Arthritis is the loss of the cartilage lining the joint surface (articular cartilage). Normally this is a soft glistening smooth white tissue which acts as a bearing surface to allow the joint to move freely. If the cartilage is damaged the surface becomes rough and no longer glides. This causes pain and stiffness within the joint.
The rotator cuff is a group of muscles within the shoulder which are responsible for keeping the joint centred while it moves.
The rotator cuff muscles can become torn and if teh tear is large enought the joint can “rattle around” causing damage and arthritis
Xray of shoulder with normal arthritis and an intact rotator cuff
Xray of shoulder showing the “high riding head” with cuff tear arthropathy
What Causes it?
- Rheumatoid arthritis: This condition affects joints and organs throughout the body. It affects the soft tissues (rotator cuff) as well as the cartilage
- Trauma: If the shoulder joint has been broken (fractured) at some point the cartilage may have been damaged and the tendons can be torn
- Instability: If the shoulder has dislocated in older patients the rotator cuff can be torn and.
- Chronic rotator cuff tears: If a large tear has been present for some time the cartilage can be damaged.
What are the symptoms?
Pain is usually the first complaint. It is often felt deep in the shoulder and may be difficult to locate precisely. The shoulder may feel stiff and weak. There may be a sensation of grinding or catching within the shoulder. On occasion there may be crunching which can be heard.
There is also an inability to rasie the arm. When the patient tries the arm rasies a few degrees then the shoulder hunches up. This is known as a “pseudoparalytic shoulder”.
How is the diagnosis made?
The doctor will listen to the description of the symptoms and will examine the shoulder. Plain Xrays are usually sufficient to make the diagnosis. If there is a concern that there may be more than arthritis in the shoulder (e.g. a rotator cuff tear) further investigations will be performed.Xrays, MRI and CT scans may also be undertaken.
What is the initial treatment?
There is no cure for arthritis. If the cause is rheumatoid arthritis a rheumatologist will be involved to optimize the medications to control the condition. If one of the other causes is responsible initial treatment consists of painkillers and anti-inflammatories. Exercise modification (avoiding the things that hurt) may help.
A specialist physiotherapy programme -the Ainsworth Programme– may help if the problem is more one of function than pain.
If initial treatment doesn’t work, what’s next?
Corticosteroid injection into the shoulder can give pain relief. The amount of benefit is variable as is the duration which may be as little as days or as long as months.
Arthroscopy and debridement in which the arthroscope is introduced into the shoulder and the rough cartilage is smoothed down also has variable results with benefits as available as those seen with injection although usually longer lasting.
Reverse Shoulder replacement in which the arthritic shoulder joint is replaced with a new one of metal and plastic can give relief of pain in 90% of patients. The replacements last on average 10 years.