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The Thrower’s Shoulder
The thrower's shoulder is a unique and challenging subset of sports medicine given the extreme demands placed on the glenohumeral joint and surrounding soft tissue structures. For purposes of discussion, we will mainly focus on medical issues as they relate to baseball players; however, we certainly acknowledge that many other sports (volleyball, tennis, handball) and positions (quarterbacks) have overlapping demands and injury patterns and will draw on literature based in those disciplines as well.
Generally, these are complex conditions that can present several difficulties in both diagnosis and treatment. The ability to throw a baseball at velocities exceeding 90 miles/h is the result of a complex transfer of energy from the lower extremity through the trunk, shoulder, elbow, and hand. The stresses placed on the individual links of the kinetic chain during throwing can lead to failure of and injury to these structures. The repetitive acceleration and deceleration of the arm during the throwing motion subjects the shoulder to extreme positions and stresses, which can lead to chronic overuse-type as well as acute shoulder injuries.
The thrower's shoulder endures supraphysiologic forces as professional pitchers have demonstrated the ability to generate up to 92 Nm of humeral rotation torque, which is greater than the torsional failure limit found in cadavers. The shoulder experiences forces nearly half of body weight during the late cocking phase and distraction forces of nearly the entire body weight during the deceleration phase with peak angular velocities of 7250 degrees/s. To perform such supraphysiologic feats, the shoulder makes key adaptations over time, which will be discussed further. However, the magnitude and repetition of such stresses placed on the shoulder can lead to injuries to important structures.
Sports medicine physicians who treat overhead athletes must be familiar with the subtle changes in their performance to recognize an injury to the shoulder. Differing from the general population, pitchers may not report pain or weakness, but instead complain of decreased velocity or accuracy. A thorough understanding of the anatomy and adaptive changes that occur in the thrower's shoulder along with the physiology of throwing is necessary to provide treatment in these complicated cases. In addition, a systematic approach to evaluating the shoulder is critical as many injuries are multifactorial due to mechanical, technical, training-related, and structural factors.
Adaptations to the Throwing Shoulder
Over time, overhead athletes develop well-described adaptations in response to the stresses placed on the shoulder as a result of throwing. These changes likely begin in early childhood as the athlete begins throwing regularly. Both soft tissue and bony adaptations occur, and while sometimes subtle, they are imperative to the thrower's ability to function at a high level under otherwise nonphysiologic conditions.
One of the primary physiologic changes in the thrower's shoulder is seen in range of motion (ROM). Most throwers exhibit a difference in the amount of external rotation (ER) and internal rotation (IR) between their throwing and non-throwing shoulders, generally with an increase in ER and decrease in IR on their dominant side ( Fig. 45.1 ). A comparative loss of IR greater than 20 to 25 degrees has been termed glenohumeral internal rotation deficit (GIRD) although the pathologic nature of this change has been called into question more recently.
Brown et al. reported that professional pitchers had a mean shoulder ER of 141 degrees with the arm at 90 degrees of abduction, which was 9 degrees more than their nondominant arm and also 9 degrees more than the throwing shoulders of position players. Although the magnitude of IR and ER seen in the dominant and nondominant arm differ, the total arc of motion is usually similar. Wilk et al. reported a mean ROM arc of 176 degrees (both sides) and that the total motion in the throwing shoulder was within 7 degrees of the contralateral side. GIRD has classically been felt to be a maladaptive change, and indeed, some modern literature does support increased injury risk with GIRD. However, total arc of motion and even ER deficits are increasingly recognized as perhaps more problematic and significant risk factors for injury.
Certainly, soft tissue accommodations occur over time in the static and dynamic stabilizers surrounding the shoulder, but bony adaptations have also been well documented. Several authors have demonstrated a 10- to 17-degree increase in humeral retroversion in the dominant arms of throwers relative to the contralateral side, which allows for increased external rotation. Yamamoto et al. assert that the repetitive throwing motion does not directly increase the retroversion of the humeral head but rather restricts the natural, physiologic derotation of the humeral head during growth. And while it is unclear at what age these bony changes begin to occur, they certainly appear to represent adaptive growth over time.
