Pediatric Annals

Feature 

Evaluation of Shoulder Injuries in the Youth Athlete

Brian J. Krabak, MD, MBA

Abstract

Shoulder pain in the adolescent population is quite different from the adult population. The difference relates to the immature bone structure of the shoulder region. Specific shoulder injuries in the adolescent athlete will vary from sports to sport. Athletes who use frequent overhead motion, such as in baseball, tennis, and swimming, most commonly experience such pain.

Lyman and colleagues1 reported that 26 to 35 per 100 youth baseball pitchers experience a shoulder injury during the course of a season. Also, 30% of pitchers experienced shoulder pain after a specific game.1 In adolescent elite national tennis players (boys 16 to 18 years old and girls 16 years old) 20% to 45% of all injuries are located in the upper extremity.2 Of these athletes, 25% to 30% had previous or current shoulder pain. Studies of competitive swimmers have revealed that the shoulder is the most frequently injured joint, ranging from 12% to 87% of all swimmers.3

Potential risk factors for subsequent injury will depend upon the exact sport. In the throwing athlete, risk factors include the number of pitches thrown in a game, the type of pitches, and the number of months pitched in a year.2,4 These findings have led to recommendations such as limiting the pitch count per game, days of rest, limitation in the use of curve balls and sliders, and pitching for less than 8 months in a 1-year period to avoid injury.5 Other studies have started looking at the differences in pitching kinematics and kinetics in adolescent throwers compared to adults to identify biomechanical factors that may contribute to overuse and fatigue.6

Understanding the anatomy in skeletally immature adolescents provides greater insight into typical adolescent shoulder and elbow injuries. The major differences between the skeletally immature versus mature shoulder relate to the epiphyseal plates of the shoulder/elbow and collagen composition of the supporting ligaments and tendons. The epiphyseal plate is where future bone is laid down and constantly changes during the growth years. They do not completely ossify until the late teens depending upon the specific anatomical site (eg, the lateral epicondyle at age 14 to 16 years; the medial epicondyle at 14 to 16 years; the proximal humerus at 17 to 18 years; the glenoid at 16 to 18 years; and the clavicle at 18 to 20 years).7 Additionally, the amount of type-III collagen (the major protein of ligaments and tendons) produced in adolescents is significantly greater than in adults, potentially leading to excessive laxity in the shoulder capsule and ligaments.8 It has been proposed that the combination of weaker epiphyseal plates and excessive laxity of the supporting structures in the setting of significant forces to the shoulder and elbow region during sport may predispose the young athlete to shoulder or elbow injury.8

Injuries relating to the stability of the shoulder can be divided into unilateral and multidirectional instability. Unilateral injuries are usually traumatic in nature and are commonly anterior (90% to 95%) vs. posterior (5%) dislocations.9 The dislocations occur after a high-energy injury involving a fall on the outstretched hand while the shoulder is in abduction and external rotation (anterior dislocation) or adduction and internal rotation (posterior dislocation).9 The axillary nerve is the most commonly injured structure and has been reported in 5% to 35% of traumatic anterior shoulder dislocations. In contrast, multidirectional instability does not typically involve trauma but occurs from overuse. These athletes will typically exhibit generalized joint laxity and is especially prominent in gymnasts and swimmers.10

The clinical presentation will vary depending upon the type of dislocation. For traumatic unilateral dislocations, the athletes will present with an obvious deformity. In anterior dislocations, the…

Shoulder pain in the adolescent population is quite different from the adult population. The difference relates to the immature bone structure of the shoulder region. Specific shoulder injuries in the adolescent athlete will vary from sports to sport. Athletes who use frequent overhead motion, such as in baseball, tennis, and swimming, most commonly experience such pain.

