CMC (thumb) Arthritis

Osteoarthritis (or wear and tear arthritis) of the base of the thumb is common.  A study in Sweden (1) showed that at any given time it affects 2.2% of women and 1.2% of men over the age of 20.  It is rare under the age of 40.  It affects the joint at the base of the thumb, between the thumb and the wrist.

What are the symptoms?

The symptoms start slowly.  Patients complain of an ache at the base of the thumb.  This typically strikes in a horseshoe pattern around the base of the thumb.  It is worse on use and often especially so on pinching. The base of the thumb may be swollen and stick out.

What investigations are performed?

We would normally arrange an Xray.  It is important to assess the state of the joints next to the thumb base joint.  These joints are in the wrist and are called collectively the STT joint.

What treatment is possible?

As usual it is best to start with simple methods.  In the first instance your GP may try simple painkillers and anti inflammatories, such as ibuprofen.  If this fails to help a splint may be useful.  Further measures would usually be undertaken at the hospital.  This includes an injection of steroids (“cortisone”) into the joint.  We would normally do this under an xray to ensure that the needle is in the joint.

If all of this fails then, after discussion, we can offer surgery.  The surgery usually involves taking away the diseased trapezium bone and replacing it with a strip of tissue taken from part of one of the tendons in the forearm (the flexor carpi radialis tendon).

In suitable cases we are currently also performing Maia joint replacements. The results to date are encouraging and the recovery period is shorter than with trapezectomy.

The surgery is performed as a day case; you do not normally need to stay in hospital overnight.

What is the post op recovery?

You will be followed up in the out patient clinic.  You will be in a plaster, usually for around five weeks for trapezectomy, three weeks at most for Maia.  You will then start rehab with the physiotherapists.  Although the pain relief is often felt within three to four months, It will take up to one year to get the full benefit of the surgery. The recovery is quicker than this with a Maia implant

What are the risks?

As with all surgery there is a risk of infection.  This is around 1%.  There is usually a small numb patch around the base of the thumb; this rarely causes problems.  There is a small risk of an abnormal and prolonged pain response to surgery.

With an implant there is a risk of fracture and of implant failure.

References:  

1.     Wolf JW, Turkiewicz A, Atroshi I, Englund M  Prevalence of doctor-diagnosed thumb carpometacarpal joint osteoarthritis: analysis of Swedish health care, Arthritis Care & Research DOI: 10.1002/acr.22250