Soft tissue adaptations are also seen as a result of the large rotational and distractive forces acting upon the glenohumeral joint, resulting in posterior capsular tightness and anterior capsular laxity. The term microinstability has been used to describe the acquired capsular laxity that allows increased humeral head translation and rotation. While a variety of theories exist, the cause of this microinstability is believed to be repetitive tensile loading as a result of scapular protraction or repetitive ER, particularly as it relates to the deceleration phase of throwing. But despite the restrictive posterior soft tissue envelope, pitchers appear to have increased overall laxity of the shoulder compared with athletes who play other positions. Bigliani et al. found a sulcus sign in 61% of dominant shoulders in professional pitchers compared to only 47% in position players. While there is likely a congenital component that self-selects for shoulders able to tolerate repetitive overhead motion, these capsular changes appear to be a necessary (as opposed to pathologic) adaptation to throwing as increased anterior–posterior humeral head translation has been demonstrated in both symptomatic and asymptomatic pitchers.
Biomechanics of Throwing
To fully understand the spectrum of injuries, the stresses placed on the shoulder during the action of throwing must be understood. The overhead throwing motion can be broken down into six discrete phases: wind-up, early cocking, late cocking, acceleration, deceleration, and follow-through ( Fig. 45.2 ). The entire motion takes approximately 2 seconds although 75% of that time occurs during the pre-acceleration phases.
During the first phase of throwing (wind-up), the body rises over the center of gravity and the shoulder is placed in slight abduction and IR. At this point in the pitching motion, no stress is placed on the upper extremity.
Early cocking is the second phase where the arm is placed into abduction and ER, and the arm rotates behind the body axis approximately 15 degrees. Once the arm reaches the top of its motion and stops moving backward, this is the onset of the late cocking phase.
The third phase is late cocking, which begins as the lead leg contacts the ground and ends when the arm reaches maximal ER of nearly 180 degrees. During this phase, the scapula retracts to provide a stable glenoid surface for the humeral head to compress against. The upper arm is maintained in 90 degrees to 100 degrees of abduction, and the elbow moves even with the plane of the torso. The humerus progresses into ER, and the humeral head translates posteriorly on the glenoid because of the increasing tightness of the anterior structures. The infraspinatus and teres minor muscles are active early in the late cocking phase, leading to the ER of the humerus. The subscapularis becomes active late in this phase as IR begins. The result is that the rotator cuff as a whole compresses the humeral head against the glenoid with significant force.
The acceleration phase begins as the humerus internally rotates and ends when the ball is released. Although significant angular velocity is developed by the muscular forces around the shoulder during this phase, little stress is noted in the shoulder. The triceps becomes active early in the acceleration phase, followed by the pectoralis major and the latissimus dorsi muscles later.
The fifth phase (deceleration) begins just after the ball is released and ends when humeral IR ceases. This phase leads to tremendous stresses generated by the rotator cuff muscles as the arm is brought to an abrupt halt. Eccentric loads on the posterior cuff reach 1000 N as the muscle dissipates the kinetic energy generated in the earlier phases of the throw.
The final phase of the throwing motion is the follow-through. It is at this point of the pitch that the body regains balance and stability. The muscles cease to fire and the compressive forces across the glenohumeral joint drop significantly.
Pathophysiology
Internal Impingement
In 1992, Walch et al. initially reported on contact that occurs between the supraspinatus tendon and the posterosuperior edge of the glenoid cavity in tennis players and coined the term internal impingement. It represents a collection of injuries characterized by pathologic contact between the rotator cuff (posterior supraspinatus and anterior infraspinatus) and the greater tuberosity with the posterosuperior glenoid and labrum leading to articular-sided rotator cuff tears and posterosuperior labral tears ( Fig. 45.3 ). This contact is only possible by placing the shoulder in the supraphysiologic position of extreme ER and anterior translation seen while throwing. While the concept of internal impingement endures, no clear etiology has been established, and multiple theories exist.
The theory of microinstability centers on the idea of hyperangulation—that as the humeral shaft moves posteriorly out of the plane of the scapula, the accompanying weakness allows the humeral head to drift anteriorly and subsequently produces a lengthening of the anterior capsule, which leads to a subtle form of anterior instability. Jobe and Pink believed that the repetitive and forceful overhead activity causes a gradual stretching out of anteroinferior capsuloligamentous structures, leading to subclinical instability and impingement . Indeed, throwers often have an element of hyperlaxity as previously discussed, and some would posit that tipping the scale from laxity to instability is the catalyst for developing internal impingement.
