take anywhere from 6–24 mos. There are some that do not improve serratus anterior firing but improve their function by muscular compensation with other scapulothoracic stabilizers (usually trapezius):
  - In the early phase of rehabilitation, avoid further injury by limiting any overhead or painful activities.
  - As pain decreases, progress to gentle range of motion of the shoulder and scapula to avoid adhesive capsulitis. Avoid stretching the serratus anterior muscle by limiting passive scapular retraction.
  - As the serratus strength improves, shoulder girdle strengthening exercises can be started. Reducing the amount of winging during rehab and everyday activities is important during conservative treatment.
  - Scapular bracing may help, but is often restrictive and has poor compliance. Doing rehab while lying supine will stabilize the winged scapula.
- SAN: Conservative management is not as effective. A trial of protection, bracing, and progression as above is advised for 6–12 mos.

Surgery/Other Procedures

WS: If symptoms continue despite compliant conservative management for 12 (SAN) to 24 mos (LTN), surgical intervention must be considered. Dynamic muscle transfer procedures show improved function, fewer symptoms of pain and winging, and are replacing many of the older procedures.

Additional Reading

Forthomme B, Crielaard JM, Croisier JL. Scapular positioning in athlete's shoulder: particularities, clinical measurements and implications. Sports Med. 2008;38:369–386.

Kibler WB, McMullen J. Scapular dyskinesis and its relation to shoulder pain. J Am Acad Orthop Surg. 2003;11:142–151.

Manske RC, Reiman MP, Stovak ML. Nonoperative and operative management of snapping scapula. Am J Sports Med. 2004;32:1554–1565.

Martin RM, Fish DE. Scapular winging: anatomical review, diagnosis, and treatments. Curr Rev Musculoskelet Med. 2008;1:1–11.

Codes

ICD9

736.89 Other acquired deformity of other parts of limb