0
    88
    views

    Management of the Painful Throwing Shoulder

    The authors review the cause, diagnosis, and proper management of the most common etiologies of shoulder pain in the overhead throwing athlete, including decreased total arc of motion, SLAP tears, rotator cuff pathology, scapular dyskinesis, anterior instability, and neurovascular conditions.

    Authors

    Hunter L. Bohlen; Stephen G. Thon, MD; and Felix H. Savoie III, MD

    Introduction

    Managing the disabled throwing athlete is a complex clinical dilemma for the practicing orthopedic surgeon. Throwing a baseball or softball requires the athlete to generate tremendous force, channeling energy from the legs, through the trunk, into the scapula, and, ultimately, the glenohumeral joint, which must translate that force into ball movement. This kinetic chain is the key to generating the large forces required for pitching a baseball or softball. [1-3] Any abnormality of the kinetic chain will place increased stress on the athlete, increasing the risk for injury. [4]

    To achieve maximal performance, the ligaments and tendons of the shoulder must have enough laxity to tolerate such forces, while also possessing enough stability to prevent injury and subluxation of the humeral head. This leads to adaptive changes of the throwing shoulder, complicating physical examination. [3] The combination of large forces and complex relationships makes pinpointing the cause of shoulder pain challenging, which necessitates a comprehensive understanding of the kinetic chain and how at-risk structures are affected during each phase of the throwing cycle (Figure 1).

    Figure 1. Depiction of the 6 stages of the throwing cycle.

    Initial evaluation of any athlete with a painful throwing shoulder should focus on abnormalities of the kinetic chain, including analysis of: [3]

    • Throwing mechanism
    • Core strength
    • Hip stability
    • Scapular position

    Early recognition and diagnosis are key in developing a proper management plan and preventing progressive injury that may put the athlete’s career at risk. The first-line treatment for a painful throwing shoulder consists of controlled rest and rehabilitation to prevent progression of injury and allow correction of underlying system wide abnormalities. [5] A period of rest and rehabilitation should almost always be done prior to surgical consideration. This does not mean immobilization of the shoulder in a sling, but rather avoidance of pain-generating activities, such as throwing, while aggressively rehabilitating the entire kinetic chain.

    In this paper, we review the cause, diagnosis, and proper management of the most common etiologies of shoulder pain in the overhead throwing athlete, including:

    • Decreased total arc of motion
    • Superior labrum from anterior to posterior (SLAP) tears
    • Rotator cuff pathology
    • Scapular dyskinesis
    • Anterior instability
    • Neurovascular conditions (rare)

    Decreased Total Arc of Motion

    Although evaluation of the capsule has traditionally focused on loss of internal rotation that produces a de-centering of the humeral head, it is now believed that the decrease in total arc of motion in the affected shoulder compared with the opposite, uninvolved shoulder is more significant. [3,6] Recent studies have found that glenohumeral internal rotation deficit (GIRD) may change in short periods of time and may actually represents edema in the posterior shoulder. Thus, the total arc of motion is thought to be a better measure of readiness to play safely.

    The arc of motion should be measured with the patient supine, the arm in 90° of abduction, and the scapula stabilized anteriorly at the coracoid process (Figure 2). Total external and internal rotation of the arm in this position should be measured using a goniometer, and both sides compared. [7] A decrease as small as 10° from the opposite side has been shown to produce an increased risk of injury. [7]

    Figure 2. Photographic demonstration of total range of internal and external rotational motion. Measurements should be done with the shoulder in 90° of abduction

    Manual stretching in external and internal rotation, as well as pec minor stretching, is necessary in overhead athletes. Surgery for capsular release is usually not necessary unless it is part of an overall procedure for the disabled throwing shoulder that has failed adequate rehabilitation.

    SLAP Tears

    The glenoid labrum provides an important stabilizing force during the throwing motion. The most common form of labral injury, at least according to magnetic resonance imaging (MRI), is a peel-back type posterior superior SLAP tear. [8] When the shoulder is in the abducted and externally rotated position of the late cocking phase, the biceps anchor places translation and torsional force on the posterior superior labrum, known as the peel-back mechanism. This effect is most likely a necessary adaptation to the throwing mechanism and as such, rarely requires operative treatment. [9,10]

    Occasionally, there may be excessive internal impingement in the late cocking and early acceleration phase, producing symptoms. In these cases, the labrum may require stabilization, and the undersurface impingement tearing of the infraspinatus may require debridement (Figure 3). [5,8]

    Figure 3. As the arm is moved from an adducted position (left) to an abducted and externally rotated position (right), a peel-back posterior superior labral lesion is visualized from the posterior portal.

