Scapulothoracic Disorders

The scapula connects the upper extremity to the thorax and allows for complex movements about the shoulder. Although there are minimal bony connections to the axial skeleton, the scapula plays an integral role in the function of the upper extremity and especially in the throwing mechanism. In total there are 17 muscles that have their origin or insertion on the scapula ( Table 53.1 and Fig. 53.1 ), which acts to collect forces passing through the trunk and transfer them to the arm. These muscles provide intrinsic, extrinsic, and stabilization/rotational functions of the shoulder. Scapular motion is critical to the phases of throwing, with protraction and retraction required from cocking to deceleration. Errors in timing are critical because the glenoid and humeral head must remain centered to allow maximum efficiency during this activity. Altered strength and mechanics of the scapula can have detrimental effects on the throwing shoulder.

TABLE 53.1

Scapula Muscular Attachments

From Moore KL. Clinically Oriented Anatomy . 6th ed. Baltimore: Lippincott Williams & Wilkins; 2010.

Region	Muscle	Scapular Attachments	Action
Rotator cuff	Infraspinatus	Infraspinous fossa	Rotates arm laterally
	Subscapularis	Medial two-thirds of subscapular fossa	Adducts and rotates arm medially
	Supraspinatus	Supraspinous fossa	Abducts arm
	Teres minor	Upper portion of lateral border of scapula	Rotates arm laterally
Scapulohumeral	Biceps brachii	Short head—coracoid process; long head—supraglenoid tubercle of scapula	Flexes arm and forearm, supinates forearm
	Coracobrachialis	Apex of coracoid process	Flexes and adducts arm
	Deltoid	Spine of scapula, acromion, lateral third of clavicle	Abducts, adducts, flexes, extends, rotates arm medially and laterally
	Teres major	Dorsal surface of inferior angle of scapula	Adducts and rotates arm medially
	Triceps brachii (long head)	Infraglenoid tubercle of scapula	Extends forearm at elbow joint; accessory adductor and extensor of the arm
Scapulothoracic	Latissimus dorsi	Attaches as it crosses the inferior angle of scapula	Adducts, extends, and rotates arm medially; retraction and downward rotation of scapula
	Levator scapulae	Medial border of scapula	Elevates scapula, rotates glenoid cavity
	Omohyoid	Inferior belly from medial lip of suprascapular notch and suprascapular ligament	Depresses and retracts hyoid and larynx
	Pectoralis minor	Coracoid process of scapula (medial border and upper surface)	Depresses and protracts scapula; elevates ribs
	Rhomboid major	Medial border of scapula	Adducts scapula
	Rhomboid minor	Root of spine of scapula	Adducts scapula
	Serratus anterior	Costal surface of medial border of scapula	Protraction and rotation of scapula, keeps medial border and inferior angle of scapula opposed to thoracic wall
	Trapezius	Spine of scapula, acromion	Adducts, rotates, elevates, and depresses scapula

Scapulothoracic (ST) disorders can be broken down into three main categories: scapular bursitis and crepitus, scapular winging, and scapular dyskinesis or SICK scapula. These disorders are seldomly found in isolation but frequently are associated with scapular malposition and tracking disorders, as well as structural injuries, including labral and rotator cuff tears. Often, successful treatment and rehabilitation of the painful shoulder depend heavily on recognizing scapular disorders. This chapter provides an overview of ST disorders, focusing on accurate diagnosis and successful treatment.

Scapular Bursitis and Crepitus

The shoulder has three major and several minor described bursae ( Table 53.2 and Fig. 53.2 ), although significant variability exists among individuals. In addition, some of the minor bursae may be absent all together. The term “snapping scapula” has been used when the scapular bursitis and crepitus becomes symptomatic. These symptoms can result from numerous etiologies ( Box 53.1 ).

