The shoulder joint, or more properly the glenohumeral joint, is the articulation between the head of the humerus (the arm bone) and the glenoid (part of the scapula or wing blade. The humeral head is the ‘ball part of the joint and the glenoid is the ‘dish’ or ‘socket’ part of the joint. The clavicle or collar bone acts as strut between the sternum (breastbone) and the scapula and attaches to the scapula at the acromioclavicular joint
The humeral head is nearly half a sphere. It points slightly upwards and backwards towards the glenoid.The glenoid is small and shallow (about a 1/3 of the surface area of the humeral head). This allows the shoulder to be the most mobile joint in the body, which is good for placing the hand where you want it to be, but at the cost of being the most unstable large joint in the body (shoulder dislocation is quite common). The structures which provide stability to the joint are the labrum (a rim of gristle or cartilage attached to the rim of the glenoid), the joint capsule and ligaments (which attach between the labrum and the anatomical neck of the humerus) and also the four rotator cuff muscles. The latter also control movement of the shoulder and provide strength together with the big deltoid muscle on the outside of the shoulder.
Any of these structures can be damaged either through injury, overuse or wear and tear.Shoulder pain is common and is the third most common cause of musculoskeletal consultation in primary care.1% of adults consult their GP each year with new shoulder pain and the self-reported prevalence of shoulder pain is between 16% and 26% (i.e 16%-26% of adults have shoulder pain at any one time).
What causes shoulder pain?
The shoulder is the most mobile joint in the body. The main shoulder joint is a ball-and- socket joint, which allows a very wide range of movement. A group of four muscles and their tendons make up the rotator cuff, which controls movement and also helps to hold the joint together.
There are many causes of shoulder pain, but the most common reason is related to the rotator cuff. These muscles have to work with every arm activity we do day to day. Sometimes, due to overuse, a change in activity or just normal age related changes these muscles don’t do their job as well which can result in pain.
The good news is that if you have shoulder pain that has come on gradually or without any history of trauma then simple exercises that help these muscles work better can help get your pain better.
What are the symptoms?
- Pain around the front and/or side of the shoulder.
- Spontaneous or gradual onset
- Pain is made worse by movement, e.g. raising arm above shoulder level or the action of putting on a coat. Some people will complain of pain at night, particularly when lying on the affected side.
Diagnosing Shoulder Pain
There are many causes of shoulder pain but generally, as long as you haven’t had a history of a fall or injury most shoulder pain responds well to exercises that make the rotator cuff muscles stronger. Half of all first time episodes of shoulder pain get better without treatment in 6 to 12 weeks.
X-rays and other investigations are not usually necessary during the first episode of pain. They are only indicated if you fail to respond to the advice and exercises recommended below.