Boutonniere - observation

Historical Overview

• Boutonniere deformity is derived from the French word “boutonniere,” meaning button hole.  When this occurs in a finger the head of one of the proximal phalanx pops through the opening in the extensor hood, as though bone is popping through a button hole.

Description

• Boutonniere deformity is an extensor tendon injury characterized by proximal interphalangeal joint (PIP) flexion and distal interphalangeal (DIP) joint extension.  As the disease progresses, the deformity becomes a permanent fixed PIP flexion contracture. 

Pathophysiology

• Boutonniere deformity arises from articular erosions and soft-tissue laxity.
• Boutonniere deformity also arises from injuries to the extensor tendon hood at the PIP.
• The injury often is a traumatic rupture or laceration of the extensor hood.

Instructions

1. Ask the patient to extend his/her affected finger and observe the lack of PIP joint  extension.
2. Extend the finger passively to evaluate whether there is an extension lag or fixed contracture.
3. Observe patient’s range of motion, i.e. extension and flexion of PIP joint and DIP joint.

Variations

• The boutonniere can be a PIP joint extension lag where the joint can be passively extended by the examiner or a fixed contracture of the joint that can not be actively or passively extended.

Related Signs and Tests

• Extensor tendon exam
• Intrinsic muscle testing