Lyman and colleagues1 reported that 26 to 35 per 100 youth baseball pitchers experience a shoulder injury during the course of a season. Also, 30% of pitchers experienced shoulder pain after a specific game.1 In adolescent elite national tennis players (boys 16 to 18 years old and girls 16 years old) 20% to 45% of all injuries are located in the upper extremity.2 Of these athletes, 25% to 30% had previous or current shoulder pain. Studies of competitive swimmers have revealed that the shoulder is the most frequently injured joint, ranging from 12% to 87% of all swimmers.3

Potential risk factors for subsequent injury will depend upon the exact sport. In the throwing athlete, risk factors include the number of pitches thrown in a game, the type of pitches, and the number of months pitched in a year.2,4 These findings have led to recommendations such as limiting the pitch count per game, days of rest, limitation in the use of curve balls and sliders, and pitching for less than 8 months in a 1-year period to avoid injury.5 Other studies have started looking at the differences in pitching kinematics and kinetics in adolescent throwers compared to adults to identify biomechanical factors that may contribute to overuse and fatigue.6

Adolescent Shoulder Anatomy

Understanding the anatomy in skeletally immature adolescents provides greater insight into typical adolescent shoulder and elbow injuries. The major differences between the skeletally immature versus mature shoulder relate to the epiphyseal plates of the shoulder/elbow and collagen composition of the supporting ligaments and tendons. The epiphyseal plate is where future bone is laid down and constantly changes during the growth years. They do not completely ossify until the late teens depending upon the specific anatomical site (eg, the lateral epicondyle at age 14 to 16 years; the medial epicondyle at 14 to 16 years; the proximal humerus at 17 to 18 years; the glenoid at 16 to 18 years; and the clavicle at 18 to 20 years).7 Additionally, the amount of type-III collagen (the major protein of ligaments and tendons) produced in adolescents is significantly greater than in adults, potentially leading to excessive laxity in the shoulder capsule and ligaments.8 It has been proposed that the combination of weaker epiphyseal plates and excessive laxity of the supporting structures in the setting of significant forces to the shoulder and elbow region during sport may predispose the young athlete to shoulder or elbow injury.8

Shoulder Injuries

Instability/Dislocation

Injuries relating to the stability of the shoulder can be divided into unilateral and multidirectional instability. Unilateral injuries are usually traumatic in nature and are commonly anterior (90% to 95%) vs. posterior (5%) dislocations.9 The dislocations occur after a high-energy injury involving a fall on the outstretched hand while the shoulder is in abduction and external rotation (anterior dislocation) or adduction and internal rotation (posterior dislocation).9 The axillary nerve is the most commonly injured structure and has been reported in 5% to 35% of traumatic anterior shoulder dislocations. In contrast, multidirectional instability does not typically involve trauma but occurs from overuse. These athletes will typically exhibit generalized joint laxity and is especially prominent in gymnasts and swimmers.10

Presentation

The clinical presentation will vary depending upon the type of dislocation. For traumatic unilateral dislocations, the athletes will present with an obvious deformity. In anterior dislocations, the humeral head may be visible anteriorly, the acromion may be prominent, and the arm will be held in internal rotation. In posterior dislocations, the athlete will exhibit loss of external rotation and along with prominence of the humeral head posteriorly.8 In both cases, the athlete may report a “dead arm” due to a transient loss of sensation and/or numbness in the involved extremity.

Upon physical examination, the athlete will note apprehension with attempted anterior or posterior displacement of the humeral head. In multidirectional instability, the athlete will complain of non-specific shoulder pain and a feeling of shoulder subluxation or dislocation with overhead activities. Upon physical examination, he or she will have evidence of generalized ligamentous laxity (ie, hyperextension at the elbows, the ability to approximate the thumbs to the forearms, and hyperextension of the metacarpophalangeal joints), positive apprehension signs, and a positive sulcus sign indicative of inferior instability.10 In all cases, athletes experience strength deficits relating to the scapular stabilizers and rotator cuff muscles.

