For people who have arthritis of the shoulder and also an irreparable retracted rotator cuff tear.

A reverse total shoulder replacement is an orthopaedic procedure used to maintain the shoulder joint for people who have arthritis of the shoulder joint and also an irreparable, retracted rotator cuff tear. The rotator cuff is the collective term for a group of tendons that blend together to help stabilise the shoulder and which keep the ball of the humerus centred in the shoulder socket.
 

 
The rotator cuff is what enables us to lift our arms up thus loss of integrity of the rotator cuff is a common cause of shoulder weakness. Those patients with large rotator cuff defects have difficulty raising the arm or rotating it out towards the side.

Tears of the rotator cuff tendons occur with increasing frequency as people age. It is unusual for a patient younger than 40 years to have a tear whereas up to 50% of patients over the age of 75 years have a tear in one or other rotator cuff tendon.

Traditional shoulder replacements replicate with metal the typical bony structure of the shoulder - a ball shaped end at the top of the humerus or upper arm bone, fitting into a cup shaped shoulder socket as shown below.

Standard shoulder replacements can’t be used when there are no rotator cuff tendons. If a conventional replacement is used, the ball would slowly move up (superiorly) due to no rotator cuff tissue to hold it centred in the socket. As a consequence, the glenoid (socket) replacement would loosen and the conventional replacement would fail.

The answer to this dilemma was to reverse the socket and the ball, placing the ball portion of the shoulder where the socket used to be and the socket where the ball or humeral head used to be (ie. the reverse total shoulder replacement).

With this new configuration, existing muscles such as the deltoid can adequately support the joint in the absence of a functioning rotator cuff. The deltoid muscle that covers the shoulder is used to lift the arm, providing better function of the shoulder. The result is a better functioning shoulder with less pain.

 
The reverse shoulder replacement was originally designed in France in the late 1980’s and has slowly become available in Australia since the early 2000’s. With newer designs and a better understanding of the mechanics of the prosthesis, the outcome from such surgery has become much more predictable and with less complications for the patients.

This condition usually occurs in older individuals and results in a painful shoulder with loss of motion and strength. Often, individuals cannot raise the arm to shoulder level making it difficult to perform routine activities of daily living.

Plain x-rays will show evidence of arthritis and also what is described as “superior migration of the humeral head” in which the humeral head or ball of the shoulder can be seen sitting high in the glenoid because the rotator cuff is no longer able to hold it centred in the glenoid or socket.

An MRI is also used in the diagnosis to assess the rotator cuff, specifically looking for chronic tearing, retraction and atrophy of the cuff. These findings confirm that a reverse replacement is the best option as surgical repair of such poor tissue would fail.

Conservative management is always an option and this would be in the form of avoidance of the activities which cause the symptoms and also pain relief. Physiotherapy would not be a feasible option with this condition as the rotator cuff is torn and retracted therefore unable to be strengthened with exercise.

The operative solution is a reverse shoulder replacement. The two hour surgical time is similar to the conventional procedure and the outcome in terms of range of motion, pain relief and function is also becoming similar.

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