PEDIATRIC SHOULDER

PROXIMAL HUMERUS FRACTURES

Epidemiology

These account for <5% of fractures in children.

Incidence ranges from 1.2 to 4.4 per 10,000 per year.

They are most common in adolescents owing to increased sports participation and are often metaphyseal, physeal, or both.

Neonates may sustain birth trauma to the proximal humeral physis, representing 1.9% to 6.7% of physeal injuries (Fig. 43.1).

Anatomy

Eighty percent of humeral growth occurs at the proximal physis, giving this region great remodeling potential.

There are three centers of ossification in the proximal humerus:

• Humeral head: This ossifies at 6 months.

• Greater tuberosity: This ossifies at 1 to 3 years.

• Lesser tuberosity: This ossifies at 4 to 5 years.

• The greater and lesser tuberosities coalesce at 6 to 7 years and then fuse with the humeral head between 7 and 13 years of age.

The joint capsule extends to the metaphysis, rendering some fractures of the metaphysis

intracapsular (Fig. 43.2).

The primary vascular supply is via the anterolateral ascending branch of the anterior circumflex artery, with a small portion of the greater tuberosity and inferior humeral head supplied by branches of the posterior circumflex artery.

The physis closes at ages 14 to 17 years in girls and at ages 16 to 18 years in boys.

The physeal apex is posteromedial and is associated with a strong, thick periosteum.

Type I physeal fractures occur through the hypertrophic zone adjacent to the zone of provisional calcification. The layer of embryonal cartilage is preserved, leading to normal growth.

Muscular deforming forces: The subscapularis attaches to the lesser tuberosity. The remainder of the rotator cuff (teres minor, supraspinatus, and infraspinatus) attaches to the posterior epiphysis and greater tuberosity. The pectoralis major attaches to the anterior medial metaphysis, and the deltoid connects to the lateral shaft.

Mechanism of Injury

Indirect: Resulting from a fall backward onto an outstretched hand with the elbow extended and the wrist dorsiflexed. Birth injuries may occur as the arm is hyperextended or rotated as the infant is being delivered. Shoulder dystocia is strongly associated with macrosomia from maternal diabetes.

Direct: Resulting from direct trauma to the posterolateral aspect of the shoulder.

Clinical Evaluation

Newborns present with pseudoparalysis with the arm held in extension. A history of birth trauma may be elicited. A fever is variably present. Infection, clavicle fracture, shoulder dislocation, and brachial plexus injury must be ruled out.

Older children present with pain, dysfunction, swelling, and ecchymosis, and the humeral shaft fragment may be palpable anteriorly. The shoulder is tender to palpation, with a painful range of motion that may reveal crepitus.

Typically, the arm is held in internal rotation to prevent anteromedial pull of the distal fragment by the pectoralis major.

A careful neurovascular examination is required, including assessment of the axillary, musculocutaneous, radial, ulnar, and median nerves.

Radiographic Evaluation

Anteroposterior (AP), lateral (in the plane of the scapula; “Y” view), and axillary views should be obtained, with comparison views of the contralateral side if necessary.

Ultrasound: This may be necessary in the newborn because the epiphysis is not yet ossified.

Computed tomography may be useful to aid in the diagnosis and classification of posterior dislocations and complex fractures.

Magnetic resonance imaging is more useful than bone scan to detect occult fractures because the physis normally has increased radionuclide uptake, making a bone scan difficult to interpret.

Classification

Salter-Harris (Fig. 43.3)

Type I: Transphyseal fracture; usually a birth injury

Type II: Transphyseal fracture that exits through the metaphysis; usually occurring in adolescents (>12 years old); metaphyseal fragment always posteromedial

Type III: Transphyseal fracture that exits through the epiphysis uncommon; associated with dislocations

Type IV: Rare; fracture that traverses the epiphysis and the physis, exiting the metaphysis; associated with open fractures

Neer-Horowitz Classification of Proximal Humeral Plate Fractures

Grade I: <5 mm displacement

Grade II: Displacement less than one-third the width of the shaft

Grade III: Displacement one-third to two-thirds the width of the shaft

Grade IV: Displacement greater than two-thirds the width of the shaft, including total displacement

Treatment

Treatment depends on the age of the patient as well as the fracture pattern.

Newborns

Most fractures are Salter-Harris type I. The prognosis is excellent.

Ultrasound can be used to guide reduction.

Closed reduction: This is the treatment of choice and is achieved by applying gentle traction, 90 degrees of flexion, then 90 degrees of abduction and external rotation.

Stable fracture: The arm is immobilized against the chest for 5 to 10 days.

