Impingement syndrome is the compromise of the bursa and rotator cuff in the subacromial space of the shoulder, causing pain with overhead or rotational movements like throwing or swimming. This syndrome is seen in people who do repetitive overhead activities for work or play. It is initially treated with rotator cuff strengthening exercises, anti-inflammatory medicine, and injections. If nonsurgical treatment doesn’t work, then acromioplasty can be done to open up the subacromial space and relieve pressure on the soft tissues.
Impingement of the rotator cuff is classified into three stages:
Stage I – initial inflammation and swelling
Stage II – tendonitis
Stage III – tearing of the rotator cuff
The shoulder is not a single joint, but a complex arrangement of bones, ligaments, muscles, and tendons that is better called the shoulder girdle. The primary function of the shoulder girdle is to provide strength and range of motion to the arm. Learn more about the structure and function of the shoulder girdle.
The Subacromial Space
The subacromial space is beneath the acromion and above the rotator cuff. The subacromial bursa outlines this space and provides frictionless gliding of the rotator cuff beneath the arch formed by the acromion and coracoacromion. Bone spurs on the underside of the acromion are thought to narrow this space, irritate the bursa and contribute to tears in the rotator cuff.
12 Million people a year see their doctor for shoulder pain. About half of all shoulder injuries involve the rotator cuff.Impingement occurs when the rotator cuff tendon and the bursa are pinched between the humerus and the front edge of the shoulder blade (acromion). As the arm is lifted, the acromion rubs, or “impinges” on, the surface of the rotator cuff causing pain and limiting movement. Impingement occurs during normal activity, but constant overhead use of the arm may result in irritation of the bursa and tendons. This leads to inflammation of the bursa, called bursitis. It can also lead to wear and tear on the rotator cuff tendons, called tendonitis. In some cases, a partial tear of the rotator cuff may cause impingement pain.
Inflammation of these soft tissues can cause swelling which reduces the amount of space between the acromion and the humeral head increasing the chances of developing bursitis. This space can also be reduced by bone spurs from the AC joint or variations in the anatomy of the acromion.
Risk Factors for Impingement Syndrome
People who do repetitive activities for sports (such as swimming, tennis, or baseball) or their job (painters, construction workers or paper hangers) are at risk for impingement.
Symptoms of Impingement Syndrome
The symptoms of bursitis and impingement on the rotator cuff include local swelling and aching in the front of the shoulder, that may radiate towards the neck and down to the elbow. Laying on the shoulder at night may be especially painful. Upward movement of the humerus, such as shrugging of the shoulder, can be very painful. Most people with rotator cuff symptoms complain of pain in the front of the shoulder and with overhead activities. Pain at night, stiffness and weakness are also common complaints. Advanced cases may progress to a frozen shoulder.
Diagnosis of Impingement Syndrome
The diagnosis of impingment and bursitis is usually made on the basis of the history and physical examination. Pain when performing the lift-off test indicates impingement. The lift-off test is done by resting the back of the hand of the affected arm on the lumbar spine area of the back. Then lift your hand off (away from) your back without straightening your elbow. If you can’t lift your hand that’s a positive test for impingement.
Xrays can only see bones and are used to confirm the presence of an abnormal acromion, or degeneration and spur formation in the acromioclavicular joint.
An MRI scan, arthrogram or ultrasound can be done to see the soft tissues of the joint and subacromial space. These test can show fluid or inflammation in the bursa and rotator cuff. An MRI may be ordered if there is a suspected tear of the rotator cuff tendons.
In some cases, an injection of a local anesthetic into the bursa can ensure the pain is actually coming from the shoulder and not radiating from the neck.
Treatment Impingement Syndrome
Intial treatment for impingement usually includes:
• resting the joint by avoiding overhead activities
• taking a mild anti-inflammatory medication
• stretching exercises to improve range of motion
• a physical therapy program for strengthening
If these measures fail to improve your pain, an injection of cortisone into the bursa may be done to reduce inflammation. Cortisone is a potent anti-inflammatory medication. It may bring the inflammation under control and ease your pain. Most patients have gradual improvement and a return of normal function. Treatment can take several weeks to months. There are special exercise that focus on rotator cuff recovery from injury.
If all conservative (non-surgical) measures fail, surgery may be required to remove the impingement by creating more space for the bursa and rotator cuff. Surgery for impingement usually begins by removing a portion of the acromion. Any bone spurs that appear to be rubbing on the bursa and tendons are removed and the coracoacromial ligament is cut to widen the space. This gives the tendons room to move without rubbing, and will decrease the pain and inflammation in the bursa and tendons.
In some cases opening up the subacromial space can be done arthroscopically, and you may be able to go home the same day. In other cases, an open incision is needed to remove the bone. An open incision may require a one or two night stay in the hospital. After surgery, the arm is in a sling for a short time to allow healing and support. A rehab program to regain strength and range of motion will be started based on what was found during surgery and the amount of repair needed. It takes about 2-4 months to get complete pain relief, but could take as long as a year.