The design of the shoulder gives it an extensive range-of-motion, but little stability. An injury to the shoulder or wear and tear of the joint can lead to pain or stiffness.
Pain in the shoulder may be mistakenly called bursitis. Bursitis refers only to inflammation in the bursa. Many problems can lead to inflammation of the bursa, or bursitis, including impingement.
The shoulder is made up of three bones: the scapula (shoulder blade), the humerus (upper arm bone) and the clavicle (collarbone).
The tendons of four muscles form the rotator cuff
These muscles include the supraspinatus, infraspinatus, teres minor and subscapularis. Tendons attach muscles to bones, and muscles move bones by pulling on the tendons. The rotator cuff tendon connects the humerus with the scapula (shoulder blade) and helps raise and rotate the arm.
As the arm is raised, the rotator cuff also holds the humerus tightly in the socket (glenoid) of the scapula. The part of the scapula that makes up the roof of the shoulder is called the acromion.
Between the acromion and the rotator cuff tendons is a bursa. There are many bursae all over the body where tissues must move against one another. The bursa is a lubricated sac of tissue that protects the muscles and tendons by allowing the moving parts to slide against one another with minimal friction.
Usually, there is enough room between the acromion and the rotator cuff to allow the tendons to slide easily underneath the acromion as the arm is raised. Each time the arms are raised, there is rubbing on the tendons and the bursa between the tendons and the acromion, which is called impingement.
Impingement is normal and is caused by day-to-day activities when the arm is above shoulder level. Continuously working with the arms raised overhead, such as during 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.
Conditions that decrease the space between the acromion and the rotator cuff tendon worsen the impingement. 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. Because this joint is directly above the bursa and rotator cuff tendons, if bone spurs develop underneath the joint, the normal impingement action can become painful and cause complications.
Early symptoms of impingement syndrome include generalized aching of the shoulder and 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 be an indication that the rotator cuff tendons are torn.
The diagnosis of impingement and bursitis is made after a history and physical examination. Your doctor will be interested in your daily activities and activities related to your job, because this condition is frequently related to continuous overhead motion.
Some people have a misshapen 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 used to look for this abnormal type of acromion or bone spurs from the acromioclavicular (AC) joint. Either the MRI scan or arthrogram may be performed if there is 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 the bones of the shoulder and whether the tendons have been torn. The MRI scan is painless and requires no needles or dye to be injected.
The arthrogram requires injecting dye into the shoulder joint and taking several x-rays. If the dye leaks out of the shoulder joint where it was placed, the rotator cuff tendons may be torn. Both tests are widely used.
Sometimes it is unclear whether the pain is coming from the neck or the shoulder. An injection of a local anesthetic (like novocaine) into the bursa can be used to make the correct diagnosis.
If the pain goes away immediately after the bursa is injected with novocaine, then most likely the bursa is the cause of the pain. Pain from a pinched nerve in the neck would not normally be removed by injecting the shoulder with novocaine.
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 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.
Medications: Your physician may prescribe anti-inflammatory medications. These include aspirin and ibuprofen. If these measures fail to reduce 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.
Physical Therapy: It is very important to maintain the strength in the muscles of the rotator cuff since these muscles help control the stability of the shoulder joint. Strengthening these muscles can 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 allowing you to do them on your own.
Surgery is commonly used to relieve the constant rubbing of impingement. The major goal of surgery is to increase the space between the acromion and the rotator cuff tendons. Initially, bone spurs under the acromion that are rubbing on the rotator cuff tendons and the bursa are removed.
Usually a small part of the acromion may also be removed to give the tendons 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 AC joint in addition to impingement. If there is reason to believe that the 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 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 done using arthroscopy where a small TV camera is inserted into the joint through a minor incision. Through similar incisions around the joint, the surgeon can insert special instruments to cut and burr away bone while viewing the TV screen. If your surgery is done with the arthroscope, you may go home the same day.
In other cases, an open incision of 3 or 4 inches is made over the top of the shoulder to allow removal of the bone. Bone spurs are removed, along with part of the acromion, and then smoothed. If necessary, the end of the clavicle is removed to perform the resection arthroplasty of the AC joint. This surgery may require a hospital stay of one or two nights.
Physical therapy will probably be needed for several weeks after your surgery, but recovery from shoulder surgery can take several months. Getting the shoulder moving as fast as possible is important, but this must be balanced with the need to protect the healing muscles and tissues.