This article evaluates the spectrum of epidemiology and treatment of children presenting with shoulder pain. These injuries are discussed to further understand the mechanism of injury, the variation of these injuries with age, treatment options, and outcomes and complications that may arise. A retrospective clinical review was performed to compliment the findings of the literature review.
Key points
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Pediatric shoulder injuries behave and heal different than adult shoulder injuries because of the biomechanics of the open physis.
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Fractures are more common in younger patients, whereas instability is common in older and more skeletally mature patients.
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Proximal humerus fractures are more likely to require surgery than clavicle fractures in children, although younger children can tolerate more displacement than older children.
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The increased participation in single year-round sports leads to a specific overuse injuries such as Little League shoulder.
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Treatment of overhead shoulder injuries, such as internal impingement, includes rest, strengthening exercises, and proper throwing mechanics education; however, surgery may be necessary for intra-articular disorders that fail to improve.
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Dislocation and instability can be treated with physical therapy, but the recurrence rate is high in this young population.
Introduction
With about 45 million children and adolescents in organized youth athletics, injuries are common and there are approximately 2 million high school athletic injuries annually. Shoulder injuries are a common component of that number ( Fig. 1 ), accounting for nearly 1 million outpatient visits per year in the general population. Although varied, the musculoskeletal shoulder disorders that present to a physician can include fractures, overuse injuries, and instability.
This article has 2 aims: (1) to evaluate the causes of musculoskeletal shoulder pain in the pediatric population, and (2) to present the mechanism of injury and treatment associated with the various causes of shoulder pain. To confirm historical findings, a retrospective chart review was performed after obtaining Institutional Review Board approval, on all children who met inclusion criteria for shoulder pain, treated between August of 2008 and 2009 at our tertiary care children’s hospital. There were 613 individuals who met the inclusion criteria: 370 boys (60.4%) and 243 girls (39.6%). The mean age was 13.3 years (range 0.17–21.75 years). Patients outside the normal pediatric age range all presented with childhood comorbidities and were included.
Fractures (proximal humerus and clavicle)
Introduction to Shoulder Fractures
The proximal humerus fracture in the skeletally immature represents about 0.45% of all pediatric fractures, less than 5% in the adolescent age group, and 4% to 7% of all epiphyseal fractures in children. These injuries were reported to occur most commonly between the ages of 11 and 17 years in one study and 10 to 14 years in another.
Forces that act on the proximal humerus may:
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Result in fracture: forced extension, forced flexion, forced extension with lateral or medial rotation, and forced flexion with medial or lateral rotation.
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Displace the epiphysis: muscular forces such as abduction, flexion, and slight external rotation.
Ossification of the proximal humerus occurs in the following sequence:
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At birth, the epiphysis is cartilaginous.
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Ossification centers are first noticeable by 4 to 6 months of age.
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Secondary ossification centers are present after 6 months of age.
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Three ossification centers are seen: the humeral head, the greater tuberosity, and the lesser tuberosity ( Fig. 2 ).
Fig. 2
Ossification center locations on the proximal humerus.
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Greater tuberosity ossifies between 7 months and 3 years of age.
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Lesser tuberosity ossifies between 5 and 7 years of age.
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The three ossification centers combine to create the proximal humeral epiphysis by 5 to 7 years of age.
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Closure of the proximal humerus physis occurs at 14 to 17 of age in girls and 16 to 18 of age in boys (some reports suggest 19 and 22 years of age). It is at this age range that this study distinguishes the skeletally immature from mature.
Certain age groups are prone to certain fracture patterns according to the growth of the proximal humerus:
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Neonates to 5 years old: Salter-Harris I injury
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From 5 to 11 years old: metaphyseal fractures
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From 10 to 11 years old: Salter-Harris II injuries
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Adolescents: Salter-Harris II, III, and IV injuries
It has been reported that about 20% of proximal humerus fractures in the skeletally immature are associated with athletic activities. During review of our own patient population, there were 190 fractures (40% of the cohort) and most of the fractures involved the proximal humerus. The mean age of the patients with fractures (9 ± 4 years) was significantly lower than the mean age of the patients with instability (16 ± 2 years, P <.001) ( Table 1 ). Fractures were caused by the following:
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Falls (121 patients, 63.7%)
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Wheeled activities (32 patients, 16.8%)
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Sports (25 patients, 13.2%)
| Injury | Mean Age (y) | Standard Deviation | N |
|---|---|---|---|
| Acromioclavicular separation | 14.55 | 2.42 | 15 |
| Fracture | 9.05 | 4.63 | 190 |
| Instability | 15.51 | 2.27 | 158 |
| Neurologic | 8.74 | 9.04 | 8 |
| Overhead | 15.14 | 2.11 | 42 |
| Pain | 14.91 | 2.59 | 102 |
| Post labrum | 15.71 | 1.40 | 8 |
| Rotator cuff | 15.05 | 2.42 | 52 |
| SLAP | 16.58 | 1.77 | 28 |
| Tumor | 11.73 | 3.42 | 4 |
| Weakness | 14.17 | 2.96 | 6 |
| Average | 13.25 | 4.46 | 613 |
In contrast with the proximal humerus, the clavicle is a distinct long bone composed of cancellous material without a medullary cavity. Clavicle fractures are the most common long bone fracture in children, representing 5% to 15% of fractures in this population. They are unique in that they are the most common iatrogenic fractures, occurring in 1% to 7% of large babies (more than 4500 g), shoulder dystocias, or special instrumentation births.