Burkhart and Morgan proposed that the pathology is a result of a hypertwisting mechanism with large shear stresses leading to fatigue failure of both the rotator cuff and the biceps tendon insertion point of the labrum. These lesions result from an acquired posterosuperior instability that is caused by posteroinferior capsular tightness, which they termed the peel-back mechanism. They reasoned that the posterior capsule must withstand tensile forces of up to 750 N during the deceleration and follow-through phases of throwing. The posterior tensile forces placed on the shoulder during these actions are offset by the eccentric contraction of infraspinatus and the posteroinferior capsule, including the posterior band of the inferior glenohumeral ligament. The posterior contraction is believed to shift the center of rotation of the shoulder to a more posterosuperior location, creating instability with the shoulder in abduction and ER.
Muscle fatigue and imbalance may also play a role in the development of internal impingement by altering the mechanics of the shoulder. Fatigue-related humeral hyperextension can occur during the late cocking phase when the rotator cuff muscles cannot completely resist the large acceleration forces generated while pitching. Progressive delamination of the posterior capsulolabral structures and the rotator cuff may occur as the violent deceleration of the arm during follow-through may cause an abrasive degeneration of the rotator cuff on the posterosuperior aspect of the glenoid. Whether it is the driving force or simply a result of the process, scapular dyskinesis is also often seen with internal impingement.
Although a range of theories have been proposed regarding the pathophysiologic etiology of internal impingement, it seems clear that the causes of disability in the shoulder used for throwing are multifactorial and require an equally multicentric approach to care.
Dynamic Shoulder and Scapular Stability
Particularly in overhead athletes, focal weakness and muscle imbalance play a role in the development of shoulder pain. Multiple studies have demonstrated the protective effect of maintaining shoulder strength (especially ER strength) as a means of preventing injuries. Any muscle imbalance alters the anterior–posterior force couple that stabilizes the glenohumeral joint and increases the compression forces in the joint. Disrupting the agonist–antagonist balance impairs a pitcher's ability to appropriately accelerate and decelerate while throwing.
Although often neglected, the scapula is the critical link in the kinetic chain of energy transfer from the trunk to the humerus. The scapula provides a stable base upon which the rotator cuff muscles activate, and it coordinates scapulohumeral rhythm, the coupled movement between the scapula and the arm allowing for placement of the upper extremity in space. Scapular movement combines three motions (upward–downward rotation, internal–external rotation, and anterior–posterior tilt) with two sliding translations (up–down and anterior–posterior). It is commonly believed that scapular malposition can also be a cause of shoulder problems in throwers.
Kibler and Thomas described dyskinesis as an alteration of static scapular position or dynamic scapular motion in coordination with arm motion. The resulting protracted, downward rotated and anteriorly tilted scapula is caused by abnormal muscular imbalances. The protracted scapula is almost universally unfavorable for shoulder function as it decreases the subacromial space and effectiveness of the rotator cuff while also increasing impingement and strain on the static glenohumeral ligaments and dynamic shoulder stabilizers. Accordingly, most goals of management center on regaining functional retraction. And while dyskinesis may itself be the source of a thrower's dysfunction, it can also merely be the byproduct of underlying pathology. Recognition by the physician is key, but high-quality rehabilitation by a thoughtful physical therapist is the cornerstone of treatment for dyskinesis with the possibility of operative intervention if concomitant surgical pathology exists.
The mnemonic SICK scapula was originally coined by Burkhart and colleagues in 2003 and is a subset of dyskinesis relating exclusively to overhead athletes. It represents s capular malposition, i nferior medial border prominence, c oracoid pain, and dys k inesis. The hallmark feature is a “dropped” scapula with asymmetry in the throwing shoulder where the scapula sits lower than the nondominant side. This static asymmetry is compounded by a dynamic dyskinesis as the athlete goes through the throwing motion. The physical exam should consist of static scapular measurements with the patient standing, a meticulous coracoid exam (as the anterior pain can mimic labral pathology), and pain-free forward flexion while performing the scapular retraction test. These changes in scapular position lead to external impingement as a result of anterior tilt, internal impingement, decreased rotator cuff strength, and anterior capsular strain. Altered static and dynamic scapular mechanics arise from overuse and weakness of scapular stabilizers and posterior rotator cuff muscles. Thus SICK scapula is a nonoperative condition that improves with diligent rehabilitation; however, success hinges on athlete compliance and the ability to get the scapula back to a symmetric position with the contralateral side and keep it there.
