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Throwing injuries of the upper extremity: Clinical presentation and diagnostic approach

Throwing injuries of the upper extremity: Clinical presentation and diagnostic approach
Literature review current through: Jan 2024.
This topic last updated: Oct 31, 2023.

INTRODUCTION — Millions of people throughout the world participate in sports that involve throwing or throwing-like movements. These movements range from classic ball throwing, as performed by baseball pitchers or cricket bowlers, to throwing implements other than balls, such as a javelin, to throwing-like actions that do not involve a ball directly, such as a tennis serve or volleyball spike. All such movements involve complex biomechanics and great stresses being placed on the musculoskeletal system. Improper biomechanics, excessive stress beyond the capacity of an individual's musculoskeletal system, or cumulative trauma from throwing too frequently can cause injury. Differences in the mechanics of non-classic throwers make such athletes susceptible to other injuries not discussed in this topic.

The clinical presentation of throwing related injuries and an approach to diagnosing them are reviewed here. Throwing biomechanics, treatment of specific injuries, and physical examination of the shoulder are discussed separately. (See "Throwing injuries: Biomechanics and mechanism of injury" and "Throwing injuries of the upper extremity: Treatment, follow-up care, and prevention" and "Physical examination of the shoulder".)

PRESENTATION, EXAMINATION, AND RADIOGRAPHIC FINDINGS OF SPECIFIC INJURIES

Shoulder injuries — Specific shoulder injuries incurred by the throwing athlete are described below, but the clinician should keep in mind that the structures described here are intimately related and more than one may be involved in producing shoulder pain in the throwing athlete [1]. With repetitive throwing, a number of anatomic adaptations develop that can produce pathologic changes in movement, ultimately resulting in structural damage. Key findings for common and important throwing injuries of the shoulder and elbow are summarized in the following table (table 1) and flow charts (algorithm 1 and algorithm 2).

Excessive throwing in youth may cause a decrease in humeral derotation, a normal part of skeletal maturation. This manifests in the older throwing athlete as increased proximal humeral retroversion, with increased shoulder external rotation and decreased internal rotation [2,3]. With repetitive microtrauma, beyond the athlete's ability to heal, proximal humeral epiphysiolysis (stress fracture or Little League shoulder) can develop.

Decreased internal rotation is caused by tightening of the posterior capsule and muscular tightness over time. Once the total loss of motion exceeds 20 degrees (loss of internal rotation far exceeds gains due to increased external rotation), some secondary anterior translation of the humeral head will occur during the cocking phase. The result is "Dead arm syndrome" and internal impingement involving pinching of the posterior capsule and labrum. Prolonged tension on the posterior inferior glenohumeral ligament and/or repetitive pinching of the posterior inferior labrum and glenoid can cause a Bennett lesion.

In the cocking phase of throwing (90 degrees of abduction and maximal external rotation), substantial torsional forces are exerted on the long head of biceps, which produce traction on the posterior superior labrum, possibly creating a labral tear. Labral pathology can progress and lead to further alteration in glenohumeral motion with increasing pain and instability, mechanical sensations, and worsening performance.

Transient subluxation ("Dead arm syndrome") — Although the phrase "Dead arm syndrome" has been used to describe any malady that causes the throwing athlete to lose effectiveness, the term refers more precisely to a syndrome that involves the sudden onset of pain during the late cocking or acceleration phases of throwing [4]. Episodes are most commonly associated with transient glenohumeral subluxation. Underlying causes include superior labrum anterior posterior (SLAP) lesions and rotator cuff pathology. The shift in humeral head position may cause pinching of the anterior capsule, transient stretching of the brachial plexus, or stretching of the infraspinatus. (See "Superior labrum anterior to posterior (SLAP) tears" and "Subacromial (shoulder) impingement syndrome" and "Rotator cuff tendinopathy" and "Presentation and diagnosis of rotator cuff tears" and "Multidirectional instability of the shoulder".)

Pitchers with dead arm syndrome complain of a sudden onset of pain accompanied by loss of throwing velocity during late cocking or acceleration [4]. They often describe associated episodes of shoulder instability. The shoulder apprehension test is typically positive (picture 1 and movie 1) [5,6] as is the Jobe's relocation test [4].

Diagnostic imaging may reveal labral or rotator cuff pathology, but because these episodes of instability generally occur only during throwing the transient subluxation itself cannot be captured, even with a dynamic ultrasound examination [7,8]. (See 'Diagnostic imaging' below.)

Rotator cuff injuries — The rotator cuff muscles are the most important structures for stabilizing the humeral head and keeping it centered within the glenoid during throwing. Rotator cuff weakness allows the humeral head to sublux, which can lead to shoulder impingement, capsular stretching, or labral tearing.

Players with rotator cuff injury often complain of lateral shoulder pain at rest and shoulder pain with overhead motions during activities of daily living. However, depending upon the muscles involved and the site of injury, pain may manifest at other parts of the shoulder and be provoked by other movements. Pain often increases when the patient lies on the affected shoulder or side. Throwers may complain of pain in the posterior-superior shoulder at terminal cocking, particularly if they have internal impingement associated with an undersurface rotator cuff tear. On examination, patients typically manifest pain with shoulder abduction of between 70 to 120 degrees, or with maximal external rotation. They often demonstrate weakness in one or more of the rotator cuff muscles (most often the supraspinatus), particularly with higher-grade rotator cuff tears. Although athletes may demonstrate less weakness than expected because of stronger secondary muscles (eg, deltoid, superior trapezius), the strength tests used to assess the individual rotator cuff muscles are generally effective at minimizing the contribution of secondary muscles [9]. (See "Physical examination of the shoulder", section on 'Examination for rotator cuff pathology'.)

