Shoulder Injuries in Pediatric Athletes




Shoulder injuries in pediatric athletes are typically caused by acute or overuse injuries. The developing structures of the shoulder lead to injury patterns that are distinct from those of adult athletes. Overuse injuries often affect the physeal structures of the proximal humerus and can lead to pain and loss of sports participation. Shoulder instability is common in pediatric athletes, and recurrence is also a concern in this population. Fractures of the proximal humerus and clavicle are typically treated with conservative management, but there is a trend toward surgical intervention.


Key points








  • Shoulder injuries in pediatric athletes may be acute injuries or caused by repetitive overuse.



  • Acute injuries in skeletally immature shoulders tend to be fractures or sprains, as opposed to tendon or muscle injuries.



  • Chronic overuse injuries tend to occur in overhead athletes. Baseball pitchers who have high pitch counts are at highest risk.






Introduction


As the number of children and adolescents participating in competitive sports has increased, especially in overhead activities, there has been a corresponding increase in the number of injuries to the shoulder. Skeletally immature athletes present with many of the same complaints as more mature athletes, but differences in anatomy and technique often lead to age-specific injuries. Although traumatic injuries, such as sprains or fractures, are common across the spectrum of competitive activities, overuse injuries predominate.


Overuse injuries in young athletes are typically caused by repeated stress and cumulative trauma to the developing physis of the proximal humerus as well as adaptive changes in the soft tissue stabilizers of the glenohumeral joint. Physeal injuries are usually diagnosed by history and physical examination and may be confirmed on radiographs. Soft tissue injuries such as SLAP (superior labrum anterior and posterior) lesions, glenohumeral instability, and rotator cuff disorders may be more difficult to diagnose definitively.


Traumatic injuries to the skeletally immature shoulder may occur with any activity, but are more common with high-energy collision sports such as football. Traumatic injuries include ligament sprains, muscle strains, fractures of the humerus, and fractures of the clavicle. Knowing the anatomic differences of the developing osseous structures of the shoulder girdle is key in diagnosis and management.


Anatomy


During growth, the anatomy of the proximal humerus osseous and ligamentous structures undergoes multiple changes. The proximal humeral physis typically closes at between 14 and 17 years in girls and 16 to 18 years in boys. This physis also contributes about 80% of the overall humeral length, making an injury to this area at a young age possibly more consequential but also allowing extensive remodeling of acute fractures.


Any activity that involves stress of the physis, such as overhead throwing or repetitive upper extremity activities, puts the physis at risk of injury. Injuries vary from chronic stress reaction caused by overuse to acute fracture of the physis. The physis is thought to be a weak point of the upper arm compared with the ligamentous structures. The ligaments of the glenohumeral joint provide static stability depending on the position of the arm. The rotator cuff muscles, scapular stabilizers, and long head of the biceps also contribute to dynamic stability of the shoulder.


The clavicle is the first bone in the body to start the ossification process via intramembranous ossification. It shows both intramembranous and endochondral types of ossification. The lateral clavicular epiphysis typically does not ossify until 18 years of age. The medial clavicular epiphysis is the last to appear, at approximately 18 to 20 years of age, and does not fuse until 23 to 25 years of age, making the clavicle the last bone in the body to completely fuse. Strong ligaments provide significant stability at the medial and lateral ends of the clavicle, thereby making fractures in the middle of the clavicle more likely.




Introduction


As the number of children and adolescents participating in competitive sports has increased, especially in overhead activities, there has been a corresponding increase in the number of injuries to the shoulder. Skeletally immature athletes present with many of the same complaints as more mature athletes, but differences in anatomy and technique often lead to age-specific injuries. Although traumatic injuries, such as sprains or fractures, are common across the spectrum of competitive activities, overuse injuries predominate.


Overuse injuries in young athletes are typically caused by repeated stress and cumulative trauma to the developing physis of the proximal humerus as well as adaptive changes in the soft tissue stabilizers of the glenohumeral joint. Physeal injuries are usually diagnosed by history and physical examination and may be confirmed on radiographs. Soft tissue injuries such as SLAP (superior labrum anterior and posterior) lesions, glenohumeral instability, and rotator cuff disorders may be more difficult to diagnose definitively.


Traumatic injuries to the skeletally immature shoulder may occur with any activity, but are more common with high-energy collision sports such as football. Traumatic injuries include ligament sprains, muscle strains, fractures of the humerus, and fractures of the clavicle. Knowing the anatomic differences of the developing osseous structures of the shoulder girdle is key in diagnosis and management.


