Swimmer's Shoulder

As the shoulder is pushed to its limits of strength and endurance, the rotator cuff muscles generally fatigue before the power muscles, allowing micromotion and subluxation of the humeral head. This, in turn, decreases stroke efficiency, while leading to injuries of the rotator cuff, biceps tendon, and glenoid labrum.

Superior subluxation of the humeral head is particularly problematic as it can impinge the rotator cuff tendons against the acromion above, leading to tendinitis and/or tears. The overlying subacromial bursa (also referred to as the subdeltoid bursa) often becomes inflamed, leading to painful bursitis.

A study of risk factors for shoulder pain and instability in 236 female competitive swimmers concluded that symptomatic swimmers younger than 12 years of age had reduced shoulder flexibility, weakness of the middle trapezius and shoulder internal rotators, and latissimus dorsi tightness, whereas symptomatic swimmers aged 12 years or older had pectoralis minor tightness and decreased core endurance.[2]  A study in 201 competitive swimmers (96 male, 105 female) who were initially pain free concluded that posterior shoulder muscle endurance and hand entry error were among the strongest predictors for the development of shoulder pain.[3]  In a study that included 76 young competitive swimmers (mean age, 14 years), Mise et al found that hypomobility and hypermobility of the shoulder complex were risk factors for shoulder pain in male and female swimmers, respectively.[4]

A study of electromyographic activity of selected shoulder girdle muscles in elite swimmers with and without shoulder pain found that swimmers with pain had greater activation of the upper trapezius, serratus anterior, and latissimus dorsi muscles, but found no difference in the activation of the middle and lower trapezius, middle deltoid, and sternocleidomastoid muscles. These researchers suggested that "altered muscle activation patterns may contribute to the painful shoulder in elite swimmers and need to be considered within the rehabilitation interventions."[5]

The incidence of swimmer's shoulder in the United States has been reported to be as low as 3% and as high as 67%. When specifically defined as "significant shoulder pain that interferes with training or progress in training," an incidence of 35% has been reported in elite and senior level swimmers.[6]

The shoulder girdle is made up of 3 bones (the scapula, clavicle, and proximal humerus), 2 joints (the glenohumeral and acromioclavicular joints), and numerous ligaments, muscles, and tendons. The subacromial bursa overlies the rotator cuff and can provide it with some mechanical protection from the bony acromion above in the face of impingement.

The key ligaments are the glenohumeral ligaments (inferior, middle, superior), which are thickened regions of the joint capsule, of which the inferior glenohumeral ligament is most important. Their role is to help stabilize the glenohumeral joint, in support of the rotator cuff muscles.

The key muscle group of the shoulder is the rotator cuff, made up of (from anterior to posterior) the subscapularis, supraspinatus, infraspinatus, and teres minor. The primary role of the rotator cuff is to function as the dynamic and functional stabilizer of the glenohumeral joint. The long head of the biceps tendon, located between the subscapularis and supraspinatus, also assists the rotator cuff in stabilizing the glenohumeral joint. These muscles and their tendons can be overused and injured in shoulder dominant activities such as swimming, with the most commonly injured portion of the cuff being the supraspinatus. On the other hand, the "power muscles" of the shoulders, including the latissimus dorsi, pectoralis, and deltoid, are responsible for moving the arm through space or water, but only infrequently sustain significant injury.

Finally, the trapezius, levator scapulae, rhomboids, and serratus anterior muscles stabilize and position the scapula and shoulder girdle, and are therefore very important to the swimming stroke. Without a stable platform from which to work, the shoulder and arm cannot function efficiently. Fortunately, they also are only occasionally the source of significant injury in the swimmer.

The 4 basic strokes used in competitive swimming are the freestyle, backstroke, breaststroke, and butterfly. Biomechanically, each stroke can be divided into as many as 5 different phases; however, for the purpose of this article, each stroke is divided into two main phases: propulsion and recovery.[7]

Strength and power are required for maximal propulsion, while flexibility is required for an efficient and faster recovery. Increased shoulder flexibility and ROM are beneficial to all strokes but can result in increased laxity of the glenohumeral joint capsule and ligaments, the static stabilizers of the shoulder. This laxity must then be compensated for by a stronger rotator cuff, to keep the humeral head centered in the glenoid socket during stroke activity, a requirement for efficient stroke work as well as to avoid injury to the labrum and cuff.

