Athletes susceptible to shoulder injuries

The explosion in popularity of organized youth sports over the past few decades has led to a rise in shoulder injuries in pediatric and adolescent athletes. Throwing sports, particularly baseball, have increased the incidence of such injuries in skeletally immature individuals. Although shoulder injuries are seen much less frequently in this population than in adults, such injuries in younger patients may lead to long-term disabilities and deformities.  

Pediatric and adolescent athletic shoulder injuries have a tendency to be sport-specific and to correlate directly with the competitive level of the patient. Sports such as baseball, weight-lifting, competitive swimming, and volleyball put greater forces on the youngster's shoulder and place it under significantly greater tensile stresses than those experienced by participants in  nonthrowing sports. However, when performed properly and with gradual progression of intensity, competitive and intensive training for children and adolescents is thought to be safe and a good outlet for physical activity. It is vitally important for primary-care clinicians to understand the mechanism of injury and proper interventions for prevention of sport-specific shoulder injuries.

Adolescents and children with upper-extremity injuries (specifically shoulder injuries) comprise up to 70% of visits to the pediatric sports medicine clinics at some leading institutions. This is a staggering number when compared with data over the past 15 years, in which the percentage of visits by patients with such injuries was only 20%. Increased pressure from coaches contributes to the growing number of shoulder injuries in highly competitive athletes. This is especially true as it pertains to competitive youth baseball. (Coaches at the high school level are able to rely on three or four top pitchers to carry them through a season.) Also, many, if not all, of today's youth pitchers are using their arms at other positions on the field when they are not on the mound. Finally, athletes in all sports play on multiple teams year-round in hopes of improving their skills and attracting the attention of college coaches and professional scouts. Here we present two of the most common overuse shoulder injuries in the skeletally immature athlete.

Rotator cuff injuries

The rotator cuff, one of the most important components in the shoulder, is a network of four muscles and several tendons that form a covering around the humeral head. The cuff holds the humerus in place and enables the arm to rotate. At the other end, the muscles of the cuff (supraspinatus, infraspinatus, subscapularis, and teres minor) attach to the scapula. In general, the growth plate is more prone to injury in the skeletally immature athlete; however, several injury patterns show that tendons and ligaments are also at risk.1 And when tendinitis and subacromial impingement do occur in the pediatric population, they are usually seen in overhead athletes, such as swimmers, tennis players, gymnasts, wrestlers, and baseball players. The increase in the total number of recorded shoulder injuries among young athletes is reflected in the literature, where reports of upper-extremity injuries in overhead athletes have gone from single cases2,3 to a series of two,4,5 and now four to six.6
Symptoms of a rotator cuff tear include pain when lifting the arm, pain when lowering the arm from a raised position, and possible crepitus. The diagnosis of a rotator cuff tear or injury is made by taking a careful history and performing a physical exam of the shoulder, supplemented by diagnostic imaging. Physical exam findings include tests of the motor strength in the trapezius and rhomboid muscles as well as in the muscles of the rotator cuff itself. The supraspinatus muscle (Figures 1 and 2), which is responsible for resisting downward pressure, is tested with the shoulder abducted 90°, flexed 30°, and then maximally internally rotated. To assess the infraspinatus, use the dropping sign, which tests the power of external rotation at 0° of abduction. Place the patient's forearm in 45° of external rotation, and ask him to externally rotate his arm against your hand; the test is positive if the patient's arm falls back to 0° of external rotation. The teres minor is responsible for 45% of the power of external rotation and is tested by the hornblower's sign. Place the patient's forearm in 90° flexion with maximal external rotation, and use your other hand to judge external rotation force; if the patient is unable to externally rotate when your hand is removed, the test is positive. Finally, you can perform a drop arm test: For rotator cuff tears, this is done by having the patient abduct his arm to 90° and asking him to lower his arm to his side slowly while you apply gentle pressure; if, at approximately 30° of abduction, the patient is no longer able to gradually lower his arm and it falls to his side, this is a positive test and usually indicative of a rotator cuff tear.

Plain x-rays may be helpful (Figure 3). Additional tests that may determine the integrity of the rotator cuff include an arthrogram (x-rays utilizing dye injected into the shoulder) or an MRI scan. An MRI can usually distinguish a partial from a complete tear.

