Understanding Scapular Motion

ShoulderScapula

Jan 28

Scapular Dyskinesis and Dysfunction

How Scapular Movement Observation Can Affect Shoulder Function

What Does the Scapula Do?

The scapula has a dual function of offering mobility through its arc-like motion, and act as a stable base of support for arm function (1).

The motion of the scapula also acts to provide optimal muscle-length tension and glenohumeral joint alignment during arm movements (1).

There are three main scapular motions that are identifiable.

The most observable motion is the elevation and depression, which also has the greatest available range of motion. Anterior and posterior tilting is a motion that occurs along the axis of the spine of the scapula (1). Posterior tilting occurs with the inferior angle moves anteriorly and the superior border moves posteriorly, which occurs during arm elevation (1).

Excessive anterior tilting appears as winging of the scapular inferior angle.

Finally, scapular internal (down) and external (up) rotation occurs at the vertical axis, external rotation involves the lateral border of the scapula moving away from the thorax (1).

Clavicular elevation and depression is also associated with scapular superior and inferior translation respectively (1). Scapular anterior and posterior translation also occur with clavicular protraction and retraction respectively, therefore it is easy to conclude that scapular elevation and depression, and protraction and retraction occur with the ipsilateral sternoclavicular joint (1). During arm elevation, the scapula up rotates, posteriorly tilts, and internally rotates relative to the clavicle, with most of the scapular posterior tilting occurring at the acromioclavicular joint (1).

What is Scapular Dyskinesis?

Scapular kinesis is a term coined to described abnormal movement patterns in the scapula which may influence shoulder impairments and alter normal function (2). Findings for the concept of shoulder dyskinesis has been inconsistent in research that sometimes include advanced imaging. Clinical correlation of shoulder impingement has shown that patients also have increased anterior tilting, decreased posterior tilting, decreased up rotation, increased down rotation, increased superior translation, and increased internal rotation (1). These differences were also of small magnitude compared to normal shoulders, and make it unclear if these noted differences are significant (1). However, clinical tests such as manual repositioning of the scapula may be capable of identifying patients with true scapular dysfunction (1).

What Kind of Assessment Is Done?

Clinical evaluation should include visual observable scapular dyskinesis, effect of manual correction of dysfunction on symptoms, and evaluation of surrounding anatomical tissues that may be responsible for the dyskinesis (1). If scapular repositioning causes an immediate decrease in symptoms, it is suggested that scapular dyskinesis is a contributing factor for shoulder pain and symptoms (1). Traditionally the lateral scapular slide test has been used to assess scapular dyskinesis, however, it was noted that differences were found in asymptomatic individuals, and that in symptomatic patients differences were not always present (1)(2). This test also fails to measure the 3 main motions of the scapula as well. Other tests were also developed to measure dyskinesis, however, asymmetries were still noted in asymptomatic individuals. Thus, it can be ascertained that the only clinically important test is the relief of symptoms during manual positioning of the scapula. The two main tests are the scapular reposition (retraction) test, and the scapular assistance test (1).

What Are Some Tests?

The scapular assistance test is the manual assistance with upward rotation during shoulder abduction. A positive finding is a decrease in symptoms and pain. A modified version also assists in posterior tilting as well (1). The scapular retraction test is the manual reposition of the scapula into a retraction position. A positive test is a decrease in symptoms or pain during arm elevation or increased arm elevation strength while the scapula is stabilized (1). The concept behind this maneuver is providing needed stability to the scapula which may caused weakness during shoulder elevation (1). The scapular reposition test is a modified scapular retraction test. This test repositions the scapula into posterior tilt and external rotation while avoiding full retraction (1). A positive test is a reduction in pain or an increase in isometric arm elevation.

Is It Related to Bad Posture?

Forward head posture and subsequent thoracic kyphosis are two mechanisms that can precipitate scapular dyskinesis. These postures lead to adaptive shortening of muscular tissues causing the scapula to remain in a protracted position. This position can cause narrowing of the subacromial space and lead to impingement (1). Since the scapula follows the natural curvature of the rib cage, altered thoracic curvature can then alter scapular mechanics, diminishing force output with elevation (1). Adaptive shortening of the pectoralis minor muscle is considered a contributor to scapular dyskinesis and may cause shoulder impingement syndrome (1).

What Are Other Contributing Factors?

Posterior capsular or muscular tightness of the shoulder is another contributor to dyskinesis. It may cause over protraction of the scapula (1). Shoulder internal rotation at neutral can be used to measure posterior shoulder tightness. A horizontal adduction test with a manually blocked retracted scapula can also be used as a measurement of posterior shoulder tightness (1).

Scapular Dyskinesis vs Scapular Winging

If scapular dyskinesis is dysfunctional movement, scapular winging is dysfunctional static positions. Both are observational signs that may be related to the pain you are experiencing in the shoulder, upper back, neck or chest. Scapular winging is observed through your posture, whereas scapular dyskinesis is observed through your shoulder blade movements. In this regard, both types of observations can help to form a clinical picture of how your scapulothoracic joint, acromioclavicular joint, and glenohumeral joint interact with each other.

Scapular Dyskinesis Treatment Options

Since Scapular Dyskinesis is an observational finding of your scapular motion there is no targeted treatment for it. However, if your physiotherapist or chiropractor discover that this type of motion is associated with your shoulder pain, exercises are often prescribed to help you learn to control the scapula. Since there are 17 muscles that attach to your scapula and can consequently affect your scapular motion, exercises prescribed will vary from individual to individual according to their specific movement assessment. Exercises may include stretches, strengthening, mobility, foam rolling, or co-ordination movements. To find out how you can get started, book in a physiotherapy or chiropractic appointment at a clinic near you.

Does a Brace Help?

Generally, no. There is no evidence supporting that braces help with the reduction of scapular dyskinesis. Since scapular dyskinesis is a dysfunction with movement, braces which tend to be for static or postural support tend to not help to improve scapular function.

References

1. McClure P, Greenberg E, Kareha S. Evaluation and management of scapular dysfunction. Sports Medicine And Arthroscopy Review [serial on the Internet]. (2012, Mar), [cited November 8, 2017]; 20(1): 39-48. Available from: MEDLINE with Full Text.

2. Hannah D, Scibek J, Carcia C. STRENGTH PROFILES IN HEALTHY INDIVIDUALS WITH AND WITHOUT SCAPULAR DYSKINESIS. International Journal Of Sports Physical Therapy [serial on the Internet]. (2017, June), [cited November 8, 2017]; 12(3): 390-401. Available from: SPORTDiscus with Full Text.

3. Sobel J, Kremer I, Winters J, Arendzen J, de Jong B. Reviews of the literature. The influence of the mobility in the cervicothoracic spine and the upper ribs (shoulder girdle) on the mobility of the scapulohumeral joint. Journal Of Manipulative & Physiological Therapeutics [serial on the Internet]. (1996, Sep), [cited November 8, 2017]; 19(7): 469-474. Available from: CINAHL Plus with Full Text.