shoulder prosthesis in Tunisia

Anatomical principles and symptoms

The shoulder joint is a ball and socket joint with a socket on the shoulder blade and a ball on the arm. The articular cartilage covers both the socket and the patella of the joint and allows optimal sliding of the articular surfaces. Unlike the hip, the shoulder socket is flat and only covers a small portion of the kneecap. This allows the shoulder joint to be very mobile. A prerequisite for the proper functioning of this joint is therefore an intact soft tissue mantle. This includes both the joint capsule with the ligaments it contains, as well as the surrounding tendons and muscles. The musculature consists of an inner layer, the rotator cuff, which gives the joint active stability, and an outer layer - the powerful deltoid muscle. They are responsible for actively raising the arm. The nerves and vessels supplying the arm pass in close proximity to the joint.
Various diseases can lead to the destruction of articular surfaces. The most common cause is osteoarthritis of the shoulder (osteoarthritis). The cartilage is worn down and the joint increasingly loses its shape due to bone deposits on the joint edges (called osteophytes). Other causes of joint destruction are inflammatory diseases such as chronic arthritis, circulatory disorders of the patella (necrosis), the consequences of accidents, chronic instability and extensive tendon tears in the rotator cuff.

Diagnostic

Conventional x-rays are mostly done in various projections. An ultrasound (ultrasound) exam is also part of the standard rotator cuff assessment exam. Complementary examinations such as an MRI (magnetic resonance imaging) or a scanner (computed tomography) may be necessary.

Operative treatment

Artificial joint replacement is necessary when the damage to the joint surfaces is irreparable, function is restricted and the associated pain can no longer be treated. The timing of the operation depends on the individual level of suffering and the extent of the quality of life restriction. The goal of the procedure is to reduce pain and restore good shoulder function for everyday life.

The prosthesis

Different implants are available for different diseases. The upper arm components are mostly made of metal alloys or titanium. Plastic materials (polyethylene) are often used on the socket side. Depending on the quality of the bone, the components can be cemented or uncemented. If only the ball of the upper arm is replaced, it is called hemiarthroplasty, and if the socket is replaced at the same time, it is called total arthroplasty. In principle, three systems are used: the anatomical shoulder prosthesis, the surface replacement (rodless implants) and the reverse shoulder prosthesis.

The anatomical shoulder prosthesis

In case of joint destruction with an intact rotator cuff (tendon cuff) and good muscle function, a hemi or total anatomical prosthesis is used. The purpose of the anatomical shoulder prosthesis is the reconstruction of the original anatomy while protecting the tendinous attachments of the rotator cuff. The surface of the humerus is replaced by a metal hemisphere and anchored to the bone with a rod. The joint socket is replaced with a plastic plate and fixed to the scapula with pins.

Surface replacement (stemless implants)

As an alternative to the conventional total prosthesis, which is anchored via a socket component, there is often the possibility of a prosthesis implantation without a socket. A metal stemless hemisphere is attached to the bone. This method can be particularly useful in cases of altered anatomy in the upper arm area (eg due to poorly healing fractures). This implant can also be used as a hemiprosthesis or as a total prosthesis.

The reverse shoulder prosthesis

The inverted or inverted shoulder prosthesis is a particular form of artificial joint prosthesis which provides a pain-relieving solution in the event of advanced signs of cartilage and tendon (rotator cuff) wear. The scapula socket is replaced by an artificial patella and the patella of the upper arm by an artificial socket. This system has a better form fit and thus results in better stability. This change in biomechanics makes active mobility of the shoulder again possible, even with simultaneous tendon defects, because the strong deltoid muscle (outer muscle layer) supports the missing function of the rotator cuff.
However, active external rotation of the arm cannot be restored with this implant alone. Simultaneous muscle replacement surgery may need to be considered. In the event of a change of prosthesis, this implant is also very suitable as a revision prosthesis.

Follow-up care and rehabilitation

After the operation, the arm is immobilized in a sling bandage (orthogilet), at night for about four weeks, during the day only if necessary. Physiotherapy with guided movement exercises begins on the first day after the operation. Typically, you are discharged from the hospital and returned home. The affected arm can be actively moved during the day, but should not be loaded initially. Physiotherapy – combined as dry therapy and hydrotherapy – takes place approximately twice a week for a total of three to six months. Self-dissolving sutures that do not need to be removed are generally used for skin suturing. Special wound care is not required. Regular medical checks are usually carried out after six weeks, three months, six months and after one year.

Risks

Complications during and after the operation are generally rare after shoulder joint replacement. Infection is a rare (about 1%) but serious complication. Infections can occur immediately after the operation, but also much later, months or years later. These late infections are caused by bacteria that reach the implant via the bloodstream. In these cases, it may be necessary to temporarily remove the artificial joint. After antibiotic therapy, an artificial joint can be reinserted. However, long-term antibiotic therapy over months is to be expected.
Injury to blood vessels and nerves, particularly the axillary nerve, which passes in close proximity to the surgical site, is also rare (about 1%). Stretching of the nerve plexus during the operation can lead to essentially temporary sensory disturbances or weaknesses. Broken bones are also very rare and can be treated with wires or strapping plates during the same surgery.

Chances of success

The extent to which the shoulder function can be improved depends in particular on the condition before the operation. A restriction of movement that has existed for many years leads to soft tissue shortening and also muscle regression. Previous operations and injuries also play an important role in the prognosis. In the majority of cases, however, excellent pain reduction and often improvement in function and range of motion can be achieved.