What is 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.