To better understand how the shoulder works in swimming, it may be helpful to think of the upper extremity as a lever or "canoe paddle" mechanism. The swimmer's hand functions as the flat end of the paddle. The rotator cuff functions as a fulcrum stabilizing the glenohumeral joint so that the power muscles of the shoulder are able to pull the arm through the water. This would be analogous to the way in which a canoeist uses one hand to stabilize the upper end of a paddle as a fulcrum, so that the lower hand can pull the paddle through the water more efficiently.

A study by Hibberd et al found that over the course of 12 weeks of training, swimmers had greater decreases in subacromial space distance and an increase in forward shoulder posture compared to nonoverhead athletes.[8]

The prognosis for a full recovery with appropriate rest and rotator cuff rehabilitation is good. Surgery is seldom required except in the most recalcitrant cases.

Educating athletes, parents, and coaches can go a long way toward successful rehabilitation and avoiding recurrent injuries. The role and importance of the rotator cuff in the swimmer's shoulder should be emphasized, and hence the importance of completing a shoulder rehabilitation program.

For patient education resources, see Rotator Cuff Injury and Shoulder Impingement Syndrome.

Taking a careful and detailed history greatly aids the physician in the diagnosis of swimmer's shoulder. The adolescent or teenaged swimmer often presents with a history of a recent growth spurt, an increase in the level of training and competition, or both.

Pain associated with swimmer's shoulder has the following characteristics:

• The pain is similar to that of rotator cuff pain. It is often poorly localized and felt to be deep within the shoulder.

• Initially, the pain is noted only during or immediately after swimming.

• On occasion, the pain can be associated with a particular position or phase of the stroke. A painful click or catch during the recovery phase of any overhand stroke suggests the possibility of a glenoid labral tear.

• As the athlete tries to swim "through the pain," it may worsen to the point where it affects nonswimming shoulder activities and might eventually be present at rest or at night.

• When the athlete finally stops swimming because of the pain, the condition often improves, but it recurs with a return to swimming if the rotator cuff has not been specifically restrengthened.

Ask the patient to localize the pain. They may describe the pain as being deep, localized to the posterior aspect of the shoulder. Less commonly, they localize the pain anteriorly or at the deltoid insertion area of the upper arm. Pain characterized as such is consistent with rotator cuff tendinitis, the most common underlying cause of pain in swimmer's shoulder.

Observe both shoulders for any asymmetry, particularly in scapular position, or rotator cuff muscle mass (atrophy). Test the following shoulder features:

• Range of motion (ROM)
• Strength
• Stability 
• Joint laxity
• Possible labral tear

Range of motion

Check the ROM of both shoulders, comparing one side to the other. The author typically measures the following:

• Forward flexion and/or abduction (> 180°, combined glenohumeral joint and scapulothoracic motion)
• Glenohumeral joint abduction (> 90°, measured by stabilizing the scapula with one hand, while abducting the glenohumeral joint alone)
• Abducted external rotation (> 90°, measured with the shoulder in 90° of abduction, with the elbow flexed)
• Abducted internal rotation (> 90°, same technique as abducted external rotation)
• Maximum internal rotation (thoracic vertebrae T4-T6, measuring combined glenohumeral joint and scapulothoracic motion by having the patient reach up his/her spine with the thumb)
• In most swimmers, both internal rotation (IR) and external rotation (ER) are greater than in the general population.

Shoulder strength

Assess the strength of the rotator cuff by resisting internal rotation (subscapularis) and external rotation (infraspinatus, teres minor) with the shoulder in the neutral position (at the side) and the elbow flexed to 90°.