Diagnostic Imaging

The diagnosis of shoulder instability is based on the patient’s history, physical examination, and radiographic findings. Diagnostic imaging is necessary to evaluate the integrity of the glenohumeral joint and should be performed in multiple planes to properly assess for any dislocation and any concurrent fractures. Typical views include an anteroposterior view with the shoulder in internal and external rotation, an axillary or modified axillary view, and the scapular Y-view.8 In unilateral dislocations, radiographs will reveal an anteriorly or posteriorly displaced humeral head and/or Hill-Sachs lesion (impaction of the posterior humeral head due to an anterior dislocation). In multidirectional instability, no abnormalities may be noted. Magnetic resonance imaging (MRI) may be helpful in evaluating the integrity of labrum or rotator cuff muscles. In anterior dislocation, the humeral head and joint capsule may tear the labrum from the rim of the glenoid, leading to a Bankart lesion. Unfortunately, evidence of a Hill-Sachs lesion carries a worse prognosis for anterior instability secondary to the decreased bony support.9

Treatment

The treatment of shoulder instability/dislocation will vary depending upon the type of injury. The initial treatment of an anterior dislocation involves closed reduction without or with anesthesia. Following reduction, the arm should be immobilized for 2 to 4 weeks in a sling with gradual range of motion and strengthening exercises as tolerated.9,11 Some authors advocate immobilizing the shoulder in external rotation, although it is unclear if this truly lowers the dislocation recurrence rate.12 Surgical treatment is typically recommended due to the high recurrence rate of instability in young athletes and high incidence of Bankart lesions. Initial posterior dislocations and multidirectional instability usually respond to conservative treatment with physical therapy for rehabilitation, unless a specific anatomic lesion is noted.9,10,13

As most athletes with multidirectional instability have hyperlaxity, stretching of the shoulder joint is typically not necessary. Strengthening exercises should initially focus on isometric to isotonic exercises for the scapular stabilizers (the serratus anterior, and pectoralis and latissimus dorsi muscles) and rotator cuff muscles.13 The exercises then progress to more integrative and functional activities specific to the athlete’s sport. Most of the patients who respond favorably to conservative treatment show a positive response within 3 months of beginning a rehabilitation program.14 Patients who have recurrent posterior dislocations or fail conservative treatment resulting in impairment of daily activities or sports should be referred to a surgeon.

Proximal Humeral Epiphysiolysis

In a skeletally immature athlete, the repetitive stress of throwing can lead to injury involving the proximal humeral epiphysis.7,15 This condition typically occurs between the ages of 11 and 15 years. Baseball has primarily been the focus of studies looking at this phenomenon; however, it can also be seen in sports such as volleyball, swimming, and badminton.16 The exact mechanism of physis injury has yet to be determined; however, it is thought to resemble a Salter Harris type 1 fracture with separation of the metaphysic from the epiphysis.

Some investigators have postulated that chronic stress injury leads to an alteration in the endochondral ossification center. Others postulate that overtraining and/or improper biomechanics in upper extremity dominant sports lead to torsional overload of the proximal humeral epiphysis, especially during maximal shoulder external rotation. Taylor noted continued widening of the proximal humeral physis even after symptoms resolved.15

Presentation

Athletes will typically describe pain in the shoulder region that is worsened with activity and improves with rest. They may note an abrupt increase in activity such as more pitching, learning a new throwing skill, or an increase in swimming yardage without rest recovery. Baseball pitchers will note pain throughout the pitching motion and swimmers will describe pain throughout all phases of swimming. Upon examination, palpation reveals pain along the proximal and lateral aspect of the humerus. Swelling, weakness, atrophy, and loss of motion are uncommon findings.15 Passive range of motion may be full and pain free. Resistance strength testing in a functional/overhead position or while inducing torque within the humerus generally reproduces the pain.