Glenohumeral Internal Rotation Deficit
Bony and soft tissue adaptations over time allow pitchers to develop a relative increase in ER and loss of IR compared to their nondominant side as well as the general population. As discussed, GIRD has classically been felt to be a maladaptive state with an increased injury risk, but this has been called into question more recently. Posterior capsule tightness has been shown to result in multiple kinematic alterations such as increased ER but decreased IR, horizontal adduction, and flexion. It has been associated with multiple injuries including external (subacromial) impingement, internal impingement, and superior labral from anterior to posterior (SLAP) tears. More recently, the importance of total arc of motion as opposed to GIRD and the importance of ER deficits over IR deficits as it relates to injury risk has been established. Further investigation may help to parse out whether GIRD is truly pathologic or merely a necessary adaptation to repetitive throwing.
History
The etiology of a shoulder injury in an overhead throwing athlete is best determined by taking a thorough history, and thus a familiarity with not only the sport but also position-specific demands is required. Pitchers, for instance, frequently describe feelings of heaviness/sluggishness, stiffness, fatigue, weakness, and the inability to “bring it.” These subjective complaints are often accompanied by objective findings of decreased velocity on fastballs, lack of movement on breaking balls, and decreased accuracy. While acute injuries do occur in overhead throwing athletes, it is much more common for injuries to be a result of overuse and fatigue. The timing of the onset of symptoms, current and previous treatment modalities, and a history of a previous injury to the shoulder should be determined. The athlete should also be asked specific pitching-related questions including any recent change in mechanics, development of a new pitch, increased pitch count, alteration to training regimen, in what phase of the throwing the pain occurs, and if any other part of the body has been injured that could be changing the throwing mechanics. The role of the hip, core, and lumbar spine are also critical as injuries to these areas can lead to compensatory alterations in throwing mechanics and increased stress on the shoulder.
Typical symptoms in an overhead throwing athlete with pain include anterosuperior or posterosuperior shoulder pain in the late cocking phase. Labral tears specifically may lead to mechanical symptoms such as popping, locking, or snapping. Although the details are beyond the scope of this chapter, questioning the athlete about symptoms related to the cervical spine or thoracic outlet syndrome is also critical to rule out pathology masquerading as shoulder pain.
Physical Examination
A thorough and systematic physical examination should be performed for all throwers who present with shoulder pain. The aid of a physical therapist and/or athletic trainer with a solid understanding of throwing mechanics can also be helpful to isolate dynamic issues less familiar to clinicians. The examination should focus not just on the upper extremity but also on the entire kinetic chain, including the lower extremities and trunk. The athlete's natural posture may be evaluated while he or she walks into the room and during history taking. The overall alignment, shoulder height and position, pelvic tilt and rotation, lower extremity alignment, head and neck position, and arm position must be evaluated. Functional movements should be assessed to determine hip and trunk control, muscle imbalance, and inflexibilities, which can be accomplished by having the patient balance on one leg and do a single leg squat. While performing these maneuvers, the patient should be observed for compensatory movements such as pelvic tilt or rotation. Ankle flexibility, lumbar and thoracic spine, and shoulder girdle mobility can be assessed by having the patient perform a full squat with heels on the ground and arms overhead. Flexibility of the hamstrings and the thoracic and lumbar spine can be assessed by having the patient perform a straight-leg toe touch. While supine, both hips should be evaluated for ROM and to determine if any femoroacetabular impingement is present.
Once a comprehensive examination of the remainder of the kinetic chain is completed, a focused evaluation of the affected shoulder is performed. The entire shoulder complex must be visualized. Male patients are asked to remove their shirts, and female athletes should be asked to wear a tank top or sports bra. First, the shoulder is inspected visually to evaluate for muscular atrophy or scapular winging. The position of the scapula at rest should be noted, including asymmetry of scapular tilt, rotation, and elevation or depression. After visual inspection, the shoulder should be systematically palpated to identify areas of pain. All bony prominences are palpated, including the bicipital groove, greater tuberosity, coracoid, and acromioclavicular (AC) joint.
