The thumb is generally considered to be the most important single digit in the
The basal joint of the thumb, or carpometacarpal joint, is made up of a
carpal or wrist bone (trapezium) and the first or metacarpal bone of the thumb.
This joint is very near the wrist and under the fleshy part of the thumb. It is
subjected to an unusual amount of stress, as the thumb must be strong enough to
counteract the force of four fingers put together. It has been calculated that
one pound of pinch between the thumb and index finger will produce six-to-nine
pounds of pressure at the basal joint of the thumb.
The joint is held in position by the contours of its surface and by the
ligaments and muscles surrounding the joint. Disruptions of the joint surface or
the supporting ligaments can lead to slipping of the joint (subluxation) as well
as pain and swelling.
Arthritis is a common term meaning inflammation of a joint. Although
arthritis can apply to more than 100 different diseases, the three most common
types affecting the basal joint of the thumb are osteoarthritis (degenerative
arthritis), rheumatoid arthritis, and traumatic arthritis (generally due to a
fracture in the joint).
Symptoms of arthritis in the base of the thumb are pain and swelling about the
thumb and wrist, particularly with grasp and pinch. These symptoms may appear
the first thing in the morning and be present for a half hour or so before the
thumb "loosens up." They might then subside throughout the middle of
the day, only to return with a "dull aching" type of pain towards the
end of the day or after vigorous use. A "bump" may appear at the
joint, due to the shifting of the base of the metacarpal bone as the ligaments
loosen through swelling.
When the doctor examines the joint, an attempt is made to determine
accurately whether the patient's pain symptoms are due to an arthritis in the
thumb basal joint. Tests to determine loosening of the joint as well as the
smoothness of the cartilage surfaces are performed. X-rays taken of the joint in
various positions help the physician determine the severity of the disease.
Treatment of the condition depends upon the symptoms and stage of the
disease. For mild-to-moderate symptoms of pain and swelling, treatment consists
primarily of anti-inflammatory medication, rest, splinting, and education.
Aspirin has been a standard anti-inflammatory medication for many years, but a
wide selection of non-steroidal anti-inflammatory medications may be used as
well. Various splints fabricated to support the joint can prove to be quite
helpful. Education is also of great importance, as the patient learns about the
arthritic process and how to minimize symptoms and protect the damaged joint
For more severe symptoms, the patient and doctor may decide on surgery.
Because basal joint arthritis is such a common problem, many types of surgical
procedures have been developed to deal with it. Surgery generally falls into two
main categories; one involves a fusion of the two bones making up the joint,
thereby eliminating the joint and the painful symptoms. A potential drawback
here is some loss of motion and some stiffening of the thumb joint.
The other major category of surgical correction involves removal of the
arthritic surfaces and insertion of material between the two ends of the bones.
Many types of materials have been developed; the most frequently used are
natural tendon from the patient or a synthetic plastic rubber shaped to fit the
space. Each type of surgery has its potential benefit and drawbacks, and each
person's requirements are different.
After surgery, the doctor may prescribe a course of therapy designed to
increase the mobility and strength in the thumb following the surgery. A hand
therapist provides vital supporting instruction and assists the patient in
regaining thumb function.
Pain and stiffness at the base of the thumb are extremely common symptoms of
an arthritic condition and should prompt consideration of an evaluation by your