Thumb Base Arthritis

Thumb Base Arthritis

Could I have thumb base arthritis?

Osteoarthritis (OA) of the basal thumb joint is very common. It is much more common in women than men, especially after menopause. One of the most common sites for arthritis is the joint at the base of the thumb which is called the basal thumb joint or carpometacarpal joint (CMCJ).

The common symptoms you may experience include:

  • Pain when you make a gripping or pinching motion, eg. turning a key in the lock, opening a jar
  • Swelling and tenderness at the base of your thumb
  • Loss of strength in your hand
  • Distortion of the thumb base
  • Reduced range of movement of your thumb


What is happening to my basal thumb joint?

The basal joint of your thumb is also called the carpometacarpal joint (CMCJ). It is the joint between the metacarpal (the long bone of the thumb) and the trapezium (one of the small bones in the wrist). The joint is very mobile and relies on numerous ligaments to maintain its stability. Laxity, the loosening, of these ligaments can cause pain around your thumb base. If your ligaments are loose, it can change how the bones work together within the joint. This, in turn, can change the wear patterns of the articular cartilage, which covers the end of the bone.

Normal joints have a layer of articular cartilage covering the bone ends that allows easy movement of the joint surfaces. If you have osteoarthritis (OA), the articular cartilage that lines your joints is lost, usually via ‘wear and tear’, and the joint surfaces no longer glide easily during movement. This is what causes pain.

As the arthritic changes progress, the bone surfaces become burnished by constant compression and direct wear without the protection of the cartilage. Extra bone around the joint margins (called Osteophytes) may form. Later, the thumb metacarpal may begin to move out of joint (subluxation). Finally, due to a difference in position of the metacarpal, other joints may begin to have compensatory posture changes, such as hyper-extension at the knuckle joint (metacarpophalangeal joint, MCPJ).


How do I find out whether I have thumb base arthritis?

During our initial consultation, we will discuss your symptoms and the effect the symptoms are having on your work and life. Following this, I will carefully examine your thumb and hand so as to minimise any discomfort you may experience. It is very important to discuss your overall medical health. Please bring a list of all your regular medications to the consultation.

It is important to consider whether there are other problems within your hand that could be contributing or causing your discomfort. Conditions such as carpal tunnel syndrome, trigger thumb, de Quervain’s tenosynovitis and scaphotrapeziotrapezoidal (STT) arthritis can cause similar discomfort to thumb base arthritis.

A thumb x-ray is a crucial part of the assessment of your hand. It is helpful if the x-ray is requested before our initial appointment, and your GP or hand therapist can usually arrange this for you.

If you have an x-ray taken before you come to see me, please let your GP or hand therapist know the following details. Optimal x-ray views include: Pronated anteroposterior, oblique and true lateral. A CMCJ stress view (30° posteroanterior view with thumb tips forcefully touching) is also helpful.


What are my treatment options for thumb base arthritis?

If you have thumb base arthritis, it should always be treated initially with conservative care. I will only recommend surgical treatment when conservative, non-surgical care options are not successful, or they are no longer controlling your symptoms.


Conservative (non-surgical) treatment

Conservative treatment for your thumb base arthritis involves a period of activity modification (during which you don’t do heavy activities or actions that cause you pain), taking non-steroidal anti-inflammatory medication, wearing a splint and sometimes a steroid injection. I will usually ask you to undergo this conservative treatment for a period of four weeks, and then we will review your symptoms together.

After four weeks, many of my patients notice a significant improvement in the comfort and function of their hand. Many people need no further treatment, while some choose to use the splint during heavy activities. As my patient, you have an open invitation to contact me should the symptoms return.

If your symptoms persist despite conservative treatment, then I will discuss surgical options with you.


Surgical treatment

There are a number of surgical options for thumb base arthritis, depending on how severe the arthritic changes within and around your thumb base are.

In very early thumb base arthritis, before there is loss of articular cartilage (which covers the end of your bones), a ligament reconstruction can improve stability around your thumb base, resolving pain and improving strength.

Once your articular cartilage is damaged, and this is the case for the vast majority of patients who come to see me, surgery on the trapezium (one of your wrist bones) is required. The most common operation is a simple trapeziectomy, where the trapezium is simply removed. This approach seems almost too simple - but is very effective at treating the pain of arthritis. If during the trapeziectomy, I find that your thumb seems unstable or no longer in its normal joint position, then I will perform a ligament reconstruction at the same time. Removing the trapezium does weaken grip and pinch strength permanently, but given the pain relief that occurs following surgery, most of my patients find that their hand function is significantly improved.

Occasionally, if you are a very young patient with isolated thumb base arthritis, I may undertake a fusion of the metacarpal and the trapezium (two neighbouring bones in your wrist). While this maintains as much grip and pinch strength as possible, it will stiffen your thumb, and therefore reduce your range of movement. It may also create unusual wear patterns and predispose you to arthritis between the other small bones of the wrist. In any case, we will discuss the advantages and risks together before you make a decision.

The recovery from any surgical procedure on the trapezium is quite long, and it may take six months until you can return comfortably to heavy activities. Such a long recovery period can make the decision to have surgery quite difficult. I will be there to answer all your questions and assist you in making the decision to proceed with surgery or maintain the status quo. Following surgery, 90-95% of patients achieve good to excellent results.


What will happen if I decide not to have treatment?

It is likely that the arthritis at the base of your thumb will worsen, but it is certainly not life-threatening. Many patients prefer to put up with the pain and alter their activities. Sometimes your symptoms may resolve with time.

Surgical treatment should have the same rate of success if it is performed at a later stage.

Read on about trapeziectomy.