Osteoarthritis of the Shoulder (Arthritis)

By Joe de Beer & Dr Renier Kriel

Introduction

The shoulder joint (gleno-humeral joint) is one of the most mobile joints in the body. The gleno-humeral joint consists of a ball (humeral head) and socket (glenoid). As in any other joint, the bone surfaces are covered with a specialised cartilage layer.

When this cartilage layer wears away, it results in bone on bone contact. Cartilage is a specialised tissue which contains no nerve supply – this is the reason why our joints can move painlessly. On the other hand bone has a very dense nerve supply and this why an osteo-arthritic joint becomes painful – due to the fact that the cartilage has now disappeared and there is now bone contacting rough bone.

The causes of osteo-arthritis are usually not known -it may result from previous trauma but this is only in rare cases. Other specific joint diseases like rheumatoid arthritis usually lead to severe destruction of most joints in the body.

Symptoms

The osteo-arthritic joint becomes painful with limited range of motion and night pain can be an important feature. A “grating” feeling may be experienced in the joint and this may even be audible. A feeling of catching or slipping may also be felt due to the rough surfaces moving over each other

Diagnosis

The diagnosis is made by clinical examination by the physician as well as x-rays.
On examination the doctor may find decreased range of motion and some very painful movements. The grating may even be audible!

On x-ray a narrow joint space with osteophytes (bony ridges on the side of the articulating surface) are noted (Fig 3). In some cases of early osteoarthritis x-rays may not reveal the diagnosis, especially if only a circumscribed area of cartilage is lost on the humeral head (Fig 4).

CT scan is often recommended to look at the joint in a 3-dimensional perspective to evaluate the wear of especially the glenoid (socket) which is common in osteo-arthritis of the shoulder joint. The wear is often more at the back of the joint than at the front.

MRI is less important to evaluate an arthritic joint except if the doctor wants to evaluate the status of the tendons of the shoulder.

Management

1. In the early management anti-inflammatory tablets and pain tablets can be efficient.
2. Physiotherapy – pain relieving modalities using physiotherapy may be of value in the early phases.
3. Cortisone injections – cortisone injections may have a marked relieving effect but they have to be placed inside the gleno-humeral joint and not into the subacromial space (the latter is where most cortisone injections into the shoulder are administered). In our unit we do this injection under ultra-sound control to ensure that it is accurately placed into the joint
4. Arthroscopy – arthroscopic “lavage” or “wash out” is an operation where an arthroscope is placed into the joint and “cleaning out” of the joint is done. This is a small procedure with few complications and will serve to confirm the diagnosis and often has a pain relieving effect. It is never curative. During such an arthroscopic procedure small areas of loss of cartilage on the surface of the humeral head may be seen (localised osteo-chondral defects) and can be treated surgically by doing “micro-fracture”. This is when small holes are drilled on the surface of the defect and could promote ingrowth of fibro-cartilage which is a scar type of tissue and can serve as a barrier against bone to bone contact (Fig. 5)

Soft tissue interposition – in this procedure is done arthroscopically, but very difficult to obtain the material in South Africa at present, due to unreasonable constraints.

Interposition Graft for Osteoarthritis of the shoulder (Our method)

We developed an arthroscopic method of resurfacing the osteo-arthritic shoulder joint. The product preferred by ourselves is the “Graft Jacket®”. This is human skin derived from donors and is provided commercially It has been de-cellularised and sterilised, in other words all cells have been removed from the tissue and only the fibrous lattice remains which will act as a scaffold for cell ingrowth. The surface of the glenoid (socket) is roughened up with special instruments and the Graft Jacket membrane is sutured onto the surface using arthroscopic methods. Stem cells will provide ingrowth of cartilage-like tissue into the membrane and form a structure resembling cartilage.

Joint Replacement (Arthroplasty)

For this procedure there are various options ranging from Hemi replacement (replacing only the head of the humerus), Total joint replacement (replacing the head, as well as the socket), and Reverse replacement.

Pyro Carbon Hemi replacement

This prosthesis is uncemented, and inserted for the following indications:

 – In osteoarthritis for younger patients.  The insertion of a glenoid prosthesis is avoided in such patients, as it is prone to earlier wear and loosening, and the humeral hemi prosthesis is then the safter option in the longer term.

 – Pyro Carbon is an advanced substance, which is very smooth and has little wear on the exposed bone of the glenoid.

Total shoulder replacement

The humeral head is replaced with a metal head, which is fixed into the humerus without cement, and a polyethelene glenoid, which is cemented into the bone.  This gives excellent pain relief, and is done in selected patients.

The shoulder replacement operation

A CT scan is usually requested before the operation to evaluate the adequacy of the bone for the glenoid part of the replacement.

We usually admit the patient to the hospital on the morning of the operation.

At the end of the operation the arm will be immobilised in a shoulder sling for a day or two simply for pain relief.  Early motion in the hospital will be encouraged.
After a day or two the patient will be allowed to be discharged, mostly not needing a sling.  He or she will be encouraged to start using the arm for everyday activities of daily living- a very gentle and natural form of easy rehabilitation.

Pain and discomfort usually subsides gradually and increasing activity is allowed within pain limits.  Clerical type of duties are usually possible after about four weeks and full recovery after 2-3 months.

It is our opinion that a Total prosthesis is not done for a patient to return to strenuous activities like heavy lifting, contact sports, etc.  Most gentle activities are permitted like gardening, playing golf, and similar.

What problems could be experienced with prostheses?

• A prosthesis could become infected.  Infection in any prosthesis is a serious problem and the infection is usually very difficult to cure, often requiring the removal of the prosthesis.  This is not a common complication.

• A prosthesis may dislocate.  The reasons may be:

  1. rupture of one of the rotator cuff muscles, especially the subscapularis muscle
  2. the shoulder had a tendency to dislocate before the prosthesis was inserted
  3. the prosthesis was not placed in the correct version (angle) by the surgeon
  4.there might be muscle paralysis e.g. the deltoid muscle.

• The prosthesis may loosen or wear out- this usually happens in time and is more relevant with increased activity.

The solution for the above complications is usually to remove the prosthesis and replace it with a new one (“revision”). It is easily understood that to remove a cemented prosthesis from the humeral shaft is risky and difficult and may result in a fracture of the bone. On the other hand, to remove and revise the less invasive prostheses (e.g. the Hemi-Cap ), is relatively easy with fewer complications

Following the humeral aspect of the procedure the glenoid (socket) is then prepared for the glenoid part of the prosthesis. A slot or holes are made into the socket and a plastic (polyethylene) prosthesis is then cemented into the glenoid.

Reverse prosthesis

This type of prosthesis is specifically designed for arthritis where the rotator cuff muscles have disappeared due to chronic degenerative tears and the tendons are not reparable. The prosthesis is specifically designed for older people and acts as a “hinge” enabling the deltoid muscle to lift the arm again, without needing the rotator cuff muscles to elevate the arm.

This prosthesis usually enables the patient to elevate the arm again after not being able before the operation. The life span of this type of prosthesis is regarded as shorter than the other prostheses mentioned above and is recommended for older people only.

Further reading