Unstable fracture: The arm is held abducted and is externally rotated for 3 to 4 days to allow early callus formation.

Ages 1 to 4 Years

These are typically Salter-Harris type I or, less frequently, type II.

Treatment is by closed reduction.

The arm is held in a sling for 10 days followed by progressive return to activity.

Extensive remodeling is possible.

Ages 5 to 12 Years

The metaphyseal fracture (type II) is the most common in this age group because this area is undergoing the most rapid remodeling and is therefore structurally vulnerable.

Treatment is by closed reduction. Most are stable following reduction.

Stable fracture: A sling and swathe is used (Fig. 43.4).

Unstable fracture: The arm is placed in a shoulder spica cast with the arm in the salute position for 2 to 3 weeks, after which the patient may be placed in a sling, with progressive return to activity.

Ages 12 Years to Maturity

These are either Salter-Harris type II or, less frequently, type I.

Treatment is typically by closed reduction.

There is less remodeling potential than in younger children.

Stable fracture: A sling and swathe is used for 2 to 3 weeks followed by progressive range-of-motion exercises.

Unstable fracture and Salter-Harris type IV: Immobilization is maintained in a shoulder spica cast with the arm in the salute position for 2 to 3 weeks, after which the patient may be placed in a sling, with progressive return to activity.

One should consider surgical stabilization for displaced fractures in adolescents.

Acceptable Deformity

Ages 1 to 4 years: 70 degrees of angulation with any amount of displacement

Ages 5 to 12 years: 40 to 45 degrees of angulation and displacement of one-half the width

of the shaft

Ages 12 years to maturity: 15 to 20 degrees of angulation and displacement of <30% the width

of the shaft

Open Treatment

Indications for open reduction and internal fixation include:

• Open fractures

• Fractures with associated neurovascular compromise

• Salter-Harris types III and IV fractures with displacement

• Irreducible fractures with soft tissue interposition (biceps tendon)

In children, fixation is most often achieved with percutaneous, smooth Kirschner wires or Steinmann pins.

Prognosis

Neer-Horowitz grades I and II fractures do well because of the remodeling potential of the proximal humeral physis.

Neer-Horowitz grades III and IV fractures may be left with up to 3 mm of shortening or residual angulation. This is well tolerated by the patient and is often clinically insignificant.

As a rule, the younger the patient, the higher the potential for remodeling and the greater the acceptable initial deformity.

Complications

Proximal humeral varus: Rare, usually affecting patients less than 1 year of age, but it may complicate fractures in patients as old as 5 years of age. It may result in a decrease of the neck-shaft angle to 90 degrees with humeral shortening and mild-to-moderate loss of glenohumeral abduction. Remodeling potential is great in this age group, however, so improvement is likely without intervention. Proximal humeral osteotomy may be performed in cases of extreme functional limitation.

Limb length inequality: Rarely significant and tends to occur more commonly in surgically treated patients as opposed to those treated nonoperatively.

Loss of motion: Rare and tends to occur more commonly in surgically treated patients. Older children tend to have more postfracture difficulties with shoulder stiffness than younger children.

Inferior glenohumeral subluxation: May complicate patients with Salter-Harris type II fractures of the proximal humerus secondary to a loss of deltoid and rotator cuff tone. It may be addressed by a period of immobilization followed by rotator cuff strengthening exercises.

Osteonecrosis: May occur with associated disruption of the anterolateral ascending branch of the anterior circumflex artery, especially in fractures or dislocations that are not acutely reduced. This is almost never seen in closed fractures.

Nerve injury: Most commonly axillary nerve injury in fracture-dislocations. Lesions that do not show signs of recovery in 4 months should be explored.

Growth arrest: May occur when the physis is crushed or significantly displaced or when a physeal bar forms. It may require excision of the physeal bar. Limb lengthening may be required for functional deficits or severe cosmetic deformity.

CLAVICLE FRACTURES

Epidemiology

Most frequent long bone fracture in children (8% to 15% of all pediatric fractures).

These occur in 0.5% of normal deliveries and 1.6% of breech deliveries (they account for 90% of obstetric fractures). The incidence of birth fractures involving the clavicle ranges from 2.8 to 7.2 per 1,000 term deliveries, and clavicular fractures account for 84% to 92% of all obstetric fractures.

In macrosomic infants (>4,000 g), the incidence is 13%.

Eighty percent of clavicle fractures occur in the midshaft, most frequently just lateral to the insertion of the subclavius muscle, which protects the underlying neurovascular structures.

Ten percent to 15% of clavicle fractures involve the lateral aspect, with the remainder representing medial fractures (5%).

Anatomy

The clavicle is the first bone to ossify; this occurs by intramembranous ossification.

