Arthritis of the base of the thumb
What is arthritis of the base of the thumb?
Having difficulty using keys and gripping with associated pain in your thumb? This could mean that you have some arthritis in one of the joints at the base of your thumb. This is usually a type of osteoarthritis (‘wear and tear’ arthritis) where the smooth gliding cartilage covering the bones of the joint is lost eventually resulting in the bones grating on each other. The joint affected is between the thumb metacarpal and one of the small bones of the wrist (trapezium).
This joint is very specialised allowing a large range of thumb motion and so arthritis here is functionally very disabling.
What are the symptoms of arthritis of the base of the thumb?
This condition affects women ten times more commonly than men. Symptoms usually start in the middle forties but can occur earlier. Initially intermittent pain is noted after gripping or pinching. This may gradually become more constant over time with associated loss of movement and strength. It becomes hard to turn keys, open jars or turn on taps. In severe cases a bump at the base of the thumb appears and the thumb becomes stiff making it to pick up larger objects.
How is the diagnosis of thumb base arthritis made?
A characteristic story and examination suggest the diagnosis. Xrays confirm the diagnosis but the severity of the xray does not always parallel the severity of the symptoms. Certain other conditions may need to be excluded.
What treatments are available for thumb base arthritis?
Most patients with this condition do not need surgery but manage with painkillers, splints and activity modification. Local anaesthetic and steroid injections into the joint can dramatically relieve symptoms, sometimes for prolonged periods.
For persistent, severe symptoms surgery can be considered. Many operations have been described for this condition. The commonest ones include removing the trapezium alone, removing the trapezium and reconstructing one of the thumb ligaments, replacing the joint and fusing the joint. Each has its pros and cons and surgery must be carefully tailored to the individual patients’ requirements. All the operations are associated with a significant period of immobilisation of the thumb (6 weeks) and further rehabilitation thereafter but are good at relieving pain and improving function.