Basal Joint Arthritis




Thumb arthritis, also called basal joint arthritis, occurs when the joint at the base of your thumb, the carpometacarpal (CMC) &/or the scaphotrapezial joints develop osteoarthritis.

Having thumb arthritis can cause debilitating hand pain, swelling, and decreased strength and range of motion, making it difficult to do simple household tasks, such as turn doorknobs and open jars.

Treatment for thumb arthritis may include self-care measures, splints, medication or corticosteroid injections. In severe cases, you may need surgery to treat thumb arthritis.


The exact cause of thumb arthritis, as with osteoarthritis in general is not known. Researchers suspect that it's a combination of factors, including being overweight, the aging process, joint injury or stress, heredity, muscle weakness and "cumulative load" to the joint (using your joint repetitively, such as in assembly line work).

Made up of the small bone at the base of your thumb (trapezium), the first bone of your thumb (first metacarpal), and the wrist's scaphotrapezio-trapezoidal joint, the basal joint allows your thumb its wide range of motion and allows your hand to pinch, grip and grasp objects. In a normal basal joint, cartilage covers the ends of the bones — acting as a cushion and allowing bones to glide smoothly against each other. With thumb arthritis, the cartilage that covers the ends of the bones deteriorates and its smooth surface roughens. The bones then rub against each other, resulting in friction and joint damage.

 Your body goes to work repairing the damage, but the repairs may be inadequate, resulting instead in growth of new bone along the sides of the existing bone (bone spurs), which can produce noticeable lumps on your thumb joint.

 You are more likely to develop basal joint arthritis if you are;

  • female
  • 40 years or older
  • Have hereditary conditions, including joint ligament laxity and malformed joints
  • Past injuries to your basal joint, such as fractures and sprains
  • Have diseases that change the normal structure and function of cartilage, such as rheumatoid arthritis



The first and most common symptom of thumb arthritis is pain. Pain occurs at the base of your thumb when gripping (which applies the most force to this joint), grasping, pinching an object between your thumb and forefinger, or applying force — such as when turning a key, pulling a zipper or opening a jar. Eventually, you may even experience pain when not using your thumb.

Signs and symptoms may include:

  • Pain at the base of your thumb
  • Swelling, stiffness and tenderness at the base of your thumb
  • Decreased strength when pinching or grasping objects
  • Decreased range of motion
  • Enlarged, bony or out-of-joint appearance of the joint at the base of your thumb

The pain, stiffness and decreased movement may be minimal or significant, depending on the severity of the Osteoarthritis.



X-rays may reveal bony projections that grow along the edges of bones (bone spurs or osteophytes), loss of joint space (worn-down cartilage) and sclerosis or whitening of the adjacent bone surfaces i.e. hardening due to bone rubbing on bone.

 Occasionally other investigations will be required such as an ultrasound or CAT scan if there is a suggestion of synovitis (excessive soft tissue of the joint), bone cysts or Carpel Tunnel Syndrome on examination. Blood tests may be ordered to exclude other causes for the arthritis. Nerve conduction studies are used to confirm the presence and severity of Carpel Tunnel Syndrome.  


Treatment focuses on helping to:

  • Reduce pain
  • Maintain or improve joint movement
  • Minimize disability

Your doctor may recommend a combination of treatments, including self-care measures, activity modification, splints, medications and physical therapy. In early stages, nonsurgical treatments are usually effective. In severe cases, surgery may be necessary.

Your doctor may recommend the use of a splint to support and off load stress from the arthritic joint. Splints help decrease pain, encourage proper positioning and give your joint some much-needed rest. Depending on your needs, you may wear a splint overnight or throughout the day. Several types of splints are available. Some are prefabricated, and you can find them in a chemist. Others can be custom-made to fit your hand. They may be soft and cloth-like or made of plastic. Your doctor or a hand therapist can help you decide which kind of splint is right for you.

Your doctor may recommend that you take Panadol or Panadol Osteo on a regular basis to relieve your joint pain. They have fewer side effects than do other pain relievers. Non-steroidal anti-inflammatory drugs (NSAIDs) decrease the inflammation and relieve the pain in your thumb and wrists. NSAIDs include such medications as ibuprofen, naproxen, diclofenac, or Mobic. NSAIDs have risks of side effects that increase when used at high dosages for long-term treatment. Side effects may include ringing in your ears, gastric ulcers, cardiovascular problems, gastrointestinal bleeding, and liver and kidney damage. Other medications that may help in some patients include Fish / Krill oil and glucosamine.

If a combination of analgesics and splint use are not effective, your doctor may recommend injecting a long-acting corticosteroid into your basal joint. Corticosteroid injections can offer some pain relief and reduce inflammation. Corticosteroid injections may give 3-12 months of relief from pain, though on occasion it may be long lasting. Usually only a couple of injections should be given to the joint and if severe  pain recurs surgery should be considered. Frequent use of corticosteroid injections should be avoided as they may cause further joint damage.


When surgery is necessary
If you don't respond to other treatments or if your ability to use your thumb is significantly compromised and you have severe pain, your doctor may recommend a surgical procedure called;

  • Trapeziectomy. In this procedure, the surgeon removes the trapezium bone that sits adjacent to the joint.
  • Joint replacement (arthroplasty). In this procedure, surgeons remove part or all of the joint and replace it with a graft from one of your tendons. New plastic or metal devices called prostheses also are being developed to replace the joint. Currently most doctors prefer soft-tissue (tendon) arthroplasty.

These two procedures are usually combined. The operation takes 1-1½ hours under general anaesthesia . You are usually in hospital for 1 -2 days afterwards. You will need to take strong pain killers e.g. Oxycontin and Endone usually for a couple of weeks after the surgery.

 After surgery, your thumb and wrist is placed in a cast for one week and then a firm plastic splint for a further five weeks. Between six weeks and 3 months you will gradually be weaned out of the splint. Once the splint is removed, you will work with the Occupational Therapist to help regain hand strength and movement. Although recovery is slow, you should be able to resume your normal activities within three months of surgery but it will be six months before you are back to full activities.



Outcome and Complications

Surgery helps over 80% of people with this problem. Surgery is generally helpful in relieving pain, but there may still be activities that cause discomfort such as forceful pinch or strong gripping. Some patients may still have mild discomfort usually due to arthritis affecting adjacent or other joints in the hand.

Complications may occur with any operation.

  • General complications of any surgery related to the anaesthetic (e.g. vomiting, chest infection, heart attack, allergic reaction) or the wound such as bleeding or infection.
  • Specific complications include
    • Scaring – this may be thick, tender and lumpy especially for the first 3 months
    • Numbness or dysthaesia (sensitivity) over the back of the hand due to damage to radial nerve
    • Ongoing pain in 10-20% patients
    • Weak pinch or grip strength
    • Rupture of the remaining wrist flexor tendon that was used to suspend the thumb
    • Secondary deformity of the thumb MCP joint inadequately corrected if pre-existing Z deformity of thumb
    • Swelling and stiffness of the fingers
    • Chronic Regional Pain Syndrome (painful, swollen, cold, stiff hand) that may take months to years to recover (rare)