Pain due to wear and tear of the joint at the base of the thumb may lead to the need for surgical intervention. The following describes the condition and its treatment.

WHAT IS OSTEO-ARTHRITIS AND WHY DOES IT OCCUR IN THE THUMB?

Osteoarthritis (OA) is degeneration of a joint generally caused by ‘wear and tear’. OA of the base of the thumb is more prevalent in the senior population (>50) and in females. The main joint at the base of the thumb is called the trapeziometacarpal (or carpometacarpal joint. It carries a lot of force during use of the thumb yet allows complex ranges of movement including rotation.  

WHAT ARE THE SYMPTOMS?

There may be aching, especially pinching between thumb and the side of the index finger (key pinch). This pain may lead to a sense of weakness on pinching and on gripping. Movements such as opening the lid of a jar, turning a key in a door or brushing/combing hair may be painful. The thumb base may be swollen and feel or sound crunch (crepitus) on certain movements. It may be misshapen (Z deformity or swan necking).   

WHAT WILL A HAND SURGEON DO?

The hand surgeon will take a history and perform an examination. X-rays may be performed to investigate the severity of OA in the joint. There may be collapse of the trapezium (the little bone on which the thumb stands), the formation of spikes of bone around the edges of the joint (osteophytes, which are painful) and involvement of other joints in the wrist or the hand. A treatment plan can then be formulated. 

WHAT CAN BE DONE ABOUT THE PAIN?

The main aims of treatment are pain relief, maintenance of function, prevention of other deformities and advice. In the early stages, specially made splints can be highly effective to support the thumb and prevent pain whilst enabling the rest of the hand and wrist to function. Injection of a steroid is often used as a holding procedure but there is uncertainty about the long term effects on the joint if used repeatedly. Surgical treatment is indicated if pain persists and interferes with function, and activities of daily living become increasingly difficult. There are several options available and some controversy as to which is best. Joint stabilisation involves either realignment of bones or ligament reconstruction using a tendon and is suitable only for a minority of patients who have an unstable joint but little damage to the surfaces of the joints. Trapeziectomy, in which the trapezium bone is completely removed, is indicated if the joint above or below it are arthritic. Some surgeons fill the gap usually with some adjacent tissue as a spacer but there are differences in opinion as to whether this step affects outcome. Trapeziectomy with ligament reconstruction is sometimes performed if there is concern that the thumb appears too slack to sit securely into the new joint created by removal of the bone. Arthrodesis (fusion) is usually reserved for young patients who require power. It has the disadvantage of stiffening the thumb.  

HOW IS A TRAPEZIECTOMY PERFORMED AND WHAT ABOUT RECOVERY?

The most commonly performed procedure is trapeziectomy and this will be discussed. This is usually performed under general anaesthesia supplemented by local anaesthesia. You will usually stay in hospital for 1 or 2 nights after the operation. The scar will be on the back of the thumb. Your hand will be in a bulky dressing including plaster to protect it. Hand elevation is very important to prevent swelling and stiffness of the fingers and hand. Movement of the hand and tip of the thumb should continue and you should perform normal light activities after the operation. Stitches are usually removed at around 2 weeks after the operation and the plaster may be changed for a lighter weight splint. Splintage will take up to 6 weeks. Exercises are taught by the hand therapist and is usually initiated around 4 weeks. It takes 6-9 months for the strength to recover but the improvement is usually steady. Patients usually notice a radical improvement in pain (some have no pain at all by that time) but strength may never be as good as it was before the start of the arthritis.  

WHAT ARE THE COMPLICATIONS OF TRAPEZIECTOMY?  

The scar on the back of the thumb may be firm and tender for a couple of months. You may be advised to massage the scar. Infection can occur after any operation and needs to be treated appropriately by the surgical team with antibiotics and/or dressings. Severe stiffness can occur in about 5% of patients whose hands are particularly sensitive to hand surgery. Their hand can become swollen, painful and stiff (algodystropy or complex regional pain syndrome). Neuroma. This can occur if a small nerve in the region is damaged during surgery which can cause a painful area in the scar and numbness on the back of the thumb. This may require a further operation to correct it. Diana E M Slade, Specialist Registrar, compiled this information sheet with thanks to Mr David Evans, Consultant Hand Surgeon (www.evans-hand.com) and Mr Harry Belcher, Consultant Hand and Plastic Surgeon (www.pncl.co.uk/~belcher/home.htm) for their useful websites