TABLE 53.2

Bursae Types

Bursa	Location
Major (anatomic)	Infraserratus	Between serratus anterior and chest wall
	Supraserratus	Between subscapularis and serratus anterior
	Scapulotrapezial	Between superomedial scapular angle and trapezius (contains spinal accessory nerve)
Minor (adventitial)	Infraserratus (superior)	Superomedial scapular angle
	Infraserratus (inferior)	Inferior scapular angle
	Supraserratus	Superomedial scapular angle
	Trapezoid	Medial base of spine of scapula underlying the trapezius

Fig. 53.2, (A) Trapezial bursa at the superior medial angle and inferior angle bursa. (B) Subscapularis (supraserratus bursa) shown just anterior to the subscapularis muscle and scapular body.

Box 53.1

Differential Diagnosis/Pathogenesis of Bursitis

Soft tissue lesions such as atrophied muscle
Fibrotic muscle
Anomalous muscle insertions
Masses such as an elastofibroma (a rare benign soft tissue tumor on the chest wall elevating the scapula) or an osteochondroma (arising from under the scapular surface or posterior aspect of the ribs)
Luschka tubercle (a prominent bone with an excessive “hook” at the superomedial aspect of the scapular)
Malunited fractures of the scapula or ribs can lead to crepitus
Reactive bone spurs (can form repetitive microtrauma of the periscapular musculature)
Incongruity of the articulation leading to altered biomechanics (may exist as a result of scoliosis or thoracic kyphosis)
Rule out unrelated disorders such as cervical spondylosis and radiculopathy, glenohumeral pathology, and periscapular muscle strain

Scapular Winging

Scapular winging is defined as abnormal motion of the scapula and may result from a number of anatomic disorders ( Table 53.3 ). Primary winging is a neurologic or muscular disorder that affects the scapular stabilizers and is described as medial or lateral. Medial winging is the result of a dysfunctional serratus anterior muscle secondary to long thoracic nerve pathology. In contrast, lateral winging is the result of a dysfunctional spinal accessory nerve (cranial nerve XI) affecting the trapezius muscle or dysfunction in the dorsal scapular nerve (C5) affecting the rhomboid muscles ( Fig. 53.3 ). Secondary scapular winging occurs in conjunction with glenohumeral pathology and involves alteration of the normal scapular rhythm. Addressing the glenohumeral pathology and instituting a rehabilitation plan that targets the scapular dynamics will typically resolve the winging.

TABLE 53.3

Causes of Scapular Winging

Etiology	Type	Injury	Causes
First degree	Medial winging	Serratus anterior palsy—long thoracic nerve (C5-C7)	Most common cause of medial winging Damage to nerve from pressure lesions or neuritis (inflammation) Enlarged subcoracoid or subscapular bursa Nerve is vulnerable to injury because of the torturous route from the neck to the serratus anterior muscle
	Lateral winging	Trapezius palsy—spinal accessory nerve (C3-C4)	Isolated loss of trapezius function is rare The most common cause is iatrogenic resulting from cervical lymph node or tumor removal Due to the superficial course of nerve
	Lateral winging	Rhomboid palsy—dorsal scapular nerve (C5)	Primarily neurogenic in nature Entrapment in the middle scalene muscle is the most common Anterior shoulder dislocation C5 radiculopathy Overhead motion muscle strain injuries
Second degree	Medial and lateral winging	Loss of scapular suspensory mechanism	Usually affects overhead-throwing athletes; causes abnormal scapula rhythm and produces scapular winging with overhead maneuvers Dislocation of the AC joint or fracture of the outer third of the clavicle causing rupture of the CC ligaments
Second degree	Medial and lateral winging	Myopathies; weakness of the scapular stabilizers	Brachial plexus injury Muscular dystrophies, most commonly FSHD Peripheral nerve disease Parsonage-Turner syndrome (brachial neuritis)

AC, Acromioclavicular; CC, coracoclavicular; FSHD, fascioscapulohumeral dystrophy.

Fig. 53.3, Lateral winging of the scapula.