The secondary centers develop via endochondral ossification:

• The medial epiphysis, where 80% of growth occurs, ossifies at ages 12 to 19 years and fuses by ages 22 to 25 years (last bone to fuse).

• The lateral epiphysis does not ossify until it fuses at age 19 years.

Clavicular range of motion involves rotation about its long axis (approximately 50 degrees) accompanied by elevation of 30 degrees with full shoulder abduction and 35 degrees of anterior–posterior angulation with shoulder protraction and retraction.

The periosteal sleeve always remains in the anatomic position. Therefore, remodeling is ensured.

Mechanism of Injury

Indirect: Fall onto an outstretched hand.

Direct: This is the most common mechanism, resulting from direct trauma to the clavicle or acromion; it carries the highest incidence of injury to the underlying neurovascular and pulmonary structures.

Birth injury: Occurs during delivery of the shoulders through a narrow pelvis with direct pressure from the symphysis pubis or from obstetric pressure directly applied to the clavicle during delivery.

Medial clavicle fractures or dislocations usually represent Salter-Harris type I or II fractures. True sternoclavicular joint dislocations are rare. The inferomedial periosteal sleeve remains intact and provides a scaffold for remodeling. Because 80% of the growth occurs at the medial physis, there is great potential for remodeling.

Lateral clavicle fractures occur as a result of direct trauma to the acromion. The coracoclavicular ligaments always remain intact and are attached to the inferior periosteal tube. The acromioclavicular ligament is always intact and is attached to the distal fragment.

Clinical Evaluation

Birth fractures of the clavicle are usually obvious, with an asymmetric, palpable mass overlying

the fractured clavicle. An asymmetric Moro reflex is usually present. Nonobvious injuries may be misdiagnosed as congenital muscular torticollis because the patient will often turn his or her head toward the fracture to relax the sternocleidomastoid muscle.

Children with clavicle fractures typically present with a painful, palpable mass along the clavicle. Tenderness is usually discrete over the site of injury, but it may be diffuse in cases of plastic bowing. There may be tenting of the skin, crepitus, and ecchymosis.

Neurovascular status must be carefully evaluated because injuries to the brachial plexus and upper extremity vasculature may occur. Rule out brachial plexus palsy.

Pulmonary status must be assessed, especially if direct trauma is the mechanism of injury. Medial clavicular fractures may be associated with tracheal compression, especially with severe posterior displacement.

Differential diagnosis

• Cleidocranial dysostosis: This defect in intramembranous ossification, most commonly affecting the clavicle, is characterized by absence of the distal end of the clavicle, a central defect, or complete absence of the clavicle. Treatment is symptomatic only.

• Congenital pseudarthrosis: This most commonly occurs at the junction of the middle and distal thirds of the right clavicle, with smooth, pointed bone ends. Pseudarthrosis of the left clavicle is found only in patients with dextrocardia. Patients present with no antecedent history of trauma, only a palpable bump. Treatment is supportive only, with bone grafting and intramedullary fixation reserved for symptomatic cases.

  Radiographic Evaluation

Ultrasound evaluation may be used in the diagnosis of clavicular fracture in neonates.

Because of the S-shape of the clavicle, an anteroposterior (AP) view is usually sufficient for diagnostic purposes; however, special views have been described in cases in which a fracture is suspected but not well visualized on a standard AP view (Fig. 43.5):

• Cephalic tilt view (cephalic tilt of 35 to 40 degrees): This minimizes overlapping structures to better show degree of displacement.

• Apical oblique view (injured side rotated 45 degrees toward tube with a cephalic tilt of 20

  degrees): This is best for visualizing nondisplaced middle third fractures.

   

   

   

Patients with difficulty breathing should have an AP radiograph of the chest to evaluate possible pneumothorax or associated rib fractures.

Computed tomography may be useful for the evaluation of medial clavicular fractures or suspected dislocation, because most represent Salter-Harris type I or II fractures rather than true dislocations.

Classification

Descriptive

Location

Open versus closed

Displacement

Angulation

Fracture type: segmental, comminuted, greenstick, etc.

Allman (Fig. 43.6)

Type I: Middle third (most common)

Type II: Distal to the coracoclavicular ligaments (lateral third)

Type III: Proximal (medial) third

Treatment

Newborn to Age 2 Years

Complete fracture in patients less than 2 years of age is unusual and may be caused by birth injury.

Clavicle fracture in a newborn will unite in approximately 1 week. Reduction is not indicated. Care should be taken when lifting the child. A soft bandage may be used for immobilization.

