Osteoarthritis base thumb (CMC joint osteoarthritis)

Find out how this form of degenerative arthritis at the base of the thumb can be treated

This is the name given to the degenerative arthritis which causes pain and stiffness at the base of the thumb, adjacent to the wrist.

The process of osteoarthritis involves wearing/ thinning of the smooth cartilage joint surfaces as well as stiffening of the soft tissue surrounding the joint. These aspects combine to produce swelling, inflammation and pain. Several factors normally combine to cause symptoms of osteoarthritis:

Previous joint damage (from trauma or other conditions such as such as gout and rheumatoid arthritis)
Age (risk increases with age)
Family history (genetics)

Most commonly a deep pain is felt on the thumb side of the wrist, at the base of the thumb, on movement of the joint.

Fortunately, the presence of thumb CMCJOA does not always cause pain so it is quite possible to be pain free despite reasonably advanced arthritis. In addition, the joint undergoes a ‘’wear and repair’’ cycle so pain can improve spontaneously or with appropriate treatment.

Pain with forcible activity involving the thumb is the most common symptom. Movements involving opposition/ gripping, especially if this involves rotation, such as turning a key in a lock are often aggravating activities. If CMCJ OA becomes more severe the movements of the thumb may become increasingly stiff.

Thumb CMCJ OA can be reliably diagnosed by your doctor or physiotherapist by taking a history of your condition and by conducting a physical examination.

The main feature on examination is often a reduced range of movement with associated crepitus (a crunching noise). Therefore, X-rays and scans are NOT routinely required but may be requested if there is diagnostic doubt or symptoms are severe enough that surgery is being considered.

Non-surgical management

In the majority of cases, the symptoms of thumb CMCJ OA can be managed effectively for a prolonged period by non-surgical measures as described below.

Avoidance of aggravating activities

If the increase in pain has been triggered by an increase in activity eg gripping a hammer doing DIY, a period of relative rest will often result in improvement in symptoms.

Ice/heat

If pain is troublesome appropriate application of ice or heat may help with pain relief. Avoid prolonged application because of risk of a burn.

Wrist/thumb splint:

As mentioned above a period of relative rest may help pain. Wearing a splint intermittently when performing certain tasks may reduce stresses on the wrist & thumb joint and reduce subsequent pain. The thumb splint is often called a 'spica' and can be purchased relatively cheaply on line. It is best worn intermittently and during painful activities so as to avoid excessive joint stiffness or muscle weakness through prolonged use.

Exercises

Isometric contractions of the muscles such as gripping a tennis ball or similar may help maintain muscle strength and help symptoms.

Using painkillers when needed:

Anti-inflammatory gels may help ease symptoms and are safer than tablets. As long as you have no medical reason not to use them eg allergy, asthma they may help ease the pain. Please consult your pharmacist if doubt.

Over the counter analgesia available through pharmacies may help pain when needed. Paracetamol is most commonly prescribed. Anti-inflammatory tablets are also used eg Ibuprofen, but as there is little or no inflammation involved in osteoarthritis these are best avoided without discussing with your GP. Side effects are even more common than with paracetamol so please ensure to take appropriate medical advice. There is a good booklet on the Arthritis Research UK website with information about the various drug options.

Corticosteroid injection therapy

For individuals with thumb CMCJ OA who continue to suffer significant symptoms in spite a course of non-surgical management (outlined above), a corticosteroid injection can be offered as the next line of treatment. You can read more about local corticosteroid injections here. Injections are more effective in mild to moderate OA than in severe OA when joint movement is minimal.

Surgical management

A variety of surgical options exist for individuals who:

Have X-rays confirming advanced OA of the thumb CMCJ
Have trialed a course of non-surgical management without success
Have consistent, disabling pain significantly function and impairing quality of life

The commonest form of surgery option for thumb osteoarthritis is a trapeziectomy, also known as an excision arthroplasty, which has an excellent outcome. Surgery involves the removal of the thumb joint, replacing it with an augmented ligament reconstruction. The thumb joint can also be replaced but there are no long-term results available; or fused, again, results are not particularly good. where a small bone at the base of the thumb is removed to ease the painful joint.