Shoulder ROM, both active and passive, should be assessed in both standing and supine positions with special attention given to glenohumeral and scapulothoracic motion. Glenohumeral joint passive ROM is assessed for ER and IR at 90 degrees of abduction and for ER at 45 degrees of abduction in the scapular plane. Increased ER with the arm at the side with the patient in the supine position can be reflective of rotator interval laxity. Increased ER in the abducted and externally rotated position reflects anteroinferior capsular laxity and/or humeral retroversion. In addition to ER and IR, passive and active forward flexion and abduction need to be recorded. Palpation of the shoulder during ROM can uncover crepitus, which may indicate bursal thickening, labral tear, or rotator cuff pathology. Subacromial impingement is assessed using the Hawkins-Kennedy and Neer tests.
Muscle strength should be evaluated after shoulder ROM is determined. Careful manual muscle strength testing should aim to isolate the muscle being tested and compare to the contralateral, uninjured side.
Several tests are helpful to examine the labrum of the throwing athlete. The O'Brien active compression test is frequently used to evaluate for SLAP tears. Although the sensitivity has been reported at 100% with 97% to 99% specificity in the general population, the reliability markedly decreases in athletes (78% sensitivity, 11% specificity). The passive distraction test is performed supine with the shoulder flexed to 150 degrees and the forearm is passively pronated to elicit increased biceps tension. Deep pain or a pop with passive pronation is suggestive of a superior labral injury. Speeds test, commonly used for biceps pathology, has shown variable sensitivity and specificity in identifying SLAP tears in the literature. The Crank test evaluates the anterior glenoid labrum although the sensitivity ranges widely in the literature from 13% to 91%. The posterior labrum is evaluated with the labral shear, jerk, and Kim tests. Differentiating biceps pathology can be particularly challenging; however, the “3-pack” exam (O'Brien sign + throwing test + bicipital tunnel palpation) described by Taylor et al. has demonstrated excellent sensitivity in diagnosing both intra- and extra-articular injuries to the biceps labral complex. The shoulder should also be evaluated for frank instability by testing the integrity of the anterior and posterior labrum as well as testing for a sulcus sign.
An important but often underemphasized part of the shoulder exam is evaluation of the scapulothoracic joint. Many injured throwers demonstrate loss of ER control and elevation and posterior tilt of the scapula, which are manifested as medial scapular border winging. Both scapulas should be visualized with the arms at the sides; note is made of any asymmetry of tilt, rotation, elevation, or depression. As discussed, the SICK scapula presents with a static “dropped” appearance along with dynamic dyskinesis. Evaluation of scapular movement and scapulohumeral rhythm in comparison to the contralateral side is important. When evaluating dyskinesis, the scapular assistance test (assisted upward rotation and posterior tilt) and scapular retraction test (manually placing the scapula in a retracted position) are diagnostic by improving pain and increasing motion and strength respectively.
In summary, examination of the painful throwing shoulder must be complete and systematic as these can be complex, subtle injuries. The examiner must develop a routine to avoid missing important findings. Additionally, the examiner must avoid focusing only on the shoulder and instead perform an assessment of the entire kinetic chain. The input of a physical therapist and/or athletic trainer well versed in overhead athletes also provides tremendous benefit.
Imaging
Complete evaluation of the shoulder in an overhead throwing athlete should include the standard radiographic views of the shoulder consisting of anteroposterior, axillary, and outlet views. These images allow visualization of the glenohumeral articulation, as well as acromial morphology and visualization of the inferior glenoid. Other useful views may include the Stryker notch and West Point views depending on the situation.
After obtaining plain radiographs, the next step is generally magnetic resonance imaging (MRI). In overhead throwing athletes, the most common lesions are partial-thickness rotator cuff tears and glenoid labral pathology. MRI arthrograms (MRA) involve the use of intra-articular contrast material and can be helpful in delineating rotator cuff (particularly partial-thickness tears) and labral pathology with some studies demonstrating increased accuracy over plain MRI. However, the difference is not dramatic so our bias has generally been against the routine use of MRA for the reason that it adds a relatively large volume of fluid into the joint and distorts normal anatomy and potentially distracts from other pathology. The use of MRI alone requires modern protocols on high-quality (3-T) scanners and partnering with a trusted set of radiologists; in doing so, we have found this to be far preferable. Beyond the traditional sequences, throwers often warrant placing the arm in the abducted ER position (ABER) to delineate more subtle labral and articular-sided rotator cuff pathology ( Fig. 45.4 ). In the setting of internal impingement pathology, MRI findings include articular-sided degeneration and tearing at the junction of the posterior supraspinatus and anterior infraspinatus tendons with associated degeneration and tearing of the posterosuperior labrum. Subcortical cysts and chondral lesions may also be seen in the posterosuperior glenoid and humerus as a result of repetitive impaction.
