Chest and Shoulder Deformity

Dennis E. Kramer

Derek M. Kelly

• Basic Bony Anatomy, Development and Function

The pediatric shoulder girdle changes dramatically from the embryological period to adulthood, and each bone (scapula, clavicle, and humerus) has certain characteristics which are clinically relevant (Figure 17.1).

The scapula develops from embryological cartilage that migrates distally from the cervical spine to take its final position along the posterior chest wall during the first trimester. This has clinical importance as an undescended scapula (Sprengel deformity) may have residual tissue (fibrous, cartilaginous, or bone) that connects the scapula to the cervical spine.¹

The clavicle connects the sternum to the shoulder girdle and the shaft of the clavicle primarily by intramembranous ossification, a process whereby the bone develops directly from mesenchymal tissue rather than going through endochondral ossification.² Defects in this embryological process can result in clavicular pathology such as congenital pseudarthrosis of the clavicle or even complete absence seen in cleidocranial dysplasia. The ends of the clavicle develop and grow by means of endochondral ossification, and the medial clavicular physis typically is the last one in the body to close sometime during the middle 20s. Consequently, sternoclavicular injuries in children are primarily growth plate fractures and rarely dislocations. The lateral clavicle articulates with the acromion process of the scapula through
a capsular and ligamentous structure called the acromioclavicular (AC) joint. Sprains and dislocations to this joint can occur in children, but, similar to the medial clavicle, the lateral clavicle of the growing skeleton is much more prone to fractures than ligamentous injuries.

FIGURE 17.1 Shoulder physes and apophyses: location and name of each.

The proximal humerus develops from three primary ossification centers: the greater and lesser tuberosities and the humeral head. These three coalesce and eventually fuse with the humeral shaft. Greater than 80% of the growth of the humerus comes from the shoulder and thus a great deal of remodeling can be expected in fractures in this area that are displaced. This also means, however, that damage to the proximal humeral physis that leads to early cessation of growth can result in noticeable limb length inequalities.

The primary functions of the shoulder girdle are to help position the hand in space and transfer weight from the upper extremity to the torso. To accomplish these tasks, the shoulder has a large number of muscular attachments to accomplish weight transfer and to produce a wide variety of possible motions (Figure 17.2). The motions of the shoulder are made up of a complex interplay between
scapulothoracic and glenohumeral motions. While scapulothoracic motion is important to full shoulder function, most shoulder motion comes from the glenohumeral joint. The glenohumeral joint is largely unconstrained, moving through a large arc of motion within the glenoid. This makes the shoulder prone to conditions of instability, but it also means that large deformities of the proximal humerus can exist with little impact on overall shoulder function.

FIGURE 17.2 Boney anatomy of the pediatric shoulder region.

• General Physical Examination

Bony Anatomy/Surface Landmarks

Figure 17.3 shows the surface landmarks of the shoulder girdle in a pediatric patient along with the corresponding bony structures. During the physical examination, close attention should be paid to asymmetries. These are particularly noticeable at the sternoclavicular joint, acromion, AC joint, inferior pole of the scapula, and scapular spine. Swelling, bruising, or tenderness to palpation near these bony landmarks can indicate trauma or infection. Suspected bony trauma should be palpated very carefully to avoid a painful experience for the pediatric patient.

Shoulder Range of Motion

The glenohumeral joint is a ball-and-socket joint in which the ball is the head of the humerus and the socket is the glenoid which is directly attached to the scapula or shoulder blade. The glenohumeral joint is designed to allow the greatest arc of motion of any joint in the human body. Shoulder range of motion is a combination of glenohumeral and scapulothoracic motion. Maximal range of shoulder motion typically occurs through combined glenohumeral and scapulothoracic motion in a 2:1 ratio.³ When necessary, true glenohumeral motion can be differentiated from combined glenohumeral/scapulothoracic motion in any range of motion test by stabilizing the scapula to prevent scapulothoracic range of motion (Figure 17.4).

The shoulder physical examination should always be performed bilaterally to provide comparison. Range of motion can be evaluated with the patient supine or upright. If active range of motion is limited, passive range of motion and/or isolated glenohumeral motion should also be assessed.

Forward flexion of the shoulder is assessed by asking the patient to stand straight and with elbows extended and forearms supinated, to raise arms vertically to maximal height above the head (forward and perpendicular to the plane of the body) (Figure 17.5). The zero starting position is with the arm at the side of the body. The amount of forward elevation is referenced off the plane of the body in the sagittal plane. Conversely, shoulder extension involves backward motion of the arm in the sagittal plane, referenced off the body. Typical normal forward elevation is 150° to 180°.

Shoulder abduction is measured in the horizontal plane of the body by raising the arm away from the medial side of the body to maximal height above the head (Figure 17.5). Normal shoulder abduction is typically 150° to 180° and involves both glenohumeral and scapulothoracic motion with a 2:1 ratio. Shoulder adduction is more difficult to measure because the body blocks movement toward its medial plane. Shoulder adduction can be assessed by having the patient forward flex the arm to 90° and then bring the arm toward the medial plane of the body with the elbow either extended or flexed.