Tests that may reproduce the pain include:

Jobe test of the supraspinatus (picture 2)

Hawkins Kennedy and Neer anterior shoulder impingement tests (picture 3 and picture 4 and movie 2)

Gerber push-off test of the subscapularis (picture 5)

The diagnosis of rotator cuff injury can be confirmed using magnetic resonance imaging (MRI) or ultrasound. However, the presence of a rotator cuff tear on MRI does not necessarily indicate causation, as studies have found that 21 to 52 percent of asymptomatic professional baseball pitchers have rotator cuff tears on MRI [10,11]. With experienced operators, ultrasound is as accurate as MRI for identifying full thickness rotator cuff injuries; partial thickness articular surface tears can be difficult to diagnose with either modality. (See "Rotator cuff tendinopathy", section on 'Diagnostic imaging' and "Presentation and diagnosis of rotator cuff tears", section on 'Imaging studies' and "Musculoskeletal ultrasound of the shoulder".)

Labral tears — The most common labral injury in throwers is the superior labrum anterior to posterior (SLAP) tear. The exact mechanism of injury is unknown, but may be related to the repeated compressive and shear forces placed on the labrum during throwing. Scapular dysfunction may contribute to the injury. The mechanics, clinical features, diagnosis, and management of SLAP tears are discussed in detail separately. (See "Superior labrum anterior to posterior (SLAP) tears".)

Athletes with labral tears typically complain of pain deep within the shoulder joint when throwing but often not with general activities of daily living. Pitchers may complain that their throwing arm feels weak or "dead." Other complaints include popping, clicking, or catching within the shoulder, particularly with overhead motions. Pain may be reproduced by provocative maneuvers, including the following.

Anterior glide test (movie 3)

Compression-rotation test (movie 4)

Active compression (O'Brien's) test (picture 6)

Crank test (movie 5)

Modified dynamic labral shear test (movie 6)

It should be noted that the specificity and sensitivity of these and other tests designed to elicit pain from SLAP injuries are limited. Therefore, different clinicians may prefer different tests, and all clinical findings must be interpreted in light of the history and other clinical findings [12-15]. When clinically indicated, advanced imaging is necessary to confirm the diagnosis. (See "Superior labrum anterior to posterior (SLAP) tears", section on 'Diagnostic imaging'.)

Glenohumeral internal rotation deficiency (GIRD) — During the deceleration phase of throwing, the posterior capsule is placed under tension. With repeated throwing, such repetitive stress of the posterior capsule causes microtrauma, which leads to thickening of the capsule, and ultimately reduced internal rotation of the glenohumeral joint, or GIRD. Due to the increased thickness of the capsule and resulting tightness, the humeral head is forced anteriorly and superiorly, pinching the rotator cuff and the superior labrum. In addition, repeated anterior-superior translation of the humeral head stresses the posteroinferior glenohumeral ligament, which may result in a Bennett lesion (discussed immediately below).

An athlete with symptomatic GIRD typically complains of pain deep in the posterior shoulder. However, GIRD does not necessarily cause symptoms, as shown in a study of asymptomatic professional pitchers in which GIRD of greater than 25 degrees was present in 44 percent [16]. On examination, there is loss of internal rotation compared with the non-throwing shoulder of at least 20 degrees in symptomatic pitchers [14]. This loss of internal rotation relative to the non-throwing shoulder is a more useful assessment than a reduction based on absolute measurements (ie, degrees of rotation).

Nevertheless, some researchers have found that a shoulder with less than 180 degrees total arc of internal plus external rotation with the shoulder abducted to 90 degrees is at high risk for symptomatic GIRD [4]. Examiners must account for the typical changes in external rotation and total glenohumeral range of motion when determining the extent of motion loss in throwing athletes [17]. The easiest way to measure this is to place the patient supine with the shoulder abducted to 90 degrees and the elbow in 90 degrees of flexion, and then compare the total arc of motion from maximum internal rotation (picture 7) to maximum external rotation (picture 8) in the throwing shoulder to the non-throwing shoulder (movie 7). A loss of at least 20 degrees is considered abnormal [5].

Traditionally, the presence of GIRD in a throwing athlete was thought to be associated with a significant risk for developing pain and subsequent shoulder injury [5,17]. Subsequent data suggests that GIRD may not place the shoulder at risk for more severe types of shoulder injury, at least in professional pitchers [18]. Such risk may be more closely related to decreased total arc of motion, or possibly decreased external rotation [18,19]. Our understanding of these conditions is evolving, but treatments that decrease GIRD or that restore total arc may prevent the development of shoulder injuries.

Bennett lesion — A Bennett lesion is mineralization that develops at the posteroinferior glenoid in throwing athletes (image 1). The underlying pathogenesis is thought to involve repetitive capsular traction at the attachment of the posteroinferior glenohumeral ligament [20]. Bennett lesions are usually asymptomatic. However, they may cause posterior shoulder pain in the throwing athlete, although the exact mechanism is unknown [21]. When present, posterior shoulder pain develops at the end of external rotation with the shoulder abducted to 90 degrees. Tests of labral pathology are often positive. Bennett lesions are best seen on plain radiograph using a Stryker-Notch view, computed tomography (CT) scan, or MRI.

Proximal humeral epiphysiolysis (Little League shoulder) — Repetitive loading of the humerus with the torque and distraction forces of throwing can cause microtrauma and irritation of the proximal humeral physis, which is substantially weaker than the surrounding bone. According to high speed motion analysis studies, youth pitchers can generate substantial forces at the shoulder [22].

Little League shoulder typically presents in baseball pitchers between 11 and 16 years old, with a peak incidence at 13 years. The athlete usually complains of progressively worsening, non-focal shoulder pain with throwing. Palpation reveals tenderness over the lateral proximal humerus in the area of the patient's growth plate [23,24].

The diagnosis of proximal humeral epiphysiolysis is made by radiograph. Widening of the proximal humeral physis is seen best on plain radiograph using an anteroposterior view of the shoulder with the arm in external rotation (image 2). However, such changes may be found in asymptomatic pitchers; thus, clinical correlation with symptoms is important [25]. Widening may be subtle and comparative radiographs of the opposite shoulder may be helpful to confirm the diagnosis.

