The shoulder girdle is composed of a series of complex bones and joints linked by ligaments, tendons and muscles to the breastbone (sternum), neck (cervical spine) and chest (thorax). Shoulder pain is a common complaint and can arise from any of these structures or less commonly, be referred from the neck, heart or abdomen. Pain can be due to trauma (physical injury), mechanical problems (such as subacromial impingement or instability), inflammation (such as arthritis, bursitis or capsulitis), degeneration (such as rotator cuff tears) or nerve irritation (involving nerves around the shoulder or in the neck). Assessment of shoulder pain depends largely on a careful history of the onset, duration and location of the pain, and its relation to sleep, rest or activity. It may also be associated with other symptoms. Detailed physical examination and selective imaging such as x-rays, ultrasound, CT or MRI scans may be required to establish a precise diagnosis, although in some complex conditions arthroscopy (keyhole surgery) may be necessary to define the underlying cause. In most cases there are features that can suggest the likely problem. The following covers some of the more common sources of shoulder pain:
1. Shoulder joint: localised to the jointline in front or behind, related to movement often worse at night.
2. Rotator cuff and subacromial bursa: often felt in the top of the arm in the deltoid muscle, with radiation down the lateral side of the arm towards the elbow. Tends to be maximal during the mid-arc of elevation of the arm.
3. Acromioclavicular joint: localised to the joint itself, but may radiate up into the neck or back over the shoulder blade. Tends to be worse in the high arc of elevation of the arm or in reaching across the chest toward the other shoulder.
4. Biceps tendon: felt within the joint or in a groove along the front of the top of the arm, particularly when lifting the arm forwards.
5. Neck: the C5 and C6 nerve roots supply the shoulder and pain arising from the neck may radiate in a diffuse pattern over the shoulder generally. May be associated with sensory disturbances such as numbness or pins and needles and often unrelated to movement.
Usually the cause can be readily identified and treated, and in some cases this may require surgery. Occasionally no structural or pathological problem can be identified and therefore pain management is important to relieve symptoms and maintain function.