Merck Manual

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Boutonnière Deformity

(Buttonhole Deformity)


David R. Steinberg

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

Reviewed/Revised Apr 2022 | Modified Sep 2022
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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 Osteoarthritis (OA) Osteoarthritis is a chronic arthropathy characterized by disruption and potential loss of joint cartilage along with other joint changes, including bone hypertrophy (osteophyte formation). Symptoms... read more Osteoarthritis (OA) , or rheumatoid arthritis Rheumatoid Arthritis (RA) Rheumatoid arthritis is a chronic systemic autoimmune disease that primarily involves the joints. Rheumatoid arthritis causes damage mediated by cytokines, chemokines, and metalloproteases.... read more Rheumatoid Arthritis (RA) . 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.

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.

Boutonnière and Swan-Neck Deformity

Boutonnière and swan-neck deformities
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NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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