The knuckle joints sit at the base of your fingers. They are the knuckles you see when you make a fist. Pain, swelling or stiffness here has several possible causes. Osteoarthritis is common in the joints near the fingertips. It affects the knuckles much less often. So your doctor will not assume it, and will look for the cause. This guide explains the causes, the tests, treatment without surgery, and when surgery may help.
This guide covers the knuckles of the index to little fingers. Arthritis at the base of the thumb has its own guide. Heberden and Bouchard nodes in the finger joints are covered in Finger osteoarthritis: Heberden and Bouchard nodes.

Where is the joint, and what does it do?

Doctors call the knuckle the . It links a hand bone to the first bone of the finger. It bends and straightens the finger at its base and lets you spread your fingers. Ligaments on each side keep it stable. The tendon that straightens the finger runs over the top. Pain and stiffness here can greatly reduce the use of the finger and the whole hand1.
Clicking or locking near the base of a finger is usually not a joint problem but trigger finger.

Why does the knuckle joint become painful?

Osteoarthritis — less common here than in other finger joints

In a large study in Rotterdam, X-rays showed osteoarthritis in the knuckles of about 8 in 100 people aged 55 or over. The joints nearest the fingertips were affected in about 47 in 100. When the knuckles were affected, other joints in the hand were too, in 86 in 100 cases2. In a scan study of people aged 63, 10 in 100 had at the index knuckle. At the joint nearest the fingertip, 70 in 100 had them3.
In people already treated for hand osteoarthritis, knuckle changes show up on X-ray more often. In one clinic group, about 1 in 3 had them, mostly at the knuckle (MCP) joints of the thumb and index finger. The changes were usually mild. They were more common in the dominant hand and in people doing manual work. They were not linked to how bad the symptoms were4.
Knuckle arthritis at a fairly young age, without an injury, is unusual for osteoarthritis5. That is one reason your doctor looks for other causes.

Inflammatory arthritis

can damage the knuckle joints. It can bend the fingers out of shape and cause pain and loss of hand use6. In advanced disease the joints can partly dislocate, and the fingers drift towards the little finger7. To make the diagnosis, doctors look at how many joints are swollen and where. They also look at blood tests and how long symptoms have lasted. Early diagnosis matters, because early treatment aims to stop lasting joint damage8.
Your doctor will also think about psoriatic arthritis. Clues include psoriasis — now, in the past or in your family — nail changes, and a whole finger that swells like a sausage9.

Crystals in the joint

In , crystals collect in a joint. They can cause a sudden, painful swollen joint, or long-term pain and stiffness. This is more likely with older age, worn joints, an overactive parathyroid gland, haemochromatosis and low magnesium10. Finding crystals in fluid drawn from the joint confirms the diagnosis; doctors also consider symptoms and scans1011.
Urate crystals (monosodium urate) cause gout. Gout usually affects one joint in the foot, often at the base of the big toe. Finding crystals confirms gout, and typical changes on scans can also help11. A high uric acid level in the blood is not enough on its own12.

Haemochromatosis

is an inherited condition. The body stores too much iron13. It usually affects the knuckles of the index and middle fingers. It limits their movement, and X-rays show a narrow joint space and bony spurs14. Hook-shaped spurs can form on the heads of the hand bones15.
Joint symptoms often start many years before haemochromatosis is diagnosed — on average about 8 to 9 years in studies516. In one group, the knuckles were most often the first joints affected. The authors advise tests for haemochromatosis if knuckle or ankle arthritis has no clear cause and no injury came first5.
Finding it early and removing iron by regular blood draws can prevent liver scarring (cirrhosis) and other problems17. But joint changes that have already formed often do not get better. New joints can be affected even while treatment goes on13.

A past injury

A break in the head of a hand bone — the part that forms the knuckle joint — is uncommon. It makes up about 4 in 100 metacarpal (palm-bone) fractures. If the pieces have moved, they usually need to be put back in place and fixed, most often with surgery18. Arthritis after an injury is one reason people have a knuckle joint replaced1920.

How is it assessed?

Your doctor will ask when and how the symptoms started and about any injury. They will ask how many joints hurt or swell, and how long stiffness lasts in the morning. They will also ask about psoriasis and about arthritis in your family. Then they will look at and examine both hands.
An X-ray is the first scan. Scans help tell worn joints apart from other joint problems21. But the X-ray does not show well how much the joint will hurt2. Ultrasound may pick up bony spurs more readily than an X-ray3 and can help to look for calcium pyrophosphate deposits10.
Depending on what your doctor suspects, they may arrange:

When to seek help urgently

Go to an emergency department straight away if you have:
  • a joint that has suddenly become red, hot, swollen and very painful, more so if you also have a fever — an infected joint needs to be drained and treated quickly, and having no fever does not rule out infection23;
  • a cut over a knuckle from punching someone in the mouth, even a small one — these are among the worst bite wounds of the hand24.
See your doctor soon, though not as an emergency, if even one joint stays swollen, especially with morning stiffness or psoriasis. Early referral to a rheumatologist matters when joints are inflamed22. Pain, swelling or a bent finger after an injury also needs checking. A break into the joint may need to be set18.