Diagnostic musculoskeletal ultrasound (MSK US) is commonly used to help diagnose this condition in clinical settings with experienced ultrasonographers [26]. Although widening of the growth plate is difficult to quantify, MSK US demonstrates increased hypo-echoic swelling surrounding the affected shoulder that is not seen on the contralateral side. When a definitive diagnosis must be made in a timely fashion in patients with normal plain radiographs but a suspicious history and examination, MRI is useful for confirming the diagnosis [24].

SICK scapula syndrome and scapular dyskinesis — The SICK scapula syndrome refers to scapular malposition, inferior medial border prominence, coracoid pain and malposition, and dyskinesis of scapular movement (picture 9) [27]. The key features of this condition are asymmetric scapular positioning and altered motion in the throwing shoulder compared with the non-throwing shoulder. These changes lead to impingement of the rotator cuff and compression of the labrum.

The patient with scapular dysfunction usually complains of insidious anterior shoulder pain, typically in the area of the coracoid process. Inspection shows the affected scapula to be lower than the uninvolved scapula and to have a prominent inferior medial border (picture 10). In addition, the scapula may be laterally displaced and abducted compared with the opposite side (picture 11). Scapular prominence (ie, winging) is not dramatic, and the presence of such winging suggests injury of the long thoracic nerve (picture 12).

Close observation of the scapula reveals one of several distinct abnormal movement patterns. Scapular dyskinesis patterns include:

Type I – Inferior medial scapular border is prominent at rest. With cocking motion, this border becomes more prominent and there is a notable limitation of both acromial elevation and full retraction. This movement pattern is associated with (1) inflexibility of pectoralis major and minor; (2) weakness of the lower trapezius and serratus anterior; and (3) labral pathology.

Type II – Entire medial scapular border is prominent at rest and becomes more prominent with cocking motion. This movement pattern is associated with (1) upper and lower trapezius and rhomboid weakness; and (2) labral pathology.

Type III – Superomedial border of the scapula is prominent both at rest as well as throughout the arc of shoulder abduction. In addition, there is increased scapular protraction during motion. This pattern is associated with impingement and rotator cuff pathology.

Palpation reveals tenderness in the area of the coracoid. Pain in the area is aggravated by passive forward flexion, and there is diminished terminal shoulder flexion. The special tests below can help determine whether scapular dysfunction is contributing to overall shoulder pain and dysfunction; performance of the tests is described in detail separately. (See "Physical examination of the shoulder", section on 'Special tests'.)

Scapular repositioning test (ie, scapular retraction or stabilization test) (picture 13)

Scapular assistance test (picture 14 and movie 8)

Elbow injuries — Specific elbow injuries incurred by the throwing athlete are described below, but the clinician should keep in mind that the structures described here are intimately related and more than one may be involved in producing elbow pain. With repetitive throwing, a number of anatomic adaptations develop that can produce pathologic changes in movement, ultimately resulting in structural damage. Repetitive throwing causes increased proximal humeral retroversion in the shoulder that manifests as increased external rotation and decreased internal rotation. There is some evidence that this increased retroversion in the shoulder can result in increased risk for elbow, as well as shoulder, injury [28]. Key findings for common and important throwing injuries of the shoulder and elbow are summarized in the following table (table 1) and flow charts (algorithm 1 and algorithm 2).

Ulnar collateral ligament (UCL) injury — Traditionally, UCL injuries were thought to occur in older, high-level pitchers who throw at high velocities. However, data from small observational studies suggest that this injury is occurring at increasing rates in high-school-aged pitchers [29]. Important risk factors include throwing at relatively high velocity, which increases the forces exerted at the elbow, insufficient recovery time, and overuse, which is reflected in the high number of pitchers who experienced elbow discomfort prior to sustaining the acute injury [30,31]. Forces exerted across the UCL are similar with fastballs and curveballs but lower with slower pitches, such as change-ups.

Of course, all such risks are relative and depend in part on individual anatomy (eg, size of the UCL) and throwing mechanics. Factors that increase valgus elbow loads during throwing include late trunk rotation, reduced shoulder external rotation, increased elbow flexion, use of a sidearm delivery [32], decreased shoulder rotation arc, and decreased shoulder flexion [19]. Players whose throwing motion produces greater elbow valgus loads and shoulder external rotation torque are at increased risk for elbow injuries [33].

Complete UCL tears usually present as acute injuries, but in many cases they result in part from accumulated microtrauma that has gradually weakened the ligament. A fastball thrown at 80 miles/hour (130 km/hour) generates approximately 64 Newton-meters (Nm) of torque, of which approximately half is transmitted to the UCL [30]. Cadaver studies suggest that the UCL is at increased risk for rupturing when subjected to torque greater than 32 Nm. Thus, in theory, any pitch thrown at 80 miles/hour (130 km/hour) or faster has the potential to injure the UCL. Professional baseball pitchers can generate up to 120 Nm of torque [34]; fortunately, the muscles around the elbow are able to dissipate enough energy that acute failure of the UCL is relatively rare. Because elbow torque averages only 18 to 28 Nm, UCL injury is much less common in this age group [35,36]. However, muscle fatigue increases the force transmitted to the UCL, and the likelihood of injury. Chronic repetitive stress on the UCL with inadequate recovery time has been associated with an increased risk of elbow injury in these younger athletes and may be responsible for the increasing numbers of UCL surgeries among youth athletes [37].

The pitcher with a UCL sprain (mild or partial tear) typically complains of medial elbow pain that increases during the acceleration phase of throwing. On examination, the athlete is tender directly over the UCL, and stress testing of the UCL causes pain and demonstrates laxity. Such tests include:

Valgus stress testing (picture 15 and movie 9) – With the patient's elbow passively flexed to about 30 degrees and their forearm in neutral position (ie, not pronated or supinated) [38], the clinician applies a valgus stress to the elbow. A soft endpoint or joint widening 2 mm or greater compared with the other elbow marks a positive test.

