Shoulder prosthesis

It is called this because it replicates the natural anatomy of the shoulder joint. Where the humeral head used to be, there is now a metal head of the same size, which is anchored in the bone via a shaft. And where the socket used to be, there is a socket made of a specific polyethylene. This prosthesis has the great advantage that it completely restores the mobility of the shoulder joint and therefore fulfils very high demands. Sports can be played with this prosthesis, sometimes even tennis. One study showed that golfers were able to tee off further after prosthesis surgery than before the operation. The disadvantage is that this prosthesis is dependent on the rotator cuff functioning properly. If this is not the case or if the function of the muscles deteriorates over time, the prosthesis cannot develop or loses its functionality and the arm can only be used inadequately.

In the 1980s, after intensive anatomical and biomechanical studies, the Frenchman Paul Grammont developed the concept of a prosthesis that would be able to function without the rotator cuff. The prototype was called the trumpet, and eight such trumpets were implanted between 1986 and 1987. With success: people with previously immobile shoulders were able to lift their arms again.

The great achievement is that it is not the anatomy of the shoulder joint that is copied, but its function. This is achieved by reversing (inverting) the components. A hemisphere is implanted where the glenoid cavity used to be, and a socket is anchored where the humeral head used to be. Because this socket is significantly deeper and has a smaller diameter than the original joint socket, it has greater stability of its own and is therefore not dependent on the rotator cuff. The humeral head is now moved by the deltoid muscle alone. The deltoid prosthesis has been created.
The great advantage of this prosthesis is that it also works with a severely damaged or worn shoulder. The price you pay for this is a somewhat reduced mobility of the shoulder joint, which is particularly limiting when moving over the head and behind the back

As mentioned at the beginning, the question of which prosthesis is right for you depends on the condition and function of your shoulder.

Shoulder prosthesis surgery usually takes about two hours. The duration of the operation depends on the circumstances of the specific patient. However, the procedure is well standardised and in the vast majority of cases proceeds without complications. The patient recovers quickly after the operation and shoulder surgery is not very stressful for the whole body.

Musculature and mobility

It is helpful if you have the best possible musculature in the shoulder girdle and good mobility in the joint before the operation. Both will help you considerably during post-operative rehabilitation. There is a risk of post-operative frozen shoulder, particularly in joints with poor mobility (fortunately, this is not common with the prosthesis). The physiotherapist will work out a programme with you that you can do at home and that will help you to maintain your strength and mobility.

Cortisone infiltrations

It is very important not to have any more infiltrations into the joint at least four months before a major operation. Otherwise, the risk of joint infection around a prosthesis operation increases considerably.

Immune system

A strong and healthy immune system helps to minimise complications associated with an operation. Well-tolerated nutritional supplements as well as a healthy lifestyle, enough sleep and sufficient outdoor exercise help to minimise this.

To further minimise the risk of infection around an operation, we recommend that you shower with a special disinfectant the evening before the operation.

General practitioner

Before any operation, it is important to have the necessary pre-operative investigations carried out by your family doctor. He or she will pass these on to the anaesthetist and surgeon so that they are fully informed about your condition.

Dental check-up

Infections of artificial joints can be caused by regular oral bacteria. We therefore recommend a visit to the dentist before a prosthesis operation to have your teeth cleaned if necessary. A visit to the dental hygienist is also recommended. After the operation, however, no dental work or dental hygiene should take place for at least three months in order to protect the fresh prosthesis.

After just one or two days, you can use your arm again for light activities. You will usually stay in hospital for around five days, depending on how quickly you recover and how much pain you are in. The operation is not very painful, but a pain catheter is often administered to promote rapid mobility after the operation.

Avoiding complications is the top priority in orthopaedic surgery. This is why shoulder operations are highly standardised so that you know at all times what the next step is and what anatomical environment you are in. Structures that need to be spared (e.g. the axillary nerve) are visualised in advance so that their anatomy is completely clear. Nevertheless, every operation is a separate piece of work and every patient is different. A good surgeon must therefore be well prepared on the one hand, but also be able to adapt to the unexpected.

General risks occur with every operation and include, among others: Infections, wound healing disorders, haematoma and post-operative bleeding. Shoulder-specific risks arise due to the complex anatomy, as the nerves and vessels for the arm are very close. Theoretically, they can be injured, but fortunately these are rare exceptions. The muscles of the shoulder are also strained during the operation, but they recover quickly. It is important to place the individual prosthetic components correctly, which is sometimes not easy due to the anatomy and clarity. If they are placed incorrectly, this results in restricted movement. It is very rare for the bone that is supposed to support the prosthesis to break when it is implanted. As a rule, the joint is somewhat stiff and immobile in the first few weeks after a prosthesis operation. However, it recovers very quickly with physiotherapy. Fortunately, pain is not an issue with the vast majority of prostheses.

Most patients recover so quickly after the operation that inpatient rehabilitation is hardly ever necessary. As the patient's ability to walk is retained and they are soon able to use their arm again in everyday life, they are only slightly restricted at home.

As the inverse prosthesis changes the anatomy of the shoulder joint, the external appearance sometimes also changes slightly. The shoulder is slightly less wide and therefore has a sloping appearance.

The prostheses used by Paul Grammont lasted up to 15 years. Because modern prostheses are subject to constant innovation and newer types of implants are used today, it is not always possible to determine how long a prosthesis will last. However, all recent studies show that the longevity rate is more than 90 per cent after ten years. There is an older study by Prof L. Favard, who found a weakening of the deltoid muscles after seven to ten years. However, these results were most likely due to the old types of prosthesis, which pulled the muscle very hard. Modern implants no longer require this. It is mainly the anchoring of the joint socket in anatomical prostheses that can become loose over time, and this is the limiting factor. In addition, some prostheses lead to bone resorption around the implant. In the vast majority of cases, however, this has no consequences.

A major risk for the prosthesis are falls, which not only dislocate the shoulder but can also lead to fractures around the prosthesis. These are difficult to treat and usually require further surgery.

The risks of a first operation are low. The risks increase with repeat operations or in patients who have already undergone surgery.

There is a lifelong risk of prosthesis infection, e.g. in connection with a tooth infection or pneumonia. For this reason, denture wearers must take special precautions against infections. Inform your doctor and dentist if you have a prosthesis. An infection in an artificial joint is very difficult to treat and often requires the joint to be removed and, if possible, a new one inserted later. These major revision operations are difficult and stressful and require special expertise.