The shoulder is a ball and socket joint. The ball and socket parts are covered with cartilage.
Cartilage does not have nerve endings. This is to allow pain free movement when the bony parts glide with movement. If the cartilage gets damage the bone gets exposed.
Bone does have nerve endings and this is why it becomes painful when the cartilage wears off and there is bone-to-bone contact.
The causes of the cartilage wear include trauma, degeneration due to age and bony diseases like rheumatoid arthritis.
Once cartilage is damaged there is, unfortunately, nothing to replace it. The body reacts to this by forming new bone at the edges of the joints called oseophytes. They cause stiffness of the joint and the range of motion decrease.
The treatment of arthritis would typically be:
- Pain control with pain killers and anti-inflammatories.
- Intra-articular cortisone injections
- Injections with Hyaluronic acid- viscosupplementation
- Arthroscopic debridement (washing out of the joint)
- Shoulder replacement surgery
Shoulder replacement surgery:
There are different types of shoulder replacements.
A hemi arthroplasty ( also known as a half a shoulder replacement) is done typically for patients with an intact rotator cuff and wear and tear which affects the ball side of the joint.
This type of replacement has fallen out of favor due to glenoid (socket) erosion. A new type of a hemi replacement with PYRO carbon instead of metal is available in Europe and hopefully soon surgeons in South Africa will be able to use it too.
In a total shoulder replacement or anatomical replacement both the ball and the socket part are replaced. Bone no longer rubs against bone.
This would be the definite treatment for severe arthritis. All the tendons of the rotator cuff should be intact for one to be able to do this type of replacement.
A CT scan will also be done before the operation to judge the bony measurements of the glenoid and if it would be possible to do this type of a replacement.
The next option available is a reverse total shoulder replacement. This type of a replacement puts the ball onto the shoulder blade and the socket part moves to the upper arm.
The deltoid muscle is the only muscle then required to move the shoulder. It is done when the rotator cuff muscles are not functioning or when the bone stock of the glenoid does not allow for an anatomical prosthesis .
The fracture reverse works on the same principal as a reverse prosthesis but is specifically designed for a fracture of the ball part of the joint.