Pain in the shoulder can result from several different reasons and can be triggered by trauma or a chronic underlining condition. The shoulder is a highly versatile ball-and-socket joint and its great ability of movement is also its greatest weakness. This makes it, in fact prone to instability that can lead to pain and dysfunction. To make it even more complicate there is a second small joint, the acomio-clavicular joint (ACJ) that can be affected and cause pain.
The shoulder is often injured during sport but also during manual labour, especially if this involves repetitive movements. Shoulder pain may affect young people as well as the elderly.