Moving stress test – The examiner places a valgus stress on the patient's fully flexed elbow and maintains that stress while quickly moving the elbow into full extension [39]. The following video clip shows the non-modified moving stress test (movie 10). A positive test reproduces the elbow pain in the olecranon fossa and at the posteromedial elbow. Maximal pain typically occurs with the elbow flexed between 30 degrees and terminal extension (picture 16).

Milking maneuver (picture 17 and movie 11) – With the elbow flexed to 90 degrees and maximally supinated, the examiner grasps the patient's thumb and applies valgus stress by pulling on the thumb. A positive test is marked by a soft endpoint or increased joint widening compared to the opposite side.

MRI arthrogram has high sensitivity and specificity and remains the test of choice to confirm UCL sprain [40], but radiologists and other clinicians with extensive experience viewing UCL injuries on plain MRI can identify most UCL injures using this technique, which can be useful for helping to determine which injuries are amenable to nonoperative treatment [41]. In experienced hands, ultrasound may be useful for identifying partial UCL tears and chronic degeneration of the ligament, in addition to diagnosing gross tears [40,42-44]. Stress ultrasound increases sensitivity compared with standard techniques.

Common flexor tendon sprain — Flexor tendon sprains may present in a similar fashion to UCL sprains. However, onset tends to be insidious, and careful examination reveals tenderness anterior and lateral to the medial epicondyle rather than directly over the UCL. In addition, pain increases with resisted wrist flexion and pronation, but there is no increase in pain and no joint widening with UCL stress testing. Severe sprains may manifest changes on ultrasound or MRI.

Valgus extension overload (VEO) syndrome — This term had been used to describe any injury caused by repetitive valgus stress of a thrower's elbow. The term now refers primarily to injuries caused by compression of the posteromedial ulnohumeral articulation. The compressive forces involved can reach up to 780 N during each pitch [34]. Excessive valgus forces and UCL laxity predispose athletes to VEO syndrome [45,46]. The cumulative effects of this trauma can cause osteophytes to develop on the olecranon and chondromalacia of the posteromedial humeral trochlea and olecranon fossa.

Typically, athletes with VEO complain of pain in the posterior elbow when the ball is released. On examination, the patient experiences pain when a valgus stress is applied to the elbow while it is repeatedly moved between 30 degrees of flexion and terminal extension (picture 16 and movie 10) [47]. There may be some loss of terminal extension. Plain radiographs may show osteophytes or loose bodies (image 3).

Olecranon stress fracture — The loads that contribute to VEO syndrome may also cause an olecranon stress fracture [48]. When the primary stress involved stems from triceps traction and extension, a transverse stress fracture usually develops; when the primary stress is due to valgus and extension-related loads, an oblique stress fracture usually occurs [49].

Typically, the area over the posterior or posteromedial olecranon is tender. The athlete may have pain with resisted elbow extension, but the triceps tendon is nontender. The patient may lack full elbow extension. Valgus stress testing causes pain in the olecranon if the olecranon is engaged in the olecranon fossa (ie, elbow is flexed to 90 degrees or less) [49]. Plain radiographs may show a fracture line or sclerotic changes [50]. Bone scan or MRI may reveal some stress fractures that are not visible on plain radiographs (image 4). (See "Overview of stress fractures".)

Triceps tendinopathy — This overuse syndrome is caused by the repetitive extension and hyperextension of the elbow. The onset of pain is typically insidious, as the athlete complains of progressively worsening pain as the number of pitches thrown increases. Palpation reveals tenderness at or just proximal to the insertion of the triceps tendon on the olecranon and pain increases with resisted elbow extension. Plain radiographs may be normal or reveal an osteophyte in the distal tendon. Ultrasound and MRI are typically unrevealing but are useful for ruling out a partial or complete triceps tendon tear [51].

Ulnar neuropathy — Repeated valgus loading of the elbow can lead to traction on the ulnar nerve at the cubital tunnel, ultimately causing neuritis. Athletes with laxity of the ulnar collateral ligament are at increased risk for stretching the nerve. A second cause of ulnar neuropathy is repeated subluxation of the ulnar nerve in the region of the medial epicondyle during elbow extension and flexion. Athletes with ulnar neuropathy describe an electrical sensation running up and down the forearm when they throw. The subluxed nerve can be palpated posterior to the medial epicondyle with the elbow in a maximally flexed position. The athlete may have a positive Tinel's sign (picture 18). A dynamic ultrasound examination can identify nerve subluxation, enlargement, or compression. MRI may identify suggestive findings (image 5). (See "Ulnar neuropathy at the elbow and wrist".)

Osteochondrosis of elbow (Panner's disease) — Panner's disease is the most common cause of chronic lateral elbow pain in the young thrower (aged 7 to 12 years old). It is caused by a focal lesion in the subchondral bone of the capitellum and its overlying articular cartilage. Typically the condition develops in the anterior central capitellum. Patients present with a swollen elbow and complain of a dull, achy pain that is aggravated by throwing and other activities. Radiographs often show a fragmented capitellar ossification center. The syndrome has three stages: first, osteonecrosis of the capitellar growth center; second, regeneration; and third, recalcification. (See "Osteochondritis dissecans (OCD): Clinical manifestations, evaluation, and diagnosis", section on 'Panner disease'.)

Osteochondral defect of the elbow — In older adolescent throwers, typically aged 13 to 16 years, lateral elbow pain is more likely from an osteochondral defect. Osteochondral defects of the elbow occur most often in the capitellum from repeated compression of the radiocapitellar joint during throwing. The athlete usually complains of lateral elbow pain with throwing and may have episodes of locking. Common examination findings include crepitus, joint effusion, and tenderness of radiocapitellar joint. Occasionally, a loss of terminal extension is found. However, the patient may have a completely unremarkable examination. The diagnosis is made with plain radiographs. MRI is used to stage the lesion and guide treatment (image 6).

