The first and most common symptom of thumb arthritis is pain. Pain occurs at the base of your thumb when you grip, grasp or pinch an object between your thumb and forefinger or use your thumb to apply 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.
Other signs and symptoms may include:
- 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
When to see a doctor
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.
Thumb arthritis usually occurs as a result of trauma or injury to the joint. Some people also develop thumb arthritis in association with osteoarthritis in larger joints.
The basal joint gives the thumb a wide range of motion, allowing you to pinch, grip and grasp objects. The bones in the thumb's basal joint are the first metacarpal bone, which runs through the heel of your hand, and the trapezium (truh-PEE-zee-um), a small bone at the base of your thumb.
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.
The damage to the joint may result 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 may increase your risk of thumb arthritis:
- Being female
- Being age 40 or older
- Having certain hereditary conditions, including joint ligament laxity and malformed joints
- Experiencing 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
- Performing certain activities and jobs that put high stress on this joint