Assess the strength of supraspinatus using the Jobe test position, with resisted shoulder elevation with the arms extended, internally rotated, and positioned in the scapular plane (approximately 30-45° anterior to the coronal plane). If weakness is apparent, retest the supraspinatus in the same arm position except with the arms externally rotated (ie, thumbs pointing upwards).

Assess the strength of the subscapularis with the subscapularis lift-off test. Perform this test by placing the shoulder in internal rotation with the back of the patient's hand against the small of the back. The patient attempts to lift hand away from back against the examiner's resistance.

Early on, the above tests may only produce pain. In advanced cases, however, weakness in the involved muscle—most commonly, the supraspinatus—may be noted.

Shoulder stability

Perform a shoulder apprehension test by placing the shoulder in maximum abduction and external rotation (90-90 position) while applying an anteriorly directed force to the shoulder from behind in an attempt to elicit a feeling of apprehension or instability. This test typically elicits some discomfort but no apprehension or sense of instability in most swimmers.

Perform anterior and posterior drawer tests of the humerus both in neutral with the patient sitting, and supine with the arm abducted 90°, while axially loading the glenohumeral joint (load and shift test). Compare with the opposite shoulder.

Most swimmers have a mild-to-moderate increase in shoulder laxity, indicating multidirectional laxity. Occasionally, this can lead to symptomatic instability, in which the swimmer complains of the shoulder subluxing or shifting with use.

Shoulder laxity

Assess inferior laxity by identifying the presence of a sulcus sign. This is completed by pulling the arm inferiorly, while checking for a gap or sulcus between the humeral head and lateral edge of the acromion, indicating inferior subluxation of the humeral head. This is graded as follows:

• Grade 1 - Less than 1 finger breadth (< 1 cm)
• Grade 2 - One finger breadth (1-2 cm)
• Grade 3 - Greater than 1 finger breadth (> 2 cm)

Compare results with the opposite shoulder. Laxity should be similar, except following unilateral traumatic injury.

Check for generalized ligamentous laxity (GLL) in other joints (eg, hyperextension at elbows and knees, thumb to forearm test, middle finger hyperextension to forearm). Generalized ligamentous laxity indicates a significant amount of inherent joint laxity related to the individual's collagen composition and is more commonly found in females than males. Multidirectional instability (MDI) is more difficult to manage in the presence of GLL.

Labral tear

A labral tear is suggested when a painful click is noted during the recovery phase of any overhand stroke. Often, the swimmer can reproduce this click during the exam.

The O'Brien test can suggest a superior labral tear, or the so-called SLAP (superior labrum anterior and posterior) lesion. Have the athlete resist a downward force with the arm extended in the forward flexed position, adducted 15° toward the midline, with the shoulder in maximal internal rotation (thumb pointing down). Pain produced with this maneuver and relieved with the arm externally rotated suggests a SLAP lesion.

Radiographs

An anteroposterior (AP) scapular Y or outlet view and axillary view of the shoulder should be obtained when the pain persists after 6 weeks or more of rest and rehabilitation. These radiographs are performed to rule out the much less likely skeletal causes of shoulder pain (eg, stress fracture, infection, tumor) or evidence of prior trauma or instability, such as a loose body, bony Bankart lesion, or Hill-Sachs lesion.

Magnetic resonance imaging (MRI)

If imaging is needed, MRI is the study that is most likely to be helpful for determining the source of injury in swimmer's shoulder. An MRI images the full spectrum of rotator cuff pathology, which is by far the most likely source of pain in swimmer's shoulder, while also depicting the bones, ligaments, and other tendons in the shoulder.

In most cases of swimmer's shoulder, the MRI findings are normal. On occasion, the MRI may demonstrate some increased signal in the substance of the supraspinatus tendon, indicating tendinitis or tendinosis. If fluid is detected in the subacromial bursa, bursitis may be present, along with a partial tear or fraying of the rotator cuff.

If a labral tear is suspected, an MRI arthrogram (MRA) with intra-articular gadolinium is more sensitive and should be considered.