Shoulder internal/external rotation can be measured with the patient supine and the arm abducted to 90° and the elbow flexed to 90°. In this position, the examiner can stabilize the scapula by placing his or her palm over the patient’s shoulder and applying mild pressure to its anterior aspect to isolate true glenohumeral rotation. Internal and external rotations are then assessed by rotation of the forearm cephalad (external rotation) or caudad (internal rotation) with the forearm perpendicular to the floor (0°) considered as the starting position (Figure 17.6).

Shoulder internal and external rotation can also be measured with the patient standing and the arm at the side of the body with the elbow flexed 90°. In this position, external rotation is measured
by rotation of the forearm away from the body and referenced off the zero position of the forearm perpendicular to the body. Internal rotation is more difficult to assess with this technique because the chest wall blocks motion and is typically assessed by having the patient reach behind his or her back and determining the highest vertebral level the patient can reach with his or her thumb (Figure 17.7).

FIGURE 17.3 Bony and muscular landmarks of the chest and shoulder. AC, acromioclavicular; SC, sternoclavicular.

FIGURE 17.4 Total shoulder abduction is about 180 degrees and is the sum of motion at the glenohumeral joint and scapulothoracic motion. The examiner can isolate glenohumeral motion by first stabilizing the scapula with her left hand (A). The examiner can record glenohumeral motion by abducting the arm with her right hand until the scapula starts to move on the thorax (B). The contribution to total abduction via scapulothoracic motion is realized by releasing the scapula (C) and documenting total abduction.

Scapulothoracic motion, or motion between the anterior scapula and the posterior chest wall, can be assessed for dyskinesis by comparison to the other side. The patient is asked to do 10 wall push-ups and 10 full shoulder abduction exercises. The examiner looks for evidence of abnormal scapulothoracic motion (dyskinesis) present as a “hitch” or jump in an otherwise smooth motion pattern. Motion and position should be examined both in the ascending phase and in the descending phase of the arm. Dyskinesis will be noted more frequently in the descending phase of arm movement.

FIGURE 17.5 (A) Forward flexion and (B) abduction.

FIGURE 17.6 Internal and external shoulder motion measured in the supine position.

FIGURE 17.7 Shoulder internal rotation can be characterized as the highest level the thumb can reach or the distance from the spinous process of C7 (yellow line) and compared with the other side.

Shoulder Muscle Testing (

Video 17.1)

Shoulder muscle testing is done bilaterally to assess for weakness in specific shoulder muscles. Muscle strength typically is recorded on a 0 to 5 scale: 0: no palpable muscle contraction; 1: muscle flicker; 2: muscle contracture producing full joint movement with gravity eliminated; 3: full joint movement against gravity only (no resistance); 4: near-normal muscle strength; and 5: normal strength. A grade of 4 allows the examiner to subjectively grade strength as 4+ (near-normal/slight weakness) or 4- (profoundly weak but able to contract against resistance greater than gravity).

The rotator cuff is a group of four muscles that surround the shoulder like the cuff of a shirt. Two rotator cuff muscles—the more anterior supraspinatus and more posterior infraspinatus—lie on top. The subscapularis is positioned in front of the shoulder, and the teres minor lies in the back of the shoulder. The rotator cuff muscles all form tendons that attach to the head of the humerus. The top supraspinatus and infraspinatus work to bring the arm above the head and are most important in overhead sports.

Surrounding the rotator cuff muscles is the deltoid muscle. The deltoid muscle originates at the clavicle and acromion and attaches to the lateral humerus, surrounding and enveloping the rotator cuff anteriorly, posteriorly, and laterally. The deltoid muscle is tested with the arm adducted to the side and the elbow flexed to 90°. The patient is asked to forward flex (anterior deltoid), abduct (middle deltoid), and extend (posterior deltoid) the arm against resistance.³ The biceps muscle forms two cordlike tendons that lie in the anterior shoulder region and help to flex the elbow and supinate the forearm. The biceps strength is best assessed with the arm adducted (at the side) and the elbow flexed to 90°. The patient is asked to flex the elbow or supinate the forearm against resistance.

The supraspinatus typically is assessed by the “full can” and “empty can” tests. These tests are done with the shoulder forward flexed to 90° in the plane of the scapula (30° of adduction). The examiner asks the patient to forward flex (push upward toward the ceiling) with the thumb up (full can) and thumb down (empty can) while the examiner attempts to push the arm downward. The patient’s strength is assessed in comparison to the other side (Figure 17.8). The full can test specifically evaluates the anterior supraspinatus, while the empty can evaluates the posterior supraspinatus.

The infraspinatus is assessed by having the patient externally rotate the humerus from neutral with the elbow flexed and the arm in varying degrees of abduction (30°, 60°, and 90°) (Figure 17.9).