Diagnostic Imaging

Radiologic work-up including radiographs and MRI can be helpful to visualize the extent of injury. Radiographs including anteroposterior comparison views of the proximal humerus in internal and external rotation are the best views to assess the growth plate. Images will show widening of the physis at the lateral aspect of the proximal humerus in the acute setting and lateral fragmentation, calcification, sclerosis, and cysts in the chronic setting. MRI will show increased signal involving the growth plate on T2 views, with possible widening in the acute setting.

Treatment

Treatment is non-operative, focusing on a significant period of rest and recovery that can take between 6 to 8 months. Unfortunately, there are no rigorous studies to define the most efficient method of treatment and time until return to play. Initial treatment should focus on eliminating any painful activities while allowing the athlete to maintain cardiovascular fitness through cross training.

Physical therapy may be helpful after a period of rest, focusing on the correction of flexibility and strength deficits that may have contributed to the injury. The athlete’s training program should be reviewed to indentify factors that may have contributed to the injury (ie, pitching/swimming biomechanics, dry-land training exercises, and days of rest). Physical therapy can progress to functional sport-specific exercises prior to any discussions regarding return to play. As radiographic evidence of physis closure can take several months, it is typically not used as a marker of when to return to the offending activities. Once a patient can perform functional overhead activities in a pain-free manner, they are gradually allowed to return to play. Wasserlauf and Paletta17 recommend elimination of throwing for a minimum of 6 weeks after diagnosis and no throwing for an additional 6 weeks during the strengthening phase of rehabilitation, for a total of at least 3 months of rest from throwing. All goals should be clearly outlined and coordinated through the athlete, parents, therapists, and coaches to allow a safe return to play.

Rotator Cuff Injuries

Although common in the adult athlete, rotator cuff injuries are much less common in the adolescent athlete. In adults, rotator cuff injuries have been attributed to primary impingement with wearing of the outer-surface (bursal side) of the rotator cuff from tensile overload or secondary impingement from underlying instability.18

In the youth athlete, research has shown that rotator cuff dysfunction is often due to under-surface (articular side) tears from overuse. Specifically, it is hypothesized that excessive tightness of the posterior shoulder capsule and/or overlying musculature combined with inappropriate biomechanics lead to the inappropriate contact of the rotator cuff tendons. The posterior region of the supraspinatus and superior aspect of the infraspinatus tendon impinge with the posterior glenoid rim, resulting in a partial-thickness tearing of the under-surface of these tendons and/fraying of the posterior superior glenoid labrum.

Presentation

Evaluation of adolescent shoulder injuries should include a detailed history and examination of the shoulder and spine complex. Athletes in throwing sports will complain of pain and weakness during the arm cocking, acceleration, and/or follow-through phases of motion.1,5,17 They may report decreased velocity and/or precision. Swimmers may complain of pain on the pull-through or recovery phase of the swim stroke. Athletes often describe subacromial pain being worsened with overhead activities, but they do not report radiation of the pain into the hand or numbness. Upon physical examination there will be pain with abduction/internal rotation of the shoulder and weakness with testing of the supraspinatus and infraspinatus muscles. Impingement signs (eg, Hawkins and Neer) will reproduce pain. The athlete will exhibit scapular dyskinesis with motion and may have loss of shoulder internal rotation. Itoi and colleagues19 found that in most patients with rotator cuff tears, lack of strength of a specific muscle but not location of pain was a more reliable indicator of a specific rotator cuff injury. The physician should evaluate the spine to assess for any core inflexibilities or strength deficits that might be contributing to overuse of the shoulder.

Diagnostic Imaging

Diagnostic imaging of the rotator cuff may vary depending upon the availability of resources. Both MRI and ultrasound are the primary imaging modalities to visualize the rotator cuff. Studies suggest both MRI and ultrasound are highly accurate for diagnosing full-thickness tears, showing similar accuracy (95%–96%) and specificity (85%–91%).20 However, they are less accurate in detecting partial-thickness tears (80%–93%). MRI may offer an advantage of greater visualization of other structures in the shoulder region but it costs more than ultrasound. Ultrasound can provide better visualization of the soft tissue structure of the shoulder, especially with dynamic movement, but is dependent upon the expertise of the individual performing and interpreting the study.

