Answer :
Final answer:
A flexion deformity at the proximal interphalangeal joint is known as a boutonniere deformity, characterized by flexion at the PIP and hyperextension at the DIP joints. Thus option (b) Boutonniere deformity is the correct option.
Explanation:
A flexion deformity located at the proximal interphalangeal joint is known as boutonniere deformity. This condition involves a fixed flexion of the proximal interphalangeal joint with hyperextension of the distal interphalangeal joint, resembling the way a flower or button fits through a buttonhole, which is how it gets its name. Other options like swan neck deformity, trigger finger, and Dupuytren's contracture represent different kinds of finger deformities or conditions.
