BASE OF THUMB ARTHRITIS
This is arthritis between the base of the metacarpal bone of the thumb and a bone in the wrist, the Trapezium.
WHAT CAUSES IT?
This joint is extremely mobile and subjected to a great deal of strain and for this reason it is one of the most commonly affected joints in the body. It affects women more often than men and generally develops in patients above the age of 50 years.
WHAT ARE THE SIGNS AND SYMPTOMS?
Pain is the predominant feature of this. This tends to be a continuous dull background pain that is made worse by strenuous activity. Typically pinching and gripping activities present the greatest difficulty. In more advanced cases a lump may develop at the base of the thumb and the thumb itself can be hyper-extended (bent backwards).
HOW IS IT DIAGNOSED?
A detailed history and examination are generally suggestive of the problem however you will need an X-ray to confirm the problem.
HOW IS IT TREATED?
This depends on the severity of the condition. The treatment is targeted at pain relief and improving the ability to perform day-to-day activities. The treatment starts with simple painkillers and is supported by splints. A hand therapy programme will help educate you about your illness and the therapist will suggest adjustments making it easier to perform your day-to-day activities. Injections of steroid into the joint under x-ray guidance are another useful way of gaining pain relief. If this non-operative treatment fails to give you enough pain relief, an operation either involving the removal of the trapezium bone or a fusion of the trapezium and the thumb metacarpal bone may be appropriate.
WHAT DOES THE OPERATION INVOLVE?
A Trapeziectomy involving the removal of the Trapezium bone is the most frequently performed operation for this problem. This operation is performed through a curved incision at the base of the thumb curving into the palm. The operation is supplemented with the use of part of the Flexor Carpi Radialis tendon. This is a tendon in the wrist. This tendon is used to both fill the gap left by removing the bone and to stabilise the base of the metacarpal bone which loses its support at the base with the removal of the trapezium. This is referred to as a Ligament Reconstruction and Tendon Interposition. The operation is normally performed under a general anaesthetic and can take approximately 1 hour to complete. An alternative operation that involves fusing the joint is an option for people with heavy occupations. This involves combining the trapezium and the base of the metacarpal to eliminate any movement at the joint. This has the benefit of reducing the pain resulting from movement at this joint.
AFTERCARE
Following the operation you will have a temporary cast applied to your hand. Your wound will be assessed at 48hrs and a temporary plaster is re-applied. The stitches are removed at 10 days and a full cast applied at this point. You will remain in the plaster for an additional 2-3 weeks, making it 4 weeks in plaster in total. A removable splint that you will wear at all times except when exercising then follows this. This will be for an additional 4 weeks making it 8 weeks in total with some form of splint or plaster. After this period there is no further splint and you are encouraged to try and regain your movement. For a fusion operation the patient will remain in a cast for between 6-8 weeks until there are signs that the bones are beginning to heal together.
RETURN TO WORK
This depends on the nature of your work but in almost all cases will involve at least 4 weeks off work. This is the period that you are in plaster. This may be shorter for those who do not need to drive to work and longer for those in manual occupations.
DRIVING
You cannot drive for the first 4 weeks. Following this it may be possible for you to drive with your splint on but this will need to be clarified with your insurance company. Some insurance companies will not allow you to drive with a splint and in this situation you will not be able to drive for 8 weeks.
RETURN TO SPORT
Return to most sports is possible after 3 months however this is dependent on the intensity of the sport.
COMPLICATIONS
Like with any surgery there are a number of small risks associated with this operation.
Infection (1%) is a risk with all surgery. In the majority of cases these are infections around the wound and can be treated with a course of antibiotics. The more unusual deep-seated infections however can require admission to hospital and surgery to clean the wound out if necessary.
Swelling and Stiffness can remain for many months following surgery. It is important to elevate the limb and keep all joints that are not immobilised with a splint, active.
Scar Sensitivity is often a problem with surgery in the hand, particularly the palm. This is often self-limiting and daily massage of the scar can shorten the duration of the symptoms. The sensitivity does settle in all cases with time.
Nerve Injuries a potential but very rare risk with this surgery. Often the nerves at greatest risk are the tiny nerves supplying skin in the area of the wound and cutting through these may result in an area of numbness that is not often troublesome. The superficial Radial nerve which supplies feeling to the back of the hand on the thumb side, can occasionally be irritated during the operation and may cause some sensitivity which settles within a few months.
Reduced Grip and pinch grip strength The grip strength generally does not return to normal but in most cases is better than it was prior to the operation. This is largely because the reduction in pain affords a stronger grip. A fusion operation is generally better at preserving grip strength which is why it is preferred in patients in heavy manual occupations.
Complex Regional Pain Syndrome is an extremely rare (1%) complication that can follow any injury or surgery to a limb. In this situation the nerves in the arm over-react to the point where the hand becomes very painful, swollen and sensitive. This condition does improve with time but can be problematic for many months (see section on Complex Regional Pain Syndrome).