Given that pitching is a repetitive, supraphysiologic exercise, caution must also be used when interpreting MRI imaging on throwers as there is a high rate of asymptomatic pathology. Connor et al. reported that 40% of dominant shoulders in asymptomatic overhead throwing athletes had partial- or full-thickness rotator cuff tears in their throwing arm compared with no tears in the nondominant shoulders. Similarly, Halbrecht et al. demonstrated a 30% rate of labral tears and 40% cuff tendinosis with dominant-arm MRIs performed in the ABER position compared with the contralateral side. Because MRI findings are often abnormal, particularly in elite athletes, the history and physical exam are critical to help delineate the source of the pathology and must be used in conjunction with imaging.
Computed tomography (CT) is less commonly used in the setting of the painful throwing shoulder. However, it remains the gold standard for evaluation of bony anatomy and measuring both humeral and glenoid version.
Decision-Making Principles
Decision-making in the management of the throwing shoulder ideally follows an algorithmic approach based on available findings and evidence-based treatments. In general, the initial management of most shoulder injuries in overhead athletes is nonoperative, consisting of a period of rest, activity modification, and rehabilitation. Corrective efforts are directed not only at the shoulder but also at abnormalities of the entire kinetic chain. The younger the athlete, the more conservative our approach and the more willing we are to remove them completely from sports for a period of time. However, elite and professional athletes constitute a unique population in which relative rest and targeted therapy may be done to maintain fitness and certain skills while rehabbing. As discussed, the role of a thoughtful physical therapist who understands the demands on that specific athlete cannot be overstated, and communication between patient, physician, therapist, and team is critical.
Wilk and colleagues have described several phases of rehabilitation for overhead throwers with shoulder pain, including the acute phase, intermediate phase, strengthening phase, and return to throwing phase. In the acute phase, local therapeutic modalities focus on reducing pain and inflammation. Nonsteroidal antiinflammatory drugs, injections, ice, and iontophoresis may be used to accomplish this goal. A key to this phase is discontinuation of all activity to allow the shoulder to rest and the modalities to take effect. Shoulder motion must be addressed during this phase of rehabilitation. Stretches such as the sleeper's stretch ( Fig. 45.5 ) are used to treat posterior capsule tightness. A major focus of the first phase of rehabilitation is improving the strength and muscle balance. Focus is therefore placed on returning strength to the external rotators, scapular, and lower extremity muscles.
The goals of the intermediate phase are to progress with strengthening and enhanced flexibility of the shoulder. More aggressive isotonic strengthening activities are used as focus is placed on strengthening the external rotators, scapular retractors, protractors, and depressor muscles. Wilk prefers side-lying ER and prone rowing into ER. Strengthening of the lumbopelvic region and core are also a focus of the intermediate phase of rehabilitation. Jogging and sprinting are integrated into this phase as well to improve lower extremity strengthening and endurance. Upper extremity stretching exercises are also continued.
During the third phase of rehabilitation, the goals are to enhance power and endurance, perform functional drills, and gradually initiate throwing activities. Plyometric drills are also initiated during this phase. These drills are used to enhance dynamic stability, enhance proprioception, and gradually increase the functional stresses placed on the shoulder joint. Dynamic stabilization drills are also performed to enhance proprioception and neuromuscular control. During this phase, an interval throwing program is started. The interval throwing program is started once the athlete has a satisfactory clinical examination, nonpainful ROM, reliable kinetic chain movements, satisfactory isokinetic test results, and appropriate progress in his or her overall rehabilitation program.
Return to throwing is the fourth and final phase of the rehabilitation protocol. This phase typically involves progression of the throwing program. Although a number of approaches for this phase have been described with some variation, the general principles emphasize a strategic progression, often over a period of 6 to 12 weeks, during which the athlete progresses from the initial phase, consisting of short throwing over a limited duration to long toss and subsequently to position-specific throwing and/or throwing from the mound. Each step is taken in a careful fashion, and any increase in symptoms prompts a short period of rest combined with a retreat to the prior phase to allow for resolution of symptoms. Once the athlete has accomplished the final phase of position-specific throwing, the decision can be made to return to competition. A judicious return to play (RTP) is recommended with careful monitoring of activity, innings, pitch count, and periods of rest aimed at limiting the risk of symptomatic recurrence.