    Patients typically present with posterior shoulder pain and a click with rotation in the 90/90 position. [11] The most clinically relevant exam maneuvers for SLAP lesions should reproduce the peel-back mechanism, as those that fail to do so are likely to yield false negatives. [12] Such maneuvers include:

    • Modified Dynamic Labral Shear test (DLS)
    • Biceps load
    • Biceps load II
    • Pronated load
    • Pain provocation
    • Resisted supination external rotation

    The DLS test is the authors’ preferred test to evaluate the significance of a SLAP tear in the overhead athlete. This test is performed with the practitioner standing behind the patient, holding the patient’s arm at the wrist in the 90/90 position. The patient’s arm is then elevated from 90° to 150° with maximal external rotation. This test is considered positive either with pain reported by the patient or with the examiner feeling a click at the posterior joint line between 90° and 120° of elevation.

    The biceps load II test is performed by first placing the patient’s arm in 120° of abduction. Next, the arm is placed into maximal external rotation, and the forearm supinated. The patient is asked to flex the biceps in this position against resistance. The presence of deep shoulder pain is indicative of a SLAP lesion and a positive test. [13]

    Conservative measures to initially manage the overhead athlete with a SLAP tear should include:

    • Core strengthening
    • Scapular bracing and taping
    • Back hip abductor strengthening
    • Stretching of the lead hip to allow increased internal rotation

    Arthroscopic surgical repair is indicated in patients who have failed these conservative measures and who still wants to continue to throw at a high level (see Surgery for the Disabled Throwing Shoulder, below). Return to play at the same or higher level, however, has been difficult to achieve after shoulder surgery. Although excellent results have been reported for operative repair, in general, a true return to pre-injury level of play is less than ideal. [14-16] Recent work by Lintner et al [10] has helped demonstrate that conservative treatment is superior to surgical repair in long-term management of elite athletes with these tears. Treatment is currently an area of debate, as recent literature has suggested that surgical repair may not be as successful as previously thought. [9,10]

    Rotator Cuff

    A balanced, strong rotator cuff associated with a retracted scapula is essential for tolerating the high stress levels placed on the shoulder during the throwing motion. Damage to the rotator cuff occurs most commonly on the articular side of the infraspinatus tendon as a result of internal impingement. [17] This process is exacerbated in patients with decreased motion, in which case increased pathologic internal impingement, along with maltracking of the humeral head on the glenoid, results in increased tension and torsional forces on the posterior superior cuff. [8] If unaddressed, this may progress to partial or full-thickness tears over the course of a season. [12]

    Internal impingement of the supraspinatus and infraspinatus tendons typically presents as pain during the late cocking phase, when the arm is abducted and externally rotated. The posterior impingement sign developed by Meister can be used to help detect symptomatic internal impingement. The test is done with the patient supine, and the shoulder placed in 90° of abduction and full external rotation. This often produces vague posterior superior shoulder pain. The humeral head is then translated posteriorly, and a decrease in pain is considered a positive test for internal impingement. [18]

    A thorough physical examination and evaluation of other possible etiologies of shoulder pain should be performed before pursuing treatment for a rotator cuff tear in the overhead athlete, as many asymptomatic patients have demonstrable rotator cuff pathology on MRI. [19] MRI of a throwing athlete must include imaging in the abduction external rotation (ABER) position to allow evaluation of the extent of internal impingement and peel-back superior labral changes (Figure 4).

    Figure 4. Right shoulder MRI demonstrating ABER view

    Initial treatment should consist of:

    • Rest from throwing
    • Anti-inflammatory medication
    • Physical therapy program aimed at restoring balance to the entire kinetic chain

    In some patients, this may mean delaying the rotator cuff exercises until the scapular position is corrected, or at least manually stabilizing the scapula during all shoulder exercises. The key points during therapy are restoration of correct posture, muscle balance, and improved total arc of motion.

    Physical therapy should be continued and surgery avoided as long as the athlete is showing improvement. [19] Surgical debridement may be indicated for management of these so-called PAINT – partial thickness articular surface intra-tendinous – lesions. [20]

    Surgery for the Disabled Throwing Shoulder

    Surgical management of the disabled throwing shoulder should be undertaken with reluctance. The 4 main areas that may need to be addressed are:

    • Peel-back SLAP lesion
    • Undersurface infraspinatus rotator cuff tear
    • Capsule in the area of the posterior inferior glenohumeral ligament (PIGHL) and Bennet’s lesion
    • Possible excessive laxity of the anterior capsule at the midpoint (3 o’clock or 9 o’clock) position

    The sequence of treatment of these lesions should mirror the findings during the history, physical examination, and rehabilitation. This allows an initial surgical sequence to be planned. Examination under anesthesia is utilized to recheck the total arc of motion, as well as to confirm existing PIGHL contracture or anterior subluxation. The diagnostic arthroscopy is followed by direct visualization of the shoulder in the abducted and externally rotated position to evaluate the amount of internal impingement, peeling back of the superior labrum, and extent of the partial infraspinatus tear (Figure 5).