Anatomy


During growth, the anatomy of the proximal humerus osseous and ligamentous structures undergoes multiple changes. The proximal humeral physis typically closes at between 14 and 17 years in girls and 16 to 18 years in boys. This physis also contributes about 80% of the overall humeral length, making an injury to this area at a young age possibly more consequential but also allowing extensive remodeling of acute fractures.


Any activity that involves stress of the physis, such as overhead throwing or repetitive upper extremity activities, puts the physis at risk of injury. Injuries vary from chronic stress reaction caused by overuse to acute fracture of the physis. The physis is thought to be a weak point of the upper arm compared with the ligamentous structures. The ligaments of the glenohumeral joint provide static stability depending on the position of the arm. The rotator cuff muscles, scapular stabilizers, and long head of the biceps also contribute to dynamic stability of the shoulder.


The clavicle is the first bone in the body to start the ossification process via intramembranous ossification. It shows both intramembranous and endochondral types of ossification. The lateral clavicular epiphysis typically does not ossify until 18 years of age. The medial clavicular epiphysis is the last to appear, at approximately 18 to 20 years of age, and does not fuse until 23 to 25 years of age, making the clavicle the last bone in the body to completely fuse. Strong ligaments provide significant stability at the medial and lateral ends of the clavicle, thereby making fractures in the middle of the clavicle more likely.




Overuse injuries


Introduction


Pediatric or adolescent athletes involved in repetitive overhead activities, such as baseball, swimming, or volleyball, are at risk for overuse injuries to the shoulder. Overuse injuries are very common, comprising approximately 60% of all sports injuries in children and adolescents. Female athletes typically present more often with overuse injuries, but male athletes participating in certain demanding team sports, such as baseball, are at highest risk. It is estimated that 50% of overuse injuries in physically active children and adolescents may be preventable. Volume of activity, whether measured in number of repetitions or quantity of time, may be the greatest predictor of overuse injury. Shoulder pain, fatigue, and/or decreased velocity should be an indication to coaches and parents that an overuse injury may exist. Educating players, coaches, and trainers about these symptoms may help identify overuse injuries early.


Baseball in particular has been the focus of extensive research with regard to pediatric shoulder injuries. Seasonal incidence of shoulder pain ranges from 32% to 35%, with nearly 9% of all pitching performances resulting in shoulder symptoms. The incidence of injury for pitchers was found to be 37.4%, whereas it was only 15.3% for position players. Overall, pitchers experienced 47.1% of all shoulder injuries in baseball. In a study of youth baseball players by Olsen and colleagues, athletes who underwent surgery for shoulder or elbow injuries caused by pitching were more likely to have increased number of pitches thrown per inning and per game, more likely to pitch with pain, and pitched with higher velocity. There was no significant difference between injured and uninjured athletes with regard to injury prevention programs, types of pitches thrown, or private pitching instruction.


The role of specific types of pitches on shoulder pain incidence is inconclusive. Although some data exist that show higher levels of injury in curveball throwing, other studies have found higher mechanical demands with fastball throwing. In general, many of the issues of the throwing shoulder are rooted in poor biomechanics, scapular dyskinesis, muscular imbalance, glenohumeral internal rotation deficit, and excessive throwing or overhead activity.


Biomechanics of Throwing


The mechanism of baseball throwing is a complicated process involving the coordination of the upper and lower extremities as well as core musculature. Throwing is typically divided into 6 phases: wind-up, early cocking, late cocking, acceleration, deceleration, and follow-through ( Fig. 1 ).




Fig. 1


Phases of throwing.

( Adapted from DiGiovine NM, Jobe FW, Pink M, et al. An electromyographic analysis of the upper extremity in pitching. J Shoulder Elbow Surg 1992;1:16; with permission.)


During the late cocking phase, the arm is in an abducted and externally rotated position, creating an anteriorly directed force of the humeral head. This force is then counterbalanced by the static and dynamic stabilizers of the glenohumeral joint. During the acceleration portion of throwing, the arm moves at speeds of several thousand degrees per second, creating a large rotational force at the proximal humerus, often several times greater than the rotational strength of the proximal humeral physis.


Youth pitchers show several changes compared with mature pitchers. Younger pitchers tend to begin trunk rotation earlier in the throwing process. There is also a trend toward more open pelvic position during throwing. Both of these mechanisms have been proposed to increase the likelihood of injury to the developing physis because of higher rotational stress at the proximal humerus.