Subacromial injection

This can be a useful test in the older swimmer whose condition has failed to respond to rest and rehabilitation, suggesting a partial or complete rotator cuff tear. Termed an impingement test when performed with lidocaine alone, a subacromial injection can be both diagnostic as well as therapeutic when a corticosteroid (eg, methylprednisolone) is added.

Immediate relief of pain following the injection (as evidenced by a negative Neer test result) would suggest an injury of the rotator cuff and/or the overlying bursa. The addition of a corticosteroid to the injection can give the athlete a prolonged period of pain relief, lasting weeks or months, during which time a rotator cuff strengthening program can be instituted.

Intra-articular injection

This can be a diagnostic as well as therapeutic procedure. Injection is within the glenohumeral joint with lidocaine alone or with a corticosteroid (eg, methylprednisolone, triamcinolone). The addition of a corticosteroid to the injection can give the athlete a prolonged period of pain relief if the derangement is intra-articular in nature.

Treatment of swimmer's shoulder in the acute phase is primarily with physical therapy. Working with a physical therapist can be helpful, particularly one with expertise in treating shoulder injuries and swimmers, who can oversee a rehabilitation program that helps the athlete transition from dry land exercises to swimming. Surgical intervention may be considered in athletes with persistent pain.

Rehabilitation program

Pain relief, which is the first goal of treatment, involves resting the shoulder. In most cases, the athlete should stop or significantly decrease his or her swimming activities. A physical therapist can help modify shoulder and activities to help avoid re-aggravation of the rotator cuff. Anti-inflammatory treatment in the form of regular icing and nonsteroidal anti-inflammatory medications should also be instituted until the athlete is pain free.

The second goal of treatment is to restore normal strength in the rotator cuff. Regaining strength can be accomplished with a supervised exercise program for the rotator cuff using relatively light weights (2-3 lb, up to a maximum of 5 lb) and high repetitions (12-20 reps per set). These exercises can be performed on a daily basis or every other day.

 The addition of therapist-administered therapeutic modalities can help further reduce pain and inflammation during the acute phase of injury. These may include the following:

• Ultrasound
• Phonophoresis
• Iontophoresis
• Electrical stimulation 

Surgical Intervention

Surgical intervention is considered in athletes who continue to have shoulder pain after a minimum of 6 months of guided rest and rehabilitation.

The surgical procedure should include an examination under anesthesia to determine the degree of laxity, a diagnostic arthroscopy (to look for labral or rotator cuff tears and capsular laxity), and, when indicated, a surgical tightening of the lax capsule (capsulorrhaphy). In the older athlete, a subacromial decompression is typically performed if there is arthroscopic evidence of impingement.

The athlete should be cautioned about the postsurgical trade-off of increased shoulder stability for some loss of flexibility, resulting in difficulty in returning to swimming at the same level as before the injury.

Baker et al determined that arthroscopic management of symptomatic multidirectional instability can return athletes to sports with a high rate of success.[9]  In their study of 40 athletes (mean age 19.1 y; 24 males; 16 females), at a mean of 33.5 months follow-up, the mean American Shoulder and Elbow Surgeons score was 91.4 of 100 (range, 59.9-100), and the mean Western Ontario Shoulder Instability postoperative percentage score was 91.1 of 100 (range, 72.9-100).[9] Full or satisfactory range of motion was reported in 91% of the patients, normal or slightly decreased strength was noted in 98%, and 86% of the athletes had little or no limitation on returning to their sport.

Using electromyography, Illyes et al compared the muscle activity in patients who received conservative therapy (n = 34) and those who underwent capsular shift with postoperative rehabilitation (n = 31) with the muscle activity of individuals with stable shoulder joints (n = 50) before and after treatment during pull, push, and elevation of upper extremities and during overhead throw.[10] The investigators found that the post-therapy muscle patterns of both treatment groups were similar to those of the healthy control group. However, whereas conservative therapy restored muscular control, the open capsular shift treatment combined with postoperative conservative rehabilitation resolved the patients' labrous ligamentous abnormalities and restored muscular control.[10]

Kiss et al compared the kinematic parameters and the on-off muscle patterns of patients with multidirectional instability treated by physiotherapy (n = 32) or by capsular shift and postoperative physiotherapy (n = 19) before and after treatment during elevation in the scapular plane. Both treatment groups' results were compared with those of 25 healthy individuals.[11] Patients with multidirectional instability had different scapulothoracic and glenohumeral rhythms as well as increased relative displacement between the scapular and humeral rotation centers relative to the healthy subjects.