Little League elbow — Little League elbow is the name sometimes given to a constellation of problems that cause elbow pain in youth baseball pitchers, including capitellar osteochondritis dissecans (image 7), posteromedial ulnohumeral impingement (VEO syndrome), and ulnar collateral ligament (UCL) tear. (See "Osteochondritis dissecans (OCD): Clinical manifestations, evaluation, and diagnosis", section on 'Elbow'.)

A more precise definition restricts the use of the term specifically to apophysitis (image 8) or avulsion fracture (image 9) of the medial epicondylar growth plate in skeletally immature athletes [52]. This growth plate typically closes by the mid-teens and Little League elbow is thus most commonly seen in 9 to 14-year-old pitchers. The injuries to which young pitchers are most susceptible vary by age and adolescent pitchers (generally 12 to 14 year olds, who are at the peak of their adolescent growth spurt) may sustain avulsion fractures of the medial epicondyle (figure 1), rather than apophysitis (table 2). Little League elbow is discussed in more detail separately. (See "Elbow injuries in active children or skeletally immature adolescents: Approach", section on 'Medial elbow pain'.)

During the cocking and acceleration phases of throwing, the elbow experiences valgus and distraction forces. These repetitive stresses result in microtrauma and irritation of the physis. Symptoms of medial epicondyle apophysitis usually begin insidiously in the young thrower. The young pitcher complains of progressively worsening pain as the number of pitches thrown increases. The medial elbow is tender and pain is elicited with valgus stress of the elbow. Radiographic studies are often normal with apophysitis [53]. Because of the irregularity of the epiphysis, contralateral comparison views may be helpful in the diagnosis of avulsion fractures.

Lateral plica syndrome — While lateral elbow joint-line pain is relatively rare among throwing athletes, sometimes a plica (fold of the synovium (image 10)) causes an intermittent catching sensation at the lateral elbow, which may be accompanied by pain. The clinical examination is often unremarkable. In some cases, a click may be felt when palpating the joint line while the elbow is passively flexed and extended in combination with pronation-supination of the forearm, or pain may be present at terminal elbow extension [54]. A posterolateral radiocapitellar plica test may be useful [55]. A positive test is marked by pain with compression of the posterolateral radiocapitellar joint, with the elbow held in extension. Pain decreases as the elbow is moved from extension to greater than 90 degrees of flexion, with the forearm pronated during the maneuver.

Axillary-subclavian vein thrombosis — Paget-Schroetter syndrome refers to thrombosis of the axillary-subclavian vein (figure 2) associated with repetitive activity of the affected upper extremity [56]. The pathogenesis involves repetitive trauma to the endothelium of the vein. Often the patient has anatomic variants associated with thoracic outlet syndrome, such as a cervical rib, congenital bands, hypertrophy of the scalenes, or abnormal insertion of costoclavicular ligament. These anatomic variations are thought to decrease the normal mobility of the subclavian vein, increasing its susceptibility to trauma from arm activity. Repetitive trauma leads to intimal hyperplasia, inflammation, and fibrosis. Arm use also leads to activation of the coagulation cascade. Athletes with underlying genetic thrombophilic conditions, such as factor V Leiden, are at higher risk. (See "Overview of thoracic central venous obstruction".)

The typical presentation involves discomfort and swelling of the dominant arm. Other possible signs include redness or discoloration of the arm, cyanosis of the arm, and notable dilated veins across the shoulder and upper arm (Urschels sign) [56]. Compression Doppler ultrasound is usually the initial screening test. MR venography is both sensitive and specific and is used most often to establish the diagnosis.

Summary of key findings for major throwing injuries — Key findings for common and important throwing injuries of the shoulder and elbow are summarized in the following table (table 1) and flow charts (algorithm 1 and algorithm 2). For additional details about these conditions, refer to the descriptions above.

HISTORY — A careful history provides the foundation for working up the patient with a throwing injury. The history determines the initial differential diagnosis, which in turn directs further evaluation, including the selection of appropriate special examination maneuvers and diagnostic imaging. Questions that help characterize the injury include the following:

Where does it hurt? Injuries to the throwing athlete can occur almost anywhere but are most common in the shoulder and the elbow.

How did the injury occur? Classically, sports injuries are divided into acute and chronic injuries. However, many "acute" injuries are more accurately described as acute injuries to a chronically damaged structure. Nonetheless, for purposes of the diagnostic work-up, we consider an injury acute if the patient attributes it to a single specific incident. If the patient describes a vague or longer time period during which symptoms developed, the injury is more likely chronic. However, even if the patient specifies an exact moment when the injury occurred, the clinician should ask about pain that preceded said incident, as this may represent an "acute-on-chronic" injury.

Did you feel or hear a "pop"? A pop suggests an acute injury, often involving a tendon or ligament.

Did swelling develop soon after the injury? Immediate swelling occurs from bleeding into the joint or soft tissues and suggests acute injury. Mild soft tissue swelling following activity may occur with either acute or chronic injury.

What position do you play? Among baseball players, pitchers and catchers are at the highest risk for overuse injury [57]. Injuries in position players are more likely to be acute. However, keep in mind that many younger athletes play multiple positions. A youth player may consider themselves primarily a position player but still pitch on occasion.

How would you describe the pain? Grinding pain often stems from an intra-articular source. Burning, "electric," or radiating pain is more likely to be neurologic.

What is the typical pain pattern? Pain the goes away after warming up but returns either late during activity or after activity is often related to overuse. Pitchers may not complain of pain but instead say it takes longer to loosen up.

