What is shoulder impingement syndrome?

Shoulder impingement syndrome is a common injury affecting those who play ‘overhead’ sports and there are a wide range of activities that involve a repetitive movement which elevates the arm above the head, including cricket, tennis and swimming.

Known as one of the most common causes of shoulder pain, the twinge you feel when you execute your tennis serve can quickly become persistent and affect your ability to perform even the most mundane, everyday activities.

Understanding shoulder impingement syndrome

Simply put, shoulder impingement syndrome is diagnosed when a tendon of the muscle catches within the shoulder. This in turn leads to weakness in the arm and pain when the arm is lifted above the head.

It is the rotator cuff tendon that causes the condition; responsible for connecting the shoulder muscles to the very top of the arm, this long, thick tendon is situated within a narrow space, known as the sub acromial space. If it becomes trapped within the space, the tendon begins to rub against the bone, causing pain and sometimes, inflammation.

If inflammation of the tendon does occur, it is referred to as rotator cuff tendonitis. This will develop if shoulder impingement syndrome isn’t treated early enough. There’s also the chance that the tendon could start to wear away and become thinner over time.

What causes shoulder impingement syndrome?

There are actually two different types of causes of shoulder impingement syndrome referred to as primary and secondary.

Primary cause: If you are diagnosed with primary based rotator cuff impingement, it refers to the structural narrowing of the shoulder. It is possible to be born with a naturally narrow subacromial space, significantly increasing your risk of impingement. However, structural narrowing can also develop due to osteoarthritis. The condition can cause bony spurs to develop within the space, further narrowing it.

This type of shoulder impingement syndrome increases the risk of shoulder tendonitis and bursitis.

Secondary cause: This secondary cause of shoulder impingement is referred to as dynamic instability. It occurs when the muscles around the shoulder joint are weak, along with abnormal joint laxity and too much movement in the joints.

It is this type which is most commonly found in athletes, caused by repetitive activity overhead, incorrect posture or injury. The shoulder is required to work much harder if it is unstable, increasing the risk of impingement.

If it is left untreated, secondary rotator cuff impingement will worsen and re-occur.

Identifying the symptoms of shoulder impingement syndrome

There are a number of distinctive symptoms associated with shoulder impingement syndrome including:

• Weakness in the arms
• Intense pain when the arm is raised overhead
• The shoulder is painful to lie on
• Pain which extends down from the shoulder to the elbow

As the condition worsens, you could also begin to experience pain even when the shoulder is resting. Some patients experience a constant, dull ache, rather than intense pain. The condition will need to be diagnosed, typically with the aid of an ultrasound scan. This is most commonly used to identify dynamic impingement.

Shoulder impingement treatment options

The type of treatment required will depend entirely upon where the injury has occurred. Numerous structures can be affected during shoulder impingement syndrome, so identifying the problem area is key to diagnosing the correct treatment.

London Shoulder Specialists’ consultant surgeon Mr Andy Richards spoke on shoulder impingement syndrome, particularly in relation to rugby players, at last year’s Fortius International Sports Injury Conference:

“Younger rugby players – by which we mean under age of 35 – often have more functional impingement and an inability to control their humeral head with superior translation. They also have a high percentage of sub-clinical instability and standard treatments of injections and subacromial decompression will fail in this group.

“For younger patients you have to look at the pathology and identify labral or partial cuff tears and whether ACJ inflammation is also contributing to the pain they are experiencing. The MRI Arthrogram is definitely the investigation of choice. If there is no structural abnormality, then this group can be rested and rehabbed, with guided steroid injections to the bursa, but if they have a structural abnormality or fail to rehab, then surgery is the best option.”