Excerpted from: (Page, Frank, Lardner. Assessment and Treatment of Muscle Imbalance, The Janda Approach. 2010, Human Kinetics, Champagne IL.)
As with most other chronic musculoskeletal pain, upper-extremity pain may manifest as global changes throughout the body. Long-standing Upper-Crossed Syndrome (UCS) may be compensated for with Lower-Crossed Syndrome (LCS). Therefore, the entire body should be included in the assessment of upper-extremity chronic pain.
It is commonly thought that posture is related to muscle imbalance and dysfunction. Poor posture has been described with UCS changes (see ). Noted common posture deviations in healthy individuals include: forward head posture 66%, increased thoracic kyphosis 38%, rounded shoulders 73%. Forward head posture and increased thoracic kyphosis are associated with interscapular pain.
Forward head posture (protraction of the cervical spine)is often increased in patients with shoulder pain. A forward head posture reduces flexion ROM of the shoulder. Forward head posture and rounded shoulders change the normal orientation of the scapula from 30˚to 45˚ anterior to the frontal plane. This slouched posture significantly alters the kinematics of the scapula during elevation. Shoulder protraction also reduces the height of the sub-acromial space (SAS) implicating rounded shoulders in impingement syndrome. Shoulder strength can also be affected by poor posture. Positioning the scapula in protraction or retraction significantly reduces shoulder elevation and rotation strength.
The characteristic postural deviations seen in UCS include: forward head posture (tight suboccipitals and weak deep neck flexors, rounded shoulders (tight pectoralis and weak shoulder stibilizers), and scapular winging and protraction. Winging of the scapula (prominence of the medial border) is often attributed to weakness of the serratus anterior, but may also be caused by weakness of the rhomboids or trapezius. Pseudowinging (prominence of the inferior angle as opposed to the medial border) is related to tightness of the pectoralis major. Three presentations of scapular instability include:
- Pronouncement of the inferior medial border, due to imbalance in scapular tilt across a transverse axis.
- Prominence of the entire medial border (winging) due to imbalance across a vertical axis.
- Superior translation and prominence of the superior medial border.
The SICK scapula:
- Scapular malposition
- Inferior medial border prominence
- Coracoid pain
- dysKinesis of scapular movement
is most commonly seen in athletes with impingement who rely on overhead movements. Typically, the scapula is depressed, protracted, and downwardly rotated.
Janda described a manual test for scapular instability resulting from weakness of the rhomboid or serratus anterior. Using one hand to stabilize the anterior shoulder, the clinician places the other hand, with the finger extended, at the vertebral inferior angle. The clinician then pushes the finger upward under the scapula. Normally, fingers disappear only to the distal interphalangeal joints; with scapular weakness and instability, the fingers will progress further.
Balance and Gait
Patients with chronic shoulder pain should be assessed for single-leg balance. Subtle compensations are sometimes apparent in the single-leg stance, such as elevation of the contralateral shoulder. Such elevation may indicate an overactive trapezius that is facilitated with every step, thus leading the clinician to suspect that the source of shoulder pain may be located somewhere else in the kinetic chain.
Janda’s utilized two primary tests for upper-extremity function; the push-up test and the shoulder abduction test.
In the push-up test, normally abducts and upwardly rotates as the trunk is lifted upward. There is no associated scapular elevation. Winging of the scapula, excessive scapular adduction, or inability to complete the scapular ROM in the direction of abduction indicates overactivity of the serratus anterior. Shoulder shrugging during the push-up indicates over activity of the upper trapezius and levator scapula.
During the shoulder abduction test, any elevation of the shoulder girdle that occurs before 60˚ of shoulder abduction is positive for impaired force couples, such as hypertonic upper trapezius and levator scapula combined with weak middle and lower trapezius.
Muscle Length and Strength
The shoulder complex is vulnerable to muscle imbalance because of its large range of movement and dependence on force couples for dynamic muscular stability.
Janda’s UCS includes shoulder muscle imbalance characterized by a tight upper trapezius, levator scapula and pectoralis major combined with a weak lower trapezius and serratus anterior. Janda further noted that both the posterior rotator cuff and deltoid are prone to weakness, possibly jeopardizing the critical rotator cuff-deltoid force couple. The pectoralis minor is also prone to tightness which can alter scapular kinemeatics. Imbalance in the scapular rotator muscles also affects the trapezius-serratus anterior force couple. Inhibited lower trapezius and serratus anterior muscles can result in scapular instability.
Imbalances in ROM and flexibility (typically measured by internal and external rotation) alter shoulder kinematics. Anterior tightness alters scapulohumeral rhythm and decreases posterior scapular tilt, while posterior tightness causes more superior and anterior translation of the humeral head. Posterior capsular tightness, often demonstrated by a loss of internal rotation, may increase anterior translation of the humeral head.