The shoulder is a ball and socket joint. The top of the arm bone, which is shaped like a ball, fits inside the socket in the shoulder blade and is held in place by tendons and ligaments, which form a capsule around the joint to help to support its movement. The rotator cuff is a specialised group of muscles provided fine control movements of the shoulder.
Above the main shoulder joint is a smaller joint called the acromioclavicular, which supports the wide range of movement of the shoulder particularly when you are raising your arm or lifting overhead
The shoulder is a complex joint with the widest range of movement of any joint in the body. This can put the ligaments and muscles under a lot of strain and makes the joint prone to dislocation.
If your pain has suddenly after an injury it is very possible that a fracture or ligament or tendon tear has occurred, and you should seek specialist advice as soon as possible.
Another common reason for sudden severe shoulder pain is calcific tendinopathy(formerly tendinitis). Calcium has built up in a tendon for no particular reason and causes excruciating pain. It can be diagnosed and treated very successfully and quickly after a simple x-ray test.
Chronic shoulder pain develops more gradually – sometimes months or years – and is usually much harder to diagnose accurately.
Common causes of chronic shoulder pain
It is very common for the discomfort from a chronic shoulder problem to be felt in the upper arm, elbow or even wrist! This is called referred pain. However, if the pain comes on with movement of your shoulder it is very likely to be related to your shoulder.
There can be a number of reasons why your shoulder might be painful, including:
- Wear of the smooth joint cartilage, this is called arthritis.
- Wear of the tendons which often eventually results in a tear.
- Tightness and inflammation of the capsule, called frozen shoulder
- Tearing or stretching of the ligaments, this will often feel like the joint is ‘popping’ or partially dislocating.
- Inflammation which is the body’s response to any of these conditions. The bursa, which is the fluid-filled cushion between the bones and soft tissues, will become inflamed as your body’s natural attempt to heal itself, but this causes pain in itself.
- A problem in another part of your body, such as your neck, which can also cause referred shoulder or upper arm pain.
Shoulder pain symptoms may give a clue
It is notoriously difficult to accurately to diagnose chronic shoulder pain. Most conditions occur much more commonly in certain age groups and provide a guide to the most likely cause of pain. However, any condition can occur at any age, but it is just much less likely.
The usual cause is tearing or over-stretching of the ligaments that hold the ball centred in the socket. This is called instability. If there has been an injury in the past there is often an associated labral tear. It may cause a range of symptoms from deep pain in your shoulder with certain activities to repeated full dislocation of the joint.
Rotator cuff tendinopathy (formerly tendinitis or impingement syndrome) is the most common cause. The pain is felt down the outer part of your arm when lifting the arm away from your body and is often especially bad at night. Tiny ‘micro tears’ have developed in one of the tendons around your shoulder over the years. Bursitis develops as a natural healing response but sometimes does not work, leaving you in chronic pain. If the condition goes on undetected over time a full rotator cuff tear will develop.
Another common cause is frozen shoulder. The capsule of the shoulder becomes inflamed and scarred. It is more common in people with diabetes but very often happens for no good reason. It is very often mistaken for rotator cuff pain in the early stages, but the pain is usually more severe and harder to pinpoint. After a few months severe stiffness will develop but prompt treatment will usually avoid this happening.
If you have a manual job, or like going to the gym a lot, it is very possible that acromioclavicular joint arthritis has developed. The pain is normally felt on top of your shoulder and is worst when lifting your arm high above your head.
Rotator cuff problems can still occur regularly in patients of this age group but shoulder joint arthritis is the usual cause of pain. In fact, chronic severe tearing of the rotator cuff often results in arthritis. Joint movement becomes more restricted with time and ‘grinding’ noises are often heard and felt with movement.
As you can see, there are many causes of shoulder pain so an accurate diagnosis is the first step to better understanding the cause.
Diagnosis and treatment of shoulder pain
If your symptoms are related to an injury, severe or you have had them for a long time, you should seek medical help. This always starts with questions about your symptoms and a physical examination. To complement this your doctor may recommend a range of imaging tests. These should always examine both the bone (e.g. xray or CT scan) and the soft tissues (e.g. ultrasound scan). An MRI scan is an all-encompassing scan that visualise all parts of the shoulder and is therefore often preferred.
There are a range of treatments available depending on what is causing your symptoms, but your doctor will always recommend less invasive non-surgical treatments first before suggesting surgery.
In the first instance it is always important to get an accurate diagnosis so you can begin a tailored treatment plan for your particular condition.