Understanding thumb arthritis: from symptoms to treatments

Thumb arthritis refers to arthritis — usually osteoarthritis — of the joint at the base of the thumb. Osteoarthritis refers to the wear and tear of joints over time, such that the cartilage that covers the ends of bones that form a joint wears away, eventually allowing the bones to rub against each other — this causes joint pain, inflammation, swelling and stiffness of the joint, and weakness of grip. 

When osteoarthritis affects the thumb, it usually affects the thumb carpometacarpal joint, also known as the trapeziometacarpal joint. This is one of three joints in the thumb, which includes the metacarpophalangeal joint in the middle of the thumb and the interphalangeal joint in the top half of the thumb. The carpometacarpal joint sits at the base of your thumb. 

In most cases, thumb arthritis is caused by osteoarthritis; however, less commonly, it can be caused by rheumatoid arthritis — a type of arthritis caused by your immune system mistakenly attacking the cartilage in your joints. 

Who is at risk of thumb arthritis?

Thumb arthritis is more common in women but can also affect men. It usually occurs after age 45 with around a quarter of all women aged 55 and over having some symptoms of thumb arthritis. Your risk of developing thumb arthritis is higher if you have previously fractured a bone in your thumb that affects a joint. 

Your genetics can increase your risk of thumb arthritis too; if you have a family history of thumb arthritis, you’re more likely to develop thumb arthritis when you get older. Certain inherited health conditions also increase your risk such as joint ligament laxity or malformed joints.

Symptoms of thumb arthritis

Common symptoms of thumb arthritis include pain and swelling at the base of your thumb, stiffness of your thumb joint, tenderness on pressing the base of your thumb and a weak grip when pinching using your thumb and forefinger. 

You may notice that daily activities that involve a pinch grip become painful and harder to do eg opening tight jars, turning a key in a lock or turning a doorknob. 

Diagnosing thumb arthritis

A doctor can usually diagnose thumb arthritis through a physical examination of your thumb, its appearance and position, and whether it feels tender when gently pressed. They may also feel your thumb for crepitus when moving your thumb ie a palpable crunching or grating sound on moving your thumb joint. 

They may recommend an X-ray to confirm your diagnosis, where they will look for changes in your thumb joint, including a reduction in the joint space, and the formation of bone spurs in reaction to your thumb bones rubbing against each other.

Non-surgical treatments for thumb arthritis

The first course of treatment for thumb arthritis is hand physiotherapy. This involves performing specific daily exercises to strengthen the muscles around the base of your thumb to help prevent your thumb joint from moving more out of line. 

Your hand therapist may also recommend wearing a splint to support your thumb. There are different types of thumb splints including soft and supportive “thumb wrap” splints and more rigid plastic thumb splints that are more supportive but also a little more restrictive for movement.

You can also take over-the-counter pain medication, such as paracetamol or anti-inflammatory tablets, use anti-inflammatory gels, and take steps to avoid certain activities that aggravate your symptoms (ie activity modification). 

If these conservative treatments aren’t effective at managing your symptoms, your doctor may recommend steroid joint injections. These are administered under a local anaesthetic and the guidance of an X-ray or ultrasound scanning. Steroid joint injections can provide temporary pain relief for four to six months but cannot be given too many times — usually a maximum of two or three times — as they can damage your joint tissues if overused, and also tend to have less of an effect each time they are given. 

Surgical treatments for thumb arthritis

If non-surgical treatments aren’t enough to manage your symptoms, your doctor may recommend surgery. There are two types of surgery: a trapeziectomy and a joint replacement. Both types of surgery are performed either under a general anaesthetic or a regional block, where your arm is numbed and you have the additional option of light sedation.

In rare cases, a fusion of the joint may be appropriate. This is usually in young patients with arthritis that has occurred after a fracture of the joint.

Trapeziectomy

The traditional surgery for thumb arthritis is a trapeziectomy ie removal of the cube-shaped trapezium bone of your thumb, which is one of the two bones that forms the carpometacarpal joint at the base of your thumb.  

This surgery usually takes around 60 minutes and involves making a small cut into the back of your hand at the base of your thumb through which the trapezium bone can be removed. 

A trapeziectomy will resolve the pain caused by thumb arthritis, but it will not improve your pinch strength. Recovery from a trapeziectomy can be painful and usually takes four to six months. The final outcome is usually very good from the point of view of pain relief. 

Joint replacement surgery

Joint replacement is increasingly the preferred surgical treatment for thumb arthritis, over a trapeziectomy. This involves creating a ball-and-socket joint made out of metal and polyethylene implants to replace the worn-out joint at the base of your thumb. 

A socket (cup) is inserted into the trapezium bone at the base of your thumb and a stem is inserted into the metacarpal bone that sits above the trapezium bone. The cup and stem are coated with hydroxyapatite, which helps the bone around them bond to the implants. 

Recovery from a thumb joint replacement is usually faster than for a trapeziectomy, taking six to 12 weeks, and offers both pain relief and an improvement in your pinch grip. 

However, as the new joint is a ball-and-socket joint, there is a small risk that it may dislocate, and a longer-term risk that the cup in the trapezium bone will loosen over time, and then need revision surgery or a trapeziectomy. 

Recovering from surgery 

For the first two weeks after surgery for thumb arthritis, your thumb will be in a plaster cast and your arm will be in a sling. Once your cast is removed, your stitches will be removed and you will need to wear a splint for the next four weeks. 

Around four weeks post-surgery, you will start mobilising your thumb through hand physiotherapy exercises. However, post-operative regimes can vary between surgeons and you should follow the advice of your surgeon.

In most cases, you can return to driving six weeks after your surgery but need to wait until 12 weeks post-surgery before returning to heavy hand work, such as DIY, and sports.