Patient education: Shoulder impingement syndrome (Beyond the Basics)

SHOULDER IMPINGEMENT SYNDROME OVERVIEW — Shoulder impingement syndrome (SIS) is a condition that causes shoulder pain. To diagnose SIS, health care providers look for a specific set of shoulder symptoms and certain clinical findings, which together suggest that the patient has the condition. In SIS, a part of a person’s shoulder is compressed against another part, and this causes pain with some shoulder movements.

EPIDEMIOLOGY AND RISK FACTORS — Shoulder pain is extremely common in the general population and is often caused by shoulder impingement syndrome (SIS). The condition is especially common among people who have certain shoulder weakness patterns or do repetitive activities that involve raising their arms to or above shoulder level. For example, SIS is more common among those who regularly perform overhead movements, which may include (among others) the following activities:

●Swimming

●Throwing

●Playing tennis or pickleball

●Lifting weights

●Playing golf

●Playing volleyball

●Doing gymnastics

●Painting

●Stocking shelves

SHOULDER IMPINGEMENT SYNDROME CAUSES — In shoulder impingement syndrome (SIS), a number of anatomical structures in and around the shoulder joint can be affected, but the condition is not defined by an injury to any particular structure. Instead, SIS is defined by a range of symptoms and clinical findings, which indicate that tissues within and around the shoulder joint are inflamed or compressed. If the compression is chronic, it can result in structural breakdown over time. The following stages represent the full spectrum of SIS. Each stage tends to affect a different age group:

●Stage 1: This stage tends to happen in people younger than 25. It consists of swelling and inflammation.

●Stage 2: This stage tends to happen in people age 25 to 40. In addition to swelling and inflammation, it consists of weakening of the tendons in the shoulder, a problem called tendinopathy. (Tendons are strong bands of tissue that connect muscles to bones.)

●Stage 3: This stage tends to happen in people older than 40. It consists of advanced tendinopathy, rotator cuff tear, biceps tendon tear, or changes to the bones in the shoulder.

The changes associated with each of the stages listed above happen when the muscles, tendons, and other soft tissues in the shoulder get compressed between the upper arm bone—called the humerus—and the other bony parts of the shoulder. Soft tissues become compressed for a number of reasons. For example, the joint can loosen or become unstable, making it possible for the humerus to move more than it should; the bones in the shoulder can be shaped in a way that makes them more likely to compress nearby tissues; or the bones can develop spurs (bony protrusions) that jut out into the joint. In addition, the way many people hold their body, particularly those who spend a lot of time at a desk or computer, with their head forward and shoulders hunched, predisposes them to shoulder impingement (picture 1).

Throwing athletes — Throwing athletes suffer from a unique form of SIS. This is because the repeated action of "cocking" for a throw can cause the tissues inside the back part of the shoulder joint to get compressed (figure 1). This type of SIS, called "posterior SIS," affects mostly baseball pitchers but can also affect other throwing athletes (eg, participants in American football or softball) or athletes who participate in other sports that involve a lot of overhead movements (eg, volleyball or swimming).

SHOULDER IMPINGEMENT SYNDROME SYMPTOMS — The main shoulder impingement syndrome (SIS) symptom is pain that occurs when the person lifts his or her arms overhead or reaches backwards. The pain can be at the shoulder, near the top of the arm, or down the outside of the arm, and it frequently happens at night or when the person lies on the affected shoulder.

Symptoms in athletes — Throwing athletes with SIS complain of shoulder stiffness and a difficult or prolonged warm-up period. In athletes, pain tends to occur when they position the arm behind them to get ready for a throw, or when they start to move the arm forward to start the throw. At first, athletes have a hard time localizing the pain, but with time the pain focuses at the back of the shoulder in cases with posterior SIS. Athletes who serve—as in tennis and volleyball—sometimes complain of pain when they are following through or finishing a serve.

SHOULDER IMPINGEMENT SYNDROME DIAGNOSIS — If you have symptoms of shoulder impingement, your health care provider will examine you to learn what movements elicit symptoms. As part of the evaluation, he or she will likely ask to watch as you move your own arm and shoulder (called active motion), and also explore what you feel if he or she moves your arm and shoulder for you (called passive motion).

