What is the characteristic posture of a boutoniere deformity?

The characteristic posture of a boutonniere deformity is marked by flexion at the proximal interphalangeal (PIP) joint and hyperextension at the distal interphalangeal (DIP) joint. The mechanism behind this deformity lies in the disruption of the central slip of the extensor tendon over the PIP joint, which leads to the inability to extend the PIP while allowing the DIP to extend due to the retained tension from the surrounding structures.

This positioning is essential for recognizing and understanding the implications of the boutonniere deformity in clinical settings, particularly for planning effective interventions and management strategies in orthotic and prosthetic practices. Identifying this specific deformity helps practitioners to differentiate it from other types of finger joint deformities, which can exhibit different joint positions involving the PIP and DIP joints.