Do you have night pain? While the large majority of throwing injuries do not cause night pain, some exceptions include complete rotator cuff tears, larger osteochondritis dissecans (OCD) lesions and stress fractures. However, the night pain associated with these injuries, when present, tends to be equal to or less than the daytime pain. If pain is worse at night, clinicians should consider systemic illness or more serious pathology, such as a bone tumor.

Do you experience any associated symptoms, such as locking, catching, or instability in a joint? True locking episodes, in which a mechanical obstacle (eg, torn cartilage) prevents movement, indicates articular pathology. Clicking and catching also suggest articular pathology, although extra-articular causes may be responsible. Clinicians should ask the patient to describe what happens, as non-mechanical causes such as severe pain may account for the inability to move. Patients with true locking often describe being able to use certain motions or manipulations to "unlock" the joint.

Complaints of joint instability may be due to subluxation or weakness of the joint stabilizers.

Do you have any numbness or tingling? Pain or paresthesias radiating down the arm or to the neck raise suspicion for a neurologic injury.

How often do you throw, and how much rest do you get? The frequency of pitching games, number of pitches thrown, and days of rest between pitching games and overall are important risk factors for injury. Does the athlete throw when the arm is fatigued? It is important to account for the totality of throwing, including all pitches during competition, warm-ups, team practices, and informal throwing with parents, friends, and during other activities (eg, against a wall). It is often helpful to learn the number of teams a pitcher plays on and whether the athlete is participating in throwing "showcases" (tournaments where scouts from higher level teams come to assess potential players), as participation in such events appears to be associated with a higher risk of developing overuse injuries. Does the thrower have an off season? It is important, particularly in youth athletes, to determine how much time during the year is spent in non-throwing activities since year round throwers are at much higher risk for throwing-related injuries. Asking this question also helps reinforce the importance of rest in the minds of the patient and their parents.

For youth pitchers:

-What types of pitches do you throw? Contrary to classic teaching, throwing curveballs is no harder on the arm than throwing fastballs [36,37,58]. Nevertheless, pitchers working on a new pitch may recently have increased the total number of pitches they are throwing.

-How hard do you throw? If a pitcher knows exactly how hard he or she can throw, it is likely that some adult involved with their team has a radar gun. Youth pitchers who consistently attempt to maximize their velocity often do so at the expense of placement and mechanics and are at higher risk for injury.

During which part of throwing do symptoms occur? Certain injuries are more likely to occur or become symptomatic during different phases of throwing (see "Throwing injuries: Biomechanics and mechanism of injury"). This assessment is particularly useful for acute injuries. With chronic injuries, the athlete may alter his or her throwing motion to compensate and thus the mechanics seen by the clinician do not reflect those that contributed to the injury.

Other important questions:

History of previous injury or surgery, particularly if it involves the extremity under evaluation.

History of other activities including work, sports, and hobbies that might cause arm or shoulder fatigue—eg, weightlifting, swimming, painting, or other work requiring repetitive overhead motions, lifting, or carrying.

Past medical history – Especially of thyroid disease, connective tissue disorders, autoimmune disease, diabetes, and infectious disease that is recent or involved the upper extremity being evaluated (eg, septic arthritis). Such conditions either predispose the athlete to slower soft tissue healing or in the case of autoimmune and infectious disease may be the cause of pain.

History of constitutional signs and symptoms – Including weight loss, fevers, chills, night sweats, or rash. Presence of constitutional signs and symptoms should prompt evaluation for an infectious, autoimmune, or neoplastic source of pain.

Family history – Especially of connective tissue disorder and autoimmune conditions.

PHYSICAL EXAMINATION — The history helps to determine where to focus the examination. Nevertheless, a general assessment of mobility and strength should be performed. Since throwing is initiated by the lower extremities, it is important to examine both lower extremities and the trunk, before moving on to the upper extremities. In general, the throwing side should be compared with the non-throwing side, with special attention paid to joints whose arcs-of-motion are unequal. A video analysis of the athlete's throwing motion may be useful in diagnosing the injury.

Critical areas to examine in the thrower include:

Rotator cuff strength (see "Physical examination of the shoulder", section on 'Examination for rotator cuff pathology'); overall shoulder mobility and strength, including internal and external rotation

Posterior shoulder capsule laxity/tightness (see "Physical examination of the shoulder", section on 'Special tests for shoulder instability' and "Physical examination of the shoulder", section on 'Range of motion')

Elbow mobility (including flexion, extension, supination, pronation) and ulnar collateral ligament (UCL) laxity (see "Evaluation of elbow pain in adults", section on 'Range of motion')

Scapular position and motion (see "Physical examination of the shoulder", section on 'Scapulothoracic motion and strength')

The general physical examination should include:

Observation: Look for evidence of acute injury such as swelling, ecchymosis, deformity

Assessment of alignment and motion with patient standing, including:

Evaluation of ankle, knee, hip, and trunk – Typically, most of the force necessary for throwing in sport is generated by the lower extremities and transferred to the upper extremity via the trunk. Asymmetry or restriction of motion at any part of the kinetic chain outside the upper extremity may put the thrower at risk for injury. Motion restriction or weakness in a lower extremity may cause an athlete to generate force primarily from the shoulder resulting in overuse injury. The examiner should note any asymmetries in the patient's posture and stance, restrictions in spine motion, and atrophy of the lower extremity musculature.

Evaluation of elbow-carrying angle – The normal carrying angle is 5 to 10 degrees in males and 10 to 15 degrees in females, with the dominant arm having a slightly larger carrying angle compared to the non-dominant side (picture 19). A smaller carrying angle may be due to bone spurs or soft tissue restrictions. A larger carrying angle may be due to the increased size of the medial epicondyle. This can occur with traction apophysitis, which causes the anterior capsule of the elbow to become tight, producing a loss of terminal elbow extension.

