A shoulder surgeon is a specialist orthopaedic surgeon. Orthopaedic surgeons specialising in surgery to bones, joints and associated structures such as the ligaments and tendons.

The shoulder is a ball and socket joint at the top of the arm. It is where the humerus (upper arm bone) meets the scapula (the shoulder blade). The shoulder joint is particularly complex because it has to be very mobile, allowing you to move your arm in all directions as well as being very strong, to allow you to lift heavy weights or pull and push things. To be very mobile, there is not much in the way of a bony socket - which means that strength has to be supplied by the soft tissues such as the ligaments and muscles.

Another difficulty for the shoulder surgeon, that is not appreciated by many people, is that the shoulder blade or scapula is not connected to any major part of the skeleton. This is unlike the leg where the hip joint goes straight into the pelvis which is part of the spinal column.

The scapula is held on the back of the chest by a number of muscles often thought of as a "sea of muscles". The only bony connection between the scapula and the main skeleton of the body is the clavicle (also known as the collar bone).

Therefore a shoulder surgeon not only has to understand the ball and socket joint at the top of the arm, but also how this is held in place by the clavicle and muscles of the chest wall.

Just under the shoulder joint runs the major artery and vein to and from the arm (the axillary artery and vein) as well as the major nerves to the arm and hand (the brachial plexus). Therefore any problem with the shoulder, or any operation on the shoulder, puts these structures at risk and therefore shoulder surgery needs to be performed by specialists.