Thumb arthritis, also called basal joint arthritis, occurs when the joint at your wrist and the base of your thumb — the basal, or carpometacarpal (CMC), joint — develops 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, isn’t 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. This is when you use 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.
These factors increase your risk:
- Being female
- Being 40 years or older
- Having certain hereditary conditions, including joint ligament laxity and malformed joints
- Past injuries to your basal joint, such as fractures and sprains
- Having diseases that change the normal structure and function of cartilage, such as rheumatoid arthritis
- Certain activities and jobs that put high stress on this joint
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 condition and how you use your hands in work and recreation.
If you have persistent swelling, stiffness or pain at the base of your thumb, seek medical advice. If your doctor determines that you have thumb arthritis, he or she can work with you to develop a pain management and treatment plan.
Also seek medical advice if you experience side effects — such as nausea, abdominal discomfort, black or tarry stools, constipation, or drowsiness — from arthritis medications.
Your doctor may use a variety of methods to diagnose thumb arthritis, including a physical examination and certain X-ray imaging techniques.
During a physical exam, your doctor will ask about your symptoms and look for noticeable swelling or lumps on your joints.
Your doctor may conduct a test in which he or she holds your joint while moving your thumb, with pressure, against your wrist bone. If this movement produces a grinding sound, or causes pain or a gritty feeling, it means the cartilage has worn down and the bones are rubbing against each other.
Imaging techniques can reveal bony projections that grow along the edges of bones (bone spurs), worn-down cartilage and loss of joint space — each indicating the presence of thumb arthritis. Your doctor may recommend the following techniques:
- Bone scans
- Computerized tomography (CT) scans
- Magnetic resonance imaging (MRI) scans
- Arthrography, an image taken after dye has been injected into your joint
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 your joint and limit the movement of your thumb and wrist. 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 medical supply stores or drugstores. Others can be custom-made to fit your hand. They may be soft and cloth-like or made of plastic. Your doctor or an occupational or physical therapist with special training in treating hand disorders (hand therapist) can help you decide which kind of splint is right for you.
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.
If a combination of analgesics and splint use isn’t 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 are only a temporary solution. This is because frequent use of corticosteroid injections 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, your doctor may recommend a surgical procedure called arthroscopy.
During arthroscopy, your surgeon makes a tiny incision in the area around your joint and inserts a tubular instrument called an arthroscope. The arthroscope contains a light and a small camera, which projects an enlarged image of the interior of your joint onto a video monitor so that your surgeon can view it. If your joint needs repairing, the surgeon can insert surgical instruments into the joint through the arthroscope or through additional small incisions.
Based on what your doctor discovers during arthroscopy, or based on your history, physical exam and imaging studies, he or she may recommend the following treatments:
- Joint fusion (arthrodesis). In arthrodesis, surgeons permanently fuse bones in a joint to increase stability and reduce pain. The fused joint can then bear weight without pain, but has no flexibility.
- Osteotomy. In this procedure, sometimes called bone cutting, surgeons reposition your bones to help correct deformities.
- 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, however, doctors prefer soft-tissue (tendon) arthroplasty.
Each of these surgical procedures can be done on an outpatient basis. After surgery, your thumb and wrist is placed in a cast or splint for up to six weeks. Once the cast is removed, you may work with a physical therapist to help regain hand strength and movement. Although recovery is slow, you should be able to resume your normal activities within six months of surgery.
Self-care measures can help relieve pain, improve mobility and ultimately increase your independence. Here’s what may help:
- Perform range-of-motion exercises. Exercises that move your thumb through its full range of motion can help improve your joint’s mobility. Your doctor or a hand therapist can demonstrate the specific techniques that are best for you.
- Modify household equipment. Consider purchasing adaptive equipment, such as jar openers, key turners and large zipper pulls. Enlarge the grasp on garden tools, kitchen utensils and writing devices — or buy items with large handles. Replace traditional door handles, which you must grasp with your thumb, with levers. Adaptive equipment is often available by catalog. Ask your doctor or hand therapist for recommendations.
- Apply heat or cold. Your doctor may recommend using heat or cold — or alternating between them to improve your swelling and pain and to soothe your joints.
Heat can help ease pain, decrease joint stiffness and relax tense muscles. Different forms of heat work better for different people. Experiment with hot packs, electric heating pads on their lowest settings, soaking your hands and wrists in bowls of warm water or paraffin wax, or simply taking a shower or bath.
Cold can be effective for reducing pain during flare-ups or after you’ve had too much physical activity. Applying ice packs or soaking your hands in cool or cold water has a numbing effect that can be effective for dulling hand and wrist pain.
When applying heat or cold, take care not to burn yourself or get frostbite.
- Use other joints when possible. For instance, instead of grasping a doorknob to open a door, push it open with your shoulder.
- Educate yourself. Assess what causes your pain and avoid it. The more you know about your condition, the better you’ll be at recognizing the motions that produce pain — whether immediately or hours later.
Adaptive equipment can help make daily tasks easier and less painful. For instance, buy a jar opener for opening lids in the kitchen. Consider replacing traditional door handles in your home with levers, which don’t require the use of your thumb. Equipment is available for turning keys and modifying kitchen and household tools, as well.
Making smart choices also plays a part in coping with this condition. For example:
- Instead of carrying a clutch-style purse, use one with a shoulder or arm strap.
- Instead of grasping handle-type grocery bags, use paper bags that can be held on your hip and with your arm.
Talk to your doctor about other equipment and ideas that may be helpful for you.