Evaluation of shoulder and scapula position – Many pitchers manifest altered glenohumeral rotation. Motion restrictions, especially limited internal rotation of the glenohumeral joint, may predispose to injury. Asymmetry of the scapulae may represent shoulder girdle weakness or motion restrictions.

Hamstring flexibility and hip mobility – Poor hamstring flexibility may predispose athletes to hamstring strains, which tend to occur mostly while fielding and running the bases, but occasionally occur while throwing. Hamstring flexibility and hip mobility are important for proper foot placement when pitching [59]. Loss of motion, particularly rotational movement, may cause inefficient transfer of energy from the lower extremities to the trunk, leading to loss of velocity and alterations in throwing mechanics. (See "Hamstring muscle and tendon injuries", section on 'Physical examination' and "Musculoskeletal examination of the hip and groin".)

Core strength [60]

Ability to stand on one leg without significant sway

-Trendelenburg posturing (figure 3 and picture 20) or hip rotation is suspicious for proximal core weakness

One-leg squat to quarter- or half-squat position (picture 21)

-Trendelenburg posturing, hip rotation, and/or arm waving is suspicious for proximal core weakness

INDICATIONS FOR ORTHOPEDIC CONSULT OR REFERRAL — Few throwing-related injuries require immediate surgical intervention. These include:

Joint dislocation with neurovascular compromise

Open fracture (see "General principles of fracture management: Early and late complications", section on 'Acute complications')

Acute compartment syndrome (see "Acute compartment syndrome of the extremities")

In addition, immediate referral to vascular surgery and interventional radiology is prudent for axillary-subclavian vein thrombosis (Paget-Schroetter syndrome). (See 'Axillary-subclavian vein thrombosis' above.)

In the throwing athlete, the following injuries should be referred urgently for consideration of surgical treatment:

Complete or high-grade partial rotator cuff tear (see "Presentation and diagnosis of rotator cuff tears" and "Management of rotator cuff tears")

Complete rotator cuff tears have a "surgical window" which requires early surgical repair; otherwise, the ends may scar in a contracted position, making surgical repair impossible

Complete ulnar collateral ligament (UCL) tears

Displaced or rotated medial epicondyle avulsion fractures (see "Elbow injuries in active children or skeletally immature adolescents: Approach", section on 'Medial elbow pain')

Failure of the athlete to respond to nonoperative treatment warrants referral. Labral tears are among the injuries in throwing athletes less likely to respond to nonoperative management.

DIAGNOSTIC IMAGING

Plain radiographs and ultrasound — Plain radiographs are useful for general evaluation and for ruling out fractures, dislocation, tumors, and loose bodies.

A standard elbow series should include anteroposterior (AP), lateral, and oblique (eg, radiocapitellar) views (image 11 and image 12).

A standard shoulder series (image 13) should include AP (image 14), true AP (Grashey view), and lateral (eg, scapular Y view (image 15), outlet view) views. Special views are not routinely obtained but are needed in some instances (eg, prior history of shoulder trauma) and may include:

Axillary view (image 16) – Useful for evaluating glenoid rim fractures and dislocations

West Point axillary lateral (image 17) – Useful for evaluation of instability

Stryker notch views – Useful for finding Hill-Sachs lesions

Zanca view (picture 22 and image 18 and image 19) – Useful for evaluating acromioclavicular joint

Ultrasound is particularly useful for dynamic evaluation. Although operator-dependent, ultrasound is as good as MRI for the evaluation of many soft tissue injuries, such as tendon tears. (See "Musculoskeletal ultrasound of the shoulder" and "Musculoskeletal ultrasound of the elbow".)

Advanced imaging — Computed tomography (CT) scans are useful for the evaluation and presurgical planning of complex fractures.

Magnetic resonance imaging (MRI) is useful for the evaluation of soft tissue injuries, including tendinopathies, ligament sprains, plica, and chondral defects. MRI is the best test for early detection of avascular necrosis. An MRI arthrogram is used for the evaluation of some injuries (eg, superior labrum anterior posterior [SLAP] lesions) and consists of injecting a contrast media, usually gadolinium, into the joint prior to the MRI scan.

Bone scan is most useful for the evaluation of stress fractures. (See "Overview of stress fractures", section on 'Imaging studies'.)

Additional ultrasound resources — Instructional videos demonstrating proper performance of the ultrasound examination of the posterior elbow and related pathology can be found at the website of the American Medical Society for Sports Medicine: posterior elbow ultrasound examination. Registration must be completed to access these videos, but no fee is required.

All diagnostic imaging findings should be interpreted in the context of clinical findings, as studies have found that a significant percentage (over 50 percent in several studies [10,11,61]) of asymptomatic throwing athletes have abnormal radiographs [62-64].

STEPWISE CLINICAL APPROACH — Below, basic algorithms are provided to help guide clinicians through the diagnostic assessment of common throwing injuries. As with all algorithms, the distinctions made between diagnoses may be less clear when assessing actual patients, and there are always exceptions. Our intent is to provide a schematic approach to assessing throwing injuries and assistance in making a diagnosis, but ultimately clinicians must use their clinical judgment about the relevance of the algorithm and when to consider alternative diagnoses.

Initial step: Determine the location of pain – The first step is to determine where the patient feels pain. Most commonly in throwing athletes this is either the shoulder or the elbow. A complaint of diffuse pain and swelling in the upper extremity, especially on the throwing side, should raise red flags for possible effort thrombosis, which is assessed with an appropriate imaging study. (See 'Axillary-subclavian vein thrombosis' above.)

Shoulder problems

Step one: Determine if injury is acute or chronic – If the patient can pinpoint a specific incident when pain began, an acute injury is more likely. For acute injuries with the following associated findings, the diagnoses listed below are most likely:

Instability and sudden loss of control and velocity – Suspect transient shoulder subluxation ("Dead arm syndrome")

Significant weakness of rotator cuff – Suspect acute rotator cuff tear. Clinicians should be aware that most pitchers, even those who are uninjured, manifest mild rotator cuff weakness if examined immediately after pitching.

