Boutonniere Deformity

Overview

Deformity of a finger resulting in it being contracted in a position of:
- Flexion at the PIP joint
- Hyperextension at the DIP joint
Often occurs when a finger receives a traumatic force to the PIP joint while it is in a flexed position
The injury causes the central slip of the extensor tendon to be damaged, causing the deformity

Common Causes

Finger "jam" where the top of the PIP joint gets struck while the joint is in a flexed position
Laceration/cut
Full-thickness burn
Rheumatoid arthritis

These all will involve the central slip of the extensor tendon being injured

What Happens at the Extensor Tendon

The extensor mechanism includes:
- Central slip: Runs over the top of the finger and inserts on the middle phalanx
- Lateral bands: Run along each side of the finger and insert on the distal phalanx
In a boutonniere deformity, the central slip is injured
Due to this part of the tendon being injured, the PIP joint collapses into flexion because it loses its support
The lateral bands are still intact and slip downward (volarly) due to the change in balance with the central slip being affected
This change in balance causes the lateral bands to pull the DIP into hyperextension

Image adapted from Cleveland Clinic. “Boutonnière Deformity.” Retrieved from https://my.clevelandclinic.org/health/diseases/22094-boutonniere-deformity

Treatment

Serial orthotic fabrication is often performed where the affected PIP joint is put in a neutral position where it cannot move, allowing the tendon to heal
- Orthosis is usually worn at all times for 3-6 weeks
- Then worn just at night for a few more weeks
- The DIP is free in the orthosis
Active range of motion exercises of the DIP joint to prevent finger stiffness and realign the lateral bands
A full recovery is usually seen in most cases
Surgery may be required in instances where a part of the bone rips off during the injury or if the deformity does not improve with an orthosis

Quiz Questions

Which joint positions characterize a Boutonniere deformity?

A. Flexion at the DIP, hyperextension at the PIP

B. Flexion at both the PIP and DIP

C. Flexion at the PIP, hyperextension at the DIP

D. Extension at both the PIP and DIP

Which structure is primarily injured in a Boutonniere deformity?

A. Central slip of the extensor tendon

B. Volar plate

C. Flexor digitorum profundus

D. Lateral collateral ligament

What happens to the lateral bands in a Boutonniere deformity?

A. They rupture completely

B. They move dorsally and stabilize the DIP

C. They stay in place and maintain DIP flexion

D. They slip volarly, contributing to DIP hyperextension

Which of the following is a common cause of Boutonniere deformity?

A. Repetitive typing

B. Finger jam or trauma to a flexed PIP joint

C. Forceful extension of the PIP joint

D. Distal phalanx fracture

What is the primary goal of orthotic intervention for Boutonniere deformity?

A. Prevent DIP hyperextension

B. Immobilize the DIP joint for healing

C. Hold the PIP joint in neutral to allow the tendon to heal

D. Strengthen the flexor tendon

Quiz Answers

References

Binstead, J. T., Tafti, D., & Hatcher, J. D. (2025). Boutonniere deformity. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK470323/

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