At a glance

  • Shoulder pain is typically felt on the outer side of the shoulder. The exact cause is often unknown. It is sometimes diagnosed as “shoulder impingement.”
  • In about 50% of all people, the pain gets better within six months.
  • Acute pain can be temporarily relieved by cooling the area and using painkillers. Physical therapy can gradually strengthen the shoulder and improve the range of movement again.
  • Good-quality studies have found that surgery doesn’t help.

Introduction

Photo of a man working in a warehouse (PantherMedia / Wavebreakmedia ltd) Shoulder pain is one of the most common joint problems. It can be caused by a number of different things. This is because the shoulder contains a lot of muscles, ligaments, tendons, fluid-filled sacs and bones that work together in a small space. It’s not always possible to find out exactly what is causing the pain.

Shoulder pain usually arises beneath the bone that forms the “roof” of the shoulder (the acromion). It is then often referred to as shoulder impingement. Other causes of shoulder pain include things like frozen shoulder or osteoarthritis. This information is about pain under the acromion – not about pain caused by other things like osteoarthritis or acute injuries.

Pain under the acromion sometimes gets better within half a year, but it may also last longer. Until the pain gets better, it’s a good idea to avoid moving the arm too much. Acute pain can be relieved by cooling the area and taking inflammation-reducing painkillers. If the pain is very bad, it can be treated with steroid injections. Physical therapy with strengthening and mobility exercises can help to make the shoulder stronger. Surgery usually doesn’t help.

Symptoms

Pain under the acromion often occurs on the outer side of the joint. The medical term for this type of pain is “subacromial pain.” It gets worse when you lift your arm sideways (see illustration). Sometimes the pain gets worse if you lie on the affected shoulder at night. It might then wake you up.

Illustration: Positions where subacromial pain occursPositions where subacromial pain occurs

Causes

Various things can make the space under the acromion (the subacromial space) narrower. These include bony growths, “wear and tear” and calcium deposits in the supraspinatus tendon (see illustration). Other causes include an inflamed fluid-filled sac or a hooked acromion, where the tip of the shoulder blade curves down more than usual. Sometimes ligaments and tendons in the joint capsule become shorter due to weak muscles or putting abnormal strain on the muscles.

All of these things can cause parts of the shoulder tendons (“rotator cuff tendons”) and the fluid-filled sac (“bursa”) to become pinched between the acromion and the head of the upper arm bone when you lift your arm.

 

Illustration: Muscles, tendons, bursa and bones in the shoulder areaMuscles, tendons, bursa and bones in the shoulder area

 

Because so many different things can cause pain under the acromion, a variety of terms are used when diagnosing the problem. These include “shoulder impingement,” “rotator cuff syndrome” and “calcific tendinitis of the shoulder.”

Research has shown that there’s no clear link between the symptoms people have and things that can be seen on ultrasound, x-ray or MRI images. Sometimes people don’t have shoulder pain even though these images show that there are calcium deposits, tears and “wear and tear” in the rotator cuff (a group of muscles and tendons that surround the shoulder joint) or the shoulder labrum (a ring of cartilage around the shoulder socket). Because of this, many experts now prefer to call it “subacromial pain” (pain under the acromion) rather than “shoulder impingement.” It’s not clear what role soft tissue becoming pinched (impingement) actually plays in the development of shoulder pain.

Risk factors

People who frequently have to work on something above their head are at greater risk of developing subacromial pain. Common examples include painters, electricians, warehouse workers and shelf stockers.

Certain sports involve moving your arms above your head a lot as well – for instance, tennis, basketball or other ball games. Many swimmers who do the front crawl or butterfly stroke swing their arms up over their heads. Intensive training can then lead to shoulder pain.

Weak shoulder muscles, ligaments and tendons can also result in shoulder pain. The shoulder is a very movable joint that is mainly kept stable by the muscles. If the shoulder muscles are weak, the head of the upper arm bone (humerus bone) may “fall” out of the socket and push against the surrounding soft tissue.

Prevalence and outlook

Shoulder pain is one of the most common orthopedic problems, along with back and neck pain. In up to 70% of those affected, the pain arises under the acromion (“subacromial pain”).

The course of shoulder pain can vary from person to person. In about half of those affected, the pain goes away within six months. But in some people it can continue for many years.

Diagnosis

To find out what's causing the symptoms, the doctor will ask questions like

  • when the pain occurs and how it feels,
  • whether there was an injury or accident, and
  • whether it could have been caused by things like overhead work or certain types of sports.

The physical examination that follows includes several tests that involve lifting and lowering your arms sideways, and moving your elbows in various directions, inwards or outwards. The doctor will also feel your shoulder. This is usually enough to diagnose subacromial pain. During the physical examination the doctor can also rule out other possible causes of the pain, such as radiating neck pain or frozen shoulder (adhesive capsulitis).

Sometimes people have examinations with imaging techniques, too: For instance, a torn rotator cuff can be seen in ultrasound images, and the bones and calcium deposits can be seen in x-ray images. A magnetic resonance imaging (MRI) scan may be considered if the cause has still not been found.

Because there’s no clear link between people’s symptoms and the changes or “wear and tear” seen in the images, these imaging techniques aren't always needed. They may be a good idea if the symptoms don’t improve despite treatment, if surgery is being considered, or if there’s reason to believe that something else is causing the pain. For instance, x-ray images can help to find out whether the person has osteoarthritis of the shoulder joint.

Treatment

People who have acute shoulder pain are advised to

  • go easy on their shoulder, taking special care to avoid work or sports that involve lifting the affected arm up over their head,
  • cool the shoulder,
  • relieve the pain with anti-inflammatory (inflammation-reducing) painkillers such as ibuprofen, if necessary. But these painkillers shouldn't be taken for longer than 1 to 2 weeks. If the pain is very bad, steroid injections can be used too.

Going easy on your shoulder doesn't mean you should stop moving your arm completely – on the contrary: By doing certain physical therapy exercises, the shoulder can gradually become more movable and stronger again.

Shoulder surgery isn’t likely to help much in people who have subacromial pain. Good-quality studies have shown that surgery to widen the space under the acromion usually doesn't help any better than treatment where people only think they have had this surgery. Surgery is always associated with risks and can lead to other shoulder problems, so it’s important to carefully consider the pros and cons before deciding whether or not to have it done.

Learn more

Further information

When people are ill or need medical advice, they usually go to see their family doctor or pediatrician first. Read about how to find the right doctor, how to prepare for the appointment and what to remember.