Little League shoulder and overuse syndromes


Shoulder overuse injuries are most common in boys aged 11 to 16 years. The most common age of presentation is 14 years in boys. In adolescents, the most common causes of shoulder pain from overhead activities are Little Leaguer’s shoulder, glenohumeral instability, and rotator cuff disorders.


Skeletally immature pitchers tend to develop problems with developing structures of the shoulder, including the proximal humeral physis, which may manifest in young pitchers with Little Leaguer’s shoulder, which has been described as osteochondrosis, epiphysiolysis, and stress reaction of the proximal humerus. Vertically oriented collagen fibers within the zone of hypertrophy are most susceptible to injury. Radiographs may show physeal widening and fragmentation, often appearing similar to the presentation of Salter-Harris I fractures. Repetitive stress may lead to microfractures in this area and hypertrophy seen on radiographs ( Fig. 2 ).




Fig. 2


( A ) A 12-year-old boy with shoulder pain at the beginning of the baseball season. Radiograph of shoulder of throwing arm at presentation. White arrow shows widening of the proximal humeral physis. ( B ) Left shoulder radiograph taken for comparison at initial presentation.


Once the proximal humeral physis has closed, the static and dynamic stabilizers of the shoulder are more likely to be injured. Skeletally mature pitchers more often develop disorders in the anterior and superior glenoid labrum (SLAP lesions).


Glenohumeral internal rotation deficit is also seen in older throwers as a loss of internal rotation compared with the nonthrowing shoulder. Alterations in shoulder and scapular motion can lead to changes in the labrum, including SLAP tears. Baseball and softball pitchers who sustained injury during the season had significantly decreased internal rotation compared with age-matched peers as well as the nondominant arm. Rotator cuff disorders and impingement syndromes are also occasionally seen in overhead athletes, often related to instability.


History and Physical Examination


Patients typically present with increasing shoulder pain during throwing motions, which may progress to activity at rest. Important information to obtain includes the patient’s sport, level of competition, previous injuries, amount of time spent playing, recent increases in activity, and pitch counts.


In skeletally immature athletes with Little Leaguer’s shoulder, tenderness on palpation of the lateral proximal humerus is often seen. Scapular dysfunction may also be noted with forward flexion and abduction of both arms. Shoulder motion, flexibility, strength, and other components of the kinetic chain should also be assessed.


Skeletally mature throwers often show increased external rotation along with decreased internal rotation of the throwing arm with the shoulder in abduction. The overall arc of motion may be maintained without corresponding pain or dysfunction. Alterations in range of motion are often noted in young throwers as well, but the overall range of motion may be decreased.


Radiographs of the proximal humerus in skeletally immature throwers should be obtained. Radiographs of the contralateral shoulder often aid in confirmation. Although physeal widening on radiographs is often confirmatory in patients with shoulder pain, many asymptomatic throwers also show widening. It is hypothesized that physeal widening may also be caused by adaptive changes within the proximal humerus. Advanced imaging is typically reserved for patients with anterior instability or for refractory cases.


Treatment


Prevention of overuse injuries should be the goal of all athletes, coaches, and parents. Off-season condition focusing on pitching mechanics and strengthening of the kinetic chain is recommended. Monitoring players for pain during or after activities may alert coaches and parents that an overuse injury may be developing. Pitching limits should be established for players 9 to 14 years old: full-effort throwing should be limited to 75 pitches per game, 600 pitches per season, and 2000 to 3000 pitches per year. Little League Baseball, with recommendations from the American Sports Medicine Institute, has instituted specific guidelines for pitch counts ( Table 1 ) and for required days of rest ( Table 2 ). Of note, pitchers who have pitched more than 41 pitches in a game are not permitted to switch positions to catcher.



Table 1

Pitch counts for Little League Baseball






















Player Age (y) Pitches Permitted Per Day
17–18 105
13–16 95
11–12 85
9–10 75
7–8 50

Data from Little League Baseball, Incorporated. The Little League pitch count regulation guide. 2008. Available at: http://www.littleleague.org/assets/old_assets/media/pitch_count_publication_2008.pdf . Accessed November 28, 2015.


Table 2

Days of rest required after pitching








































Player Age (y) Pitches Thrown Per Day Days of Rest Required
≤14 ≥66 4
51–65 3
36–50 2
21–35 1
≤20 0
15–18 ≥76 4
61–75 3
46–60 2
31–45 1
≤30 0

Data from Little League Baseball, Incorporated. The Little League pitch count regulation guide. 2008. Available at: http://www.littleleague.org/assets/old_assets/media/pitch_count_publication_2008.pdf . Accessed November 28, 2015.