Subscapularis strength is best assessed by the “belly press” and “lift-off” tests. For the belly press test, the patient is asked to place his or her palms on the abdomen with the elbows parallel to the coronal plane of the body. The patient then forcibly pushes the elbows anteriorly. Subscapularis weakness is suggested by wrist flexion or dropping of the elbow behind the body during this maneuver (Figure 17.10). The “lift-off” test asks the patient to place the back of the hand on the lumbar spine and then lift the hand away from the back (internal rotation) (Figure 17.10). Inability to do this indicates subscapularis weakness or insufficiency.

FIGURE 17.8 Testing the strength of the different insertions of the supraspinatus muscle. Resistance is compared to the other side.

FIGURE 17.9 Testing the strength of the infraspinatus muscle.

FIGURE 17.10 Testing the strength of the subscapular muscle.

Periscapular muscle strength can be difficult to quantify. A good provocative maneuver to evaluate scapular muscle strength is to have the patient do an isometric “pinch” of the scapulae in retraction. Scapular muscle weakness can be noted as a burning pain in less than 15 seconds. Normally, the scapula can be held in this position for 15 to 20 seconds without pain or muscle weakness.

• Radiographic Studies

Plain Radiographic Imaging

As with all radiographic examinations, two orthogonal views are ideal to avoid missing important findings. The glenohumeral anteroposterior (AP) radiograph will characterize basic shoulder anatomy and pathology and is oriented 5° to 10° from a straight AP of the chest to account for the obliquity of the scapula. The orthogonal view can be a scapular Y view or an axillary view, and these can document shoulder dislocations (usually anterior) as well as scapular body or glenoid fractures. A number of special views can help in the diagnosis of a wide variety of conditions, but a complete list of these views is beyond the scope of this text. A list of common additional views and their potential indications is provided in Table 17.1.

Table 17.1 Specialized Radiographic Views of the Shoulder

VIEWS	INDICATIONS
Scapular anteroposterior (AP) and lateral	Scapular trauma or deformity or suspected neoplasia
Cross-body lateral or transthoracic lateral	Trauma when shoulder range of motion is limited by pain
Shoulder internal and external rotation	Visualization of the entire humeral head. Hill-Sachs lesions or tuberosity fractures
Shoulder apical oblique (Garth) view	Bankart or Hill-Sachs lesions
Bicipital groove (Fisk) view	Pathology of the intertubercular groove
Shoulder outlet (Neer) view	Coracoacromial arch deformity or impingement
Stryker notch view	Glenohumeral articulation, humeral head defects
Clavicular AP and AP cephalad	Acromioclavicular joint trauma or degeneration, clavicular trauma or deformity
Sternoclavicular AP, lateral, and serendipity views	Sternoclavicular trauma or deformity

FIGURE 17.11 Three-dimensional computed tomography reconstruction of a 10-year-old female patient with a large posterior humeral osteochondroma. This test is not needed for diagnosis but for surgical planning purposes and is best ordered at the discretion of the surgeon.

Computed Tomography Scan Imaging

Computed tomography (CT) of the shoulder region can be used to further define bony anatomy, particularly when additional information in the axial plane is needed, such as in trauma, congenital deformity, or neoplasia. However, the CT should not be the first imaging test ordered due to increased exposure of the patient to ionizing radiation (Figure 17.11).

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) can be used when information is needed about the soft tissues of the shoulder region such as the rotator cuff, glenohumeral joint capsule, labrum, AC joint, pectoralis, and deltoid. In some cases, MRI of the glenohumeral joint can be enhanced with arthrography (injection of MRI contrast material into the joint before the MRI) to accentuate injuries to the labrum and surrounding structures. MRI should not be ordered in hopes that an abnormal finding might explain vague pain; rather, MRI of the shoulder is most helpful to confirm a diagnosis already suggested by history and physical examination (Figure 17.12).

FIGURE 17.12 Magnetic resonance imaging scan of pediatric shoulder showing a large unicameral bone cyst in the proximal humeral metaphysis.

• Disorders of the Clavicle

Congenital Pseudarthrosis of Clavicle

Introduction

Congenital pseudarthrosis of the clavicle most commonly affects the right clavicle, except in cases of sinus inversus or dextrocardia, when the left clavicle is at risk. A suggested etiology of the pseudarthrosis is pressure of the nearby subclavian artery during embryological development.⁴ Females are more commonly affected than males. Unlike congenital pseudarthrosis of the tibia, congenital pseudarthrosis of the clavicle is unrelated to neurofibromatosis and, unlike cleidocranial dysplasia, there does not seem to be a direct genetic link.

Clinical Significance and Natural History

The bone does not heal without intervention; yet the condition is only rarely painful and may bother some children after activities involving the upper extremity.⁵

History and Physical Examination

Examination of a newborn reveals a painless prominence over the midshaft of the clavicle (Figure 17.13). As the child ages, the cosmetic deformity can become more pronounced, with a subcutaneous bony spike and a drooping shoulder girdle.

Diagnostic Tests or Advanced Imaging

Radiographs will demonstrate a dysplastic clavicle with defect in the midportion of the clavicle. A CT scan may be required to gain an accurate assessment of fragment size prior to consideration of surgical repair.