The scapula, located directly dorsal to the posterior thoracic ribs, provides important stabilizing forces to the upper limb and facilitates glenohumeral motion.¹ Notably, the scapula serves as the attachment point for numerous muscles of the chest, rotator cuff, and upper extremity. The anterior aspect of the scapula is the point of attachment for both the subscapularis and serratus anterior muscles.² The coracoid process is the anterior most portion of the scapula and serves as the point of attachment for the pectoralis minor, biceps brachii, and coracobrachialis.² The lateral aspect of the scapula is the glenoid surface, which articulates with the humeral head to form the glenohumeral joint. Further, the long head of the triceps originates from the infraglenoid tubercle of the scapula. The posterior aspect of the scapula includes the scapular spine, the acromion, and the supraspinous and infraspinous fossa. The scapular spine and acromion together form attachments for the trapezius and deltoid. On the other hand, the supraspinous and infraspinous fossa serve as attachments for the muscle bellies of the supraspinatus and infraspinatus, respectively. The medial aspect provides attachments for three muscles: levator scapulae, rhomboid minor, and rhomboid major.²

Anatomy

Scapular dysfunction can manifest as either medial or lateral scapular winging.^3-5 Lateral winging of the scapula is caused by damage to the trapezius or rhomboid muscles.⁶ Similarly, injury to either the spinal accessory or the dorsal scapular nerves, which innervate the trapezius and rhomboid, respectively, can lead to lateral winging. The trapezius inserts on the clavicle, acromion, and scapular spine, while the rhomboid major and minor insert on the medial scapular border. The normal combined action of the trapezius and rhomboids is upward rotation of the scapula and scapular retraction. When the function of these muscles is compromised, lateral winging results from the unopposed pull of the serratus anterior.³ On the other hand, medial winging of the scapula is typically caused by injury to the long thoracic nerve.^3,4 The long thoracic nerve innervates the serratus anterior muscle, which normally is responsible for anterior and lateral motion of the scapula. When this function of the long thoracic nerve or serratus anterior muscle is compromised, the unopposed pull of the rhomboids, trapezius, and levator scapula muscles creates medial scapular winging.^2,4

Pathophysiology

Scapular dyskinesis, which refers to the abnormal movement of the scapula during shoulder motion, has been noted in 67 to 100 percent of athletes with shoulder injuries.⁷ Notably, it occurs for three primary reasons: shoulder, neck, and posture-related abnormalities.⁸ Most commonly, numerous shoulder-related pathologies, including acromioclavicular joint injury, shoulder impingement, and rotator cuff injuries, are associated with scapular dyskinesis. These shoulder-related pathologies cause alterations of the scapulohumeral rhythm, which is the coordinated movement of the scapula and humerus during motion.⁸ Next, scapular dyskinesis can result from cervical spine–related abnormalities, including mechanical neck pain and nerve pathologies. Mechanical neck pain includes degenerative changes in the cervical spine, or fatigue and imbalance of the musculature in the neck. Nerve pathologies include injuries to the long thoracic or spinal accessory nerves, or cervical radiculopathy. Lastly, postural-related changes to scapular motion include excessive cervical lordosis or thoracic kyphosis, which change the position of the scapula at rest.⁸

History

Patients with scapular winging or scapular dyskinesis generally present with pain and weakness in overhead activities.⁹ The pain may be diffuse over the shoulder blade, arm, and neck. Scapular winging may result from nerve injury or direct muscle damage. Common etiologies include trauma, athletics, iatrogenic injury from tumor resection or surgery, and infection.³ Therefore, it is important to inquire about participation in strenuous labor or athletics, especially collision or overhead sports. Iatrogenic injury to the long thoracic can occur in breast cancer patients undergoing axillary lymph node dissection, as the reported incidence of long thoracic nerve injury has been estimated at 0.6 to 74.7 percent in breast cancer patients.¹⁰ Similarly, iatrogenic injury to the spinal accessory nerve can occur with lymph node surgery or neck dissections in the posterior triangle. In addition, infectious causes, including Guillain-Barre syndrome, brachial neuritis, and Lyme disease, have been reported as causes of serratus anterior palsy and medial scapular winging.⁴ Lastly, facioscapulohumeral dystrophy, a genetic disorder and the third most common type of muscular dystrophy, can cause scapular winging due to weakness of either the trapezius or serratus anterior muscles.¹¹

It is important to note that some patients with scapular dyskinesis may not have a history of shoulder trauma and may not be symptomatic.⁸ Lastly, associated shoulder pathology, including acromioclavicular joint separation, shoulder impingement, rotator cuff injury, labrum injury, and clavicular fractures, should be noted, as these conditions are associated with scapular dyskinesis.⁸

Physical Examination

Physical examination of a patient with suspected scapular disorder should begin with inspection. The patient’s bilateral shoulder blades should be fully visible, and the examiner should stand behind the patient to evaluate the scapular mechanics. Any scars in the region should be noted, in addition to any atrophy in the periscapular musculature. The scapulothoracic articulation can be palpated for any crepitation. The examiner will then ask the patient to actively forward elevate as much as possible and observe scapular motion. The position of the scapula can also be noted with the shoulders at rest and then at 45 and 90 degrees of shoulder abduction. Forward elevation of the arm exacerbates scapular winging more than abduction and therefore is a more sensitive technique. In all positions, however, the examiner should still closely inspect the lateral and medial aspects of the scapula for signs of scapular winging (video 10.1; figure 10.1). Notably, lateral or medial winging can negatively affect a patient’s active range of motion at the shoulder (video 10.2).¹² The scapular position should be compared to the contralateral side to assess for any asymmetry. The examiner should assess whether manual stabilization of the scapula improves pain associated with these movements.

