Pain in the IP thumb joint: What does it mean?

Key takeaways

• The IP joint of the thumb, located just below the thumbnail, is crucial for hand movements like grasping and pinching, and pain in this joint can significantly impact daily life.
• Arthritis, particularly osteoarthritis, psoriatic arthritis, and rheumatoid arthritis, is a primary cause of pain in the IP joint of the thumb, leading to inflammation, swelling, and reduced movement.
• Treatment for IP thumb joint pain varies depending on the underlying cause and may include medications, lifestyle adjustments, and therapies to alleviate symptoms and improve joint function.

Overview

You can see and appreciate the IP joint of your thumb when you bend your thumb at a 90-degree angle. That bend is where the IP joint is located.

Your thumb’s IP joint is essential to many hand and finger movements, such as grasping, holding, and pinching. Pain and swelling in this small joint can greatly affect your quality of life. Constant pain, reduced movement, and stiffness can affect your daily routines, from holding a cup of coffee to opening a door. 

Knowing the possible causes of pain can help you find the right treatment and the relief you need.

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What is the IP joint?

The term “IP joint” stands for interphalangeal joint, or the joints that connect the bones (phalanges) of each of your fingers. Each finger has two IP joints, except the thumb, which has only one IP joint. The thumb IP joint is located just below the thumbnail.

IP joints are important because they let you flex your fingers toward the palms of your hands. In other words, they’re one of the key structures that allow you to close your hands, fold your fingers, grasp, and pinch. 

IP joints go through more wear and tear than other joints in the fingers and thumbs. With time, this can lead to pain as the joint wears down. 

When you have thumb pain, it can be due to several causes, such as:

• arthritis
• trigger thumb
• tendonitis
• carpal tunnel

It is the first cause that’s more likely to cause pain in the IP joint of the thumb.

Causes of thumb joint pain

The main cause of pain in the IP joint of the thumb is arthritis, an umbrella term that refers to more than 100 conditions that affect the joints of the body, including those of your thumb.

Thumb arthritis is the second most common type of hand arthritis. There are different types of arthritis that can particularly affect the thumb joint.

Osteoarthritis

Osteoarthritis (OA) is a chronic joint condition. Besides being the most common joint condition, OA particularly affects the joints of the hands, including the IP thumb joint. 

OA is also known as degenerative arthritis. This is because it usually happens when the cushions between the joints wear down with use and age.

Because the joints in the hands are used so often, OA can commonly affect them. It becomes more common with age, and more than 60% of people over age 60 are estimated to have OA of the IP joints in the fingers and thumbs.

About 33 million adults in the United States have OA. Its symptoms include:

• pain and aches in the thumb joint
• stiffness of the thumb
• swelling
• reduced range of motion or flexibility of your thumb

While OA can affect the IP joint, it usually occurs at the base joint of the thumb. This is where your thumb joins your hand, also known as the carpometacarpal (CMC) joint.

Compared with the CMC joint, OA of the IP joint of the thumb is slightly less common.

Psoriatic arthritis

Psoriatic arthritis (PsA) is an autoimmune condition that causes inflammation of the joints, alongside a scaly and itchy rash. PsA can affect the hand and the fingers, causing pain.

This pain stems from the inflammation that stretches the joint tissues. The ends of the joint are worn out, and the joint may become loose or crooked. 

In the United States, about 8 million people have psoriasis, and 30% of them develop PsA as well. 

People with PsA of the fingers tend to experience pain and inflammation in the middle joint of the fingers. In the case of the thumb, the IP joint is the one affected.

Some of the symptoms of PsA of the fingers include:

• pain
• swelling
• inflammation
• redness
• decreased range of motion
• difficulty bending your finger or thumb
• scaly skin patches on top of the affected finger joint 
• pitting of the nails

Rheumatoid arthritis

Rheumatoid arthritis (RA) is another chronic autoimmune condition that causes swelling and pain in the joints. This happens because the immune system attacks healthy cells in the joint lining. In the United States, 1.5 million people have RA.

RA tends to affect smaller joints, starting in the fingers and toes. One characteristic of rheumatoid arthritis is that it’s symmetrical. This means that it affects both sides of your body.

In the case of the IP joint of the thumb, both thumbs would be affected if you have RA.

Symptoms of RA of the fingers include:

• pain and tenderness of the joint
• swelling
• stiffness and morning stiffness
• reduced range of motion
• difficulty bending and straightening the thumb and fingers

RA can lead to fever, fatigue, and weight loss. It can also affect your wrists, heart, and lungs. 

Treatments for IP joint pain

Treatment for pain in the IP joint of the thumb will depend on what’s causing it.

If a healthcare professional determines that one of the forms of arthritis mentioned above is causing your thumb joint pain, they’ll prescribe medications for these conditions and recommend lifestyle measures that can help reduce pain and promote overall health. 

For osteoarthritis, medical treatments include:

• pain relievers like acetaminophen (Tylenol)
• glucocorticoid injections like triamcinolone acetonide (Zilretta) and hydrocortisone (Cortef)
• nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (Advil) or naproxen (Aleve)
• topical NSAIDs like diclofenac (Voltaren)
• topical aspirin (Aspercream)
• surgery

For PsA, medical treatments include:

• disease-modifying anti-rheumatic drugs (DMARDs) like leflunomide (Arava), methotrexate (Trexall), and sulfasalazine (Azulfidine)
• biologics like adalimumab (Humira), apremilast (Otezla), certolizumab (Cimzia), etanercept (Enbrel), risankizumab (Skyrizi)
• NSAIDs
• surgery

For RA, medical treatments include: 

• biological therapy like adalimumab (Humira), etanercept (Enbrel), and infliximab (Remicade)
• DMARDs, such as hydroxychloroquine (Plaquenil), leflunomide (Arava), methotrexate (Trexall), and sulfasalazine (Sulfazine)
• NSAIDs
• Janus-kinase (JAK) inhibitors, such as baricitinib (Olumiant), tofacitinib (Xeljanz), and upadacitinib (Rinvoq)
• corticosteroids like prednisolone (Orapred)
• surgery
• occupational therapy
• physical therapy

Some lifestyle measures that can help ease the symptoms of these types of arthritis include:

• doing hand exercises to strengthen finger muscles and lessen the demand on the joint
• wearing hand braces to reduce strain on the joints
• undergoing heat and cold therapy
• eating anti-inflammatory supplements, such as curcumin and omega-3s
• eating a balanced diet
• reducing stress, which can trigger arthritis flares

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Summary

The small IP joint of our thumbs plays a big role in our daily lives, allowing us to grasp, hold, pinch, and perform other essential hand movements. When pain and swelling affect this joint, our quality of life and day-to-day functioning are affected.

Several conditions can lead to pain in the IP joint of the thumb. But the most common reason is arthritis, an umbrella term used to refer to swelling and inflammation of the joints. Three types of arthritis tend to cause pain in the IP joint of the thumb: OA, PsA, and RA.

If you’re feeling pain and inflammation in the IP joint of your thumb, talk with a healthcare professional. They will be able to determine what’s causing it and the best course of treatment.

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