    Figure 5. Arthroscopic findings of the 4 facets of surgery for the throwing shoulder: SLAP tear viewed arthroscopically from the anterior portal (top), arthroscopic debridement of articular sided infraspinatus tear (middle, left), contracture of the posterior inferior glenohumeral ligament visualized arthroscopically from the posterior portal (middle, right), and laxity of the anterior labrum (bottom).

    In most patients with a positive DLS test that did not correct with rehabilitation, the first step is to repair the peel-back SLAP tear, lightly debride the infraspinatus, and then recheck the internal impingement. In patients in whom the total arc of motion difference was the primary pathology that did not correct, the initial step may be to release the attachment of the PIGHL and debride the underlying Bennet’s lesion.

    Each time 1 of the 4 steps above is taken, the internal impingement is rechecked. The goal is not to completely eliminate this impingement from occurring, but to make sure it occurs only with excessive external rotation (120° to 140°). Rarely are all 4 steps needed, but the tremendous variability of overhead athletes means that surgeons must be cognizant of all 4 steps and how the sequence changes with each shoulder.

    In evaluating possible surgery for the disabled throwing shoulder, the surgeon should understand that the best results are still those of the original 1985 study by Andrews et al [21] that showed an 85% return-to-play rate with simple debridement followed by extensive rehabilitation. Despite numerous advances in the understanding of the pathology of the disabled throwing shoulder, the results of more advanced surgeries have not shown the same improvement. Debridement carries a better prognosis than surgical repair for return to pre-injury level of play.

    Thus, for larger tears, attempts should be made to debride rather than repair. However, this may not be possible in tears over 75%. [17] Full-thickness tears carry a poor prognosis and can often be career-ending injuries, even with repair.

    Scapular Dyskinesis

    The scapula is an important structure in the kinetic chain of throwing, providing a base from which the muscles, ligaments, and tendons transmit forces on the glenohumeral joint. Breakdown of the proper position and motion of the scapula is known as scapular dyskinesis. If uncorrected, scapular dyskinesis may progress to a severe symptomatic form known as SICK scapula syndrome – Scapular malposition, Inferior medial border prominence, Coracoid pain, dysKinesis of scapular movement.

    In the overhead athlete, proposed mechanisms for scapular dyskinesis include: [5]

    • Posterior tightness of the shoulder capsule leading to increased protraction
    • Middle and lower trapezius fatigue with throwing
    • Suprascapular neuropathy
    • Weakness of other scapular stabilizers

    Patients present with an elevated shoulder compared with the unaffected side, complaining most commonly of anterior shoulder pain localized to the coracoid process, or posterior superior scapular pain with possible radiation into the paraspinous region. [22] This syndrome is diagnosed in clinic with static and dynamic measurements of scapular position using an inclinometer. Upward rotation, anterior tilt, and protraction should be measured bilaterally and compared to normative values. [7]

    Patients with identified scapular dyskinesis should be treated non-surgically with a closely followed rehabilitation program aimed at strengthening the scapular stabilizers and equalizing appearance of both sides. Important components of rehabilitation include:

    • McConell taping of the scapula into retraction
    • Biofeedback monitoring of scapula position during all exercises
    • Postural correction braces and shirts

    With continued adherence, this advanced, integrated rehabilitation program is highly successful at reducing symptoms and preventing recurrence. [22] A recent meta-analysis of 419 athletes found that 43% of athletes with initially asymptomatic scapular dyskinesis went on to develop shoulder pain, with common pathologies including SICK scapula, external or internal impingement, rotator cuff damage, and labral tears. [23] Thus, early identification and rehabilitation of scapular dyskinesis is critical in maintaining the long-term health of the overhead throwing athlete.