Infants may be treated symptomatically with a simple sling or figure-of-eight bandage applied for 2 to 3 weeks or until the patient is comfortable. One may also pin the sleeve of a long-sleeved shirt to the contralateral shoulder.

Ages 2 to 12 Years

A figure-of-eight bandage or sling is indicated for 2 to 4 weeks, at which time union is complete.

Age 12 Years to Maturity

The incidence of complete fracture is higher.

A figure-of-eight bandage or sling is used for 3 to 4 weeks. However, figure-of-eight bandages are often poorly tolerated and have been associated with ecchymosis, compression of axillary vessels, and brachial plexopathy.

If the fracture is grossly displaced with tenting of the skin, one should consider closed or open reduction with or without internal fixation.

Open Treatment

Operative treatment is indicated in open fractures and those with neurovascular compromise.

Comminuted fragments that tent the skin may be manipulated and the dermis released from the bone ends with a towel clip. Typically, bony fragments are placed in the periosteal sleeve and the soft tissue repaired. One can also consider internal fixation.

Bony prominences from callus will usually remodel; exostectomy may be performed at a later date if necessary, although from a cosmetic standpoint the surgical scar is often more noticeable than the prominence.

Complications

Neurovascular compromise: Rare in children because of the thick periosteum that protects the

underlying structures, although brachial plexus and vascular injury (subclavian vessels) may occur with severe displacement.

Malunion: Rare because of the high remodeling potential; it is well tolerated when present, and cosmetic issues of the bony prominence are the only long-term issue.

Nonunion: Rare (1% to 3%); it is probably associated with a congenital pseudarthrosis; it never occurs <12 years of age.

Pulmonary injury: Rare injuries to the apical pulmonary parenchyma with pneumothorax may occur, especially with severe, direct trauma in an anterosuperior to posteroinferior direction.

ACROMIOCLAVICULAR JOINT INJURIES

Epidemiology

Rare in children <16 years of age.

The true incidence is unknown because many of these injuries actually represent pseudodislocation of the acromioclavicular joint.

Anatomy

The acromioclavicular joint is a diarthrodial joint; in mature individuals, an intra-articular disc is present.

The distal clavicle is surrounded by a thick periosteal sleeve that extends to the acromioclavicular joint.

Mechanism of Injury

Athletic injuries and falls comprise the majority of acromioclavicular injuries, with direct trauma to the acromion.

Unlike acromioclavicular injuries in adults, in children, the coracoclavicular (conoid and trapezoid) ligaments remain intact. Because of the tight approximation of the coracoclavicular ligaments to the periosteum of the distal clavicle, true dislocation of the acromioclavicular joint is rare.

The defect is a longitudinal split in the superior portion of the periosteal sleeve through which the clavicle is delivered, much like a banana being peeled from its skin.

Clinical Evaluation

The patient should be examined while in the standing or sitting position to allow the upper extremity to be dependent, thus stressing the acromioclavicular joint and emphasizing deformity.

A thorough shoulder examination should be performed, including assessment of neurovascular status and possible associated upper extremity injuries. Inspection may reveal an apparent step-off deformity of the injured acromioclavicular joint, with possible tenting of the skin overlying the distal clavicle. Range of motion may be limited by pain. Tenderness may be elicited over the acromioclavicular joint.

Radiographic Evaluation

A standard trauma series of the shoulder (AP, scapular-Y, and axillary views) is usually sufficient for the recognition of acromioclavicular injury, although closer evaluation includes targeted views of the acromioclavicular joint, which requires one-third to one-half the radiation to avoid overpenetration.

Ligamentous injury may be assessed via stress radiographs, in which weights (5 to 10 lb) are strapped to the wrists and an AP radiograph is taken of both shoulders for comparison.

Classification (Dameron and Rockwood) (Fig. 43.7)

Type I: Mild sprain of the acromioclavicular ligaments without periosteal tube disruption; distal clavicle stable to examination and no radiographic abnormalities

Type II: Partial disruption of the periosteal tube with mild distal clavicle instability; slight widening of the acromioclavicular space appreciated on radiographs

Type III: Longitudinal split of the periosteal tube with gross instability of the distal clavicle to examination; superior displacement of 25% to 100% present on radiographs as compared with the normal, contralateral shoulder

Type IV: Posterior displacement of the distal clavicle through a periosteal sleeve disruption with buttonholing through the trapezius; AP radiographs demonstrating superior displacement similar to type II injuries, but axillary radiographs demonstrating posterior displacement

Type V: Type III injury with >100% displacement; distal clavicle may be subcutaneous to palpation, with possible disruption of deltoid or trapezial attachments

Type VI: Infracoracoid displacement of the distal clavicle as a result of a superior-to-inferior force vector

Treatment

For types I to III, nonoperative treatment is indicated, with sling immobilization, ice, and early range-of-motion exercises as pain subsides. Remodeling is expected. Complete healing generally takes place in 4 to 6 weeks.

