The shoulder (glenohumeral joint) is a ball and socket joint. The ball is at the top of the arm bone (humerus). The socket is the glenoid which is part of the shoulder blade (scapula).

Shoulder replacement is a treatment option for shoulder arthritis where the patient remains symptomatic despite appropriate non-operative treatment.

The worn-out surfaces of the humerus and glenoid are replaced usually with metal or ceramic or plastic (polyethylene) components.

Two main designs of shoulder replacement may be used;

1) Anatomic shoulder replacement

This design mimics the natural shape of the shoulder joint, and works best when the rotator cuff tendons around the shoulder are in good condition.

The humeral (arm bone) component may have a stem that goes down the middle of the bone. A ‘stemless’ design may be used (often in younger patients).

2) Reverse shoulder replacement

In this design, the ball and socket arrangement of the shoulder is reversed so that the ball part of the joint is attached to the glenoid and the socket part is attached to the humerus. This design is usually selected if there is a rotator cuff tendon tear in the shoulder as well as arthritis, as it allows the deltoid muscle on the side of the arm to move the shoulder more efficiently.

Surrounding the shoulder joint are the tendons of the rotator cuff. Tendons are where muscles attach to bone. Muscle pulling on bones through tendons produces movement at joints.

The rotator cuff is composed of 4 tendons – subscapularis (at the front), supraspinatus (on the top) and infraspinatus and teres minor (at the back).

Rotator cuff tears can occur acutely following trauma, or as a result of degeneration in the older age group. The tendon pulls away from its insertion site on the bone. Tears do not heal on their own. Small tears may be compensated for by the remaining intact tendons, and as such, a period of physiotherapy is usually recommended, prior to considering surgery.

If ongoing symptoms are problematic, then surgery may be recommended. The aim of surgery is to reattach the tendon firmly to the bone. This allows your body’s natural healing process to occur.

Most repairs can be done through arthroscopic (keyhole) surgery, involving 3-5 small cuts. Sometimes a larger incision is required. The repair is performed using strong suture material which is passed through the tendon and then brought down to the bone using a number of ‘anchors’ which are screwed into the bone.

The shoulder joint is a ball and socket joint. Most shoulder movements occur where the ball at the top of your arm bone (humerus) fits into the shallow socket (glenoid) which is part of the shoulder blade (scapula). The joint is designed to allow a large amount of movement. As such the joint is at risk of becoming unstable.

The main structure which helps to keep the joint in position is the glenoid labrum, a cartilage rim around the glenoid which deepens the socket.

The shoulder usually dislocates forwards and downwards so that the top of the arm bone is in front of the socket. Sometimes the ball only comes partly out of the socket (subluxation).

• It is most commonly occurring in athletes post sporting injuries (common in AFL and Rugby)

• When the shoulder first dislocates, the glenoid labrum at the front of the shoulder is usually torn.

• The glenoid labrum generally does not heal and because of this, there is a risk of further dislocation. The risk is highest in young patients, particularly in those who play contact sports (as high as 80%!)

• Further occurrences of dislocation cause further damage to the ligaments and cartilage and sometimes lead to loss of bone either from the front of the socket or the back of ball of the humeral head.

• Shoulder stabilisation surgery can be done open or arthroscopically.

• Arthroscopic stablisation is done when there is little or no bone loss around the shoulder and aims to repair the torn labrum.

• When bone loss is extensive, arthroscopic stabilisation is less effective and the ‘latarjet procedure’ is recommended. In this procedure, the coracoid bone is transferred to the front of the glenoid. This is usually an open procedure.

Is a procedure that is sometimes considered for the treatment of ‘frozen shoulder’ that has not responded to non-operative measure.

In the arthroscopic capsular release, the tightened capsule is cut to allow greater motion.