Swimmer's shoulder

Background
Swimmer's shoulder is the term used to describe the problem of shoulder pain in the competitive swimmer. Swimming is an unusual sport in that the shoulders and upper extremities are used for locomotion, while at the same time requiring above average shoulder flexibility and range of motion (ROM) for maximal efficiency. This is often associated with an undesirable increase in joint laxity. Furthermore, it is performed in a fluid medium, which offers more resistance to movement than air. This combination of unnatural demands can lead to a spectrum of overuse injuries seen in the swimmer's shoulder, the most common of which is rotator cuff tendinitis.

Sport Specific Biomechanics
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.

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

Clinical
History
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 the condition

◦Initially, the pain is only noted during or immediately after swimming.
◦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 noted at rest or at night.
◦When the athlete finally stops swimming because of the pain, the condition often improves but recurs with a return to swimming if the rotator cuff has not been specifically restrengthened.
◦The character of the pain in swimmer's shoulder is similar to that of rotator cuff pain. The pain is often poorly localized and felt to be deep within the shoulder.
◦On occasion, the pain can be associated with a particular position or phase of the stroke.
◦A reproducible click or painful catch should alert the examiner to the possibility of a glenoid labral tear.

Physical
Ask the patient to localize the area of pain. They may describe the pain as being deep, localized to the posterior aspect of the shoulder. Less commonly, they occasionally 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).

•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 increased as compared to the general population.

•Check 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; however, in advanced cases, weakness in the involved muscle, most commonly the supraspinatus, may be noted.

•Check 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 to the opposite shoulder.
◦In most swimmers' shoulders, a mild-to-moderate increase in laxity is noted, indicating multidirectional laxity. Occasionally, this can lead to symptomatic instability in which the swimmer complains of the shoulder subluxing or shifting with use.

•Check joint 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.


■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 to the opposite shoulder (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.

•Check for labral tear


◦A labral tear is suggested when a painful click is noted during the recovery phase of the 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 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.



Causes
•As the shoulder is pushed to its limits in terms 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.

Treatment
Acute Phase
Rehabilitation Program
Physical Therapy
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.

Working with a physical therapist (PT) can be helpful, particularly one with expertise in treating shoulder injuries and swimmers, who can help the athlete transition from dry land exercises to swimming. The addition of therapist-administered therapeutic modalities, such as ultrasound, phonophoresis, iontophoresis, or electrical stimulation can help further reduce pain and inflammation during the acute phase of injury.


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 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.


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 the adolescents and almost never in skeletally-immature patients.

Recovery Phase
Rehabilitation Program
Physical Therapy
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.

Maintenance Phase
Rehabilitation Program
Physical Therapy
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.