Treatment for types IV to VI is operative, with reduction of the clavicle and repair of the periosteal sleeve. Internal fixation may be needed.

Complications

Neurovascular injury: This is rare and is associated with posteroinferior displacement. The intact periosteal sleeve is thick and usually provides protection to neurovascular structures underlying the distal clavicle.

Open lesion: Severe displacement of the distal clavicle, such as with type V acromioclavicular dislocation, may result in tenting of the skin, with possible laceration necessitating irrigation and debridement.

SCAPULA FRACTURES

The scapula is relatively protected from trauma by the thoracic cavity and the rib cage anteriorly as well as by the encasing musculature.

Scapular fractures are often associated with other life-threatening injuries that have greater priority.

Epidemiology

These are less common in children than in adults where they constitute only 1% of all fractures and 5% of shoulder fractures in the general population.

Anatomy

The scapula forms from intramembranous ossification. The body and spine are ossified at birth.

The center of the coracoid is ossified at 1 year. The base of the coracoid and the upper one-fourth of the glenoid ossify by 10 years. A third center at the tip of the coracoid ossifies at a variable time. All three structures fuse by age 15 to 16 years.

The acromion fuses by age 22 years via two to five centers, which begin to form at puberty.

Centers for the vertebral border and inferior angle appear at puberty and fuse by age 22 years. The center for the lower three-fourths of the glenoid appears at puberty and fuses by age 22 years.

The suprascapular nerve traverses the suprascapular notch on the superior aspect of the scapula, medial to the base of the coracoid process, thus rendering it vulnerable when fractures occur in this region.

The superior shoulder suspensory complex (SSSC) is a circular group of both bony and ligamentous attachments (acromion, glenoid, coracoid, coracoclavicular ligament, and distal clavicle). The integrity of the ring is breached only after more than one violation. This can dictate the treatment approach (Fig. 43.8).

Mechanism of Injury

In children, most scapula fractures represent avulsion fractures associated with glenohumeral joint injuries. Other fractures are usually the result of high-energy trauma.

Isolated scapula fractures are extremely uncommon, particularly in children; child abuse should be

suspected unless a clear and consistent mechanism of injury exists.

The presence of a scapula fracture should raise suspicion of associated injuries because 35% to 98% of scapula fractures occur in the presence of other injuries, including:

• Ipsilateral upper torso injuries: fractured ribs, clavicle, sternum, shoulder trauma

• Pneumothorax: seen in 11% to 55% of scapular fractures

• Pulmonary contusion: present in 11% to 54% of scapula fractures

• Injuries to neurovascular structures: brachial plexus injuries, vascular avulsions

• Spinal column injuries: 20% lower cervical spine, 76% thoracic spine, 4% lumbar spine

• Others: concomitant skull fractures, blunt abdominal trauma, pelvic fracture, and lower extremity injuries, which are all seen with higher incidences in the presence of a scapula fracture

Rate of mortality in setting of scapula fractures may approach 14%.

Clinical Evaluation

Full trauma evaluation, with attention to airway, breathing, circulation, disability, and exposure should be performed, if indicated.

Patients typically present with the upper extremity supported by the contralateral hand in an adducted and immobile position, with painful range of shoulder motion, especially with abduction.

A careful examination should be performed to evaluate for associated injuries with a comprehensive assessment of neurovascular status and an evaluation of breath sounds.

Radiographic Evaluation

Initial radiographs should include a trauma series of the shoulder, consisting of true AP, axillary, and scapular-Y (true scapular lateral) views; these generally are able to demonstrate most glenoid, neck, body, and acromion fractures.

• The axillary view may be used to further delineate acromial and glenoid rim fractures.

• An acromial fracture should not be confused with an os acromiale, which is a rounded, unfused apophysis at the epiphyseal level and is present in approximately 3% of the population. When present, it is bilateral in 60% of cases. The os is typically in the anteroinferior aspect of distal acromion.

• Glenoid hypoplasia, or scapular neck dysplasia, is an unusual abnormality that may resemble glenoid impaction and may be associated with humeral head or acromial abnormalities. It has a benign course and is usually noted incidentally.

A 45-degree cephalic tilt (Stryker notch) radiograph is helpful to identify coracoid fractures.

Computed tomography may be useful for further characterizing intra-articular glenoid fractures.

Because of the high incidence of associated injuries, especially to thoracic structures, a chest radiograph is an essential part of the evaluation.

