Although epiphysiolysis of the proximal humerus occurs primarily in young baseball players, it has also been reported in cricket (fast bowlers), volleyball, swimming, gymnastics, and racquet sports.1,2 The proximal humeral physis accounts for 80% of the longitudinal growth of the humerus. In sports involving overhead throwing, the physis is subjected to significant amount of stress, leading to microtrauma, throwing-related pain, and characteristic changes seen on the radiographs. This is classically described as the “little leaguer’s shoulder,” because of its original description in little league pitchers.
It is unclear whether the underlying changes represent inflammation caused by overuse or stress fracture through the physis. The mechanism is believed to be repetitive, high intensity, rotational stress to the physis during throwing, and other overhead activities.
The head of the humerus develops from two ossification centers that fuse into one at 7 years of age. The proximal physis of the humerus closes between 19 and 22 years of age; most close by 17 years of age. This injury pattern is most common during rapid growth, and occurs most often in adolescent boys, between the ages 11 and 16 years, with a peak at 14 years. In baseball pitchers, throwing a curve ball and higher pitch counts have been shown to be associated with a higher rate of stress injury to the proximal humeral physis. Most throwers demonstrate excessive external rotation at shoulder, whereas the internal rotation is relatively restricted, accompanied by acquired contracture of the posterior capsule, a maladaptation referred to as the glenohumeral internal rotation deficit.
The athlete typically presents with a gradual onset of shoulder or proximal arm pain associated with throwing. The average duration of symptoms ranges from 7 to 8 months. Often, the symptoms are mild lasting for several weeks to months, and there is pressure to continue to play, thus, there is a delay in seeking medical help. Tenderness over the lateral aspect of the proximal humerus is the most common finding on examination, and may be present in almost 70% of athletes.2–4 A few athletes may have weakness of external rotators of shoulder. Usually, the active and passive range of motions of shoulder is normal, until later in the course, when a relative decrease of internal rotation develops.
The radiographic findings are characteristic and seen in almost all athletes at the time of presentation. Radiographs with shoulder in external and internal rotation, as well as AP and lateral views should be obtained. Comparison views of the opposite shoulder should also be obtained. The classic finding is a widening of the proximal physis, which may or may not be associated with fragmentation, calcification, sclerosis, and demineralization (Figure 21-1).
Figure 21-1
X-ray of stress injury of proximal humeral physis shows widening of the physis (A), compared to the normal side (A). (Used with permission from DeLee JC, Drez D Jr, Miller MD, eds. DeLee and Drez’s Orthopedic Sports Medicine. Philadelphia, PA: Saunders Elsevier Imprint; 2003: Figure 21M2-7, p 1136.)
Treatment of proximal humeral physeal stress injury is rest, modification of throwing patterns, and appropriate training and conditioning. Gradual progression to athletic activities is allowed after symptoms abate. The best treatment is advice and counseling to the parents, the child, and the coach to avoid overuse injury in the future. Most of these young athletes will on an average undergo 6 weeks of rest from throwing. Once pain-free, the athlete then undergoes an interval throwing program and returns to competition 3 to 4 months after the injury. All players should be instructed on appropriate limitations on the number and types of pitches, practices, and games they may play in (Table 21-1).5–10 Current US Baseball Medical and Safety Committee recommendations are summarized in Table 21-2. Similar treatment principles of rest, activity limitations, and training and conditioning are applied for treatment of players participating in other sports who present with proximal physeal injury.
Recommendations
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Proximal humeral osteochondrosis is a rare problem in children of unknown etiology, exacerbated by overuse in a throwing athlete with a genetic predisposition. These athletes will present similarly to little leaguer’s shoulder. Imaging studies reveal fragmentation of the proximal humeral epiphysis. Treatment of nondisplaced fragments is rest and a reduction of stresses about the shoulder. Throwers should refrain from throwing until completely asymptomatic, and then should undergo appropriate conditioning before return to full time play.
The rotator cuff muscles (see Figures 20-4 and 20-5 in Chapter 20) (supraspinatus, infraspinatus, teres minor, subscapularis) are predominantly involved in the pathophysiology of this syndrome, hence the condition is also referred to as rotator cuff impingement syndrome. External (anterior) impingement refers to a lesion of the supraspinatus tendon caused by its impingement under the undersurface of the acromion; whereas, internal (posterior) impingement refers to a lesion of the glenoid labrum—specifically superior labrum anterior–posterior or SLAP lesion caused by impingement of the articular surface of the rotator cuff.5–7 Shoulder impingement syndrome is a common cause of shoulder pain in swimmers (swimmer’s shoulder), tennis players, gymnasts, and most overhead throwing sports.
The rotator cuff muscles help stabilize the head of the humerus in the glenoid. The rotator cuff muscles along with the long head of biceps prevent the head of the humerus from moving upward when the arm is abducted. Impingement occurs when the tendons of long head of biceps and supraspinatus, the subacromial bursa, and the greater tuberosity pass underneath the coraco-acromial arch, when the arm is abducted, elevated, or externally rotated. Glenohumeral instability, tendon overload, muscle weakness, and strength imbalance mainly contribute to impingement in young athletes. Repetitive overuse in overhead activities as seen in pitchers, swimmers, and tennis players, can lead to chronic inflammation of the rotator cuff tendons leading to edema and swelling, which will compromise the subacromial space. On the other hand, in weight lifters and gymnasts the mechanism seems to be sustained isometric muscle contractions leading to tendon overload. Either way with continued activity, a vicious cycle of impingement, edema and swelling, and further impingement sets in. The natural course of untreated condition has been described as a continuum progressing from an acute inflammation and swelling (stage I), to chronic inflammation, scarring, and tendinitis (stage II), eventually leading to rotator cuff tear (stage III). Other factors believed to contribute to the development of impingement, especially in older age group, are decreased vascularity, degeneration, and calcification of the rotator cuff tendons.
