Scapular dyskinesis is an alteration in the normal position or motion of the scapula that occurs during coupled scapulohumeral movements as a response to shoulder dysfunction.

It should be suspected in patients with shoulder injury and can be identified and classified by specific physical examination.

Scapular Dyskinesis occurs most often in overhead athletes (61%) compared with the non-overhead athletes (33%).

See Also: Frozen Shoulder | Adhesive Capsulitis

Related Anatomy

The Scapula Spans from second through seventh ribs and serves as an attachment for 17 muscles. It’s anteverted on chest wall approximately 30 degrees relative to the body.

Although the scapulothoracic joint is not a true joint, it allows scapular movement against the posterior rib cage and contributes to glenohumeral joint positioning and mechanics.

The scapulothoracic joint is fixed primarily by the scapular muscular attachments.

The muscles connecting the upper limb to the vertebral column are trapezius, latissimus, both rhomboid muscles, and levator scapulae muscle.

The muscles connecting the upper limb to the thoracic wall are both pectoralis muscles, subclavius, and serratus anterior muscle.

Scapular Dyskinesis Causes

Potential Causes of Scapular Dyskinesis include:

Abnormality in bony posture or injury: Excessive scapular protraction and acromial depression in all stages of motion which increases the risk for impingement Excessive resting kyphosis. Forward head posture creates tightness to the anterior neck musculature, which again in turn facilitates the abnormal scapula position.

AC joint injuries or instabilities: Can alter the center of rotation of the scapula, leading to faulty mechanics.

Muscle function alterations: Alterations involving the serratus anterior and lower trapezius are a common source of dysfunction, especially in cases of secondary impingement Microtrauma due to excessive strain in the muscles, fatigue, and inhibition due to pain.

Contractures: Especially of the anterior musculature that attaches to the coracoid process (pectoralis minor and short biceps head) can create an anterior tilt and forward lean to the scapula, as can tightness to the posterior capsule and latissimus.

Nerve damage: It’s a rare cause.

Scapular Dyskinesis Types

There are three types of scapular dyskinesis:

Type I:

Type I is characterized by prominence of the inferior medial scapular border.

In throwers, this type may be referred to as a SICK scapula (malposition of the Scapula, prominence of the Inferior medial border of the scapula, Coracoid pain and malposition, and scapular dyskinesia).

A thrower with this syndrome presents with an apparent “dropped” scapula in the symptomatic shoulder compared with the contralateral shoulder’s scapular position.

Viewed from behind, the inferior medial scapular border appears very prominent, with the superior medial border and acromion less prominent.

When viewed from the front, this tilting (protraction) of the scapula makes the shoulder appear to be lower than the opposite side.

The pectoralis minor tightens as the coracoid tilts inferiorly and shifts laterally away from the midline, and its insertion at the coracoid becomes very tender.

Scapular Dyskinesis type I
Type I

Type II:

Type II is characterized by protrusion of the entire medial border.

Scapular Dyskinesis type II
Type II

Type III:

Type III involves superior translation of the entire scapula and prominence of the superior medial border.

Scapular Dyskinesis type III
Type III

Clinical Evaluation

Evaluation of the patient should include the trunk segments, hip and lower extremity function, and scapular position and movement analysis.

There may be pain at the coracoid process, and the entire medial border may be tender with trigger points
found in the upper trapezius.

There may even be painful scar tissue found in the musculature due to long-standing dyskinesis.

Motion about the scapulothoracic joint should be smooth with no catching or rapid movements, which are more often
seen during the lowering phase of the arm.

Strength testing can include the isometric scapular pinch, the Scapular Assistance Test, the scapular retraction test, and the lateral slide test (LST).

Scapular Dyskinesis Treatment

Once all the factors involved in the dysfunction of the shoulder are identified, Scapular Dyskinesis Treatment can begin on restoring normal scapular position and movement. More extensive therapy, including strengthening, should not occur until this step is accomplished; otherwise the shoulder is being worked in a faulty position.

The treatment of scapular dyskinesis is directed at managing underlying causes and restoring normal scapular muscle activation patterns by kinetic chain-based rehabilitation protocols.

Leg, back, and trunk flexibility and strength should be normalized, and exercises that emphasize kinetic chain activation of the leg, trunk, and scapula should be instituted.

Physical therapy for scapular dyskinesis include:

  1. trunk extension and scapular retraction,
  2. trunk rotation and scapular retraction,
  3. one-legged stance and diagonal trunk rotation and scapular retraction.

All of these exercises facilitate lower trapezius muscle activation.

Scapular Dyskinesis Treatment with scapular retraction
Scapular retraction

References

  • Burn MB, McCulloch PC, Lintner DM, Liberman SR, Harris JD. Prevalence of Scapular Dyskinesis in Overhead and Nonoverhead Athletes: A Systematic Review. Orthop J Sports Med. 2016 Feb 17;4(2):2325967115627608. doi: 10.1177/2325967115627608. PMID: 26962539; PMCID: PMC4765819.
  • Kibler WB, McMullen J. Scapular dyskinesis and its relation to shoulder pain. J Am Acad Orthop Surg. 2003 Mar-Apr;11(2):142-51. doi: 10.5435/00124635-200303000-00008. PMID: 12670140.
  • Burkhart SS, Morgan CD, Kibler WB: The disabled throwing shoulder: spectrum of pathology Part III: The SICK scapula, scapular dyskinesis, the kinetic chain, and rehabilitation. Arthroscopy 19:641–661, 2003.
  • Dutton’s Orthopaedic Examination, Evaluation, And Intervention 3rd Edition.