• Ravi Mallina

Surgical options for base of thumb arthritis

Surgery for basal joint arthritis depends on several factors. Age of the patient, occupation, stage of arthritis and patient’s preference for one treatment over the other are the predominant parameters one would consider prior to offering surgery.

Joint denervation: In an arthritic joint, it is believed that nerve fibres supplying the lining of the basal joint of thumb mediate the pain response to arthritis. The aim of denervation surgery is to remove the nerve fibres innervating the lining of the basal joint of the thumb. This would abolish transmission of pain signals to the brain and therefore patients would not perceive pain. Obviously, this is a very simple explanation, and in reality there are complex mechanisms behind how a denervation surgery benefits patients.

Joint arthroscopy: The purpose of this procedure is to “shave” the lining of the joint, called the “synovium” and shaving of any excess bony outgrowths around the basal thumb joint. Occasionally, loose pieces of cartilage and bone can be seen floating in the joint which can cause significant pain. Special instruments can be passed into the joint through two tiny incisions on the skin and these foreign bodies can be retrieved. Joint arthroscopy is however, useful in only a select group of patients who are not in very advanced stages of arthritis.

Joint fusion: Also referred as “arthrodesis”, this procedure is performed usually in patients who are young manual labourers. This group of patients like to keep the overall architecture of the thumb intact and most importantly preserve the strength of the thumb. In essence, the arthritic joint surfaces are shaved off, opposed against each other and held with a plate or screws. In about 6 to 8 weeks the joint surfaces are fused by new bone formation, thereby abolishing any movement across the joint. The patient is recommended to stay in plaster for about 6 to 8 week after surgery until X-rays show that the joint surface is fused.

Osteotomy: The main aim of this procedure is to offload the joint by realigning the thumb. The procedure involves breaking the thumb bone called metacarpal in a controlled manner and the newly aligned metacarpal is held with plate and screws. The thumb is secured in plaster for 6 to 8 weeks until the site of osteotomy (break in the metacarpal) is healed. This procedure is reserved for young patients with early basal thumb joint arthritis who would like to preserve their natural joint, thereby preserving the natural thumb movements.

Trapeziectomy: This procedure is one of the commonest surgeries performed for basal joint arthritis. In essence, the surgeon takes out the arthritic trapezium. The space is either allowed to fill with scar tissue or reinforced with a strip of tendon which passes very close to the basal joint of the thumb. Patient is placed in plaster for about 4 to 6 weeks. Once the plaster is taken off, patient is reviewed by a hand therapist who commences some gentle exercises around the thumb. As a general rule it takes about 4 to 6 months to see the full benefit of trapeziectomy.

Joint replacement surgery: Broadly speaking there are two forms of joint replacement surgery: full joint replacement and partial joint replacement surgery. In case of full joint replacement surgery, the worn out trapezium is replaced by an artificial ball and socket embedded in the body of the metacarpal (thumb bone) and the trapezium, respectively. This whole construct essentially resembles a “mini hip replacement !!!” The ball and socket is made of polyethylene and titanium. In the case of partial joint replacement surgery, the space between the bones of the basal joint is simply filled with an artificial medical grade material such as “pyrocarbon.” Both these options have advantages and disadvantages and your hand surgeon should be able to talk them through.