I am a 55 year-old woman and I have developed pain and a bump at the base of the thumb. The pain increases when I turn a key or doorknob. Do you know what is causing this pain and how it might be treated?

JS, Billings

Dear JS,

You have likely developed arthritis in the joint at the base of your thumb. Basilar joint arthritis is a condition commonly experienced by women, especially after age fourty. The cause of the condition is still unknown, but may include gradual changes in the ligaments that support the joint which reduce its stability. Over time, the increased joint laxity increases the shear forces across the joint surface which, in turn, increases cartilage wear. Patients with thumb basilar joint arthritis notice increasing pain when they stress the joint, such as pinching or gripping objects. The "bump" you describe is probably the base, or bottom part, of the thumb that has slid out of position where it joins the wrist.

In more severe cases, the space between the thumb and index finger can narrow making it more difficult to grasp objects. The pain can also become more constant, including the development of nighttime symptoms.

Effective treatment is available for this common condition. Many patients respond to simple measures, especially in the earliest stages. Antiinflammatory medication, bracing, and activity modification can all help alleviate symptoms by reducing joint inflammation and stress. If these measures are unsuccessful, a corticosteroid injection into the joint may provide symptom relief.

In cases refractory to bracing and medication, a variety of surgical options are available. Standard surgical alternatives include simply removing the bone at the base of the joint, combining bone removal with ligament reconstruction (joint arthroplasty), or fusing the joint (joint arthrodesis). A more recent option for some patients involves an arthroscopic removal of debris and bone from the joint and tightening the ligaments with a special thermal (heat-generating) probe. Finally, newer joint replacement devices make this a potential option for very select patients.

My advice to you is to seek a consultation with your primary care physician or local orthopaedic specialist to see if you might benefit from one of these options.

Good Luck,
Ralph M. Costanzo, MD