This common complaint is voiced by about one of every five adults at some time in their
lives. In younger people, athletic injuries are most often responsible, but in the rest of us, normal wear and tear take their toll over the years — which is why shoulder pain is actually more common at the age of 70
than 30.
Swing a golf club, take a book off a high shelf, or reach back to put your arm in your sleeve and you'll learn why shoulder pain is so common: The shoulder has an enormous range of motion, and that mobility
is used repeatedly in daily life, to say nothing of sports. Yet to achieve free motion, the shoulder has to sacrifice stability and strength. Instead of being a snug joint held together by strong ligaments, the shoulder
has to depend on muscles and tendons for much of its stability and strength as well as its mobility. To compound matters, the shoulder apparatus is not one joint but four, all of which must move together smoothly to
perform the simplest motion. Add three bones, nearly 30 muscles and their tendons, and a bursal sac and you can see why shoulder pain is so common — and so complex.
The Normal Shoulder
The structure of the shoulder is provided by three bones: the humerus or upper arm, the clavicle or collarbone, and the scapula or shoulder blade (see figure 1). The major joint lies between
the humerus and the scapula; it's a ball-and-socket arrangement, but since the ball is big and the socket shallow, it sacrifices stability to gain mobility. As a result, the glenohumeral joint is the most frequently
dislocated joint in the body; it is surrounded by a protective capsule, but to allow mobility, the capsule is lax and flexible.
Every time the arm bone rotates in its socket, it causes movement in the three
smaller joints: at the junction of the collarbone and scapula (acromioclavicular joint), the collarbone and the breastbone or sternum (sternoclavicluar joint), and the shoulder blade and chest wall (
scapulothoracic joint).
Shoulder motion depends on coordinated contractions of the shoulder muscles, each of which is anchored to bone by a tendon. The deepest muscles are the four that collectively form the
rotator cuff, the key to the shoulder's stability. The other muscle groups are closer to the surface but are no less important for motion. A bursal sac filled with fluid lies between the deep muscles and those closer to
the surface.
The Painful Shoulder
Shoulder pain can originate in any structure in this complex apparatus–and it can also be referred from the neck (herniated cervical discs and pinched
nerves, for example), hand (carpal tunnel syndrome), abdomen (irritated diaphragm), or even the chest (angina or heart attack). But in most cases the shoulder itself is to blame, and a few simple clues may point to the
problem. For example, pain that's worse at night when you are lying on your shoulder suggests a rotator cuff problem, pain triggered by overhead activities points to the impingement syndrome,
and general stiffness and immobility are characteristic of a frozen shoulder.
To determine the cause of your pain, your doctor will ask when it started and if it came on after a fall or injury. He'll want to know if certain activities make the pain worse and if any
position seems to help. Next, he'll ask you to put your shoulder through its motions and to relax while he moves your arm and shoulder and presses on specific areas. If you've had an injury
that could produce a dislocation or fracture, an ordinary x-ray can help greatly, but if soft tissues like muscles and tendons are the likely culprits, an x-ray won't be helpful, and your doctor will have to order a
magnetic resonance imaging (MRI) test if he thinks an image is necessary. In many cases, a primary care doctor can evaluate and treat shoulder pain, but fractures,
dislocations, and complex or severe soft tissue injuries are best treated by orthopedists. A skilled physical therapist can be extremely helpful, both in diagnosing and treating nearly all shoulder problems.
Here's a brief rundown of the most common causes of shoulder pain that does not result from trauma.
Rotator Cuff Tendinitis
This is most common cause of shoulder pain. In young people
who throw curve balls or hit serves, overuse is the trigger, and swelling and inflammation, the result. But beyond the age of 45, the cause is a gradual thinning and fraying of the supraspinatus tendon,
with the gradual involvement of the three other tendons if the condition progresses. The earliest symptom is a dull ache at the tip of the shoulder. The pain is aggravated by
reaching overhead, lifting the arm up to the side, or reaching back to put on a jacket. In time, the pain becomes more severe and extends over the entire shoulder, but it doesn't move up
into the neck or down the arm. Night pain is characteristic and is often severe enough to interfere with sleep; lying on the affected shoulder can be excruciating. The impingement
syndrome is another name for rotator cuff tendinitis that is severe enough to interfere with overhead activity. An x-ray is not helpful, but an MRI can pinpoint the problem. Most cases of
rotator cuff tendinitis respond nicely to programs of rehab exercises and anti-inflammatory medications.
