This photo shows multiple boutonnière deformities of the fingers and thumbs in this patient with advanced rheumatoid arthritis. Boutonnière deformity is characterized by flexion at the proximal interphalangeal joint and hyperextension at the distal interphalangeal joint.
By permission of the publisher. From Matteson E, Mason T: Atlas of Rheumatology. Edited by G Hunder. Philadelphia, Current Medicine, 2005.