Ossification of the clavicle:
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Ossification centers are both medial and lateral
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The medial center provides 80% of the longitudinal growth of the clavicle
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Ossification begins by 5 weeks of gestation
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Closure of the lateral growth center occurs from a few months of age to about 18 or 19 years of age, but is difficult to see on radiographs
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Closure of the medial growth center occurs around 22 to 25 years of age
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Eighty percent of the clavicle growth is completed by 9 years of age in girls and 12 years of age in boys
Locations of clavicle fractures:
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The junction of the middle and lateral thirds accounts for 90% of midshaft fractures
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The lateral third is the next most common, with 10% to 25%
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Acromioclavicular (AC) separations are suspected, but AC dislocations are rare in children, with physeal injury being more common
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The medial third of the clavicle is the location in 2% to 3%
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As with AC separations, sternoclavicular joint injuries are rare in the pediatric population, with medial clavicle physeal fractures being more common
Displacement of the clavicle fracture has the following characteristics: proximal fragment elevated superiorly because of spasm of the sternocleidomastoid or the trapezius muscles. The mechanism of clavicle fractures includes:
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Most commonly, a direct fall onto the lateral aspect of the shoulder
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A direct blow to the clavicle (10%)
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An indirect mechanism such as a fall on an outstretched hand (5%)
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For sternoclavicular injury, an indirect force transmitted along the clavicle from a direct blow to the lateral shoulder
As stated earlier, injury to the (open) clavicular physis is more common compared with AC or sternoclavicular joint dislocations, because the costoclavicular, sternoclavicular, and coracoclavicular ligaments are stronger than the physes.
The work-up of any shoulder injury in a child should start with obtaining a good history, performing a physical examination, and initial plain films of the area of clinical suspicion. Computed tomography imaging is occasionally required for complex comminuted fractures and/or for sternoclavicular injuries.
Therapeutic Options for Shoulder Fractures
With a fracture diagnosis, treatment can be initiated based on the severity and location of the injury. For the clavicle, treatments may include:
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Physeal clavicle injuries: conservative management with sling
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Clavicle fractures less than 12 years old: conservative management with sling or figure-of-eight brace
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Surgery
Indications for surgery on the clavicle in children are relative and controversial :
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Open fractures
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Risk of skin perforation caused by skin tenting
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Fracture with shortening
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Floating shoulder injuries
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A clavicle fracture in the settling of multitrauma
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Pathologic fractures
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Cosmetic (unappealing bump with shortening or great displacement)
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Established painful nonunions and possibly comminuted fractures
Treatment options for the proximal humerus include:
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Sling immobilization, less than 11 years old, for any displacement
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Sling immobilization, more than 11 years old, with less than 50% displacement and less than 20° to 40° angulation
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However, most investigators recommend at least attempting a closed reduction in all cases
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Percutaneous pinning and closed reduction for those with displacement or angulation outside the acceptable range for age
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Open reduction and internal fixation, if closed reduction fails
Indications for surgery on the proximal humerus include :
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Irreducible fragment
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Insufficient reduction in patients near skeletal maturity
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Displaced or unstable fractures in those who do not tolerate immobilization
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Open or neurovascular lesions
In our series of patients, those found to have a fracture around the shoulder were treated with:
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Immobilization (84%)
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Physical therapy (11%)
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Surgery (5%)
Outcomes and Complications of Shoulder Fractures
