Health Questions and Answers

Question: What mechanisms underlie the classic boutonnière deformity?

Answer:

Flexion contracture at the PIP with extension of the DIP is referred to as the boutonnière deformity. The pathogenesis of this deformity is thought to be related to injury of the extensor tendon. If it becomes lengthened or torn, the flexor tendons are unopposed. The altered mechanics and location of the joint lead to functional shortening of the lateral tendons and hyperextension of the DIP joint.

Reference:  Resnick D (ed): Diagnosis of Bone and Joint Disorders, 4th ed. Philadelphia, W.B. Saunders, 2002

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