Impingement syndrome of the rotator cuff is a common overuse injury seen in athletes who participate in sports that require repetitive overhead activities. However, if not carefully diagnosed, this injury can be misdiagnosed as a torn rotator cuff. The problem of misdiagnosis is that the treatment and rehabilitation for each follows a very different protocol.
A basic understanding of shoulder anatomy is necessary to understand what impingement syndrome is. Four muscles make up the rotator cuff muscle group including the supraspinatus, infraspinatus, teres minor, and subscapularis. Each muscle has a specific function because of its location.
The infraspinatus and teres minor originate on the back of the scapula and insert on the top anterior portion of the humerus. Together, they are responsible for external rotation of the humerus.
The subscapularis originates on the front of the scapula and is responsible for internal rotation of the humerus. Last, the supraspinatus originates on the top of the scapula and runs under the acromion process inserting on the top anterior portion of the humerus.
Along with internally and externally rotating the humerus, the rotator cuff muscles are responsible for maintaining the position of the head of the humerus within the glenoid fossa of the scapula. Healthy and strong rotator cuff muscles enable the head of the humerus to glide and rotate safely and effectively within the joint. However, if there is inflammation or weakness in one of the rotator cuff muscles, the normal functioning of the shoulder can be compromised.
Impingement syndrome is inflammation of the supraspinatus tendon as it runs underneath the acromion process and through the subacromial space. When the athlete lifts his/her arm, the inflamed tendon becomes impinged between the acromion process and the head of the humerus causing pain with any movements in which the arm is raised.
What are the classifications of impingement syndrome?
Impingement syndrome is classified into three stages depending on the severity of the symptoms.
Stage one is usually seen in athletes age 25 and younger and is characterized by a dull ache at the top of the shoulder initially just after activities but then progressing to pain during activities. Tenderness may be felt at the top of the shoulder at the insertion of the supraspinatus tendon.
This stage is also characterized by a “painful arc” of motion (pain is experienced when the arm is abducted between 70 and 120 degrees). There may be atrophy of the rotator cuff muscles with some associated swelling in the subacromial space.
If the impingement can be diagnosed during this stage, the condition can be reversed and the athlete can have a full recovery. However, if it is not correctly diagnosed and treated, permanent damage to the structures can occur.
Stage two is typically seen in athletes between the ages of 25 and 40. Because the condition has deteriorated over time, the structures involved may experience permanent physiological changes including:
• Thickening of the subacromial bursa
• Fibrotic changes to supraspinatus tendon
• Fibrotic changes to biceps tendon
The athlete may experience limited range of motion in abduction and external rotation with significant pain through the painful arc. Because of the amount of pain, the athlete may begin to alter his/her mechanics during sport and during functional activities (reaching overhead into a cabinet, washing hair).
Stage three is the most severe stage characterized by pathological changes of involved tissues. This individual may complain of a long history of chronic shoulder pain with a gradual deterioration and decline in functional abilities.
By this stage, a rotator cuff tear may be evident with associated degeneration of the tendon. Noticeable supraspinatus and infraspinatus atrophy may also be evident along with multidirectional instability of the humerus due to the weakened condition of the rotator cuff muscles. Because of the instability of the head of the humerus, a torn labrum (a tear of the dense connective tissue encircling the glenoid fossa) may also occur.
Bony degeneration may also be seen in the acromion process, acromioclavicular joint, and greater tuberosity of the humerus (attachment of the supraspinatus tendon). Because of all of the pathological changes seen in stage three, surgery is usually necessary to repair the damage to the involved tissues.
Who gets impingement syndrome?
Impingement syndrome is seen in older athletes (40 years or older) who compete in repetitive overhead activities such as swimming, baseball, softball, and tennis. If the athlete is young, the athlete might actually have multidirectional shoulder instability (looseness within the joint in all directions) with impingement syndrome of the rotator cuff as a secondary diagnosis.
What causes impingement syndrome?
Impingement syndrome can be initially caused by inflammation of the supraspinatus tendon or subacromial bursa due to overuse/repetitive motion or by degeneration of the tendon over time. Repeated injuries to the supraspinatus tendon may also lead to impingement syndrome.
As the rotator cuff weakens, the muscles are not able to maintain the head of the humerus within the glenoid fossa during abduction of the arm (when the arm is raised up sideways). When the arm is abducted, the humerus slides up further than it should progressively worsening the impingement syndrome.
Other risk factors contributing to impingement syndrome include:
• Lack of flexibility and strength of the supraspinatus and biceps brachii muscles
• Weakness of the posterior rotator cuff muscles (infraspinatus and teres minor)
• Tightness of posterior rotator cuff muscles
• Hypermobility of the shoulder joint
• Imbalance in muscle strength and coordination of scapular muscles
• Shape of acromion process
• Use of training devices (hand paddles for swimming)
What can I do to prevent impingement syndrome?
Because the risk factors of impingement syndrome focus on tightness and weakness of the rotator cuff muscles combined with overusing the shoulder, preventing impingement of the supraspinatus muscle should focus on stretching and strengthening all of the muscles of the rotator cuff.