    Anterior Instability

    Anterior instability of the shoulder was previously thought to be a primary cause of shoulder pain in overhead throwing athletes. More commonly, it can be a secondary issue resulting from pathology to the posterior superior labrum, with transmission of instability to the opposite side of the labral ring, known as pseudolaxity. [8,24]

    The anterior fulcrum test can be used to evaluate anterior instability of the shoulder. This test is done with the patient supine and the shoulder brought into 90° of abduction and external rotation. An anterior force is then applied on the posterior glenohumeral joint, with the arm stabilized in horizontal abduction and the other hand at the elbow. The amount of translation and end laxity should be compared with the opposite shoulder. Other tests can be used, including the anterior Lachman and the anterior and posterior drawer tests. [12]

    Treatment of patients with anterior shoulder instability is analogous to management of SLAP tears, as conservative management is usually successful and should be followed by surgery only in refractory cases. The goal of surgical treatment is stabilization of the posterior superior SLAP lesion. If necessary, posterior inferior capsule release and suture plication of the anterior middle capsule may also be done to achieve optimal results. [25] Balancing the capsule is quite important, as some anterior laxity and the associated increase in external rotation is necessary to be able to throw well. If anterior capsular surgery is needed, it should be performed with the patient’s arm in 100° to 120° of external rotation to prevent over-tensioning of the capsule.

    Primary anterior instability of the shoulder may occur as a Bankhart lesion following anterior dislocation. Surgical repair is indicated as the initial treatment in this case, with the goal of repairing the damaged capsule. [25] It is imperative to distinguish whether the cause of anterior stability is from chronic or traumatic injury, as treatment differs between the 2 groups.

    Neurovascular

    Although uncommon, neurovascular etiologies of shoulder pain can cause significant pain and morbidity in the overhead athlete. Diagnoses include: [5]

    • Suprascapular neuropathy
    • Thoracic outlet syndrome
    • Axillary artery aneurysm and thrombosis
    • Quadrangular space syndrome

    Many of these may be related to posture, and often respond to advanced rehabilitation.

    Clinical presentation is often similar to that of intrinsic shoulder pathologies, with athletes complaining of pain during the throwing cycle, loss of velocity, and fatigue. These athletes often complain of neurologic dysfunction and have a pale, cool extremity or plethora of the affected arm, depending on which neurovascular structures are involved. [5]

    If a neurovascular etiology is suspected, the surgeon should do a thorough diagnostic workup that includes:

    • Electromyography/ nerve conduction studies
    • Radiographs searching for an extra rib
    • Venous and arterial ultrasound exams
    • Possibly arterial and venous studies with the arm in the throwing position

    Treatment varies according to the diagnosis, and surgery may be indicated in severe cases.

    Clinical Pearls

    • The first stage of treatment should be centered on evaluation and correction of biomechanical irregularities in the kinetic chain, including evaluation of throwing mechanism, core strength, hip stability and flexibility, and scapular position.
    • Controlled rest and physical rehabilitation should always be completed prior to surgical consideration.
    • MRI findings may help in establishing the diagnosis. However, they should be used with caution: Physiologic adaptive changes are often mischaracterized as pathology. A thrower’s MRI scan should always include the ABER views.
    • In refractory cases, surgical treatment may be considered.  
    • Less is more: During surgical repair, limiting intervention may help reduce further iatrogenic injury, specifically with regard to the rotator cuff. Surgical repair is almost always career-ending in these unique athletes.
    • Prevention is the key: All overhead athletes, especially baseball pitchers, should perform regular stretching and muscle balancing exercises of the shoulder and the entire kinetic chain to prevent development of a painful throwing shoulder.

    Author Information

    Hunter Bohlen; Stephen Thon, MD; and Felix H. Savoie III, MD, are from Tulane University, New Orleans, Louisiana.

    Disclosures

    The authors have no disclosures relevant to this article.