In many of these patients, the clinician can prescribe conservative, nonsurgical treatment, which includes rest and limiting overhead activity (e.g., putting a pitcher on no-pitch restriction), immobilization with a sling and/or shoulder immobilizer, nonsteroidal anti-inflammatory drugs, and physical therapy for slow progression to normal pitching activity. In addition to these noninvasive recommendations, consultation with a pediatric orthopedic surgeon may be warranted.

Thrower's shoulder

The proximal humeral growth plate, or physis, is prone to overstress from repetitive pitching motions. This overuse may lead to a fatigue/stress fracture that actually widens the physis and leads to a condition known as epiphysiolysis. Typically the patient will present with nonspecific pain that is exacerbated by throwing. This pain will be localized to the proximal humerus at the precise level of the physis. The athlete can also experience pain in the axilla or armpit. An x-ray is needed to positively identify the fracture. Plain radiographs are useful for imaging the widening of the proximal humeral physis. Obtain comparison views to avoid misreading normal physeal widening that may have some radiographic projection abnormality.

The primary-care provider can manage this condition by following strict guidelines. If a patient has pain at the proximal humerus but no radiographic evidence of physeal widening, recommend four weeks of rest with a gradual return to sports. If, however, there is definite physeal widening on radiographs, recommend that the patient refrain from throwing activities for three months.

With the return to activity, a progressive strengthening and interval throwing program should be instituted. The clinician should educate the family, coaches, trainers, and the patient on recommended pitch counts. Some advocate limiting pitchers to no more than six innings per week with three days of rest between outings, while others favor limiting players to 60-80 pitches per game and 30-40 pitches per practice. The American Sports Medicine Institute has taken all recommendations into consideration and developed guidelines for the maximum number of pitches per week per player broken down into age groups and touching on types of pitches that should be thrown (Table 1).7 These recommendations should be discussed with every pediatric or adolescent pitcher.

Indications for clinicians

Primary-care clinicians should be able to recognize the pediatric and adolescent athlete who may be at risk for shoulder injuries. As the first clinician to encounter the patient, you can help by educating the family, coaches, trainers, and athlete on the importance of monitoring pitch counts, frequency of pitching sessions, and how to decrease the amount of pitching while still allowing the patient to be active and happy.

The keys to prevention of overuse injuries include educating coaches, parents, and young athletes alike to the potential hazards associated with premature sport specialization and emphasizing the recreational value of sports. In addition, since rotator cuff injuries and impingement are patterns of injuries that occur secondary to repetitive loading and chronic overuse, guidelines regarding pitching technique, pitch counts, and frequency of pitching in baseball, as well as early recognition of these injuries, will help prevent their progression.

For a discussion of other sports-related injuries affecting adolescents, see “Treating youngsters' athletic injuries,” April 2008, also available on the Web at www.clinicaladvisor.com.

Mr. Kleposki is a pediatric orthopedic nurse practitioner in the division of orthopedic surgery at the Children's Hospital of Philadelphia. Dr. Wells is attending surgeon and assistant professor of orthopedic surgery at the University of Pennsylvania School of Medicine, also in Philadelphia.

References

1. Kocher MS, Waters PM, Micheli LJ. Upper extremity injuries in the paediatric athlete. Sports Med. 2000;30:117-135.

2. Battaglia TC, Barr MA, Diduch DR. Rotator cuff tear in a 13-year-old baseball player: a case report. Am J Sports Med. 2003;31:779-782.

3. Sugalski MT, Hyman JE, Ahmad CS. Avulsion fracture of the lesser tuberosity in an adolescent baseball pitcher: a case report. Am J Sports Med. 2004;32:793-796.

4. Paschal SO, Hutton KS, Weatherall PT. Isolated avulsion fracture of the lesser tuberosity of the humerus in adolescents. A report of two cases. J Bone Joint Surg Am. 1995;77:1427-1430.

5. Ross GJ, Love MB. Isolated avulsion fracture of the lesser tuberosity of the humerus: report of two cases. Radiology. 1989;172:833-834.

6. Tarkin IS, Morganti CM, Zillmer DA, et al. Rotator cuff tears in adolescent athletes. Am J Sports Med. 2005;33:596-601.

7. Lyman S, Fleisig GS, Andrews JR, Osinski ED. 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.

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