The mainstay of treatment is rest from all throwing activities. Treatment algorithms vary, but most include a period of absolute rest from throwing, then gradual return to activities. Nonsteroidal antiinflammatory medication may also help with pain and inflammation during recovery. Strengthening exercises focusing on the rotator cuff musculature, core strengthening, and pitching mechanics are emphasized. Stretching exercises focusing on abduction and internal rotation are also recommended. Most athletes are able to return to baseball in 3 months.


For patients with SLAP lesions, a short period of physical therapy and rest may help to resolve symptoms. However, when there is continued pain and MRI consistent with labral injury, surgical repair may be indicated ( Fig. 3 ).




Fig. 3


( A ) SLAP tear in 12-year-old baseball pitcher. ( B ) Labrum repaired with 2 suture anchors.




Anterior instability


Anterior shoulder instability is a common problem in adolescent athletes, comprising 85% to 95% of all shoulder instability. Incidence is reported to be 11.2 occurrences per 100,000 person-years. Younger male athletes are at particularly high risk, because nearly 40% of shoulder instability events occur in males athletes younger than 22 years. The presence of an open physis seems to be slightly protective for anterior dislocation, with a lower percentage occurring in children younger than 13 years, likely secondary to Salter-Harris fractures occurring through the proximal humeral physis rather than glenohumeral dislocation. Athletes participating in contact or collision sports are also at highest risk.


Although the rates of initial anterior shoulder instability episodes are high in adolescents, perhaps more significant is the rate of recurrence. The rate of recurrence has been found to be 51% to 100%. In a study by Lawton and colleagues, of 70 shoulder dislocations in 66 patients aged 16 years or younger, 40% eventually underwent surgery. Those who underwent surgery were less likely to report continued instability at more than 2 years’ follow-up compared with those treated with physical therapy alone.


A classic study by Rowe of 500 shoulder dislocations found a high rate of initial dislocation in patients between 10 and 20 years old. The recurrence rate of instability in this group was 83%, with a 100% rate in patients less than 10 years old. A report of 9 children with open physes and shoulder dislocation found a recurrence rate of 80%.


History and Physical Examination


A history of traumatic dislocation from a single event is common in patients involved in contact or collision sports. Any reduction maneuvers performed, whether on field or in an acute care setting, should be documented. A history of pain or paresthesias with overhead activities, especially with the arm in external rotation and abduction, may be present without a frank dislocation episode. Pain with the arm in adduction and internal rotation may indicate posterior instability. This condition may be seen in football linemen during blocking or pushing against a heavy object.


Initial physical examination should include a complete neurovascular examination of both extremities. Nerve dysfunction has been seen in 5% to 25% of shoulder fractures and dislocations, most commonly axillary nerve injuries. Patients should be examined for loss of motion, both active and passive. Examination should include both shoulders to evaluate for differences of range of motion, scapular motion, muscle atrophy, swelling, or bruising.


Specific shoulder tests to be performed include the anterior apprehension test, Jobe relocation test, anterior and posterior drawer test, and sulcus test. The anterior apprehension test is performed by having the patient lay supine on the examination table and slowly abducting and externally rotating the arm. Feelings of pain or instability are suggestive of anterior instability. The Jobe relocation test is then performed with the arm kept in the abducted and externally rotated position and applying a posterior-directed force on the humeral head. This test is positive if pain or feelings of instability resolve. Drawer testing is performed by placing the arm in line with the scapula and evaluating the amount of humeral head translation with force applied to the proximal humerus. Laxity is defined as grade 1 to 3 translation based on the amount of motion of the humeral head on the glenoid.


Imaging should begin with standard shoulder radiographs, including internal rotation, external rotation, and either axillary or scapular Y views. More specific imaging may include West Point view for anterior glenoid deficits or Stryker notch views for Hill-Sachs lesions. MRI with arthrography is recommended for imaging of the glenoid labrum, glenoid surface, and rotator cuff. Bankart and Hill-Sachs lesions have been noted in most first-time dislocations, with a smaller number of SLAP lesions ( Fig. 4 A, B). Glenoid bone loss is common in adolescents and is a risk factor for recurrence. Computed tomography (CT) may be performed to further delineate bone loss of the humeral head or glenoid.


Oct 6, 2017 | Posted by in ORTHOPEDIC | Comments Off on Shoulder Injuries in Pediatric Athletes

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