Surgical options should be reserved for cases when nonoperative treatment fails and in the setting of certain acute injuries. The surgical procedure is determined by the shoulder pathology that is present; however, the approach in this population is patient-specific. All surgical pathology must be considered and managed systematically for optimal recovery of the athlete, which may require several concomitant surgical interventions such as SLAP repair and articular-sided rotator cuff débridement in the example of recalcitrant internal impingement.
Treatment Options
Aside from acute, operative injuries, the timing of surgery may depend on the relationship to the season of play. An athlete who is currently in-season may attempt to manage a structural shoulder injury conservatively to get through the season before undergoing surgery. This again emphasizes the importance of communication with all of the involved parties and allowing the athlete to participate in shared decision-making. How aggressive the timing and nature of the treatment are also depends on the age of the athlete and his or her level of play.
Internal Impingement
One of the challenges with internal impingement is differentiating normal adaptations from pathologic degeneration. We believe that many of the changes seen on imaging and even at the time of surgery are normal adaptations to the repetitive loads over time in throwers—in order to attain the supraphysiologic motions and forces necessary to throw, impingement must occur. Consequently, some level of change is also seen to the undersurface of the rotator cuff as well as the labrum, creating a so-called “thrower's footprint.” Parsing out typical impingement findings from a pathologic process is challenging and underscores the need for a comprehensive nonoperative regimen.
Internal impingement is associated with a spectrum of pathology and lends itself to multiple treatment options. Those in the early states of impingement tend to have poorly localized pain and may have accompanying stiffness. Starting with a period of rest and nonsteroidal antiinflammatories is reasonable in this setting. For those throwers with more localized posterior shoulder pain, a prolonged period of rest (4 to 6 weeks) is in order along with formal physical therapy. Therapy has been shown to be acutely therapeutic as well as protective against future injuries. The rehabilitation regimen is mainly directed at posterior capsular stretching, correcting scapular dyskinesis, and core strengthening. Given that one theory behind the pathogenesis of internal impingement is microinstability, anterior capsular stretching is generally avoided. Proper throwing mechanics should also be reviewed.
Only after clear failure of high-quality nonoperative treatment of appropriate duration should surgical intervention be considered. Throwers place tremendous demand on the shoulder and should generally give one pause prior to proceeding with surgery; however, internal impingement is a particularly challenging diagnosis to solve operatively. Similar to the algorithm laid out by Heyworth and Williams, we advocate for an approach dictated by the pathology. Exam under anesthesia (EUA) of both shoulders provides a sense of asymmetric laxity, which may be addressed with labral repair ± capsulorrhaphy. Rotator cuff tears in the setting of internal impingement are generally treated with débridement with the exception of high-grade tears, which will be discussed in the following section. Similarly, tears of the posterosuperior labrum can be débrided or repaired depending on the significance of the pathology.
Partial-Thickness Rotator Cuff Tears
The treatment of partial-thickness rotator cuff tears depends on several factors, including the depth and location of the tear, the quality of the tissue, and the athlete's age and playing position. Surgical options include débridement, tear completion and subsequent full-thickness repair, transtendinous repair, and intratendinous repair constructs. However, operative intervention on the rotator cuff of a thrower should be the absolute last resort. Our preference is for a comprehensive course of nonoperative management, and the athlete must definitively fail this conservative treatment by demonstrating persistent inability to throw prior to consideration for surgery.
In the general population, the conventional rule-of-thumb is that a tear involving less than 50% of the tendon insertion is débrided, whereas tears greater than 50% are more suitable for repair. These guidelines were initially adopted by several authors for overhead throwing athletes. However, Rudzki and Shaffer contend that the demands of overhead athletes are different than the average individual and they have concerns about the integrity of a repair withstanding the high forces that will be placed on it. As such, they advocate for a 75% tear threshold prior to repair.
Articular-sided partial-thickness tears represent the most common rotator cuff injuries in throwers, and as such, the vast majority of our surgical management centers around simple débridement back to healthy, stable tendon. For the select few tears involving 80% to 90% thickness, we favor tear completion and anatomic repair. This general rule is particularly relevant for tears involving the anterior or posterior margins of the supraspinatus, which represent the attachment points of the rotator cable; we are less concerned about tears in the mid-portion of the supraspinatus.
