The pseudo-boutonniere deformity.

The pseudo-boutonniere deformity is a boutonneire-like deformity resulting from a hyperextension injury to the proximal interphalangeal joint causing tearing of the volar soft tissues. It is seen almost exclusively in the little and ring fingers. The features, pathomechanics and prophylaxis of the condition are described. The treatment is by dynamic splintage and the importance of distinguishing the deformity from the true boutonniere deformity is emphasised.