Rotator Cuff Tears
In young adults, the rotator cuff tendons are so strong that
they're nearly impossible to tear. Not so, alas, in people over 60, whose tissues have thinned out over the years. Tears can be partial or complete; they almost all occur where the tendons
attach to the bone. Minor tears are treated conservatively, just like the tendinitis that usually precedes the actual tear. But major tears produce weakness and an inability to raise the arm
normally. Surgery can help restore function, but the recovery is slow, and many orthopedic surgeons prefer to reserve surgery for younger patients, for major tears that are diagnosed early,
or for vigorous senior citizens who place high demands on their shoulders.
Bursitis
When the fluid-filled sac that cushions the joint is inflamed, pain
develops at the tip of the shoulder. It usually starts abruptly and can be severe enough to make motion excruciating. The tip-off to the diagnosis is sharply localized tenderness when you
or your doctor press on the outside tip of the shoulder. Mild cases improve with anti-inflammatory treatments and exercises (see below), but severe cases may require an injection of
steroids right into the bursa; the results are excellent.
Biceps Tendinitis and Rupture
The pain is at the front of the shoulder, where the tendon of
the biceps muscle passes through a groove in the upper arm bone. The pain is aggravated by flexing the elbow to bring the palm up to the shoulder. Doctors can usually detect a point of
tenderness when they press on the biceps groove. If anti-inflammatory medications and rehab exercises don't do the trick, a steroid injection right at the point of tenderness can relieve the pain.
If the long head of the biceps muscle ruptures, there is a sudden, sharp pain in the upper arm followed by a dull ache that fades away. A little shoulder stiffness may also develop, but
most patients complain simply of a lump when they "make a muscle" by flexing the elbow. Although some patients who don't like the Popeye look request surgical repair for cosmetic
reasons, most don't need any treatment at all.
The Frozen Shoulder
Doctors call it adhesive capsulitis. You'll call it a real pain. By
any name, a frozen shoulder is a major cause of disability. It can develop from any underlying shoulder condition that causes serious pain. In turn, the pain causes patients to "favor" the
aching shoulder. In the short run, immobility may make a shoulder feel better, but in the long run it produces thickening, stiffening, and adhesions (scarring) of the soft tissues. All too
often, the result is a vicious cycle of pain and stiffness that can eventually be disabling. Recovery requires a program to put the cycle into reverse. The first step is a period of rest, which
allows the pain to settle down gradually. Next comes a slow, careful program of exercises that help the frozen shoulder thaw; anti-inflammatories or other pain relievers can be useful in this
phase of mobilization and strengthening. Manipulations, steroid injections, and even surgery can help in difficult cases. Physical therapy is invaluable.
The best way to treat a frozen shoulder is to prevent it from
developing in the first place. That's why exercise is a part of the treatment of nearly every painful shoulder.
Arthritis
Arthritis can strike any joint, and the four shoulder joints are no exception. The glenohumeral and acromioclavicular joints are the most vulnerable. Garden-variety osteoarthritis
(degenerative joint disease) is the usual culprit, but it usually strikes the knees, hips, and hands first, making shoulder pain a secondary problem.
Shouldering Responsibility
Don't shrug it off; even mild shoulder pain can lead to big trouble if you take the easy way out and don't put your shoulder through its full range of motion. It's okay to rest your
shoulder for two or three days after an injury, but then get it moving. Still, you should not attempt to return to full activity all at once. Instead, to protect your shoulder, minimize overhead
activity and avoid pulling or lifting until you've improved. Don't force your arm to move beyond the point of pain; with repetition and time, the exercises should reduce your pain and extend your range of motion.
Figures 2 and 3 illustrate exercises that will help most shoulders. For best results, warm up your shoulder with a heating pad, warm compress, or liniment for five minutes before you exercise,
then massage it with ice for five minutes afterward. Repeat the exercises three times a day. If you don't start improving within a week or so, see a doctor or physical therapist for an individual regimen.
Shoulder exercises are necessary for recovery, but they are
usually not enough. Unless you have a medical reason to avoid them, aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) can be helpful. Use them with care, however, and ask
your doctor about one of the newer prescription COX-2 inhibitors if NSAIDs bother your stomach or cause bleeding (see Harvard Men's Health Watch, January 1998). Even without fighting inflammation, acetaminophen
(Tylenol and other brands) can help by reducing your pain enough to keep your shoulder nimble. In addition to planning and supervising rehab exercises,
physical therapists can also help by using ultrasound and other tools. And physicians can help if necessary with interventions ranging from steroid injections to arthroscopic surgery and open surgery.
