Boutonnière Deformity

What is boutonnière deformity?

Boutonnière deformity is a condition that affects your ability to straighten the middle joint of a finger or — less commonly — a toe. Your joint is stuck in a bent position and won’t straighten. At the same time, the joint toward the tip of your finger or toe (extremity) is flexed upward.

If you’ve injured a tendon in your hand called the central slip extensor, you might develop a boutonnière deformity. Tendons are tissues made up of bundled fibers that connect muscle to bone so you can move. The central slip extensor goes to the middle joint of your finger or toe. In boutonnière deformity, an injury tears the tendon and a slit appears. If this situation isn’t corrected, the middle of your finger will remain bent and the tip of your finger will stick out.

It’s called a boutonnière deformity because the slit in the tendon looks like a buttonhole with the bone showing. Boutonnière means buttonhole in French.

Who does boutonnière deformity affect?

Boutonnière deformity can happen to anyone. You can even be born with it. However, it’s more likely to happen if you play sports where you can jam your finger or if you have arthritis. It also can be caused by a cut to the top of the second knuckle of your finger from the tip, the proximal interphalangeal (PIP) joint. If your tendon is severed from your bone, you won’t be able to straighten your PIP joint.

What are the signs and symptoms of boutonnière deformity?

The symptoms and signs of boutonnière deformity are visible.

• You have swelling and pain at the middle joint of the finger or toe. If your thumb is affected, it will be bent at the first joint.
• You can’t straighten out your finger or toe.
• The tip of your finger or toe is flexed up.
• Your joints are stiff, which gets worse over time.

What causes boutonnière deformity?

Boutonnière deformity happens as a result of an injury or cut to the tendon. This can happen because of:

• Arthritis.
• Hand injury that causes a deep cut, finger dislocation or fracture.
• A birth defect.

How is boutonnière deformity diagnosed?

Your healthcare provider will take a complete medical history and do a thorough examination of the affected joint. Your provider will perform an Elson’s test to evaluate your hand injury and see if the central slip is still intact.

Your provider will ask you to curl your fingers around a table edge. Then your provider will press on your middle phalanx (the bone that's between your knuckle and the joint before the tip of your finger) of the affected finger. Your provider will ask you to extend your finger. If they can feel your finger attempting to straighten out, they’ll know that the central slip isn't torn or cut. If you’re not able to extend the finger, they’ll know the central slip isn’t working.

You might need an X-ray if your provider thinks you might have a broken bone.

How is boutonnière deformity treated?

Whatever happens, early treatment is important. Your provider will likely begin with nonsurgical options, unless your torn central slip is exposed. An open wound will probably require surgery.

Nonsurgical treatment is a splint that keeps your PIP joint straight, but allows your other joints to move. You’ll have to wear the splint continuously for four to six weeks. Your provider might also suggest exercises.

If you have rheumatoid arthritis, some of your medications are designed to stop your disease from getting worse (disease-modifying anti-rheumatic drugs) and damaging tissue (biologic response modifiers). Other medications are to stop pain and inflammation (non-steroidal anti-inflammatory medications and glucocorticoids). If your joint doesn’t heal, you might need joint replacement surgery.

What complications are related to boutonnière deformity?

There are complications from boutonnière deformity that may happen with or without treatment. These include:

• Long-term swelling and stiffness.
• Arthritis after the injury.
• Impaired joint movement.
• Greater chance of damaging the joint again.

How can I prevent boutonnière deformity?

There’s really no way to prevent boutonnière deformity. However, if you have arthritis, you can make sure you take your medication as directed.

What is the outlook (prognosis) for someone with boutonnière deformity?

Your prognosis is best if boutonnière deformity is treated early. The outlook is worse if you’re older or if the damage has gone untreated for a long time.

When should I see my healthcare provider about boutonnière deformity?

If you have any injury to a joint, especially if you have an injury that amounts to a blow coming down on a flexed finger, see your healthcare provider as soon as possible. This is true also if you are cut or burned. If you can’t move a joint, especially one that is injured or has been damaged by arthritis, see your provider — the sooner the better.

What is the difference between boutonnière deformity and swan neck deformity?

Swan neck deformity and boutonnière deformity are similar in some ways. They can both happen at birth, or as a result of injury or arthritis. However, different joints are involved in these conditions. In swan neck deformity, the PIP joint is hyperextended and the distal interphalangeal (DIP) joint is bent. In boutonnière deformity, the PIP joint can’t be straightened.

What is the difference between boutonnière deformity and pseudo boutonnière deformity?

Pseudo boutonnière deformity and boutonnière deformity may look similar, but they aren’t quite the same. The PIP joint is affected in both conditions. However, with pseudo boutonnière deformity, the injury is to the volar plate, or the ligament underneath the joint. The DIP joint will move if you move it.

A note from Cleveland Clinic

See your healthcare provider if you injure a finger or toe joint, if you have swelling that won’t go down or if you find it difficult to move the joint normally. If you’ve torn your central slip and you develop boutonnière deformity, it’s important to start treatment as early as possible to avoid permanent damage. This is also true if you have arthritis and you notice your joint isn’t responding normally.