    References

    1. Weber AE,Kontaxis A, O’Brien SJ, Bedi A. The biomechanics of throwing: Simplified and cogent. Sports Med Arthrosc, 22 (2014), pp. 72-79
    2. Chu SK, Jayabalan P, Kibler WB, Press J. The Kinetic Chain Revisited: New Concepts on Throwing Mechanics and Injury. PM R. 2016 Mar;8(3 Suppl):S69-77
    3. Wilk KE, Meister K, Andrews JR. Current concepts in the rehabilitation of the overhead throwing athlete. Am J Sports Med. 2002;30:136-151
    4. Fleisig GS, Andrews JR, Dillman CJ, Escamilla RF. Kinetics of baseball pitching with implications about injury mechanisms. Am J Sports Med. 1995;23:233-239
    5. Seroyer ST, Nho SJ, Bernard RB Jr, Charles ABJ, Nicholson GP, Romero AA. Shoulder Pain in Overhead Athlete. Sports Health. 2009 Mar; 1(2): 108–120.
    6. Wilk KE, Macrina LC, Arrigo C. Passive range of motion characteristics in the overhead baseball pitcher and their implications for rehabilitation. Clin Orthop Rel Res. 2012;470:1586–1594 
    7. Wilk KE, Macrina LC, Fleisig GS, Porterfield R, Simpson CD, 2nd, Harker P, Paparesta N, Andrews JR. Correlation of glenohumeral internal rotation deficit and total rotational motion to shoulder injuries in professional baseball pitchers. Am J Sports Med. 2011;39:329–335. doi: 10.1177/0363546510384223.
    8. Burkhart SS, Morgan CD, Kibler WB. The disabled throwing shoulder: spectrum of pathology. Part I: pathoanatomy and biomechanics. Arthroscopy. 2003;19:404-420
    9. Lintner DM. Superior labrum anterior to posterior tears in throwing athletes. Instr Course Lect. 2013;62:491-500
    10. Fedoriw WW, Ramkurmar P, McCulloch PC, Lintner DM. Return to play after treatment of superior labral tears in professional baseball players. Am J Sports Med. 2014 May;42(5):1155-60.
    11. Burkhart SS, Morgan CD, Kibler WB. The disabled throwing shoulder: spectrum of pathology. Part II: Evaluation and Treatment. Arth 2003 19(5) 531-9 PMID 12724684
    12. Reinold MM, Gill TJ. Current Concepts in the Evaluation and Treatment of the Shoulder in Overhead-Throwing Athletes, Part 1: Physical Characteristics and Clinical Examination. Sports Health. 2010;2(1):39-50. doi:10.1177/1941738109338548.
    13. Wilk KE, Macrina LC, Cain EL, Dugas JR, Andrews JR. THE RECOGNITION AND TREATMENT OF SUPERIOR LABRAL (SLAP) LESIONS IN THE OVERHEAD ATHLETE. International Journal of Sports Physical Therapy. 2013;8(5):579-600.
    14. Van kleunen JP; Tucker SA, Field LD and Savoie FH. Return to high level throwing after combination infraspinatus repair, SLAP repair, and release of Glenohumeral internal rotation defecit. Am J Sports Med 2012 Oct 40(11) 2536-41 PMID 23051783
    15. Burkhart SS, Morgan C. SLAP lesions in the overhead athlete. Orthop Clin North Am. 2001;32:431-441, viii.
    16. Cohen DB, Coleman S, Drakos MC, . Outcomes of isolated type II SLAP lesions treated with arthroscopic fixation using a bioabsorbable tack. Arthroscopy. 2006;22(2):136-142.
    17. Schaffer B, Huttman D. Rotator cuff tears in the throwing athlete. Sports Med Arthrosc. 2014 Jun;22(2):101-9.
    18.  Meister K, Day T, Horodyski M, Kaminski TW, Wasik MP, Tillman S. Rotational motion changes in the glenohumeral joint of the adolescent/Little League baseball player. Am J Sports Med. 2005;33(5):693-698
    19. Economopolus KJ, Brockmeier SF. Rotator cuff tears in overhead athletes. Clin Sports Med. 2012 Oct;31(4):675-92
    20. Bollier M, Shea K. Systematic Review: what surgical technique provides the best outcome for symptomatic articular-sided rotator cuff tears? Iowa Orthop J. 2012;32:164-72.
    21. Andrews JR, Broussard TS, Carson WG. Arthroscopy of the shoulder in the management of partial tears of the rotator cuff: a preliminary report. Arthroscopy. 1985;1(2):117-22
    22. Burkhart SS, Morgan CD, Kibler WB. The disabled throwing shoulder: spectrum of pathology. Part III: the SICK scapula, scapular dyskinesis, the kinetic chain, and rehabilitation. Arthroscopy. 2003;19:641-661
    23. Hickey D, Solvig V, Cavalheri V, Harrold M, Mckenna L. Scapular dyskinesis increases the risk of future shoulder pain by 43% in asymptomatic athletes: a systematic review and meta-analysis. Br J Sports Med. 2017 Jul 22. pii: bjsports-2017-097559.
    24. Jobe, FW, Giangarra, RE, Glousman, RE, Kvitne, RS. Anterior Capsulolabral Reconstruction in Throwing Athletes. In Post, M; Morrey, B F and Hawkins, R J: Surgery of the Shoulder. Mosby yearbook, 1990
    25. Savoie FJ 3rd, O’Brien MJ. Anterior Instability in the Throwing Shoulder. Sports Med Arthrosc Rev. 2014 Jun;22(2):117-9