Treatment

Treatment of rotator cuff pathology will depend upon the severity of the tear. In general, adolescent athletes can be treated conservatively with cessation of the aggravating injury and a focused therapy program. Rehabilitation includes rotator cuff and scapular stabilizer strengthening, re-establishing proper mechanics of the shoulder and spine, and restoring range of motion. The motions should then be integrated into a functional program based on the sport-specific needs. Return to competition may be allowed after completion of a functional, progressive, and individualized throwing program without further symptoms.21 In the throwing athlete, care should be taken to review the pitch count, types of pitches, and amount of rest between pitching (Table), as these have been shown to increase the risk of shoulder injury.1,5 A throwing program emphasizing proper mechanics over a period 1 to 3 months, depending on the severity of the injury, may be initiated once pain-free motion and strength have been achieved.

Little League Baseball Pitch Count Regulations

Table. Little League Baseball Pitch Count Regulations

Conclusion

Shoulder injuries are relatively common in the youth athlete and will vary depending upon the specific sports. Fortunately, the majority of injuries can be managed conservatively with a successful return to play. Several specific injuries should prompt a surgical referral in hopes of avoiding long term consequences. It is important to emphasize a gradual return-to -play program and not treat the youth athlete the same as an adult athlete. With proper treatment and supervision, youth athletes should be able to continue participation in sports, emphasizing a healthy lifestyle incorporating exercise.