Classification

Classification by Location

Body (35%) and Neck (27%) Fractures

1. Isolated versus associated disruption of the clavicle

2. Displaced versus nondisplaced

Glenoid Fractures (Ideberg and Goss) (Fig. 43.9)

IA: Anterior avulsion fracture

IB: Posterior rim avulsion

II: Transverse with inferior free fragment

III: Upper third including coracoid

IV Horizontal fracture extending through body

V: Combined II, III, and IV

VI: Extensively comminuted

These can be associated with scapular neck fractures and shoulder dislocations.

Treatment is nonoperative in most cases. Open reduction and internal fixation are indicated if a large anterior or posterior rim fragment is associated with glenohumeral instability.

Coracoid Fractures

These are isolated versus associated disruption of the acromioclavicular joint.

These are avulsion-type injuries, usually occurring through the common physis of the base of the coracoid and the upper one-fourth of the glenoid.

The coracoacromial ligament remains intact, but the acromioclavicular ligaments may be stretched.

Acromial Fractures I: Nondisplaced IA: Avulsion

IB: Direct trauma

II: Displaced without subacromial narrowing

III: Displaced with subacromial narrowing

These are rare, usually the result of a direct blow.

The os acromiale, which is an unfused ossification center, should not be mistaken for a fracture.

Nonoperative treatment is recommended unless there is severe displacement of the acromioclavicular joint.

Treatment

Scapula body fractures in children are treated nonoperatively, with the surrounding musculature maintaining reasonable proximity of fracture fragments. Operative treatment is indicated for fractures that fail to unite, which may benefit from partial body excision.

Scapula neck fractures that are nondisplaced and not associated with clavicle fractures may be treated nonoperatively. Significantly displaced fractures may be treated in a thoracobrachial cast. Associated clavicular disruption, either by fracture or ligamentous instability (i.e., multiple disruptions in the SSSC), is generally treated operatively with open reduction and internal fixation of the clavicle alone or open reduction and internal fixation of the scapula fracture through a separate incision.

Coracoid fractures that are nondisplaced may be treated with sling immobilization. Displaced fractures are usually accompanied by acromioclavicular dislocation or lateral clavicular injury and should be treated with open reduction and internal fixation.

Acromial fractures that are nondisplaced may be treated with sling immobilization. Displaced acromial fractures with associated subacromial impingement should be reduced and stabilized with screw or plate fixation.

Glenoid fractures in children, if not associated with glenohumeral instability, are rarely symptomatic when healed and can generally be treated nonoperatively if they are nondisplaced.

Type I: Fractures involving greater than one-fourth of the glenoid fossa that result in instability may be amenable to open reduction and lag screw fixation.

Type II: Inferior subluxation of the humeral head may result, necessitating open reduction, especially when associated with a greater than 5-mm articular step-off. An

anterior approach usually provides adequate exposure.

Type III: Reduction may be difficult; fractures occur through the junction between the ossification centers of the glenoid and are often accompanied by a fractured acromion or clavicle, or an acromioclavicular separation. Open reduction and internal fixation followed by early range of motion are indicated.

Types IV to VI: These are difficult to reduce, with little bone stock for adequate fixation in pediatric patients. A posterior approach is generally utilized for open reduction and internal fixation with Kirschner wire, plate, suture, or screw fixation for displaced fractures.

Complications

Posttraumatic osteoarthritis: This may result from a failure to restore articular congruity.

Associated injuries: These account for most serious complications because of the high-energy nature of these injuries.

Decreased shoulder motion: Secondary to subacromial impingement from acromial fracture.

Malunion: Fractures of the scapula body generally unite with nonoperative treatment; when malunion occurs, it is generally well tolerated but may result in painful scapulothoracic crepitus.

Nonunion: Extremely rare, but when present and symptomatic, it may require open reduction and plate fixation for adequate relief.

Suprascapular nerve injury: May occur in association with scapula body, scapula neck, or coracoid fractures that involve the suprascapular notch.

GLENOHUMERAL DISLOCATIONS

Epidemiology

Rare in children; Rowe reported that only 1.6% of shoulder dislocations occurred in patients <10 years of age, whereas 10% occurred in patients 10 to 20 years of age.

Ninety percent are anterior dislocations.

Anatomy

The glenohumeral articulation, with its large convex humeral head and correspondingly flat glenoid, is ideally suited to accommodate a wide range of shoulder motion. The articular surface and radius of curvature of the humeral head are about three times those of the glenoid fossa.

Numerous static and dynamic stabilizers of the shoulder exist; these are covered in detail in  14.

The humeral attachment of the glenohumeral joint capsule is along the anatomic neck of the humerus, except medially where the attachment is more distal along the shaft. The proximal humeral physis is therefore extra-articular except along its medial aspect.