Scapular Dyskinesis

Scapular dyskinesia has become synonymous with the term “SICK scapula,” which was coined by Burkhart and colleagues in 2003. This acronym describes a common constellation of findings in this disorder, including S capular malposition, I nferior medial border prominence, C oracoid pain and malposition, and dys K inesis of scapular movement. In the disabled thrower, abnormal muscle activation leads to alteration in the resting position of the scapula and SICK and may be a precursor to intra-articular injuries. Scapular dyskinesis has been divided into three types, with various associated structural issues identified with each type. Type I involves prominence of the inferior medial angle of the scapula, whereas type II involves medial border prominence. Both types I and II are associated with labral pathology. Type III involves prominence of the superior medial border and is associated with shoulder impingement and rotator cuff tears.

History

ST disorders are common in patients who perform repetitive overhead activities as a result of their occupation or choice of sport. These disorders may be underrecognized in the office setting, which can lead to delay in diagnosis and treatment. Repetitive microtrauma is theorized to lead to soft tissue inflammation underlying the scapula and, if allowed to progress, to development of chronic ST bursitis. Scarring and fibrosis ensue, and the thickened fibrotic tissue occupies excessive space within the ST compartment leading to impingement and maltracking.

ST dysfunction often starts insidiously, although on occasion, the onset of symptoms is preceded by a minor traumatic event. Motion of the ST joint becomes extremely painful and is usually exacerbated by overhead activities. Patients often report crepitus in the posterior aspect of the shoulder, with or without pain. Throwing athletes with SICK scapula may report a “dead arm feeling” with resultant loss of maximum velocity and control. Pain may be variable, with some patients describing it anteriorly, posteriorly over the scapula, or even laterally and often radiating into the neck or the affected extremity. Pain anteriorly adjacent to the coracoid is a common presenting complaint. The patient should be questioned about prior surgery, including minor procedures near the long thoracic nerve, such as a lymph node biopsy .

Physical Examination

Inspection

As always, a good physical examination begins with inspection. It is imperative that the patient disrobe to allow both scapulae to be revealed simultaneously so that any signs of asymmetry in position or during motion can be observed ( Fig. 53.4 ). The superior and inferior medial angles of the scapulae should align symmetrically, and the scapular borders should be equidistance from a vertical line connecting the spinous processes. The examiner should always note whether the superior angle, inferior angle, or medial border of the scapula is most prominent.

Fig. 53.4, A throwing athlete with type II scapular dyskinesia of the left shoulder. Note the difference in shoulder height, the distance and angle of the medial border from midline, and the location of scapular prominence.

Although less common, asymmetry may result from other causes such as scoliosis, pelvic obliquity, and scapular winging. The exam should include measuring shoulder and hip height, and the spine should be inspected for scoliotic deformity. Often, the injured shoulder will appear lower on inspection from behind because the scapula moves laterally, tilts forward, and drops inferiorly ( Fig. 53.5 ). Pseudowinging is periscapular fullness that is biomechanical compensation as a result of painful bursitis.

Fig. 53.5, Marking the scapular landmarks improves diagnostic accuracy.

Palpation

Palpation of the entire scapula allows localization of symptomatic areas and masses. Patients often experience tenderness over the superior medial angle of the scapula, and in some occasions, a palpable mass may be present. In addition, the inferior medial angle is a common location for point tenderness. Patients with positive palpation at this location should raise suspicion for labral pathology, most commonly superior labrum anterior and posterior (SLAP) lesions, and should be tested for their presence. Palpable crepitus can often be detected by placing one hand over the medial aspect of the scapula while grasping the patient's symptomatic arm and performing range of motion (ROM) testing.

Ipsilateral coracoid tenderness is common in those patients with SICK scapula syndrome. The pathophysiology is likely from scapular tilt and lateral positioning of the coracoid, which lead to tightness in the pectoralis minor and conjoint tendons. Palpation over the insertion of the levator scapulae can also elicit tenderness as it becomes lengthened due to tilting away from its normal position.