References

  1. Lyman S, Fleisig GS, Andrews JR, et al. Effect of pitch type, pitch count, and pitching mechanics on risk of elbow and shoulder pain in youth baseball pitchers. Am J Sports Med. 2002;30:463–468.
  2. Kibler WB, Safran MR. Musculoskeleteal injuries in the young tennis player. Clin Sports Med. 2000;19(4):781–792. doi:10.1016/S0278-5919(05)70237-4 [CrossRef]
  3. Stavrianeas S. Aquatics. In: Caine DJ, Harmer PA, Schiff MA, eds. Epidemiology of Injury in Olympic Sports. West Sussex, UK: Blackwell Publishing; 2009:3–17.
  4. Kocher MS, Walters PM, Micheli LJ. Upper extremity injuries in the paediatric athlete. Sports Med. 2000;30(2):117–135. doi:10.2165/00007256-200030020-00005 [CrossRef]
  5. Olsen SJ 2nd, Fleisig GS, Dun S, Loftice J, Andrew JR. Risk factors for shoulder and elbow injuries in adolescent baseball pitchers. Am J Sports Med. 2006;34(6):905–912. doi:10.1177/0363546505284188 [CrossRef]
  6. Nissen CW, Westwell M, Ounpus S, et al. Adolescent baseball pitching technique: a detailed three-dimensional biomechanical analysis. Med Sci Sports Exerc. 2007;39(8):1347–1357. doi:10.1249/mss.0b013e318064c88e [CrossRef]
  7. Sabick MB, Kim YK, Torry MR, Keirns MA, Hawkins RJ. Biomechanics of the shoulder in youth baseball pitchers: implications for the development of proximal humeral epiphysiolysis and humeral retrotorsion. Am J Sports Med2005;33:1716–1722. doi:10.1177/0363546505275347 [CrossRef]
  8. Walton J, Paxinos A, Tzannes A, Callanan M, Hayes K, Murrell GA. The unstable shoulder in the adolescent athlete. Am J Sports Med2002;30:758–767.
  9. Good CR, MacGillivray JD. Traumatic shoulder dislocation in the adolescent athlete: advances in surgical treatment. Cur Opin Pediatr2005;17:25–29. doi:10.1097/01.mop.0000147905.92602.bb [CrossRef]
  10. Cordasco FA. Understanding Multidirectional Instability of the Shoulder. J Athl Train. 2000;35:278–285.
  11. Patterson PD, Waters PM: Shoulder injuries in the child athlete. Clin Sports Med. 2000;19(4):681–692. doi:10.1016/S0278-5919(05)70232-5 [CrossRef]
  12. Tanaka Y, Okamura K, Imai T. Effectiveness of external rotation immobilization in highly active young men with traumatic primary anterior shoulder dislocation or subluxation. Orthopedics. 2010;33(9):670.
  13. Kibler WB, Rubin RD. Fundamental principles of shoulder rehabilitation: conservative to postoperative management. Arthroscopy. 2002;18:29–39.
  14. Misamore GW, Sallay PI. A longitudinal study of patients with multidirectional instability of the shoulder with seven- to ten-year follow-up. J Shoulder Elbow Surg. 2005;14(5):466–470. doi:10.1016/j.jse.2004.11.006 [CrossRef]
  15. Taylor DC, Krasinkski KL. Adolescent Shoulder Injuries: Consensus and Controversies. J Bone Joint Surg Am. 2009;91:462–473.
  16. Caine D, DiFiori J, Maffulli N. Physeal injuries in children’s and youth sports: reasons for concern?Br J Sports Med2006;40:749–760. doi:10.1136/bjsm.2005.017822 [CrossRef]
  17. Wasserlauf BL, Paletta GA Jr, . Shoulder disorders in the skeletally immature throwing athlete. Orthop Clin North Am. 2003;34:427–437. doi:10.1016/S0030-5898(03)00032-4 [CrossRef]
  18. Rizio L, Uribe JW. Overuse injuries of the upper extremity in baseball. Clin Sports Med2001;20:453–468. doi:10.1016/S0278-5919(05)70262-3 [CrossRef]
  19. Itoi E, Minagawa H, Yamamoto N, Seki N, Abe H. Are pain location and physical examinations useful in locating a tear site of the rotator cuff?Am J Sports Med2006;34:256–264. doi:10.1177/0363546505280430 [CrossRef]
  20. Teefey SA, Petersen B, Prather H. Shoulder ultrasound vs MRI for rotator cuff pathology. PM R. 2009;1(5):490–495. doi:10.1016/j.pmrj.2009.03.013 [CrossRef]
  21. Axe M, Hurd W, Snyder-Mackler L. Data-based interval throwing programs for baseball players. Sports Health. 2009;1:145–153.

Little League Baseball Pitch Count Regulations

Age Limits Per Game Rest Requirements
17–18 years 105/day 76 or more pitches ➔ 4 days rest 61–75 pitches ➔ 3 days rest 46–60 pitches ➔ 2 days rest 31–45 pitches ➔ 1 day rest 01–20 pitches ➔ 0 days rest
15–16 years 95/day
13–14 years 95/day 66 or more pitches ➔ 4 days rest 51–65 pitches ➔ 3 days rest 36–50 pitches ➔ 2 days rest 21–35 pitches ➔ 1 day rest 01–20 pitchers ➔ 0 days rest
11–12 years 85/day
9–10 years 75/day
7–8 years 50/day
Authors

Brian J. Krabak, MD, MBA, is Clinical Associate Professor, Department of Rehabilitation, Orthopedic and Sports Medicine, University of Washington and Seattle Children’s Sports Medicine, Seattle, WA; Team Physician, University of Washington and Seattle University; Team Physician, USA Swimming; and Medical Director, Racing ThePlanet Ultramarathons.

Disclosure: Dr. Krabak has disclosed no relevant financial relationships.

Address correspondence to: Brian J. Krabak, MD, MBA, 4245 Roosevelt Way NE, Seattle, WA 98105; fax: 206-598-9344; email: bkrabak@uw.edu

10.3928/00904481-20120525-12

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