The main indications for shoulder replacement surgery are degenerative arthritis of the shoulder joint or fractures of the shoulder that cannot be repaired.
In patients with degenerative shoulder arthritis with an intact rotator cuff tendon, an anatomical shaped replacement of the shoulder is appropriate.
The patient under goes a general anaesthetic. Intravenous antibiotics are given to reduce the risk of infection.
An incision is made at the front of the shoulder. The interval between the deltoid muscle and pectoral muscles is identified and these muscles are spread apart to allow access to the front of the shoulder.
A portion of one of the rotator cuff tendons at the front of the shoulder joint is taken down to allow access to the joint. The humeral head is resected to remove the worn out joint surface. The socket side of the joint is resurfaced with a polyethylene prosthesis.
The humeral head is then replaced with a metallic prosthesis. This consists of a spherical head to articulate against the socket and a stem that travels down the inside of the humerus to provide stability.
The rotator cuff tendons are reattached and the wound is closed with absorbable sutures.
In cases of arthritis, patients will usually have a significant improvement in pain. It does take quite some time to regain range of movement and slowly strengthen the shoulder girdle muscles.
Reverse total shoulder replacement
When a patient has a degenerate non-functional rotator cuff tendon in association with their arthritis, a reverse total shoulder replacement is more appropriate. This involves placing the sphere on the opposite side of the joint. It is attached where the shoulder socket once lived.
This changes the biomechanics of the shoulder joint and allows patients to function even in the absence of rotator cuff tendons.
In cases of highly comminuted fractures (where the bone has fractured into many pieces), some patients will require joint replacement surgery at the time of management of the fracture.
This may involve either a total joint replacement or a half joint replacement resurfacing the humeral head. In older patients, a reverse total shoulder replacement has been shown to provide good results in management of shoulder fractures.