Thumb base arthritis: symptoms, splints, injections and surgery

The carpometacarpal (CMC) joint is where the long bone of the thumb meets the trapezium bone of the wrist. A Dudley Group leaflet explains it is designed to give the thumb a large range of motion, including bringing the thumb across the palm, but the downside is that the joint suffers a lot of stress over the years. With wear, the cartilage thins and the joint becomes painful, a condition called osteoarthritis.

NHS Lanarkshire says almost anyone can get osteoarthritis but it is more common after 40 and in women, and that the base of the thumb is particularly affected because of its anatomy and the high forces on the joint in daily activities. It also notes that osteoarthritis cannot be cured but most people can control symptoms so they do not interfere with normal activities, and that early treatment helps prevent further symptoms and joint damage.

Pain is the main problem. The Dudley leaflet says it occurs at first only with activity and later, as the condition worsens, aching may be present at rest. The most noticeable problem is difficulty gripping; it causes a sharp pain at the base of the thumb in the thick part of the heel of the hand. NHS Lanarkshire says sharp pain usually occurs when pinching, holding or pressing objects with the tip of the thumb.

Everyday tasks that load the joint include turning a key, opening a bottle or jar, writing, tearing paper or holding a plate.

• Pain at the base of the thumb on pinching, gripping or twisting

• Aching at rest in later stages

• Weak grip and dropping objects

• Stiffness, particularly after rest

The Dudley leaflet says the diagnosis begins with a detailed history, including any past injuries to the hand that might suggest another reason for the condition, and that X-rays are taken to see how much the joint is damaged. Your clinician will also examine the joint for tenderness and test movement and pinch strength.

Other conditions can produce pain near the thumb, such as tendon problems or nerve compression at the wrist, and the examination aims to separate them. X-ray severity does not always match symptoms, so treatment is guided mainly by how much pain and disability you have, which the Dudley leaflet states is the basis for treatment.

NHS Lanarkshire describes the initial treatment goal as reducing pain and inflammation, usually by supporting the joint with splints, while a hand therapist helps regain movement and strength and teaches stability exercises and self-management. Splints differ in material (hard or soft) and which joints they support, and many people need a combination. At first the splint is worn frequently to settle pain, later less often, perhaps for heavy or repetitive activities or flare-ups.

The Dudley leaflet says most people only wear the splint at night and when the joint flares up, and that it should also be worn to protect the thumb during heavy or repeated hand activities. Mild anti-inflammatory medicine such as ibuprofen may be enough early on, reducing heavy repetitive gripping may be necessary, and exercises keep the joint mobile and prevent stiffness.

Joint protection means changing how you do tasks. NHS Lanarkshire suggests keeping both joints of the thumb slightly bent when pinching and not letting them bend backwards, and warming the hand in a bowl of warm water before exercising. Exercises should be slow and gentle, for no more than 10 minutes per session, preferably every other day to avoid overloading the joints.

A cortisone injection into the joint can give temporary relief. The Dudley leaflet says relief usually lasts several weeks to months, there is a small risk of infection as with any joint injection, and there is no long-term improvement in function, stiffness or tenderness. It adds that steroid injections combined with splinting have been shown to be more successful in the early stages of CMC arthritis.

NHS Lanarkshire says injections may cause adverse effects and are mainly used when the pain becomes constant, working best when combined with hand therapy to address the mechanical problems behind the symptoms. They are one tool to calm a flare so that rehabilitation can progress, not a cure.

Surgery is considered when symptoms cannot be controlled without it. The Dudley leaflet states that surgery does not cure the arthritis. NHS Lanarkshire says the most common operation is trapeziectomy, in which the trapezium bone is removed; the surgical options are effective in reducing pain but involve a lengthy recovery, might decrease strength and have a higher risk of complications. Another option is fusion (arthrodesis), where the joint is pinned to keep it still.

The Dudley leaflet explains that in a resection arthroplasty the arthritic joint surfaces are removed and replaced by a cushion of soft tissue, sometimes using a rolled-up piece of tendon, which heals to tough scar tissue forming a flexible connection. A fusion is done quite often in younger people who need a strong grip or pinch more than fine thumb motion. Complications include infection, nerve injury, scar tenderness or continued pain.

Which option suits you depends on how much pain and difficulty you have in daily life, your hand use and your preferences; your hand therapist and surgeon should talk this through, including the recovery time and time off work or driving.

Most care starts with a GP, then an NHS hand therapy or MSK physiotherapy service for splinting and exercises, with referral to a hand or orthopaedic surgeon for injection or surgical advice if symptoms persist. NHS hand therapy teams usually lead the non-surgical programme, and consultants advise on surgery.

Private hand therapists, rheumatologists and hand surgeons can offer faster appointments and custom splints. Whichever route you choose, ask how long splints are expected to be worn, how many injections are sensible, what the recovery from trapeziectomy involves and what alternatives exist, and ask for written costs for each step.