Basal Thumb Arthritis

The bone at the base of the thumb (the metacarpal) forms a joint with one of the wrist bones (the trapezium). This forms the basal thumb joint. Smooth, slippery cartilage normally covers the ends of the bones at the joint and acts to reduce the friction at the joint to allow easy movement and also acts as a shock- absorbing layer. Wear and tear on the cartilage that covers the ends of the bones causes the cartilage to wear away and the raw bone ends to rub on each other. This causes pain and deformity of the joint so that the base of the metacarpal sticks out to the side causing a lump and the span of the hand is reduced.

The trapeziectomy is the commonest procedure for basal thumb arthritis and involves removing the trapezium bone entirely. Since this removes one of the rough and painful joint surfaces, the raw bone ends will stop rubbing together and so the pain will be reduced. A stabilisation procedure (Suspensionplasty) is also performed using a tendon or capsule from around the joint.

The thumb and wrist are placed in a bulky dressing and plaster for about ten days. The fingers are left free and should be moved, as should the tip of the thumb. To reduce swelling, the hand must also be kept elevated. The dressing will be removed and the wound is checked, following which, a plaster cast will be applied for 4-5 weeks by the hand therapist. When the plaster cast is removed, you will be asked to start massaging the scar with a moisturiser. You will have a plastic splint made to support the thumb for a further few weeks.

You may get back to driving after 6-7 weeks and can consider going back to light work 6 weeks after surgery.

In the vast majority of cases surgery is successful but there are some possible complications of surgery that you should know about. Stiffness and swelling of the thumb is common. Keeping the hand well elevated and early movement tend to limit this. You may notice that the operated thumb is slightly shorter than the normal thumb. Rarely, severe swelling, stiffness and pain occurs which does not quickly settle. This is called reflex sympathetic dystrophy and requires protracted therapy. The majority of patients get good or excellent pain relief but occasionally a little aching or intermittent twinges of discomfort remain but these will be much less severe than the preoperative pain. The hand may take up to six months to completely settle after the surgery.