A shoulder prosthesis is an artificial shoulder joint. It is implanted in severe osteoarthritis (degeneration) of the shoulder joint, in humeral head fractures and in non-repairable rotator cuff tears. However, a shoulder prosthesis is not implanted in osteoarthritis of the shoulder joint before other treatment options have proved unsuccessful.
The shoulder joint is essentially a ball-and-socket joint. It consists of the head of the humerus (humeral head) and the shoulder socket. These bone components of the joint are not able to stabilise the shoulder unaided. The shoulder joint is stabilised with the aid of a group of muscles and tendons, the rotator cuff.
A shoulder prosthesis is most commonly implanted in age-related degeneration (osteoarthritis) of the shoulder. If, despite every effort, it is no longer possible to provide adequate relief for the symptoms and pain, then an artificial shoulder joint is often the only remaining treatment option. A shoulder prosthesis may also be implanted in comminuted fractures of the joint head and non-repairable injury to the rotator cuff.
What preparations are carried out before the procedure?
Prior to the procedure, the extent of osteoarthritis or the type of injury is precisely determined based on x-ray images or MRI scans.
Patients should be fasting for the procedure. Agents used to arrest bleeding are discontinued a few days prior to the procedure. As is usual prior to surgery, blood and allergy tests may be carried out as required, and an ECG is performed or blood pressure taken.
How is the operation performed?
In most cases, shoulder replacement surgery is performed under local anaesthesia (interscalene block). During the operation, the patient sits in a recliner or deckchair position. The shoulder prosthesis has several different parts. They are essentially the head, shaft and socket. The individual parts are made of polyethylene or titanium.
First, the joint is exposed. Then the head and socket are removed, depending on the extent of the osteoarthritis or the injury. As a rule, the artificial head with the shaft is then anchored in the head of the humerus and the socket implanted in the shoulder bone. This corresponds to the anatomic shoulder prosthesis. In complex shoulder fractures with extensive injury to the rotator cuff, an inverse shoulder prosthesis is implanted. This involves implanting the head of the joint on the socket side in the shoulder bone. The artificial joint socket is accordingly anchored in the head of the humerus. The positions of the head and socket are exchanged compared to the natural location in the joint, which explains why the prosthesis is referred to as an inverse shoulder prosthesis.
In certain cases when the bone is still intact, a surface replacement prosthesis is implanted. This involves covering the head of the humerus with a cap prosthesis. Occasionally, the joint socket is covered with a cap prosthesis too. Cap prostheses are more gentle on the bone, as they do not need a long shaft to anchor in the bone.
Once the shoulder prosthesis is implanted, the position is checked using an x-ray image. Finally, drains are placed to remove wound secretions and the surgical wound closed. The procedure takes 1 to 2 hours.
What is the success rate of this procedure?
In general, patients are largely free from pain and joint mobility is increased with shoulder replacement surgery. Even though, in general, shoulder mobility cannot be fully restored, in most cases it is largely adequate for daily activities and to some extent for sporting activities, too.
What are the possible complications and risks of this procedure?
Like any other operation, there are certain risks attached to shoulder replacement surgery. As with all surgery, the operation may occasionally lead to infections, nerve damage, post-operative haemorrhaging or blood clots. In rare cases, the shoulder prosthesis may become loose and a second operation may be necessary.
What happens after the operation?
You can expect to stay in hospital for 1 to 2 weeks, depending on the type of procedure. Because the shoulder prosthesis is already sufficiently stable after surgery, you can immediately start with gentle exercises. The drains are removed after 24 hours. Physiotherapy is continued after discharge from the hospital. Depending on your job, you will be unable to return to work from six weeks (office work) to six months (heavy physical work). Sporting activities which may place strain on the shoulder can be resumed 4 to 6 months after surgery. The healing process is regularly monitored in follow-up examinations.