Merck Manual

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Boutonnière Deformity

(Buttonhole Deformity)


David R. Steinberg

, MD, Perelman School of Medicine at the University of Pennsylvania

Last full review/revision May 2020| Content last modified May 2020
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A boutonnière deformity consists of flexion of the proximal interphalangeal (PIP) joint accompanied by hyperextension of the distal interphalangeal (DIP) joint.

Boutonnière deformity can result from tendon laceration, dislocation, fracture, osteoarthritis, or rheumatoid arthritis. Classically, the deformity is caused by disruption of the central slip attachment of the extensor tendon to the base of the middle phalanx, allowing the proximal phalanx to protrude (“buttonhole”) between the lateral bands of the extensor tendon.

Boutonnière and Swan-Neck Deformity

Boutonnière and Swan-Neck Deformity

Initial treatment of boutonnière deformity consists of splinting, but it must occur before scarring and fixed deformities develop. Surgical reconstruction often cannot restore normal motion but may decrease the deformity and improve hand function.

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