boutonniere deformity

A finger with a boutonniere deformity is flexed at the middle joint and won't straighten by itself. This tendon injury is caused by a head-on hit to the outstretched finger.

by James Hubbard, M.D., M.P.H.

Your hand slips and a fingertip bangs head-on against a board. Your finger’s middle joint bows up like a ready-to-pounce cat’s back. You straighten it with your other hand, but it springs right back into pouncing mode.

You are now the probably-not-so-proud owner of a boutonniere deformity. The only chance it has ever to fully function again is to get proper treatment with a specific type of splinting.

Boutonniere is French for “buttonhole.” If you can’t remember boutonniere, I Googled “buttonhole injury” and came up with links about boutonniere deformity. Just remember to type “injury” after buttonhole. Otherwise, you come up with a lot of links for … buttonholes. So why would anyone name an injury that makes a finger look like an A-frame ski chalet a “boutonniere deformity”?

I guess whoever named it thought it sounded sophisticated at the time. Apparently they didn’t worry that nobody could spell it. What happens is one of the joint’s bones pokes through a tear in the tendon, so in surgery, it apparently looks like a bone poking through a buttonhole. Got it?

You get a boutonniere deformity by hitting the tip of your outstretched finger on something head-on or by having something hit your fingertip. This injures the tendon that extends, or straightens, that middle joint.

The joint is bent, and you can’t straighten it without using your other hand. Unless the end joint has been injured too, that one will be straight—even hyperextended. Your finger will look something like this:  -^-.

Actually, the deformity isn’t funny to those who develop it. It makes gripping more difficult, you’re always hitting the poking-out part, and I bet it’s the devil trying to get on a pair of gloves. Not to mention buttoning buttons :). I couldn’t resist.

Treatment for a Boutonniere Deformity

Try to get to a doctor, at least within three weeks, to make sure you’re treating it correctly because after three weeks, the injured tendon and joint tend to harden into permanent flexion if the injury isn’t properly looked after. Sometimes surgery is needed. Even with the best treatment, your finger may never look like or function as well as it did pre-injury.

Until you can get to a doctor, splint it straight out to look like this: — instead of this: -^-. Tape a metal strip or piece of wood over the top of the joint. Don’t splint adjacent joints unless they’ve been injured also.

Splint the boutonniere deformity continuously for six weeks, unless you’re a senior citizen. Older people’s joints stiffen more than younger people’s. I can attest to that. If you’re in your mid-sixties or older, you may want to splint it more like three weeks so you’re more likely to get good movement back. Even if you’re a youngster you’re going to have to work to get the stiffness out after splinting.

Whatever your age, if you change the splint during treatment, keep the finger straight with your other hand or by placing it palm-down on a table.

Other Causes of a Boutonniere Deformity

  • A cut: In addition to blunt trauma, a nick on top of the middle joint that injures the tendon can cause a boutonniere deformity. Until you can get to a doctor, all you can do is treat the cut and splint the finger as outlined above.
  • A dislocated finger: After getting the finger joint back in place, you may have a boutonniere deformity if the tendon has been injured. You need to splint a dislocated finger for six weeks too anyway, but with a boutonniere, you’ll need to splint it straight instead of curved.
  • Rheumatoid arthritis: People with RA can have one or more boutonniere deformities caused by the disease itself. These boutonnieres come on gradually. As such, they should be dealt with as part of the overall RA treatment by a doctor.

If you don’t remember anything else from this post, try to remember the name, “boutonniere deformity,” the buttonhole injury. Buttonhole, not butth—. Never mind.