Treatment without surgery

Treatment depends on the cause. In rheumatoid and psoriatic arthritis, a rheumatologist leads treatment. This often includes medicines that calm the disease25. Haemochromatosis is treated by removing excess iron17.
For osteoarthritis, there is little research on treating the knuckle joints alone without surgery. The advice comes from guidelines for hand osteoarthritis as a whole262728:
  • learning about the condition, exercises, gadgets that make daily tasks easier, and splints26;
  • warmth28;
  • anti-inflammatory () gels first, and NSAID tablets only for a limited time26.
Choose medicines with your doctor or pharmacist. Tell them about your other health problems and medicines.
A hand therapist can help you choose exercises, a splint and ways of doing daily tasks that put less strain on your joints2625.
Gels work about as well as tablets and cause fewer side effects29. The effect of medicines is modest, though. Many trials were pooled in one review. When finger osteoarthritis was analysed separately in that review, no medicine was shown to work better than placebo30.
A into the joint is one option for arthritis of the index knuckle25. But European and French guidelines give their injection advice for the finger joints beyond the knuckle2628. There is little research on injections into worn knuckle joints.

When is surgery considered?

Surgery may be an option when pain, stiffness, a loose joint or bent fingers still get in the way of daily life despite treatment. A review published in 2018 found no study comparing surgery with going on without it in hand osteoarthritis29. Most of what is known about results comes from following groups of people after surgery. For the knuckles of the fingers, the usual operation is joint replacement, which is done more often than fusion31. Fusion is kept for selected, unusual situations3132.

Joint replacement

In a , the damaged joint surfaces are replaced with an implant. Surgeons use either a one-piece silicone implant or a two-part implant that replaces both joint surfaces25. The silicone implant is the benchmark that newer designs are compared with1. The results of single series cannot be read as a direct comparison of implants33. A 2026 review found similar results for both types. But most studies had no comparison group, so the authors advised caution34.

Results in osteoarthritis and after injury

  • Silicone implant. In 35 people followed for more than 8 years on average, pain at the end was minimal. One person needed a revision operation (a further operation on the implant). X-rays showed 5 of 40 implants had broken, without causing symptoms35.
  • Two-part pyrocarbon implant. In one series, the estimated chance of an implant lasting 10 years without a revision operation was 88%. All revision operations happened within 18 months36. In another, of 44 joints followed for 6 years on average, 8 needed another operation, including 5 revision operations on the implant37. A review found 9 of 87 such implants failed over 5.5 years on average, and the satisfaction rate was 91%33.
In these series, pain after surgery usually fell clearly and movement improved moderately — in one of them from 44 to 58 degrees1937.

Results in rheumatoid arthritis

In one study, people whose knuckles had badly slipped or drifted chose what to do. Some had silicone joint replacements; others carried on without surgery. After 3 years, those who had surgery had better hand function, rated the look of their hand higher and were more satisfied. Finger alignment improved, but grip strength did not7. The benefits lasted at 7 years, and hand function in the people without surgery stayed stable6.
One study compared osteoarthritis with rheumatoid arthritis. The estimated chance of a silicone implant lasting 10 years without a revision operation was 94% and 91%. The fingers drifted sideways again much more often in rheumatoid arthritis38. With two-part implants in rheumatoid arthritis, the implant sank or bone was lost around it more often19.
Little is known about the results of knuckle replacement in people with haemochromatosis.

Risks

Possible problems include tendon or ligament damage, a loose joint, a bone breaking during surgery, and the implant coming loose37. A silicone implant can break, often without symptoms357. Infection and fingers drifting again have also led to revision operations38. A large study of insurance claims covered knuckle and middle finger joint replacements. Some complication within 2 years was recorded in 35 in 100 people20.

Recovery

The result depends a great deal on careful surgery and on intensive rehab, planned for you1. After surgery you will wear a splint and do exercises with a hand therapist. One study, without random allocation, looked at people operated on after an injury. A splint that limited sideways finger movement for 8 weeks was linked with fewer broken silicone implants, with no difference in movement39. The type of splint and how long you wear it depend on the implant and your tissues, so your surgical team will decide. General advice on aftercare is in recovering after hand surgery.

Joint fusion — only in selected cases

means the bones of the joint are made to heal together permanently. Stiffness at the knuckle can greatly reduce the use of the finger and the whole hand1, so keeping its movement matters. That is why fusing a finger knuckle is not a routine alternative to joint replacement. It is considered only in selected cases. Examples are some people who put very high demands on the hand, or a joint broken beyond repair31. Another is a failed replacement where the joint stays loose or painful3240. The aim is to reduce pain, at the cost of losing that joint's movement for good. The bones may not heal together, and another operation may be needed3132. Whether fusion is right in such a case is something to discuss with your surgeon.

Summary

Pain and swelling in the knuckles can have several causes. Osteoarthritis is less common here than in other finger joints. Inflamed joints, crystals, haemochromatosis and past injury also need to be thought about. A sudden hot, swollen joint needs urgent care. Treatment starts with finding the cause. For osteoarthritis, treatment without surgery mainly follows advice for hand osteoarthritis. Joint replacement aims to ease pain and can improve finger alignment, but some people need further surgery. Fusion is kept for selected cases. It aims to reduce pain, but that joint loses its movement for good. You and your hand surgeon decide together, after talking through the benefits, the risks and the time needed for rehab.