Although physiotherapy strengthened the rotator cuff, biceps brachii, triceps brachii, and deltoid muscles, as well as increased the neuromuscular control of the shoulder joints in patients with multidirectional instability, it did not restore the alteration in shoulder kinematics in these patients.[11] However, capsular shift and postoperative physiotherapy angulation at 60º of scapulothoracic and glenohumeral rhythms restored the relative displacement between the scapular and humeral rotation centers as well as the duration of muscular activity.

Consultations

In cases unresponsive to rest and rehabilitation, consultation with an orthopedic surgeon is recommended.

Other Treatment

A corticosteroid injection may be considered in older patients but is rarely used in adolescents and almost never in skeletally immature patients.

A capsulorrhaphy usually requires immobilization in an arm sling or immobilizer for 4-6 weeks to allow the capsule to heal in the surgically-tightened position. This is then followed by a rotator cuff strengthening program in physical therapy. Passive range of motion (PROM) is typically restricted during this time so as not to stretch out the capsule. ROM commonly returns on its own with exercise and normal shoulder use. One can expect about 50-75% of the normal shoulder motion to return by 3 months and 100% of motion by 6 months following successful surgery. Modified stroke work can begin once the athlete achieved a minimum of 80% of normal motion and strength in the shoulder. Return to competitive swimming is anticipated between 6 and 12 months following surgery.

The maintenance phase is the final phase of rehabilitation. The athlete should be independent with a strengthening program as instructed by his or her athletic trainer or physical therapist. The therapist and coach should both be involved in re-assessment of swimming mechanics and stroke technique, addressing any errors to prevent recurrence of injury.

Anti-inflammatory medications are the mainstays of medical therapy for swimmer's shoulder. These agents are used to help decrease inflammation of the rotator cuff, and in doing so, help relieve pain, prevent further damage, and speed recovery.

Class Summary

Agents are mostly oral, systemic medications (except for Toradol), which are used to decrease inflammation without the side effects of corticosteroids. COX-2 inhibitors may decrease the risk of GI toxicity and bleeding problems due to platelet inhibition caused by older NSAIDs.

Ibuprofen (Advil, Excedrin IB, Motrin)

DOC for patients with mild to moderate pain. Inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.

Celecoxib (Celebrex)

Inhibits primarily COX-2. COX-2 is considered an inducible isoenzyme, induced during pain and inflammatory stimuli. Inhibition of COX-1 may contribute to NSAID GI toxicity. At therapeutic concentrations, COX-1 isoenzyme is not inhibited, thus GI toxicity may be decreased. Seek lowest dose of celecoxib for each patient.

Class Summary

Either oral or injectable are perhaps more potent than NSAIDs, they can last longer, but have more side effects and are seldom used in teenage athletes, unless there is a pressing, agreed upon reason for exposing the athlete to the somewhat higher risk of side-effects and complications arising from their use.

Methylprednisolone (Medrol Dose Pack)

Decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reversing increased capillary permeability.

Triamcinolone (Kenalog)

Decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reversing capillary permeability.

Athletes are allowed to return to swimming on a gradual basis once they are completely pain free, have a full range of motion, and have normal strength of the rotator cuff, as compared with the opposite shoulder. Return to swimming should preferably occur under the guidance of a physical therapist or athletic trainer and swim coach.

A structured rotator cuff strengthening program during the off-season and a gradual increase in training at the beginning of the season can help prevent the occurrence of swimmer's shoulder. Avoiding rotator cuff fatigue through proper mechanics and conditioning is the key to preventing injury. Knowing the signs and symptoms of rotator cuff fatigue and tendinitis can help the physician, trainer, and coach determine when a swimmer should rest his or her shoulder.