Superior Labral From Anterior to Posterior Tears
Injury to the superior labrum in overhead throwing athletes can occur in conjunction with other pathologies or in isolation. Understanding the normal anatomic variants of the superior labrum and biceps insertion is critical to recognizing pathologic changes to the structures. Although the utilization of SLAP repair in the general population is decreasing, it still has a viable role in throwers. Similar to our treatment of partial-thickness rotator cuff tears, a thrower with a SLAP tear must fail extensive nonoperative management and be unable to throw prior to consideration for surgery. In the setting of true pathology to the superior labrum, the stability of the SLAP tear dictates its treatment. Type I SLAP lesions are characterized by fraying of the central labrum without detachment of the biceps anchors and are treated with débridement. Type II lesions consist of isolated detachment of the superior labrum and biceps anchor either anteriorly (II-A), posteriorly (II-B), or involving the entire biceps anchor (II-C); these are typically treated with repair as the tear is believed to be unstable. A bucket-handle tear is present in type III lesions; these tears are treated with débridement and removal of the bucket-handle tissue. Type IV tears involve a bucket-handle component that extends up into the biceps tendon itself, and treatment involves repair of the SLAP ± biceps tenodesis as described in the next section.
Biceps Tenodesis
The popularity of biceps tenodesis is increasing dramatically ; however, there has been understandable trepidation to perform this procedure in overhead athletes. Generally, we have avoided tenodesis in throwers if at all possible given historically poor outcomes; however, in a very selective population, we have had success even with professional pitchers. Type IV SLAP tears that involve a significant portion of the biceps tendon (>30%), such that it is unstable, are candidates. The other role for biceps tenodesis is in the setting of so-called biceps chondromalacia on the humeral head assuming this is consistent with history and physical exam as the etiology of the athlete's symptoms.
Posterior Capsular Contracture and Glenohumeral Internal Rotation Deficit
Posterior capsular contractures have generally responded well to conservative treatment. The “sleeper stretch” is typically the first-line treatment with historical failure rates being exceedingly low, especially in younger pitchers. There are some conflicting reports in more recent literature, though. A randomized, controlled trial of college-level overhead athletes found significant improvement of both IR and adduction with the sleeper stretch. However, a systematic review attributed no benefit to the sleeper stretch and instead found cross-body adduction to be more efficacious. Stretching certainly has limitations based on athlete compliance, and it can only be expected to overcome soft-tissue contracture with the understanding that certain bony adaptations may exist that inherently limit the motion of the shoulder. Still, nonoperative management is overwhelmingly the front-line treatment for posterior capsular tightness.
Authors’ Preferred Technique
The surgical bar should be set very high when discussing the dominant shoulder of a thrower, and aside from acute traumatic injuries, we advocate that athletes complete comprehensive conservative management prior to operative intervention. It must also be emphasized that our discussion centers around general algorithms that should be individually tailored to the clinically relevant pathology of each athlete. When approaching surgery on a throwing athlete, it is important to understand the spectrum of injuries that are commonly seen, as outlined above, and to be prepared to address all intraoperative possibilities. We have found that utilizing a consistent team from nursing to surgical technician to anesthesiologist provides high-level, efficient care for this unique subset of patients.
Regional anesthesia provides tremendous benefit in shoulder surgery over traditional methods with regards to both intra- and postoperative courses ; particularly with the advent of ultrasound guidance, we have found interscalene and supraclavicular blocks to be safe and effective in general practice. However, as it relates to the narrow population of elite and professional athletes, we generally avoid the use of neuraxial blocks given the risk, albeit small, of nerve injury and lasting dysfunction postoperatively. It is important to discuss this prior to surgery with the team as well as the patient to ensure a uniform understanding of the plan.
In terms of positioning, patients are placed in a modified beach chair that is fairly vertical such that the acromion is parallel to the floor. A beanbag is utilized and placed at the medial border of the scapula, which allows for maximal clearance as well as customized support and elevation of the ipsilateral trunk. An articulated arm holder is used for arm positioning throughout the procedure. Prophylactic antibiotics are always given. The skin is cleaned the evening prior and morning of surgery with chlorhexidine as well as formal surgical scrub prior to draping, also with chlorhexidine.
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