In most cases, health care providers can tell when a person has shoulder impingement syndrome (SIS) based on the results of the physical exam. Still, in some cases it’s hard to tell the difference between SIS and other shoulder problems. If your health care provider is uncertain about your diagnosis or thinks that you might need surgery, he or she might refer you to a doctor who specializes in muscle and joint problems, such as an orthopedist, rheumatologist, or rehabilitation and physical medicine specialist.

Imaging — People with suspected SIS do not typically need radiographs, but an ultrasound exam or radiographs of the shoulder can sometimes help with the diagnosis. Magnetic resonance images (MRIs) are reserved for people who do not get better after initial treatment or for people who appear to have certain types of injuries or structural abnormalities beyond SIS.

SHOULDER IMPINGEMENT SYNDROME TREATMENT — If you have shoulder impingement syndrome (SIS), the right treatment for you will depend on your individual situation. If your health care provider suspects you have a rotator cuff tear or another type of injury, he or she might recommend you see a specialist such as an orthopedic surgeon to find out what treatment options are available, possibly including surgical repair. But if your health care provider does not think that is warranted, he or she will likely suggest medication, exercises, stretches, or avoiding painful activities.

If your health care provider prescribes physical therapy, work with a knowledgeable professional, such as a physical therapist or athletic trainer who has experience managing shoulder disorders.

When symptoms first start — When symptoms of SIS first start, you should rest the affected arm and shoulder, and avoid activities that bring on the pain. You can also ice the shoulder and, if necessary and deemed safe by your health care provider, take nonprescription pain medications, such as acetaminophen (sample brand name: Tylenol), ibuprofen (sample brand names Advil, Motrin), or naproxen (sample brand name: Aleve).

Physical therapy — When it is time to begin physical therapy, your therapist will provide a series of treatments and exercises designed to help you regain as much function as possible and ultimately decrease your pain.

A rehabilitation program for SIS should focus first on restoring mobility (if mobility is restricted), then on strengthening the muscles that stabilize the shoulder blade, and later on regaining overall strength and function. A qualified physical therapist or athletic trainer can work with your health care provider to design and implement an effective rehabilitation program for SIS, which generally includes:

●Range of motion exercises to improve motion in all directions

●Exercises to stretch the tissues surrounding the shoulder joint

●Strengthening exercises

●Stabilization exercises, commonly focused on the muscles of the scapula (shoulder blade)

●Training to teach proper technique, for example in throwing

●Exercises to improve the strength and stability of the shoulder muscles and to help the person return to the activities he or she specifically wants to do

●Possible kinesio-taping (taping to support muscles and improve positional sense during activity)

Athletes who play sports that require them to reach overhead should refrain from those activities for two to four weeks but should do physical therapy during that time. As symptoms improve, athletes can slowly return to their usual activities. With the right rehabilitation program, about 95 percent of throwing athletes return to their previous level of function.

Steroid injections — Health care providers sometimes suggest injections of medications called glucocorticoids, known commonly as "steroids", directly into the shoulder, beneath a bone called the acromion (figure 2). Steroids help to relieve inflammation and pain, and consequently make it easier for you to perform physical therapy effectively.

Unproven treatments — There are some treatments for SIS that remain unproven, although some patients may find them helpful. Unproven treatments include:

●Electrical stimulation, phonophoresis, and iontophoresis

●Therapeutic ultrasound

●Laser

●Acupuncture – Some evidence suggests that acupuncture may provide some benefit when combined with physical therapy.

FOLLOW-UP CARE — Two to four weeks after starting treatment for shoulder impingement syndrome you should follow up with your health care provider to see how your symptoms are progressing and check whether any aspect of treatment should change. After that, your follow-up will be directed by your doctor, physical therapist, or other health care provider. You may need additional guidance on how to resume normal activities.

If you do not get better within 8 to 12 weeks, your health care provider might suggest additional testing or that you speak to an orthopedic specialist.

RETURN TO SPORT OR WORK — Once you regain full range of motion, strength, and shoulder stability, you can resume your usual activities. It's best to start slow and gradually increase your activity level.

If you are an athlete, make sure everyone involved in your care, including not just your health care provider, but also your trainer and coach, are aware of your condition so they can monitor your progress and help facilitate any needed changes in athletic technique and assist as needed with physical therapy and strength programs.

[1-7]