As in most pediatric joint injuries, the capsular attachment to the epiphysis renders failure through the physis much more common than true capsuloligamentous injury; therefore, fracture through the

physis is more common than a shoulder dislocation in a skeletally immature patient.

In neonates, an apparent dislocation may actually represent a physeal injury.

Mechanism of Injury

Neonates: Pseudodislocation may occur with traumatic epiphyseal separation of the proximal humerus. This is much more common than a true shoulder dislocation, which may occur in neonates with underlying birth trauma to the brachial plexus or central nervous system.

Anterior glenohumeral dislocation may occur as a result of trauma, either direct or indirect.

• Direct: An anteriorly directed impact to the posterior shoulder may produce an anterior dislocation.

• Indirect: Trauma to the upper extremity with the shoulder in abduction, extension, and external

  rotation is the most common mechanism for anterior shoulder dislocation.

Posterior glenohumeral dislocation (2% to 4%):

• Direct trauma: This results from force applied to the anterior shoulder, dislocating the humeral head posteriorly.

• Indirect trauma: This is the most common mechanism.

  • The shoulder is typically in the position of adduction, flexion, and internal rotation at the time of injury with axial loading.

  • Electric shock or convulsive mechanisms may produce posterior dislocation owing to the

    overwhelming of the external rotators of the shoulder (infraspinatus and teres minor muscles) by the internal rotators (latissimus dorsi, pectoralis major, and subscapularis muscles).

Atraumatic dislocations: Recurrent instability related to congenital or acquired laxity or volitional mechanisms may result in anterior dislocation with minimal trauma.

Clinical Evaluation

Patient presentation varies according to the type of dislocation encountered.

Anterior Dislocation

The patient typically presents with the affected upper extremity held in slight abduction and external rotation. The acutely dislocated shoulder is painful, with muscular spasm in an attempt to stabilize the joint.

Examination typically reveals squaring of the shoulder caused by a relative prominence of the acromion, a relative hollow beneath the acromion posteriorly, and a palpable mass anteriorly.

A careful neurovascular examination is important with attention to axillary nerve integrity. Deltoid muscle testing is usually not possible, but sensation over the deltoid may be assessed. Deltoid atony may be present and should not be confused with axillary nerve injury. Musculocutaneous nerve integrity can be assessed by the presence of sensation on the anterolateral forearm.

Patients may present after spontaneous reduction or reduction in the field. If the patient is not in acute pain, examination may reveal a positive apprehension test, in which passive placement of the shoulder in the provocative position (abduction, extension, and external rotation) reproduces

the patient’s sense of instability and pain. Posteriorly directed counterpressure over the anterior shoulder may mitigate the sensation of instability.

Posterior Dislocation

Clinically, a posterior glenohumeral dislocation does not present with striking deformity; moreover, the injured upper extremity is typically held in the traditional sling position of shoulder internal rotation and adduction.

A careful neurovascular examination is important to rule out axillary nerve injury, although it is much less common than with anterior glenohumeral dislocations.

On examination, limited external rotation (often <0 degrees) and limited anterior forward elevation (often <90 degrees) may be appreciated.

A palpable mass posterior to the shoulder, flattening of the anterior shoulder, and coracoid prominence may be observed.

Atraumatic Dislocation

Patients present with a history of recurrent dislocations with spontaneous reduction.

Often, the patient will report a history of minimal trauma or volitional dislocation, frequently without pain.

Multidirectional instability may be present bilaterally, as may characteristics of multiple joint laxity, including hyperextensibility of the elbows, knees, and metacarpophalangeal joints. Skin striae may be present.

Sulcus sign: This is dimpling of skin below the acromion with longitudinal traction.

Superior and Inferior (Luxatio Erecta) Dislocation

This is extremely rare in children, although cases have been reported.

It may be associated with hereditary conditions such as Ehlers-Danlos syndrome.

Radiographic Evaluation

A trauma series of the affected shoulder is indicated: AP, scapular-Y, and axillary views.

Velpeau axillary view: Compliance is frequently an issue in the irritable, injured child in pain. If a standard axillary view cannot be obtained, the patient may be left in a sling and leaned obliquely backward 45 degrees over the cassette. The beam is directed caudally, orthogonal to the cassette, resulting in an axillary view with magnification.

Special views (see  14)

• West Point axillary view: Taken with the patient prone with the beam directed cephalad to the axilla 25 degrees from the horizontal and 25 degrees medially. It provides a tangential view of the anteroinferior glenoid rim.

