[Boutonniere deformity].

This paper was presented at the 1986 Congress of the GEM, as a teaching conference on treatment of the boutonniere deformity, based on the experience of the Nancy Hand Unit. The results of early treatment namely prevention of deformities and stiffness, are in most cases satisfactory, in contrast with late surgical correction which necessitates extensive exposure and tenolysis, and complicated repairs. Conservative rehabilitation and dynamic splinting should always precede, prepare and facilitate late operations, and sometimes avoids any surgery.