Thumb Base Arthritis
The joint right at the base of the thumb (carpometacarpal or CMC joint), near the wrist, quite frequently becomes painful due to
arthritis. Osteoarthritis is the common type of arthritis and is usually due to wear and tear that damages the cartilage of the joint.
Many things that we do with our hand transmit a significant force through this particular joint and this is the reason that arthritis
occurs here. Certain activities may exacerbate pain in this condition, for example turning a key in a lock, writing or knitting.
Thumb base arthritis can often be diagnosed from the typical symptoms and signs; an X ray will help confirm the diagnosis and show the
degree of damage to the joint.
In mild cases I will recommend a joint stabilisation programme; by strengthening the muscles around the CMC joint the load on the joint
is reduced. My hand therapy team will teach you the exercises and supervise the strengthening programme. It takes about 3 months of
daily thumb exercises to get the full benefit of this treatment but it is well worth persevering with it as most patients with mild thumb
base arthritis will have long term improvement of symptoms. I will prescribe a suitable antiinflamatory medication which will improve
symptoms during the early stages of the strengthening programme.
In cases where there has been an acute flare up of pain, a thumb splint may be used for 1-2 weeks to allow it to settle down. The thumb
splint is custom made from a light weight mouldable plastic and is easy to take on and off with Velcro strips.
For more advanced cases, a steroid injection is considered. This is done in the clinic with a local anaesthetic injection first. Most
patients find the thumb is rather sore for a couple of days following the injection. The effect of the steroid starts about 10 days after
the injection. The steroid injection is usually effective for 4-6 months and during this period a muscle strengthening programme is
started. Steroid does not repair the damage to the joint but works by reducing the inflammation that causes the pain in arthritis.
Steroid injection into the thumb base joint can be repeated.
Severe cases of thumb base arthritis are treated by surgery. The operation is called trapeziectomy and involves removing a small bone
(about the size of a dice) called the trapezium from the arthritic joint. There are many variations of this operation; the procedure
that I generally use uses surrounding tissue that is used to fill the space created after removing the bone. This operation is simple
and effective and I have had good results with it.
After surgery a splint is worn to protect the healing area for 4-6 weeks and a hand therapy programme is started. The recovery time after
this operation is about 3 months.