The physicians of Muir Orthopaedic Specialists believe good medical care is a result of mutual understanding, respect and trust.  In today's fast paced world, we recognize the importance of communication and spend as much time as possible to provide information explaining condition and treatment options so that our patients can make informed decisions about their care.

IMPINGEMENT SYNDROME

Introduction
The shoulder is a very complex piece of machinery.  Its elegant design gives us the ability to do many things.  This design gives the shoulder joint great range of motion but not much stability.  As long as the parts of this elegant machine are in good working order, the shoulder can move freely and painlessly.  An injury to the shoulder, or wear and tear in the parts of the shoulder, can lead to pain with movement or stiffness in the shoulder.  Many people are probably familiar with the term bursitis.  Any pain in the shoulder is sometimes mistakenly referred to as bursitis.  The term bursitis really only means that the part of the shoulder called the bursa is inflamed.  In reality, there are many different problems that can lead to symptoms from inflammation of the bursa, or bursitis.  Impingement is one of those things that can cause bursitis.  Let's see how this machine called the shoulder is put together and what might cause a breakdown. 

Causes
Usually, there is enough room between the acromion and the rotator cuff so that the tendons slide easily underneath the acromion as the arm is raised.  But each time the arm is raised, there is a bit of rubbing on the tendons and the bursa between the tendons and the acromion. This rubbing, or pinching action, is called impingement.  Impingement occurs to some degree in everyone's shoulder, caused by day to day activities that we do using the arm above shoulder level. But continuously working with the arms raised overhead, repeated throwing activities, or other repetitive actions of the arm can cause impingement to become a problem.  Raising the arm tends to force the humerus against the edge of the acromion.  With overuse this can cause irritation and swelling of the bursa.

If any condition decreases the amount of space between the acromion and the rotator cuff tendons, the impingement process may get worse.  Bone spurs can further reduce the space available for the bursa and tendons to move under the acromion.  Wear and tear of the joint between the collarbone and the scapula, the acromioclavicular (AC) joint, is a fairly common cause of bone spurs around this joint.  This joint sits right above the bursa and rotator cuff tendons and if bone spurs develop underneath the joint, this can make impingement worse.

Symptoms
Early symptoms of Impingement Syndrome include generalized aching of the shoulder, pain when raising the arm out from the side or in front of the body. Most patients complain of difficulty sleeping due to pain, especially when they roll over on the affected shoulder.  A very reliable sign of impingement is a sharp pain when trying to reach into your back pocket.  As the process continues, discomfort increases and the joint may become stiffer.  Sometimes a "catching" sensation is felt when the arm is lowered.  Weakness and inability to raise the arm may indicate that the rotator cuff tendons are actually torn.

  
Diagnosis
The diagnosis of impingement and bursitis is usually made on the basis of the history and physical examination.  You doctor will be interested in your activities and your job, because this condition is frequently related to continuous overhead activities.  Some is people have an odd anatomy of the acromion, where the bone tilts too far down and reduces the space between the acromion and the rotator cuff. X-rays may be ordered  bone spurs from the acromioclavicular (AC) joint.  The MRI scan, or arthrogram, may be performed if there is also a suspected tear of the rotator cuff tendons.  An MRI scan is a special radiological test where magnetic waves are used to create pictures that look like slices of the shoulder.  The MRI scan shows more than the bones of the shoulder.  It can show the tendons as well, and whether there has been a tear in those tendons.  The MRI scan is painless, and requires no needles or dye to be injected.  The arthrogram is an older test.  This test is done by injecting dye into the shoulder joint and taking several x-rays. If the dye leaks out of the shoulder joint where it was placed, it suggests that there is a tear in the rotator cuff tendons where the dye leaked out. Both tests are still widely used. 
    

Prevention/Treatments/Medications
Anti-inflammatory medications may be prescribed by your physician.  These include aspirin and ibuprofen.  If these measures fail to improve your pain, an injection of cortisone into the bursa may reduce the inflammation and control the pain.  Cortisone is a very strong anti- inflammatory medication and can reduce the inflammation in the bursa and tendons of the rotator cuff.

Rest:  Your physician or therapist may prescribe a sling to provide adequate rest to the shoulder.  It is crucial that the sling be removed several times daily while you perform your home exercises.  This is paramount in order to prevent a stiff or "frozen" shoulder.

Ice:  Ice decreases the size of blood vessels in the sore area, halting inflammation and relieving pain.  Choices of application include cold packs, ice bags, or ice massage.  Ice massage is an easy and effective way to provide first aid.  Simply freeze water in a paper cup.  When needed, tear off the top inch, exposing the ice.  Rub three to five minutes around the sore area until it feels numb. 

Physical Therapy:  It is very important to maintain the strength in the muscles of the rotator cuff.  These muscles help control the stability of the shoulder joint and strengthening these muscles can actually decrease the impingement of the acromion on the rotator cuff tendons and bursa.  Long term management of this problem should also address worksite alterations to reduce the need for overhead activity.  A posterior capsular stretching program and rotator cuff strengthening program may be started by your physical therapist.  These programs are simply a set of exercises that will help keep the shoulder strong and flexible and help reduce the irritation from impingement.  Your therapist will make sure you understand the exercises and are doing them correctly before turning you loose on your own.

Surgery
Surgery to relieve the constant rubbing of impingement is not uncommon.  When surgery becomes necessary, the major goal of the surgery is to increase the space between the acromion and the rotator cuff tendons.  The first thing that must be done is to remove any bone spurs under the acromion that are rubbing on the rotator cuff tendons and the bursa.  Usually a small part of the acromion may be removed as well to give the tendons even more space and allow them to move without rubbing on the underside of the acromion.  In patients who have an abnormal tilt to the acromion, more of the bone may need to be removed.      

Impingement may not be the only problem in a shoulder that has begun to show wear and tear due to aging and overuse.  It is very common to see degenerative (wear and tear) arthritis in the acromioclavicular (AC) joint in addition to impingement.  If there is reason to believe that the acromioclavicular (AC) joint is arthritic, the end of the clavicle may be removed as well.  This procedure is called a resection arthroplasty.  After removal of about one inch of the clavicle, scar tissue fills the space left between the clavicle and the acromion to form a false joint. This stops the arthritic pain in the    acromioclavicular (AC) joint caused by bone rubbing against bone.  The scar tissue that forms creates a stable, flexible connection between the clavicle and the scapula.   

In some cases this can be using the arthroscope.  The arthroscope is a small TV camera that can be inserted into joint through a small incision.  Through other small incisions around the joint the surgeon can insert special instruments to cut and burr away bone while he watches what he is doing on a TV screen.  If your surgery is done with the arthroscope you may be able to go home the same day.

In other cases, an open incision is made to allow removal of the bone.  Usually an incision about 3 or 4 inches is made over the top of the shoulder.  Any bone spurs are removed and a part of the acromion is removed and smoothed by the surgeon.  If necessary, the end of the clavicle is removed to perform the resection arthroplasty of the acromioclavicular (AC) joint.  If your surgery is done in this way, you may have to stay a night or two in the hospital.

Copyright 2003 Muir Orthopaedic Specialists