Step two: If chronic, determine the region of shoulder involvement:

A flow chart outlining the diagnostic approach to chronic, throwing-related shoulder injuries is provided (algorithm 1).

Lateral pain

-Older athlete (closed growth plate) – Suspect rotator cuff tendinopathy or tear or anterior impingement

-Younger athlete (open growth plate) – Suspect Little League shoulder

Anterior pain (area of coracoid process)

-Suspect SICK scapula syndrome with anterior impingement or coracoid impingement

Deep pain

-Loss of internal rotation – Suspect glenohumeral internal rotation deficit (GIRD) usually more posterior pain

-Catching sensation – Suspect labral tear

Elbow problems

Step one: Determine if injury is acute or chronic – If the patient can pinpoint a specific incident when pain began, an acute injury is more likely. For acute injuries with the following associated findings, the diagnoses listed below are most likely:

Significant weakness – Suspect a muscle or tendon rupture (uncommon)

Instability – Suspect ulnar collateral ligament (UCL) injury in the mature athlete or an avulsion fracture in the skeletally immature

Locking sensation – Suspect osteochondritis dissecans (OCD) or a loose body within the joint. Both are related to chronic underlying injuries but locking symptoms may start abruptly.

Radicular pain – Suspect a neurologic cause of pain. Must consider referred pain (eg, herniated cervical disc, particularly in older athletes).

Step two: If chronic, determine the region of elbow involvement:

A flow chart outlining the diagnostic approach to chronic, throwing-related elbow injuries is provided (algorithm 2).

Lateral-sided pain – Suspect OCD, particularly if patient has experienced locking episodes. Osteochondrosis of the capitellum (Panners disease) is an important consideration in young throwers (age 7 to 10).

Medial-sided pain

-Valgus stress causes pain – Suspect UCL injury if skeletally mature

-Resisted wrist flexion causes pain – Suspect common flexor strain

-Neurologic symptoms – Suspect ulnar neuropathy

-Young athlete (open growth plate) – Suspect avulsion fracture or apophysitis (Little League elbow)

Posterior elbow pain

Valgus stress causes pain:

-Posteromedial tenderness – Suspect valgus extension overload

-Point bony tenderness – Suspect olecranon stress fracture

Resisted elbow extension causes pain:

-Point bony tenderness – Suspect olecranon stress fracture

-Diffuse tenderness or non-bony tenderness – Suspect triceps tendinopathy

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: General issues in muscle and tendon injury diagnosis and management" and "Society guideline links: Muscle and tendon injuries of the upper extremity (excluding shoulder)".)

SUMMARY AND RECOMMENDATIONS

Key concepts – Throwing-related injuries can be sustained through classic ball throwing, as performed by baseball pitchers or cricket bowlers, by throwing implements other than balls (eg, javelin), or by performing throwing-like actions (eg, tennis serve or volleyball spike). All such movements involve complex biomechanics and exert large forces on the shoulder and elbow.

Improper biomechanics, forces beyond the capacity of an individual's tissues, or cumulative trauma from excessive throwing can cause injury. The biomechanics of throwing and the risk factors for throwing injuries are discussed separately. (See "Throwing injuries: Biomechanics and mechanism of injury".)

Several focal shoulder or elbow injuries may be incurred, but all structures involved in throwing are intimately related, and more than one may contribute to upper extremity pain.

In throwing athletes, anatomic adaptations develop that can produce pathologic changes in movement, ultimately resulting in structural damage. Important findings for common and important throwing injuries of the shoulder and elbow are summarized in the following table (table 1). Each diagnosis is described in greater detail in the text.

Shoulder injuries – Common throwing injuries of the shoulder include:

Transient subluxation

Rotator cuff injuries

Labral injuries

Glenohumeral internal rotation deficiency

Bennett lesion (mineralization at posteroinferior glenoid)

Proximal humeral epiphysiolysis ("Little League shoulder")

Scapular dysfunction (see 'Shoulder injuries' above)

Elbow injuries – Common throwing injuries of the elbow include:

Ulnar collateral ligament injury

Tendon injuries

Valgus extension overload syndrome

Stress fractures

Osteochondroses

Other conditions (see 'Elbow injuries' above)

History and physical examination – Key elements of the history and physical examination for throwers with upper extremity symptoms are reviewed in the text. In all such patients, clinicians should perform the following assessments:

Overall shoulder mobility and strength

Rotator cuff strength

Posterior shoulder capsule tightness

Scapular position and motion

Elbow mobility and ulnar collateral ligament laxity (see 'History' above and 'Physical examination' above)

Indications for surgical consultation – Immediate surgical consultation is required for any open fracture, acute compartment syndrome, joint dislocation with neurovascular compromise, and axillary-subclavian vein thrombosis. Urgent orthopedic consultation (within a few days) is indicated for complete or high-grade partial rotator cuff tears, complete ulnar collateral ligament tears, and displaced or rotated medial epicondyle avulsion fractures. (See 'Indications for orthopedic consult or referral' above.)

Diagnostic imaging – Plain radiographs are commonly obtained as part of the initial evaluation and are useful for ruling out fractures, dislocation, tumors, and loose bodies. Bedside ultrasound allows for dynamic assessment and comparisons with the contralateral extremity. Additional imaging studies are obtained based upon the most likely conditions. (See 'Diagnostic imaging' above.)

Stepwise diagnostic approach – A stepwise approach to diagnosis is provided in the text. Key steps include determining whether the injury is acute or chronic, and, if chronic, determining the focal site of symptoms. The following flow charts outline the diagnostic approach to chronic, throwing-related injuries of the elbow (algorithm 2) and shoulder (algorithm 1). (See 'Stepwise clinical approach' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Tracy Ray, MD for his assistance developing this topic.

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References

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