Swimmers and other overhead athletes will often have significantly weak scapular stabilizer muscles as well, and many will demonstrate scapular winging on examination, with a weak serratus anterior and other periscapular muscles, as well as poor overall coordination of the periscapular muscle groups.
The athlete presents with progressively worsening, insidious onset shoulder pain of several days or weeks duration, exacerbated with activity. Some athletes will have discomfort at rest as well as nocturnal pain, especially when associated with glenohumeral instability. The pain is usually diffuse in most athletes, described as deep in the shoulder; however, sometimes it is noted predominantly superolaterally or posteriorly. The pain is exaggerated by overhead movements of the arm. Pain is felt specifically upon abduction between 70 and 120 degrees. The athletes notice that their performance has deteriorated.
Initially, the range of motion is not affected; however, later in the course there may be limitation of abduction and internal rotation. Palpation may reveal tenderness under the acromion process and over the long head of biceps tendon as it traverses the bicipital groove anteriorly, if it is also inflamed. Supraspinatus is tested for pain on resisted movement and weakness. Resistance is applied to arm abducted to 90 degrees, forward flexed at 30 degrees, and internally rotated (empty can sign) (Figure 20-9). Pain is also elicited with abduction, internal rotation, flexion of the arm (Figure 20-8), and forward flexion of the internally rotated arm (Figure 20-7) (impingement signs). Glenohumeral stability should be assessed by moving the humeral head in anterior, posterior, and inferior directions in relation to the glenoid (load and shift test, Figure 20-15). With anterior instability, pain, and discomfort can be elicited when the shoulder is abducted and externally rotated, and improves when the humeral head is moved in a posterior direction (relocation test) (Figure 20-14). Laxity in other joints should also be assessed, because generalized laxity is not an uncommon finding in adolescents. Pain can be temporarily relieved by injection of xylocaine into the subacromial bursa.
Plain radiographs are normal in most young athletes and magnetic resonance imaging scan is not indicated unless rotator cuff tear, or glenoid labral tear is suspected and surgical intervention is a consideration. Tear of the rotator cuff, especially the supraspinatus, is extremely rare in young athletes. Other conditions to be considered in the differential diagnosis of recurrent or chronic shoulder pain in a young athlete are listed in Table 21-3.
Relatively more common |
Stress injury of the proximal humeral physis |
Glenohumeral joint instability |
Rotator cuff tendonitis and impingement |
Subacromial bursitis |
Relatively less common |
Glenoid labral tears |
Atraumatic osteolysis of the distal clavicle |
Scapular dyskinesis |
Relatively rare |
Stress fracture of scapula |
Long thoracic neuropathy |
Suprascapular neuropathy |
Scapulothoracic bursitis |
Treatment consists of pain control, modification of activities, and progressive rehabilitation. Initially, complete rest from offending activities may be necessary for a short period of time. A progressive rehabilitation program will help restore full range of motion, strength, balance, and endurance of the rotator cuff muscles. Rehabilitation is followed by sport-specific training and conditioning. Training errors must be identified and corrected. Prognosis for resolution of symptoms and full return to sports is excellent in young athletes, although, it may take several weeks to months before the athletes may return to their previous level of participation. Surgical treatment is rarely a consideration in young athletes. Surgical release of acromio-clavicular ligament has been shown to be effective in some cases. Failure to respond to the conservative treatment should prompt reevaluation and careful consideration of any other underlying cause for the pain. If a cuff or labral tear is suspected orthopedic consultation should be obtained (Box 21-1).
Stress injury of the proximal humeral physis1,2 |
Dislocation of long head of biceps tendon2 |
Glenoid labral tears with persistent pain2 |
Failed nonoperative treatment of atraumatic instability2 |
Atraumatic osteolysis of distal clavicle desiring operative treatment2 |
Peripheral neuropathies about the shoulder3 |
Glenohumeral instability refers to excessive motion of the glenohumeral joint associated with relatively greater laxity of the joint stabilizers that result in either acute (traumatic) or chronic (nontraumatic) clinical symptoms and signs.11 The spectrum of instability can range from microinstability to subluxation to dislocation of the glenohumeral joint. Although shoulder instability has been described based on the degree, frequency, acuity, etiology, and direction, for practical purposes, it is useful to consider two broad clinical presentations, namely acute traumatic dislocation (anterior, posterior, inferior) and chronic nontraumatic symptomatic instability (anterior, posterior, inferior, and multidirectional). Acute traumatic shoulder dislocation is covered in Chapter 20. Atraumatic instability is reviewed here.
The main static stabilizers of the glenohumeral joint are the head of the humerus and the glenoid, the glenohumeral ligaments, and the glenoid labrum, whereas the main dynamic stabilizers are the rotator cuff muscles. The role of the long head of the biceps brachii muscle in shoulder function has not been fully elucidated. The major mechanisms underlying the chronic atraumatic shoulder instability are described in Table 21-4. Shoulder laxity can be part of various genetic syndromes (e.g., Marfan, Ehler-Danlos) and systemic disorders.
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Multidirectional instability itself is a common problem, particularly in young female athletes, and can be one cause of rotator cuff tendonitis. Psychologic factors should be explored in the history. Most athletes with atraumatic instability are asymptomatic. The athlete with symptomatic instability will present with shoulder pain associated with overhead movements, a sense of weakness, and deterioration in sport performance. There may be a positive family history of the shoulder laxity.
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