The four muscles that raise and lower the arm (and their respective tendons) are collectively known as the rotator cuff. This group of tissues fits neatly under the roof of the shoulder--an extension of the shoulder blade known as the acromion. However, if the cuff becomes inflamed, or some bone deformity exists in the acromion, the rotator cuff and acromion can rub against one another, causing a painful condition known as impingement. Each time the arm is raised there is a bit of rubbing on the tendons and the bursa (small fluid-filled sacs located in the shoulder to lubricate the joint and reduce friction) between the tendons and the acromion, which may cause pain and inflammation.
Almost everyone will experience some degree of impingement due to the day-to-day activities that we perform with the arm above shoulder level. Impingement may become a serious problem for those who continuously work with their arms raised overhead (painters, carpenters) or those who repeatedly engage in throwing activities (pitchers).
The impingement process may get worse if any condition decreases the amount of space between the acromion and the rotator cuff tendons or if bone spurs are present.
- General ache in the shoulder
- Pain when raising the arm out from the side or in front of the body
- Pain when sleeping on the affected shoulder
- Sharp pain when reaching into a back pocket
- Stiffness
- Catching sensation when the arm is lowered
Causes and Risk Factors
Causes
- Overuse
- Wear and tear
- Arthritis
- Weak rotator cuff muscles
- Aging
Your doctor will perform an orthopedic evaluation of your shoulder that will consist of three parts: medical history, physical examination, and diagnostic tests. After carefully reviewing the results, your doctor will discuss treatment options with you. Your doctor may recommend that you have an injection of cortisone to reduce inflammation and control the pain. In addition, your doctor may refer you to a physical therapist who will guide you through a series of exercises that will help keep your shoulder strong and flexible and reduce the irritation from impingement. If the impingement is advanced or severely debilitating, surgery may be necessary. The goal of any surgery to reduce the effects of impingement will be to increase the amount of space between the acromion and the rotator cuff tendons, which will then allow for easier movement and less pain and inflammation. The first thing that an orthopaedic surgeon will do is remove any bone spurs that are rubbing on the rotator cuff tendons and bursa. A small part of the acromion may be removed (see Acromioplasty) as well to give the tendons even more space and allow them to move without rubbing. In addition to the impingement your doctor may discover other problems such as Osteoarthritis in the acromioclavicular (AC) joint. In this case it may be necessary to remove the end of the clavicle, this is called a resection arthroplasty. These procedures may be performed arthroscopically or through an open incision.