A stretching program for the rotator cuff muscles should include stretches for the back of the shoulder along with exercises that stretch both the internal and external rotation muscles.
One easy stretch for the back of the shoulder is to bring the arm to be stretched directly across the body and while using the opposite arm to apply pressure to the arm towards the body until a stretch is felt. Once a stretch is felt, the stretch should be held for 20-30 seconds and then repeated for a total of three times.
The external rotators of the shoulder can be stretched with the athlete in a side lying position. The athlete should lie on the shoulder being stretched. The shoulder should be abducted to 90 degrees with the elbow flexed. The athlete then uses the opposite arm to apply pressure pushing the forearm into internal rotation. This stretch also stretches the posterior capsule of the shoulder.
Another stretch for the rotator cuff is to move both arms to a position behind the athlete, clasp both hands together, and gently raise arms until a stretch is felt. As in the other stretches, hold the stretch for 20-30 seconds and then repeat.
The rotator cuff muscles can be strengthened using progressive resistance exercises. Care must be taken to use light resistance because the muscles of the rotator cuff are small. The exercises need to be completed through the full range of motion without compromising form. If the athlete’s form is compromised, the resistance should be lowered.
Dumbbells can be used to strengthen the rotator cuff. Several exercises can be used including the following:
• Isolated abduction exercises – in a standing position with the arms beginning down by the athlete’s legs, slowly bring the dumbbells up directly from the side of the body until the arms are parallel to the floor and then slowly return arms to starting position.
• Isolating supraspinatus – in a standing position with arms down by the athlete’s legs; rotate arms inwards until thumbs are pointed down towards the floor; bring the arms slowly up at a forward angle until the arms are parallel to the floor and then slowly return arms to starting position.
• Isolating infraspinatus/teres minor – in a side lying position lying on the opposite shoulder, place the dumbbell in the hand with the elbow flexed to 90 degrees and the upper arm in contact with the body; begin with the dumbbell on the floor and slowly lift the dumbbell while keeping the upper arm in contact with the body and then slowly return dumbbell to starting position.
Stretching and strengthening the rotator cuff can help protect the rotator cuff from injury. However, care must also be taken to not overuse the shoulder during sport or exercise. If pain is felt during or after activity, the amount of activity should be modified. An ice pack can also be applied daily to the shoulder for twenty minutes after in athletes who participate in overhead activities to reduce inflammation.
How is rotator cuff impingement syndrome diagnosed?
A sports medicine professional can diagnose an impingement syndrome given a thorough medical history and comprehensive physical assessment. If a third stage impingement syndrome is suspected, an MRI can be ordered to look specifically at the soft tissue.
What is the treatment for impingement syndrome of the rotator cuff?
Management for impingement syndrome will depend on the stage that the injury is diagnosed. The earlier the syndrome is diagnosed, the better the prognosis.
If the impingement syndrome is diagnosed during stage one, the following treatment protocols should be applied:
• Activity modification including complete rest if possible
• Addition of cryotherapy including ice pack and ice massage
• Implementation of gentle stretching of rotator cuff/joint capsule
• Anti-inflammatory medication to reduce inflammation
• Elimination of training devices that add stress to the shoulder (hand paddles)
• Consultation with coach (if applicable) to analyze athlete’s mechanics and implement changes that might reduce the stress in the shoulder
• Once pain decreases, initiation of stretching and strengthening exercises
The most important aspect of treatment during stage one is to rest the shoulder. It is important during this stage that the athlete is not competing or practicing in pain. This is an injury that will not heal with continued activity or aggressive exercise. If the inflammation continues to increase because of continued activity and the athlete’s ability to function deteriorates, the athlete is at risk for permanent structural damage to the rotator cuff and associated structures.
Treatment for stage two should follow the same protocol as stage one but with a focus on modifying all activity (including activities of daily living) that cause pain. Additional modalities may be used by a sports medicine professional to assist in the healing process including ultrasound, interferential stimulation, phonophoresis and iontophoresis (use of topical prescription medication to decrease pain).
Management for stage two impingement syndrome should initially focus on conservative treatment. If conservative management does not alleviate the pain, then shoulder surgery may be considered.
Because stage three of impingement syndrome of the rotator cuff is characterized by structural damage including partial or complete rotator cuff tears, capsule/labral lesions, and/or bony adaptations, athletes diagnosed with stage three impingement syndrome are usually treated with surgery. Postsurgical rehabilitation protocols vary, but the goals of rehabilitation should include:
• Full passive and active range of motion
• Normal joint mechanics
• Full strength in all stabilizing muscles of the shoulder and scapula
• Gradual pain-free functional and sport specific activities
When can I return to sports?
Because this injury can deteriorate over time to the point of irreversible structural damage, it is important that the athlete not try to play through shoulder pain. The athlete should only attempt to return to sports when he/she has been released to participate by a qualified sports medicine professional and is pain-free in all motions of the shoulder.