The Painful Shoulder

Introduction
Shoulder problems are very common, but most cases of shoulder pain only last for a short while and are not caused by arthritis. This booklet explains why people get shoulder pain and looks at the conditions that are most likely to cause problems. The shoulder can be quite easily injured, especially in some sports, but this booklet does not cover problems directly related to an injury such as a dislocation.

Most shoulder problems will settle with simple treatments and you may not even need to see your doctor, but this booklets looks at the more specialised treatments (including surgery) that are available for severe or persistent shoulder problems.

How does the shoulder work?
The shoulder is the most mobile joint in the body and is often affected by painful problems which limit its movement. Movement takes place at the main shoulder joint (glenohumeral joint) as well as the shoulder blade (scapula) which moves over the back of the chest. The shoulder joint is a ball-and-socket type joint which allows a very wide range of movement. The joint is surrounded by a tough, fibrous sleeve called the capsule; the inner layer of this, the synovium, produces fluid to nourish and lubricate the joint. A group of four muscles and their tendons make up the rotator cuff which plays a very important part in the working of the shoulder, helping to move it and hold the joint together. Problems with the rotator cuff can cause several painful conditions.

Where is the pain coming from?
Shoulder problems may be part of a general condition such as rheumatoid arthritis, osteoarthritis or polymyalgia rheumatica or may be a more localised problem.

Not every pain felt in the shoulder area is caused by a problem in the shoulder joint. For example, problems in the neck may cause pain which is actually felt in the shoulder (known as ‘referred pain’). When the problem does originate in the shoulder joint the pain is often felt over the front of the shoulder or in the upper part of the arm. The pain can sometimes spread down the arm to the elbow, but if it spreads further down the arm, or if you have tingling or pins and needles, then the pain probably comes from a problem in the neck. If the pain is more towards the side of the neck or over the shoulder blade then, again, the neck may be the source of the pain. Pain at the top of the shoulder may come from the acromioclavicular joint at the end of the collarbone or ‘clavicle’. Sometimes the pain can come from problems in both the neck and shoulder. Your doctor or physiotherapist will be able to help make the correct diagnosis.

Where the pain does arise from the shoulder joint itself there are several possible causes:

Inflammation of, or damage to, the muscles and tendons around the shoulder especially within the rotator cuff or the joint capsule
Inflammation in the sac of soft tissue (bursa) which normally allows the muscles and tendons to slide smoothly over the shoulder bones
Damage to the bones and cartilage, which can be caused by arthritis. Rheumatoid arthritis quite commonly affects the shoulders. Osteoarthritis is less likely to affect the shoulders but may follow on from previous shoulder injuries.

Link: http://www.arc.org.uk/arthinfo/patpubs/6039/6039.asp
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