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 by metal and plastic (polyethylene).

Two main designs of shoulder replacement may be used;

1. Anatomic shoulder replacement
   This design mimics the natural ball and socket shape of the shoulder joint.
   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 and infraspinatus (at the top) and teres minor (at the back).

In a rotator cuff tear, the tendon pulls away from the bone. Tears do not heal on their own but small tears may be compensated for by the remaining intact tendons. Because of this, a period of physiotherapy is usually tried 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.

Repairs can be done through arthroscopic (keyhole) surgery, involving 3-5 small cuts or a single, small incision.

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. This also means that it has a tendency to be ‘too loose’.

There are various structures which help to keep the joint in position. The most important ones are:

• Ligaments - which hold the bones together
  A rim of cartilage (labrum) which deepens the socket
• Muscles: which keep the shoulder joint in the correct position when using or moving the arm

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). When the shoulder first dislocates, the ligaments and cartilage at the front of the shoulder are usually damaged.

The ligaments and cartilage generally do not heal themselves 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.

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.

The operation usually aims to tighten and/or repair the overstretched and damaged ligaments and labrum by reattaching them to the rim of the socket using anchors to hold them firmly in place until healing occurs. In the vast majority of cases, this can be achieved using arthroscopic (keyhole) techniques.

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). The glenohumeral joint is surrounded by a sleeve of tissue (capsule).

Sometimes the capsule of the joint can become inflamed (capsulitis) and thickened which causes pain and stiffness of the joint.

Capsulitis may sometimes occur because of other abnormalities in the shoulder such as cartilage or tendon injuries. Other times it can occur without any other problems in the shoulder (primary capsulitis or ‘frozen shoulder’)

Arthroscopic (keyhole) capsular release may be recommended when the patient remains symptomatic despite appropriate non-operative treatment (medications, injections and physiotherapy).

In this surgery, the tightened capsule is cut to allow greater motion.