The Impingement Syndrome
By: Brad Homan, D.O.
Shoulder pain is a common problem that affects people of all ages. The most common cause of shoulder pain is a condition called the impingement syndrome. Although this is commonly seen in athletes who play sports requiring overhead movements, you don’t have to be an athlete to suffer from the pain of shoulder impingement.
The shoulder joint is by nature an unstable joint- it lacks bony stability and is basically held together by ligaments, tendons and muscles. This lack of stability is actually beneficial because it gives the shoulder joint the most movement of any joint in the body. Unfortunately this situation also causes potential for problems. Multiple structures function together to lift the arm over head- when one or more of these structures is not functioning correctly injury can occur. An example of this is the impingement syndrome. Shoulder impingement is caused by the pinching of the rotator cuff tendons and bursa between the humeral head (long bone of the arm) and the acromion process (the bony point at the top of the shoulder). This condition is also known as rotator cuff tendonitis or bursitis. Impingement usually results in pain in the front or the side of the shoulder, but can refer pain to the upper back, neck and arm. The pain of impingement syndrome usually occurs when reaching overhead or behind the back.
There are several anatomic factors that can lead to shoulder impingement. One of these is the shape of the acromion bone located above the rotator cuff. Some people have an acromion that is hooked in front, or it can develop prominent calcifications such as bone spurs from wear and tear. These conditions may lead to the bottom of the acromion bone causing abrasions and inflammation in the rotator cuff, especially when lifting the arm overhead. Either way, the small space between the acromion process and the humerus is compromised further which leads to increased wear on the soft tissue structures that pass under the acromion.
Because much of the shoulder’s stability depends on the muscles that hold it all together, weakness or improper balance of those muscles may compromise the stability of the joint and impingement may result. This is because greater than average translation of the humerus in its socket can cause pinching of the soft tissues, leading to inflammation and injury to those structures.
A third possible condition is a poorly functioning scapula (shoulder blade). Too much anterior tilt of the scapula or abnormal movement of the shoulder blade can lead to poor movement of the shoulder unit, which can eventually cause damage to the soft tissue structures of the shoulder.
Initial treatment of the impingement syndrome is rest. It is important to allow your body to heal the inflammation. Anti-inflammatory medications (NSAIDS) or Tylenol can be helpful to reduce pain. Physical therapy is also a very effective way to eliminate the symptoms of impingement. If conservative measures fail, the condition may ultimately require arthroscopic surgery. If shoulder pain is persistent it is helpful to seek advice from a health care professional. The sooner the problem is diagnosed and treated the sooner you can get back to your regular active lifestyle.