Boutonniere Deformity: The Bent Finger Injury That’s Easily Missed

After a jammed finger, cut, or crush injury, you may notice your finger developing an unusual posture: the middle joint (PIP joint) is stuck in a bent position while the fingertip (DIP joint) hyperextends backward. This is a boutonniere deformity, and it’s one of the most commonly missed injuries in the hand.

What Causes a Boutonniere Deformity?

The boutonniere deformity results from disruption of the central slip—the portion of the extensor tendon that straightens the PIP (middle) joint of the finger. When the central slip is torn or cut, the lateral bands of the extensor mechanism gradually slide to the sides and below the axis of the PIP joint. This creates a mechanical imbalance: the PIP joint flexes (bends) and the DIP joint hyperextends.

Common causes include:

• Jamming or forceful bending of the finger (sports, falls)

• Lacerations over the back of the PIP joint

• Rheumatoid arthritis (chronic synovitis erodes the central slip)

• Burns or crush injuries to the dorsal finger
  

Why Is It Often Missed?

In the acute phase, the finger may appear swollen and sore but can still be straightened—the boutonniere posture develops gradually over 1–3 weeks as the lateral bands migrate. By the time the deformity becomes obvious, the injury is already weeks old and harder to treat. This is why any injury to the back of the PIP joint should be evaluated by a hand surgeon, even if the finger can initially be straightened.

Treatment

Acute/Early Boutonniere (First 4–6 Weeks)

Splinting the PIP joint in full extension for 6 weeks while allowing the DIP joint to move freely. This holds the central slip in position to heal while the DIP exercises prevent lateral band adhesion. Patient compliance with full-time splinting is critical.

Chronic Boutonniere

If the deformity has become fixed (the PIP joint cannot be passively straightened), surgical treatment may be needed. Options include central slip reconstruction, lateral band repositioning, or tenolysis. Results for chronic boutonniere deformity are less predictable than early treatment—another reason early diagnosis matters.

Frequently Asked Questions

My jammed finger is still swollen and I can’t fully straighten it. Should I worry?

Yes. Any PIP joint injury that results in difficulty straightening the finger should be evaluated to rule out a central slip injury. Early treatment prevents a chronic boutonniere deformity that is much harder to correct.

How long does recovery take?

Splinting for 6 weeks, followed by 2–4 weeks of progressive motion with therapy. Full recovery including strength is typically 3—4 months.

Finger Injury Evaluation in Phoenix

Don’t dismiss a jammed finger that’s not getting better. Early evaluation by a hand surgeon can identify a central slip injury before it becomes a chronic deformity. I see patients from across the Phoenix metro—Scottsdale, Mesa, Chandler, Gilbert, Fountain Hills, and beyond. ☎ Schedule Your Consultation

Call (602) 258-4788 or visit toddrichardsmd.com to book an appointment with Dr. Todd Richards. Most insurance plans accepted. Same-week appointments often available.