Arthritis At The Base Of The Thumb

Arthritis at the base of the thumb

Osteoarthritis of the joint at the base of the thumb is very common. It can be seen on an X-ray of the hand in a third of post-menopausal women. Of these a third will have symptoms, as will many younger women and men. The medical terms for this joint are the first carpometacarpal joint or the trapeziometacarpal joint.

It is one of the most common complaints presenting to my orthopaedic hand clinics. Patients have pain at the base of the thumb which is often worse with pinching or gripping and twisting activities such as trying to remove a tight jar lid. It can be become severe enough to disturb their sleep, and cause difficulty writing for any length of time. The diagnosis is usually easy to make by examining the patient and taking an X-ray.

To try to explain why arthritis of this joint is so common we have to go back a few million years to mans early ancestors. The human hand has evolved to allow us to make and use tools. One of the most important features of the hand which allows this is being able to oppose the thumb. This is the movement in which the thumb is rotated and flexed. It allows us to make a precision grip in which the pulp of the thumb can be pressed against the pulps of the fingers, and a power grip for firmly grasping objects. Large forces are transmitted across the thumb base joints with these gripping actions, and because these joints are also so mobile the stresses to the surface of the joint can cause it to wear out and develop osteoarthritis.