Patients suffering from lateral winging will present with winging exacerbated by ipsilateral upper extremity abduction and external rotation (video 10.3).¹³ In these patients, the shoulder girdle appears to be depressed and inferior relative to the uninjured side.

In patients with medial winging, the inferomedial scapula elevates and retracts from the rib cage relative to the contralateral side. The deformity is exacerbated with forward flexion of the ipsilateral upper extremity (video 10.4; figure 10.2).³

Special Tests

Scapular winging can be provoked through the wall test (video 10.5; figure 10.3). In the wall test, the patient is asked to stand facing a wall and place their palms flat against the wall with the shoulders in 90 degrees of forward flexion. When the patient pushes against the wall, the examiner may notice the inferior border of the scapula migrating medially, which is a sign of medial winging and could be indicative of serratus anterior weakness or long thoracic nerve damage (video 10.6).³ Conversely, if the superior aspect of the patient’s scapula becomes inferiorly and laterally displaced, that is a characteristic of lateral winging and injury to the spinal accessory nerve and trapezius muscle.3 If the inferior aspect of the patient’s scapula becomes laterally displaced, that is also a characteristic of lateral winging and injury to the dorsal scapular nerve and rhomboid muscles.³

In addition to the examination for scapular winging, there are several tests to assess for the presence or absence of scapular dyskinesis. The first of these is the yes/no test, which was first described by Kibler et al.^14,15 The patient is asked to raise their arms to maximal forward elevation 3 to 5 times. The examiner, standing behind the patient, observes for the presence of any prominence on the medial scapular border and categorizes this finding as “yes” (prominence detected) or “no” (no prominence detected”).^14,15 The repetition is designed to assess for dysfunction as a result of muscle fatigue. An alternative physical examination maneuver for the assessment of scapular dyskinesis is the scapular assistance test. In this maneuver, the examiner stands behind the patient with one hand on the medial superior border of the scapula and the other hand positioned at the inferior angle of the scapula.¹⁶ The patient is then instructed to actively elevate the affected arm, while the examiner guides the scapula to the normal elevation and rotation. If the examiner’s manipulation improves the patient’s range of motion or pain level, the test result is considered positive.

Key Terminology

Lateral Winging of the Scapula

Dysfunction in the trapezius or rhomboid muscles, or spinal accessory or dorsal scapular nerves, causes the scapula to be pulled more laterally. ↵

Medial Winging of the Scapula

Dysfunction in the serratus anterior muscle, or long thoracic nerve, causes the medial border of the scapula to be pulled medially. ↵

Scapular Dyskinesis

Abnormal or uncoordinated movement of the scapula during shoulder motion. ↵

Wall Test

Physical examination maneuver to detect winging of the scapula. The patient is asked to stand facing a wall, place their palms flat against the wall with the shoulders at 90 degrees forward elevation, and push against the wall. Movement of the medial border of the scapula medially or laterally demonstrates medial or lateral winging, respectively. ↵

References

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3. Martin, RM, Fish DE. Scapular winging: anatomical review, diagnosis, and treatments. Curr Rev Musculoskelet Med. 2008;1(1):1-11. ↵

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10. Belmonte R, Monleon S, Bofill N, Alvarado ML, Espadaler J, Royo I. Long thoracic nerve injury in breast cancer patients treated with axillary lymph node dissection. Support Care Cancer. 2015;23(1):169-175. ↵

11. Lu J., Yao Z, Yang Y, Zhang C, Zhang J, Zhang Y. Management strategies in facioscapulohumeral muscular dystrophy. Intractable Rare Dis Res. 2019;8(1):9-13. ↵

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14. Kibler WB, Sciascia A. Evaluation and management of scapular dyskinesis in overhead athletes. Curr Rev Musculoskelet Med. 2019;12(4):515-526. ↵

15. Uhl TL, Kibler WB, Gecewich B, Tripp BL. Evaluation of clinical assessment methods for scapular dyskinesis. Arthroscopy. 2009;25(11):1240-1248. ↵

16. Rabin A, Chechik O, Dolkart O, Goldstein Y, Maman E. A positive scapular assistance test is equally present in various shoulder disorders but more commonly found among patients with scapular dyskinesis. Phys Ther Sport. 2018;34:129-135. ↵