Children seem to do well with proximal humerus fractures overall, but no prospective studies have been completed to date. The healing time of a fracture can vary significantly based on age, with young patients healing faster than those who are closer to skeletal maturity. The proximal humerus in particular has great remodeling potential, accounting for 80% of longitudinal growth of the humerus and allowing even severely displaced fractures to do well with conservative management. With regard to clavicle fractures, neonates can heal within weeks and teenagers may require up to 10 weeks. Operative treatment has been associated with less disability of the upper extremity, earlier union, fever nonunions, and no malunions. In adults, there is a 15% risk of nonunion in the nonoperative group compared with 2.2% in the operative group. The same rate was seen with 100% displaced pediatric fractures treated conservatively with additional findings of chronic pain and functional loss, but no prospective study has been completed on the skeletally immature clavicle to confirm these findings. Moreover, there is a report that skeletally immature individuals have a low rate of malunion and nonunion. The surgical complication rate in clavicle fractures is 8%. Complications of surgical intervention of the fractured clavicle include:
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Incisional numbness
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An aesthetically unpleasing scar
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Removal of implants
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Pain from surgical implant
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Neuroma from supraclavicular nerve laceration
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K-wire migration causing pneumothorax
With regard to the proximal humerus fracture, one of the biggest risks in children after physeal arrest seems to be nerve palsies, with the ulnar nerve most commonly affected, followed by radial and then medial nerves. All resolved within 4 months. If surgical intervention is required in young patients, it is important to avoid disturbing the periosteum so that an epiphysiodesis does not occur, resulting in iatrogenic disruption of the proximal humerus growth. A growth arrest at this location could result in a reduction in humerus length of more than 1 cm per year ( Fig. 3 ).
Overuse shoulder injuries
Introduction to Overuse Injuries
The most common overuse shoulder injury in children is Little League shoulder. This term refers to a traction physiolysis of the proximal humerus that is caused from rotational stress that occurs during overhead throwing and should be considered a Salter-Harris I fracture to the proximal humerus physis. Little League shoulder may be increasing in frequency with year-round involvement in a single sport by adolescents. There are a few reasons why the young adolescent is at particular risk for this proximal humerus overuse injury:
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Being skeletally immature, the physis is vulnerable to injury from torsional stresses.
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Young adolescents have decreased muscular development and increased joint laxity in general, which allows more mechanical issues to arise.
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The physis is particularly susceptible during rapid periods of growth such as puberty, so teenage athletes aged 11 to 16 years are most likely to sustain throwing overuse injuries.
Another type of overuse injury seen at the shoulder in children is intra-articular disorders. The causes of this type of pain can be multifactorial but can be summarized by the term internal impingement of the shoulder. Internal impingement differs from external impingement in that the shape of the acromion plays no role in the injuries sustained. Instead, the impingement results from poor shoulder mechanics (weak rotator cuff and medial scapular stabilizer strength and glenohumeral internal rotation deficits) and results in partial articular supraspinatus tendon avulsions and posterosuperior labral tears.
In the pediatric and adolescent population, the overall incidence of rotator cuff injury is low, with only small case series present in the literature. Rotator cuff tears have typically been described in individuals more than 40 years old secondary to age-related changes from reduced mechanical properties of the shoulder (ie, degeneration of tendons). However, with the increased participation in overhead throwing sports seen over the past few decades, the incidence of overuse shoulder injuries in this younger cohort has increased substantially. It has been reported that those younger than 20 years old comprise less than 1% of all rotator cuff tears in the general population with muscular imbalances that can predispose them to injury. Our study found an incidence of 8.5% isolated rotator cuff disease and 6.9% of overhead spectrum disease (such as internal impingement, which may include rotator cuff disorders) among the 613 children in our childhood shoulder pain cohort.
Sporting activity accounted for 93% of injuries considered as overhead athlete overuse injuries in our study cohort. However, sports were only identified in 43% of the rotator cuff disorders in the cohort ( Figs. 4 and 5 ). Adolescents sustain rotator cuff injuries from specific traumatic events, acute throwing events, or chronic repetitive motions such as rotator cuff tendinitis (so-called swimmer’s shoulder). Other possible causes include:
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Contact of the supraspinatus tendon with the acromion or superior glenoid, which can lead to degeneration of tendons and eventual failure.
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Avulsion of the humeral tuberosity, with the lesser tuberosity being most commonly affected.
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High tensional forces on the rotator cuff tendons, which become overloaded from a throwing motion.
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Impingement causes, such as outlet syndromes or underlying instability in general.
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Shoulder laxity eventually leading to rotator cuff tendinitis as a secondary phenomenon in overhead athletes.
