Endoprosthetics of the shoulder

Wear of the glenohumeral joint (omarthrosis) - joint replacement (prosthesis)

Fig. 38: X-ray representing an omarthrosis.

Various diseases of the glenohumeral joint may require the implantation of an artificial shoulder joint. Apart from the alterations of the joint visible on radiology or MRI images, the patient's complaints are an indication for such an intervention. Here, primarily the severe pain at rest and under strain should be mentioned which makes a more or less regular administration of medication necessary.

Joint replacement

Shoulder joint prostheses have been available for 50 years now. During the last 15 years, shoulder endoprosthetics have made a lot of progress. In case of painful destruction of the glenohumeral joint by arthrosis (wear of the joint), rheumatoid arthritis (rheumatic joint inflammation), necrosis of the head of humerus or fracture of the head of humerus, it is successfully possible today to replace the joint surfaces of the head of humerus and the joint cavity with prostheses made of titanium and polyethylene. An indication for implanting a shoulder joint prosthesis is given in the following cases:

• severe destructive alterations of the joint visible on radiology and/or MRI/CT images
  
• severe pain at rest and under strain
  
• significant movability restriction of the glenohumeral joint

Fig. 39: Modern three-dimensional adjustable shoulder prosthesis

Fig. 40: X-ray of a new stemless humeral head repalcement (Type Eclipse)

Arthrosis (omarthrosis)

Compared to the classic wear of hip and knee joints, the wear of the glenohumeral joint occurs less often with older people. Here, the joint cartilage is destroyed and the joint surfaces are deformed resulting in a painful movability restriction of the glenohumeral joint.

Rheumatoid arthritis

The glenohumeral joint is often affected in the course of a rheumatoid disease. Surgical therapy depends on the progress of the disease. In the stage of a joint inflammation where mainly soft tissue is affected (joint mucosa, joint capsule, rotator cuff), arthroscopic debridement with removal of the joint mucosa (synovia) and the bursa is the procedure of choice. If the disease progresses and affects the joint cartilage and bone, a prosthesis should be implanted as early as possible. In an early stage, a so-called cup prosthesis may be implanted (Fig. 41).

Fig. 41. X-ray of a Cup prosthesis

Fig. 42b: X-ray after the implantation of an Eclipse prosthesis.

Necrosis of the head of humerus

Due to medication (e.g. cortisone), excessive alcohol consumption, as a consequence of an accident or due to other unknown causes, hypoperfusion of the head of humerus may occur. This results in necrosis of the bone cells leading to a deformation of the head of humerus with painful movability restriction. At an early stage of this disease, a prosthesis of the head of humerus is sufficient. Only after the joint cavity has been affected by the incongruency of the joint surfaces, an additional cavity component needs to be implanted.

Fig. 42a: X-ray of a humeral head necrosis.

Advanced cartilage damage

With younger patients showing severe cartilage defects which, if untreated, would lead to severe arthrosis, so-called partial joint surfaces (Hemi-CAP®) are screwed into the defective cartilage zone (Fig. 43).

Fig. 43: X-ray after Hemi-CAP

Defect arthropathy

With about 4% of the patients with an untreated massive rotator cuff tear (at least 2 ruptured tendons of the rotator cuff), arthrosis of the glenohumeral joint develops. In case of a massive rotator cuff tear, the head of humerus moves to the front and up thus losing its central position in the joint cavity. In addition, M. deltoideus, which still allows a sideways lift of the arm in case of a massive rotator cuff tear, is shortened and weakened.

Fig. 44 : Cuff tear arthropathy

Fig. 45: X-ray representing a cuff tear arthropathy

In this case, the joint may be replaced with a so-called reverse prosthesis system according to Prof. Paul Grammont. A "hemisphere" (glenosphere) is screwed to the original cavity, and a concave "humerus cavity" is fixed within the humerus. Thus, the humerus is moved "further down" which improves the function of M. deltoideus.

Fig. 46: Reverse Delta-III-prosthesis according to Grammont

Fig. 47: Implanted reverse total shoulder arthroplasty aaccording to Grammont

Abb. 48 Röntgenbild nach Implantation einer inversen Totalendoprothese nach Grammont

Treatment objective

The objective of the joint surface replacement is to reduce pain and improve the function of the glenohumeral joint. Post-surgical movability of the shoulder, however, depends on the state of the soft tissue controlling the joint (muscles, tendons, joint capsule). If movability had been restricted over a long time, the tendons as well as the joint capsule grow shorter so that a completely free shoulder movement cannot be achieved despite of the glenohumeral joint replacement. For this reason, it is important to identify the right time for surgery: joint replacement must not be delayed for too long, but a prosthesis must not be implanted too early, either.

Surgery technique

Fig. 49: Exposed humeral head

At first, the skin is cut on a length of about 12 cm. The glenohumeral joint is made accessible.
Next, the destroyed head of humerus is removed at the cut line, and the humerus shaft is prepared for receiving the prosthesis shaft.
Then, a test head of humerus prosthesis is inserted in order to check the optimum position of the prosthesis as well as the joint function. During this process, the size of the definite prosthesis shaft and the definite prosthesis head is determined. After removing the test prosthesis, the definite prosthesis is inserted and fixed using cement, if desired (Fig. 50,51).

Fig. 50: Implantation of the humeral head prosthesis

Fig. 51: Implanted stem prosthesis

Fig. 52: Before the definite humeal head prosthesis is fixed at the implantated stem prosthesis, the glenoid surface is exposted and prepared for the implantation of the glenoid component.

Fig. 53 Implanted glenoid tray

After fixing the metal cavity carrier within the glenohumeral joint cavity using a hollow screw, the polyethylene inlay is anchored (Fig. 54).

Fig. 54

After completing the replacement of the glenohumeral cavity, the definite prosthesis head is positioned on the prosthesis shaft (Fig. 55).

Fig. 55

The glenohumeral joint is repositioned and the muscles and skin are sutured.

Fig. 56 X-ray after shoulder arthroplasty

Follow-up treatment

During the first 2 days after surgery, the glenohumeral joint is immobilized using a tube bandage. Then an abduction splint is put on for 3 weeks. On the first day after surgery, the early functional physiotherapeutic treatment is started, but the glenohumeral joint must not be moved freely for the first 6 weeks. Subsequently free movability is trained with increasing strain according to the individual circumstances.
We advise our patients to go through a 3- to 4-week rehabilitation at a rehabilitation clinic we selected so that a reliable follow-up treatment is guaranteed.
Depending on the profession, the patient will not be able to work for at least 6 weeks.
After performing a shoulder prosthesis implantation, sports with activities above the head should be avoided.