Ultrasound-Guided Thumb Base (CMC) Joint Steroid Injection

What is thumb osteoarthritis “OA”? (Sometimes referred to as first carpometacarpal joint arthritis)

Osteoarthritis of the thumb base (also referred to as first CMCJ or carpometacarpal joint) is a slowly progressive and long-standing disease that usually results in joint pain, stiffness and swelling. Even simple daily tasks may become painful and troublesome, and the disease can affect your life quality significantly.

Relevant thumb anatomy

The first carpometacarpal (CMC) joint is the small joint at the thumb base. It is a vital joint for all complex thumb movements and connects the thumb to the hand/wrist. The joint is located between the trapezium (a small bone within the wrist) and the thumb metacarpal (the long bone at the base of the thumb, connecting it to the wrist). Anatomically, the joint is complex and has a “saddle shape”. This special configuration allows for a relatively increased range of movement and different movement capabilities at the thumb base.

The bones that form the first CMC joint (trapezium and first metacarpal) are covered by a special protective tissue (articular cartilage). This ensures smooth and frictionless movement at the joint and protects the underlying bone. Unfortunately, repeated use may wear away this protective layer over time, leaving exposed bone surfaces. This is usually painful and can result in bones rubbing against each other. Synovitis refers to inflammation and thickening of the synovium (the special tissue that lines the joint). Synovitis usually results in episodes of pain flare-ups and is linked with the progression of osteoarthritis.

What are the causes of thumb arthritis?

The incidence of thumb base osteoarthritis increases with age. This is due to the different repeated thumb movements we perform daily. The incidence of thumb osteoarthritis increases significantly after the age of 50. Other factors that can predispose to thumb arthritis include previous injuries and occupations that involve repetitive thumb movements.

How do I know if I have thumb osteoarthritis?

Osteoarthritis is a progressive condition that develops gradually over time. The initial clinical features may be occasional mild discomfort; as time progresses, however, these become increasingly persistent and painful.

Feeling a dull ache at the base of your thumb. Repeated episodes of sharp pain may indicate synovitis.
Other features include joint swelling and clicking. The swelling can be due to soft tissue inflammation (synovitis), but sometimes it is due to the formation of bone spurs as part of the osteoarthritis process. The latter is referred to as osteophytes.
Joint movements may become restricted if the condition progresses, interfering with simple daily activities (like opening doors).

What other conditions can resemble thumb osteoarthritis?

Conditions that can be confused with thumb osteoarthritis include:

De Quervain's Tenosynovitis vs thumb osteoarthritis

The age group is different for the two conditions. De Quervain's disease causes localised swelling, stiffness, and pain at the base of the thumb but is more common in people under 50 and has increased prevalence in females. It is often seen with increased activities involving the hand/thumb and can be seen in new parents because of baby lifting.

How to diagnose thumb osteoarthritis?

The diagnosis of thumb (CMC joint) arthritis usually starts with a clinical assessment performed by a hand specialist, combined with imaging. A thumb X-ray is very useful to establish the diagnosis and assess the severity of the disease.

A dedicated musculoskeletal ultrasound scan would be useful for the assessment. It can detect joint capsule thickening, joint space narrowing and bony spurs (osteophytes) formation. Doppler ultrasound assessment is very useful for assessing for active inflammation within the joint (synovitis).

What is the treatment for thumb osteoarthritis?

Treatment starts with physiotherapy, including strengthening and flexibility exercises. A thumb splint to give more support to the joint can also be useful. Over-the-counter medication like paracetamol or anti-inflammatory gel/tablets (like Voltarol) may help relieve symptoms.

What is the role of injections in the management of thumb osteoarthritis?

If your thumb pain is not responding to conservative management and your pain interferes with your daily activities, an ultrasound-guided steroid injection might be considered.

Can Hyaluronic acid injections be used for thumb arthritis?

Hyaluronic acid is a medicine designed to simulate the natural lubrication within joints to ease movement and relieve pain. It can also reduce the inflammation associated with arthritis.

Frequently asked questions about thumb steroid/cortisone injections.

What is a thumb cortisone injection?

Corticosteroid (cortisone) is a potent anti-inflammatory medicine routinely used to manage inflammatory conditions (like bursitis, arthritis, and tendinosis). A cortisone injection will reduce the inflammation in the injected area (like the thumb base or the carpal tunnel) and allow you to manage the condition, usually by undergoing a physiotherapy program. To find out more, please see our FAQs.

Should hand & wrist injections be done under ultrasound guidance?

This is our routine practice, as plenty of evidence supports ultrasound guidance when performing joint injections. Doing hand and thumb injections under ultrasound/imaging guidance allows for direct visualisation of the needle to ensure accurate placement into the area of pain/inflammation (like a bursa, an arthritic joint, or an inflamed tendon sheath). Ultrasound guidance results in more accurate, less painful, and faster procedures, with better outcomes than these injections without guidance. Ultrasound guidance avoids sensitive structures (like nerves and vessels) during the procedure.

Are thumb cortisone injections safe?

These injections are generally very safe and routinely done in our practice. There is a very small risk of infection (about 1:10.000). The procedure will be explained to you in detail during your appointment, and all your questions will be addressed. To find out more about cortisone injections in general, please see our FAQs .

What are the commonly used steroid medicines in wrist injections?

Triamcinolone (Kenalog) and methylprednisolone (Depo-medrone) are commonly used steroid injections for musculoskeletal conditions. These preparations are long-acting steroid injections that normally take a few days to start working.

How long will the effect of a thumb cortisone injection last?

Current evidence suggests that cortisone can improve pain and function for up to 3 months, but in some cases, it can last longer. Pain relief duration depends on the condition's diagnosis and severity. The steroid injection will provide a window of opportunity to undergo effective rehabilitation and attempt to address the underlying cause to enhance the pain relief achieved from the injection.

How soon will a steroid injection start to work?

A steroid injection usually takes a few days (1-3) before you notice the effect, although sometimes the pain relief can start on the same day. The injected area will often feel sore for the first few days. This is referred to as (steroid flare) and can be seen after a steroid injection.

Do steroid injections just hide/mask the pain?

Steroid injections do not just mask or hide the pain, but they act by reducing the inflammation in the targeted area, thus providing a strong and local anti-inflammatory effect to help control the symptoms and allow the patient to manage the condition, usually by undergoing effective rehabilitation.

How many steroid injections can I have?

If possible, we advise reducing the number of cortisone injections by combining any injection therapy with an effective physiotherapy programme to address the underlying cause. Repeated steroid injection into the same area should be avoided if the previous injection was less than 3-4 months ago.

Are thumb arthritis injections painful?

Pain is very subjective, and people have different pain thresholds. Most patients experience some discomfort during the injection, but the corticosteroid is usually mixed with a local anaesthetic (numbing medicine) to enhance pain relief. This will provide immediate pain relief that usually lasts for a few hours. We use ultrasound guidance to ensure the procedure is quick and efficient. Ultrasound ensures needle visualisation to choose the safest path for the injection and avoid any important or sensitive structures.