• Hill-Sachs view: An AP radiograph is taken with the shoulder in maximal internal rotation to visualize posterolateral defect (Hill-Sachs lesion) caused by an impression fracture on the glenoid rim.

• Stryker notch view: The patient is supine with the ipsilateral palm on the crown of head and the elbow pointing straight upward. The x-ray beam is directed 10 degrees cephalad, aimed at coracoid. One is able to visualize 90% of posterolateral humeral head defects.

Computed tomography may be useful in defining humeral head or glenoid impression fractures, loose bodies, and anterior labral bony injuries (bony Bankart lesion).

Single- or double-contrast arthrography may be utilized in cases in which the diagnosis may be unclear; it may demonstrate pseudosubluxation, or traumatic epiphyseal separation of the proximal humerus, in a neonate with an apparent glenohumeral dislocation.

Magnetic resonance imaging may be used to identify rotator cuff, capsular, and glenoid labral (Bankart lesion) pathology.

Atraumatic dislocations may demonstrate congenital aplasia or absence of the glenoid on radiographic evaluation.

Classification

Degree of stability: Dislocation versus subluxation

Chronology: Congenital

Acute versus chronic Locked (fixed) Recurrent

Acquired: generally from repeated minor injuries (swimming, gymnastics, weights); labrum often intact; capsular laxity; increased glenohumeral joint volume; subluxation common

Force: Atraumatic: usually owing to congenital laxity; no injury; often asymptomatic; self-reducing

Traumatic: usually caused by one major injury; the anteroinferior labrum may be detached (Bankart lesion); unidirectional; generally requires assistance for reduction

Patient contribution: Voluntary versus involuntary

Direction: Subcoracoid Subglenoid Intrathoracic

Treatment

Closed reduction should be performed after adequate clinical evaluation and administration of analgesics and/or sedation. Described techniques include (the figures in  14):

• Traction–countertraction: With the patient in the supine position, a sheet is placed in the axilla of the affected shoulder with traction applied to counter axial traction placed on the affected upper extremity. Steady, continuous traction eventually results in fatigue of the shoulder musculature in spasm and allows reduction of the humeral head.

• Stimson technique: The patient is placed prone on the stretcher with the affected upper extremity hanging free. Gentle, manual traction or 5 lb of weight is applied to the wrist, with reduction effected over 15 to 20 minutes.

• Steel maneuver: With the patient supine, the examiner supports the elbow in one hand while supporting the forearm and wrist with the other. The upper extremity is abducted to 90 degrees and is slowly externally rotated. Thumb pressure is applied by the physician to push the humeral head into place, followed by adduction and internal rotation of the shoulder as the extremity is placed across the chest. There is a higher incidence of iatrogenic fracture.

Following reduction, acute anterior dislocations are treated with sling immobilization. Total time in sling is controversial but may be up to 4 weeks, after which an aggressive program of rehabilitation for rotator cuff strengthening is instituted. Posterior dislocations are treated for 4 weeks in a commercial splint or shoulder spica cast with the shoulder in neutral rotation, followed by physical therapy.

Recurrent dislocation or associated glenoid rim avulsion fractures (bony Bankart lesion) may necessitate operative management, including reduction and internal fixation of the anterior glenoid margin, repair of a Bankart lesion (anterior labral tear), capsular shift, or capsulorrhaphy. Postoperatively, the child is placed in sling immobilization for 4 to 6 weeks with gradual increases in range-of-motion and strengthening exercises.

Atraumatic dislocations rarely require reduction maneuvers as spontaneous reduction is the rule. Only after an aggressive, supervised rehabilitation program for rotator cuff and deltoid strengthening has been completed should surgical intervention be considered. Vigorous rehabilitation may obviate the need for operative intervention in up to 85% of cases.

Psychiatric evaluation may be necessary in the management of voluntary dislocators.

Complications

Recurrent dislocation: The incidence is 50% to 90%, with decreasing rates of recurrence with increasing patient age (up to 100% in children less than 10 years old). It may necessitate operative intervention, with >90% success rate in preventing future dislocation.

Shoulder stiffness: Procedures aimed at tightening static and dynamic constraints (subscapularis tendon-shortening, capsular shift, etc.) may result in “overtightening,” resulting in a loss of range of motion, as well as possible subluxation in the opposing direction with subsequent accelerated glenohumeral arthritis.

Neurologic injury: Neurapraxic injury may occur to nerves in proximity to the glenohumeral articulation, especially the axillary nerve and less commonly the musculocutaneous nerve. These typically resolve with time; a lack of neurologic recovery by 3 months may warrant surgical exploration.

Vascular injury: Traction injury to the axillary artery has been reported in conjunction with nerve injury to the brachial plexus.