Range of Motion

On examination, shoulder ROM is often diminished as a result of pain around the scapula or in the subacromial space. Scapular stabilizers lose ability to properly rotate the scapula due to subacromial bursitis causing subacromial impingement with overhead activities.

Patients with scapular dyskinesia will often have limited forward shoulder flexion, both passively and actively. Forward flexion limitations can often be alleviated by manual repositioning the scapula.

Examining scapular motion is paramount, and the examiner should look for asymmetric movement of the scapula during elevation of the shoulder. Measuring and marking of the scapular borders and comparing with the contralateral side improves ease of diagnosis (see Fig. 53.5 ). In examining for winging of the scapula, the examiner stands behind the patient and asks the patient to slowly raise both arms overhead. Primary winging is due to neurologic abnormalities described previously, whereas secondary winging occurs in the setting of normal trapezius (lateral) and serratus anterior (medial) function and represents a painful response to glenohumeral pathology and not neurologic pathology.

Strength

Loss of strength in the shoulder from ST disorders is proportional to the severity of the subacromial symptoms present. Strength may vary from breakaway weakness to full strength. The patient should be asked to perform a shoulder shrug against resistance to test the strength of the scapular elevators. A rolling shrug should then be performed while the examiner palpates the superior medial angle of the scapula for crepitus; this is then repeated for the inferior medial angle.

Testing

Wall Push-Up

Subtle winging can be detected by having the patient perform a wall push-up, carefully noting the direction of winging ( Fig. 53.6 ).

Scapular Retraction Test

To perform the scapular retraction test, an examiner performs passive ROM from behind the patient while palpating the coracoid. A positive test is defined as coracoid tenderness with diminished forward flexion that improves or resolves with manual repositioning of the scapula medially and inferiorly, symmetric to the contralateral scapula.

Impingement Examination

Impingement examination is generally positive because the acromion is malpositioned, reducing subacromial space. Failure of the scapula to rotate out of the way during forward elevation leads to impingement of the rotator cuff. Frequently used examination maneuvers for impingement including those described by Neer and Hawkins may be useful. The empty can test or Jobe test also can be helpful. This test is performed by asking the patient to actively abduct both arms to 90 degrees in the scapular plane and rotate their arms internally until the thumbs point down at the floor. Standing behind the patient, the examiner places their hands on the patient's forearm and asks the patient to resist downward pressure. Increased pain in the shoulder indicates a positive test ( Fig. 53.7 ).

Fig. 53.7, The empty can test is performed by having the patient abduct the shoulder in the scapular plane to 90 degrees, internally rotate both arms until the thumbs point at the floor, and resist downward pressure. A positive test indicates an inflamed subacromial space.

Imaging

Radiographs

A shoulder series of radiographs with tangential views of the scapula should be obtained to rule out associated bony abnormalities or neoplastic lesions. Although radiographs are not truly necessary for diagnosis, they are encouraged for completeness.

Computed Tomography Scan

A computed tomography scan should be obtained when bony abnormalities are identified on plain radiographs because the bony anatomy of the scapula makes complete visualization of some bone lesions challenging. Bone lesions, such as osteochondromas, can be the etiology behind ST crepitus and pain and can be more thoroughly defined by computed tomography modalities. Computed tomography in the setting of normal radiographs has not been shown to be beneficial.

Magnetic Resonance Imaging Scan

A magnetic resonance imaging (MRI) scan may show increased signal and fluid accumulation as a result of bursal inflammation. The films should be ordered and viewed in consultation with a trained musculoskeletal radiologist because this area is often not heavily scrutinized and in some cases is not well visualized during normal interpretation of a shoulder MRI. The presence of palpable crepitus is enough to confirm the diagnosis of ST bursitis, and the use of MRI, especially with the use of an intravenous contrast medium, is probably best reserved for cases in which a palpable mass raises the concern for neoplasia. In addition, because secondary ST disorders may be a result of more common shoulder pathology, MRI represents an important tool to fully diagnose the cause of the ST symptoms.

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